Office of Solid Waste and Emergency Response (5305W) EPA530-R-05-006 September 2005 www.epa.gov/osw 

# Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities

Final

### This page deliberately left blank

# EPA5 30-R-05-006 September 2005



# Human He alth Risk Assessment Protocol for Hazardous Waste Combustion Faci lities

U.S. EPA, OFFI CE OF SOLIDWASTE U.S. ENVIRONMENTAL PROTECTION AGENCY

### This page deliberately left blank

## ii DISCLAIMER This document provides guidance to EPA regional and state RCRA hazardous waste programs, as well as to facilities subject to RCRA requirements and the general public. More specifically, this guidance document conveys how EPA generally intends to exercise its discretion in implementing RCRA statutory and regulatory provisions concerning combustion facilities subject to RCRA. EPA designed this guidance to explain and clarify national policy on i ssues related to EPA’s obligation to ensure that operating permits granted to combustion facilities c ontain conditions necessary to protect human health and the environment. The statutory provisions and EPA regulations discussed in this handbook contain legally binding requirements. This guidance itself does not substitute for those provisions, nor is it a regulation itself. Thus, this guidance does not impose legally binding requirements on EPA, states, or the regulated community, and may not apply to a particular situation based on the specific circumstances of the

combustion facility. EPA and state regulators base their permitting decisions on the statute and regulations as applied to the specific combustion facility and retain their discretion to use approaches on a

case-by-case basis that differ from those recommended in this guidance where appropriate. Therefore, interested parties are free to raise questions and c oncerns about the substance of this guidance document

and the appropriateness of the application of recomme ndations to a particular situation. Because this guidance is not a regulation, EPA and state regulator s will consider such questions and concerns when implementing the recommendations (for example, during the comment period provided on draft combustion permits). Whether the recommendations in this Handbook are appropriate in a given situation will depend on facility-specific circumstances.

## iii ACKNOW

LEDGMEN TS
This document was developed by the U.S. Env

ironmental Protection Agency (E PA) Region 6

and the Office o f Solid Waste. Jeff Yurk from EPA R egion 6 was t he prim ary au thor of this doc

umen t with significant technical supp ort and backg round research being

provided by

Jeff Ayers of PGM P

rofessional Services, Jeff Secrest of The A ir Group, Tetra Tech EM, I nc, under Contract No. 68-W- 99-018, an d Research Triangle I

nstitute, under Contract No. 68-W- 03-042. Karen Pollard and Timothy Taylor of the Office of Solid Waste prov ided authorship, editorial inp ut, and overall co ordination with experts in other EPA Regions,Headquarters, and the Office of Research and

Developm

ent. Special thank

s are extended to the following ind

ividuals for their valuable comm ents and contributions. U.S. EPA REVIEWERS Office of Soli d Waste Economics , Methods, and Risk Analysi s Divi sion 

### David Cozz ie Virginia Colten- Bradley Becky D aiss Stephen Kroner David Lay

land Alec McBride
Permit s and St ate Programs Divis ion



### Sasha Gerhardt Val De L aFuente Sonya Sassev ille Rosemary Workman

M unici pal and I ndustr ialSoli d Waste Divi sion



### Bill Schoenborn
Hazardous Waste Minimi zati on and Management

Divis ion 

### Fred Ch anania Office of Solid Waste and Emergency

Response Office of the Assi stantAdminis trator



### Dorothy Canter Office of Research & Development NationalCenter f

or Environme ntal Assessment/Cincinnati 

### Eletha B rady-Roberts Randy Bruins David Reism

an Glenn Rice Sue Schock Jeff Swartout Office of Research & Development (contd.) NationalCenter f

or Environme ntal Ass es sm ent

/DC 

### David Clev erly Jim Cogliano Matthew Lorber
NationalCenter f

or Environme ntal Asse ss ment /RTP 

### Judy Strickland National Exposure Research Laboratory



### Robert Ambros e Larry Johnson Donna Schwede
Nationa l Health and E nvironmen tal Effects Resea rch Lab orat ory/ RTP 

### John Nichols National Risk Management R esearch Laboratory



### Paul Lemieux Jeffrey Ryan Office of Air Quality Planning and Standard s

Air Quali ty Monitori ng Group 

### Joe Tou ma
Risk an d Exposure Asses sment Group



### Dave Guinnup Deirdre Murphy Office of Gen eral Co uncil Solid Waste and Emergency Response Law Office



### Laurel Celeste Karen Kraus

## iv EPA Region 1 Office of Ecosys tem Prote cti on Divis ion



### Jui-Yu Hsieh EPA Region 2 Divis ion of

Environmen tal Pl anning and Protect ion 

### John Bro gard EPA Region 3 Waste and Chemical s Management Divi sion



### Gary Gross EPA Region 4 Waste Management Divis ion 

### Beth Antley Rick Gillam Ken Mitchell EPA Region 5 Waste, Pes tic ide and Toxic Di visi on 

### Gary Victorine Mario Mangino EPA Region 6 M ulti media Pl anning and Per mitt ing Divi sion



### Cynth ia Kaleri Steve Thompso

n David We eks Superfun d Group 

### Ghassa n Khoury Jon Rauscher Susan Roddy EPA Region 7 Air, RCRA and Toxic s Divi sion 

### Ken Her stowski John Sm ith EPA Region 8 Hazardous Waste Program 

### Bob Benson Carl Da ly Tala Hen ry EPA Region 9 Waste Management Divis ion 

### Stacy Br aye EPA Region 10 Office of Envir onmentalAsses sment



### Rick Poeton Marcia Bailey Roseanne Lorenz ana
Of fice o f W aste a nd C hem icals 

### Catherine Massimino

STATE REVIEWERS
Texas Natural Resource Conserva tion Commission Toxicol ogy and Risk

Asses sment Secti on 

### Larry Cham

pagne Lucy Frasier Roberta Grant Laurie Haws Loren Lund Torin McCoy Robert Opiela Mark Rudolph Dom Rugg eri Andrew Tacho vsky Arkansas Department of Pollution Control

and Ecology Phillip Murphy Tammi Hy

num Colora do Dep artment of Health Hazardous Material s and Waste Management

Divis ion 

### Joe Schie ffelin R. Dav id Waltz
Utah D epartme nt of Environme ntal Qua lity Christopher Bittner Alabama Department of En vironmental Management Air Divi sion 

### John Rogers Nathan Hartman
Divis ion of

Epidemi ology 

### Brian Hughes

## v

In addition, during the public re view period of the guidance docum ent, EPA received a number o f insightful and valuable comm ents from the m

embers of the general public and industry

.

SCIENTIFIC PEER REVIEWERS On May 25 and

26, 2000, an e

xternal peer review w

orkshop was he ld. The peer review and workshop were organize d, convened an d conducted by Tech Law, an EPA contractor under the EPA contract number: 68-W-99- 017. Panel m embers and rev

iewers at this workshop included: Combustion Engineerin g Dr. Will iam S chofield Focus Environm

ental Atmospheric Modeling Dr. Walter Dabberdt National Center of Atm

ospheric Research Human Health Toxicolog y Dr. Thomas A. Gasiewicz University of Rochester
Dr. Mar y Dav is Unive rsity o f West Vir

ginia Human Health Exposu re Dr. James P. B utler Argonne Nation al Labo rator y/Univer sity of Chicago
Dr. R ich ard L . DeGr andc hamp University of Colorado Mr. Stev en Washb urn Environ Corporation Chemical Fate and Tran sport Dr. George F . Fries U.S. Departm

ent of Agriculture (retired )
Dr. Do uglas Smith ENSR I nternational

### CONTENTS

Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## vi CON TENTS

............ ............ ............ ............ ............ ............ vi FIGURE S

............ ............ ............ ............ ............ ............ . xii TABLES

............ ............ ............ ............ ............ ............ . xiii LIS T OF AC RONY

MS

............ ............ ............ ............ ............ . . xv INDEXED LIST OF VAR IABLES

............ ............ ............ ............ ..... xx 1 INTRODUCTION

............ ............ ............ ............ ........... 1-1 1.1 OBJECTIVE AND DOCUMENT ORGANIZATION

............ ............ . 1-1 1.2 BACKGROUND

............ ............ ............ ............ ...... 1-3 1.3 USING THIS DOCUMENT

............ ............ ............ ......... 1-6 1.4 PRI

MARY REF ERE NCE DOCUMENTS

............ ............ ......... 1-13 1.5 RISK NOMENCLATURE

............ ............ ............ ......... 1-17 2 CHARACTERIZING FACI LITY EMISSIONS

............ ............ ............ . 2-1 2.1 COMPILING BASIC FACILITY INFORMATION

............ ............ ... 2-1 2.2 IDENTI

FYING EMISSI ON SOURCE S & ESTIMA TING EMI SSION RATES

..... 2-2 2.2.1 Estimating S tack Emission Rates for Existing Facilities

............ ..... 2-3 2.2.2 Estimat ing Emissi on Rate s for Fa cilit ies wit h Mult iple St acks

........... 2-13 2.2.3 Estimating S tack Emission Rates for Facilities Not Yet Operational

...... 2-13 2.2.4 Estimating S tack Emission Rates for Facilities Prev iously Operated

...... 2-14 2.2.5 Emiss ions Fr

om Process U

psets

............ ............ ........... 2-15 2.2.6 RCRA Fugitive Emission s ............ ............ ............ ... 2-17 2.2.7 RCRA Fugitive Ash Em issions

............ ............ ........... 2-27 2.2.8 Cement Kiln Dust (CKD) Fugitive Emissions

............ ............ 2-28 2.3 IDENTIFYING COMPOUNDS OF POTENTIAL CONCERN

............ ..... 2-31 2.3.1 Criteria

Polluta nts

............ ............ ............ .......... 2-39 2.3.2 Endocr

ine Disruptors

............ ............ ............ ....... 2-41 2.3.3 Hexachlorobenzene and Pentachlorophenol

............ ............ . . 2-42 2.3.4 Hydrogen Chloride/Chorine Gas

............ ............ .......... 2-43 2.3.5 Metals

............ ............ ............ ............ ....... 2-44 2.3.6 Nitroaromatics

............ ............ ............ ............ 2-57 2.3.7 Particulate Matter

............ ............ ............ .......... 2-58 2.3.8 Phthalates

............ ............ ............ ............ .... 2-59

### CONTENTS (contd.)

Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## vii 2.3.9 Polychlorina

ted Biphenyl s ............ ............ ............ ... 2-61 2.3.10 Polychlorinated Dibe nzo(p)dioxins and D ibenzofurans

............ ..... 2-66 2.3.11 Polynuclear Arom atic Hydrocarbons

............ ............ ....... 2-71 2.3.12 Radionuclides

............ ............ ............ ............ . 2-74 2.3.13 Volatile Organic Com pounds

............ ............ ............ . 2-78 2.4 ESTI

MATI NG C OPCCON CEN TRATIONS FOR NON -D ETEC TS

............ 2-79 2.4.1 Definit

ions of Comm

only R eported Detect ion Lim its

............ ...... 2-79 2.4.2 Using Non-Detect Data I n the Risk Ass essment

............ .......... 2-82 2.4.3 Statistical Distribution Techniques

............ ............ ......... 2-85 2.4.4 Our Re comm

endations on Q

uantify ing N on-D etects

............ ....... 2-85 2.4.5 Estimated Maximum Possible Conc entration (EM PC)

............ ..... 2-86 2.5 EVALUA

TING CONTA MINA TION IN BLANKS

............ ............ . . 2-87 3 AIR DISPERSION AND DEPOSITION MODELING

............ ............ ....... 3-1 3.1 DESCRI

PTION OFAIR MO DELS

............ ............ ............ ... 3-3 3.1.1 Background

on Air Dispersion Mod

els for Risk Asses sment

............ . 3-3 3.1.2 Prep roce ssi ng Pro grams ............ ............ ............ ...... 3-7 3.2 PARTITIONING OF EMISSIONS

............ ............ ............ .... 3-8 3.2.1 Vapor Phase Modeling

............ ............ ............ ....... 3-8 3. 2 .2 Particle Phase Modeling (Mass Weighting)

.......................... 3-8 3. 2 .3 Particle-Bound Modeling (Surface Area Weighting)

.................. 3-12 3.3 SITE-SPECIFIC INFORMATION NEEDED FOR AIR MODELING

........... 3-14 3.3.1 Surrounding Terrain I nformation

............ ............ .......... 3-15 3.3.2 Surrounding Land Use Inform

ation

............ ............ ........ 3-16 3.3.3 Informa

tion on Facility Bu

ilding Characteristics

............ .......... 3-20 3.4 METEOROLOGI CAL DATA PR IMER

............ ............ ........... 3-22 3.4.1 Wind Direction and Wind S peed

............ ............ .......... 3-23 3.4.2 Dry B ulb Tem

perature

............ ............ ............ ...... 3-24 3.4.3 Opaque Cloud Cover ............ ............ ............ ....... 3-25 3.4.4 Cloud Ceiling H eight

............ ............ ............ ....... 3-25 3.4.5 Surface

Pressu re ............ ............ ............ ........... 3-26 3.4.6 Incom

ing Short-wave Radiation\ Leaf Area In

dex

............ ......... 3-26 3.4.7 Precipitation Amou nt and Type

............ ............ ........... 3-26 3.4.8 Upper A

ir Data (Mixing

Heig ht)

............ ............ .......... 3-27 3.4.9 Potential Data Sources

............ ............ ............ ...... 3-27 3.5 METEOROLOGICAL PREPROCESSOR DATA NEEDS

............ ........ 3-31 3.5.1 Monin- Obuk

hov L ength

............ ............ ............ ..... 3-32 3.5.2 Anemom

eter Height

............ ............ ............ ........ 3-33 3.5.3 Surface

Roug hness L ength

at Measu remen t Site

............ .......... 3-33

### CONTENTS (contd.)

Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## viii 3.5.4 Surface

Roug hness L ength

at App lication

Site

............ ........... 3-33 3.5.5 Noon-Tim

e Albedo

............ ............ ............ ......... 3-34 3.5.6 Bowen

Ratio

............ ............ ............ ............ . . 3-35 3.5.7 Anthropogenic H eat Flux

............ ............ ............ .... 3-37 3.5.8 Fraction of Net Radiation Absorbed at the G

round

............ ........ 3-38 3.6 ISCST3 MOD EL INPU T FILES

............ ............ ............ ..... 3-39 3.6.1 COntrol Pathway

............ ............ ............ ........... 3-42 3.6.2 SOurce Pathway

............ ............ ............ ........... 3-47 3.6.3 REceptor Pathway

............ ............ ............ .......... 3-52 3.6.4 MEteorological Pathway

............ ............ ............ .... 3-55 3.6.5 Terrain Grid (TG) Pathway

............ ............ ............ . . 3-56 3.6.6 OUtput Pathway

............ ............ ............ ........... 3-57 3.7 ISCST3 MODEL EXECUTION

............ ............ ............ ..... 3-58 3.8 USING MODEL OUTPUT

............ ............ ............ ......... 3-58 3.8.1 Unit Rate Output v s. COPC- Specific Output

............ ............ . 3-60 3.8.2 ISCST3 Model O utput

............ ............ ............ ...... 3-61 3.8.3 Using Model Outp ut to Estimate Media Concentrations

............ .... 3-62 3.9 MODELING FUGITIVE EMISSI ONS

............ ............ ............ 3-64 3.1 0 MODELING ACUTE RISK

............................................ 3-67 4 EXPOSURE SCENARIO IDENTIFI CATION

............ ............ ............ . 4-1 4.1 CHARACTERIZING THE EXPOSURE SETTING

............ ............ ... 4-3 4.1.1 Current and Reasonable Potential Future Land Use

............ ........ 4-4 4.1.2 Water Bodies and their As sociated Watersheds

............ ............ 4-7 4.1.3 Special Population Chara cteristics

............ ............ ......... 4-10 4.2 RECOMMENDED EXPOSURE SCENARIOS

............ ............ ..... 4-11 4.2.1 Farmer

............ ............ ............ ............ ....... 4-15 4.2.2 Farme

r Child

............ ............ ............ ............ . . 4-18 4.2.3 Resident

............ ............ ............ ............ ..... 4-18 4.2.4 Residen

t Child

............ ............ ............ ............ 4-19 4.2.5 Fisher

............ ............ ............ ............ ....... 4-19 4.2.6 Fisher C

hild

............ ............ ............ ............ . . 4-20 4.2.7 Acute R

eceptor Scenar io

............ ............ ............ .... 4-21 4.3 SELECTING EXPOSURE SCENARIO LOCATIONS

............ ........... 4-21

### CONTENTS (contd.)

Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## ix 5 ESTIMATING MEDIA CONCENTRATIONS

............ ............ ............ . 5-1 5.1 CALCULATING COPC CONCENTRATIONS IN AI R FOR DIRECT INHALATION

............ ............ ............ ............ ........ 5-2 5.2 CALCU LATIN G COPC CONCE NTRA TIONS IN SOIL

............ .......... 5-3 5.2.1 Calculating Cum ulative Soil Concen

tration ( Cs )

............ ........... 5-4 5.2.2 Calcula

ting t he COP C Soil Loss C onstant ( ks )

............ ............ 5-7 5.2.3 Calc ula tin g the D epos iti on T erm ( Ds )

............ ............ ...... 5-19 5.2.4 Site-Specific Param eters for Calculating C

umulative S oil Concentration

... 5-19 5.3 CALCULATING COPC CONCENTRATIONS IN PRODUCE

............ .... 5-22 5.3.1 Abovegroun

d Produce Concentration

Due to Direct Dep osition ( Pd )

...... 5-24 5.3.2 Abov egrou

nd Prod uce Con centrati on Due

to Air- to-P lant Tran sfer (

Pv )

... 5-32 5.3.3 Produce Concentration D ue to Root Uptak

e ( Pr)

............ .......... 5-35 5.4 CALCULATING COPC CONCENTRATIONS IN BEEF AND DAI RY PRO DUC TS

............ ............ ............ ............ ......... 5-37 5.4.1 Forage and Silage Concentrations Due to Direct Deposition ( Pd )

......... 5-39 5.4.2 Forag e and S ilage Concen trations Due to Air- to-P lant Tran sfer (

Pv )

...... 5-42 5.4.3 Forage, Silag e, and Grain Conc entrations Due to Root Uptake ( Pr)

....... 5-43 5.4.4 Beef Co

ncentra tion Re sulting

from Plant a nd Soil Ingestion (

A beef 

### )

....... 5-43 5.4.5 COPC Concentration In Milk Due to Plant and S oil Ingestion ( A milk 

### )

...... 5-49
5.5 CALCULATING COPC CONCENTRATIONS IN PORK

............ ........ 5-53 5.5.1 Fraction of Plant Type i Grown on Con taminated Soil and

Eaten by the Anim al (Swi ne) (Fi)

............ ............ ............ ... 5-54 5.5.2 Quantit

y of P lant Ty

pe i Eat en by the An imal ( Swine)Each D ay (Qpi)

.... 5-55 5.5.3 Concen

tration of COP C in Pl ant Typ e i Eate n by t he Anim al (Swi ne) (Pi)

. 5-56 5.5.4 Quantity of Soil E aten by the An imal (Swine) Eac

h Day (Qs)

........... 5-56 5.5.5 Average So il Concentration Over Exposure Duration (C s)

............ . . 5-57 5.5.6 Soil Bioavailability Factor (Bs)

............ ............ ........... 5-57 5.5.7 Metabolism Factor (MF)

............ ............ ............ ..... 5-57 5.6 CALCULATING COPC CONCENTRATIONS IN CHI CKEN AND EGGS

...... 5-57 5.6.1 Fraction of Plant Type i Grown on Con taminated Soil and

Eaten by the Anim al (Chicken) (Fi)

............ ............ ............ . 5-59 5.6.2 Quantit

y of P lant Ty

pe i Eat en by the An imal ( Chick

en) Each Day

(Qpi)

. . 5-59 5.6.3 Concen

tration of COP C in Pl ant Typ e i Eate n by t he Anim al (Chicken) (Pi) 5-60 5.6.4 Quantity of Soil E aten by the An imal (Chicke

n) Each Day (Qs)

.......... 5-60 5.6.5 Average So il Concentration Over Exposure Duration (C s)

............ . . 5-61 5.6.6 Soil Bioavailability Factor (Bs)

............ ............ ........... 5-61
5.7 CALCULATI

NG COPC C ONCENTRATI ONS IN DRINKI NG WATER AND FI SH

............ ............ ............ ............ .......... 5-61 5.7.1 Tota l COPC Loa d to the Water Body (L T

### )

............ ............ ... 5-64

### CONTENTS (contd.)

Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## x 5.7.2 Universal Soil Los s Equation - USLE

............ ............ ...... 5-69 5.7.3 Sediment Deliv

ery Ratio (SD )

............ ............ ............ 5-70 5.7.4 Total Water Body CO PC Concentration ( C wtot 

### )

............ ........... 5-71 5.7.5 Concentration of COP C in Fish ( C fish 

### )

............ ............ ...... 5-85 5.8 USING SITE-S PECIFIC vs. DEFAULT PARAMETER VALUES

............ . . 5-89 6 QUANTIFYING EXPOSURE

............ ............ ............ ............ . . 6-1 6.1 INHALATION EXPOSURE PATHWAYS

............ ............ ......... 6-2 6.1.1 Soil Inhalation Resulting from Dust Resuspension

............ ......... 6-3 6.2 INGESTION EXPOSURE PATHWAYS

............ ............ ........... 6-4 6.2.1 Body Weight

............ ............ ............ ............ ... 6-5 6.2.2 Food (Inges tion) Exposur e Pathw ays ............ ............ ........ 6-6 6.2.3 Soil (Ing estion) Exposure Pathwa y ............ ............ ......... 6-13 6.2.4 Water (Ingestio n) Expo sure Pa thways

............ ............ ...... 6-14 6.3 DERMAL EXPOSURE PATHWAYS

............ ............ ............ 6-17 6.3.1 Dermal Expo sure to Soil

............ ............ ............ ..... 6-17 6.3.2 Dermal Exposu

re to Water

............ ............ ............ ... 6-18 6.4 EXPOSURE FREQUENCY

............ ............ ............ ........ 6-19 6.5 EXPOSURE DURATION

............ ............ ............ .......... 6-19 6.6 AVERAG

ING TIME

............ ............ ............ ............ . . 6-21
7 CHARACTERIZING RI SK AND HAZARD

............ ............ ............ ... 7-1 7.1 QUANTITATI

VELY ESTIMATI

NG CANCER

RISK

............ ............ 7-3 7.2 QUANTITATIVELY ESTIMATING NONCANCER HAZARD

............ .... 7- 5 7.3 TARGET LEVELS

............ ............ ............ ............ ... 7-10 7.4 ESTIMATING ACUTE EXPOSURE FROM DIRECT INHALATION

.......... 7-10 7.4.1 Existin

g Hie rarchica l Appro aches fo

r Acute Inhalation Exposu

re ........ 7-1 0 7.4.2 Our Recomm

ended Hierarchal Approa ch

............ ............ .... 7-1 2 7.4.3 Charact

erizin g Potential H ealth Ef

fects from Ac

ute Exp osure ........... 7-1 4 8 INTERPRETING UNCERTAINTY FOR HUMAN HEALTH RISK ASSESSMENT

...... 8-1 8.1 UNCERTAI

NTY AND LI

MITATION S OF THE RI SK ASSESSMENT PR OCESS

. 8-1 8.2 TYPE S OFUNC ERTA IN TY

............ ............ ............ ........ 8-2

### CONTENTS (contd.) Chapter Page Human Health Risk Assessment Protocol Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

## xi 8.3 QUALITATIVE ESTIMATES OF UNCERTAINTY . . . . . . . . . . . . . . . . . . . . . . . . . 8-5 8.4 QUANTITATIVE ESTIMATES OF UNCERTAINTY . . . . . . . . . . . . . . . . . . . . . . . . 8-5 8.5 RISK ASSESSMENT UNCERTAINTY DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . 8-7 9 COMPLETING THE RISK ASSESSMENT REPORT AND FOLLOW-ON ACTIVITIES . . 9-1 9.1 CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 9.2 ACTIVITIES FOLLOWING RISK ASSESSMENT COMPLETION . . . . . . . . . . . . . 9-2

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R-1 A PPENDICES A CHEMICAL-SPECIFIC DATA A-1 CHEMICALS OF POTENTIAL INTEREST A-2 CHEMICAL-SPECIFIC PARAMETER VALUES B ESTIMATING MEDIA CONCENTRATION EQUATIONS AND VARIABLE VALUES B-1 SOIL INGESTION EQUATIONS B-2 PRODUCE INGESTION EQUATIONS B-3 ANIMAL PRODUCTS INGESTION EQUATIONS B-4 DRINKING WATER AND FISH INGESTION EQUATIONS B-5 DIRECT INHALATION EQUATION B-6 ACUTE EQUATION C RISK CHARACTERIZATION EQUATIONS

### Human Health Risk Assessment Protocol

Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xii

FIGURES Figure Page 1-1 HUMAN HEAL TH RISK ASS ESSMENT PROCES S

............ ............ ...... 1-10 2-1 EXAMPLE FACILITY PLOT MAP

............ ............ ............ ........ 2-18 2-2 EXAMPLE EMISSIONS INVENTORY

............ ............ ............ ..... 2-19 2-3 COPC IDENTIFICATION

............ ............ ............ ............ .... 2-32 2-4 PHASE ALLOC ATION AND SP ECIAT ION OF M ERCUR Y IN AIR

............ ..... 2-47 3-1 SOU

RCE S OFMETE ORO LOGIC AL D ATA

............ ............ ............ . 3-28 3-2 EXAMPLE IN

PUT FILE FOR “PARTI CLE PHASE”

............ ............ ...... 3-40 4-1 ISCST3 GRID NODES AND LAND USE DESIGNATIONS

............ ............ 4-23 5-1 COPC CONCENTRATION IN AIR FOR DIRECT INHALATION

............ ......... 5-2 5-2 COPC C ONCEN TRAT ION IN SOIL

............ ............ ............ ........ 5-3 5-3 COPC CONCENTRATION IN PRODUCE

............ ............ ............ ... 5-24 5-4 COP C CO

NCE NTRATIO

N I N BEEF A

ND DAIRY P ROD UCTS

............ ........ 5-38
5-5 COPC CONCENTRATION IN PORK

............ ............ ............ ...... 5-53 5-6 COPC CONCENTRATION IN CHICKEN AND EGGS

............ ............ .... 5-58
5-7 COPC LOADING TO THE WATER BODY

............ ............ ............ . 5-63 5-8 COPC CONC ENTRATION IN FI SH

............ ............ ............ ........ 5-86

### Human Health Risk Assessment Protocol

Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xiii

TABLES
Table Page 2-1 EXAMPLE CALCULATION TOTAL FUGITIVE EMISSION RATES FOR EQUIPMENT IN WASTE FEED STORAGE AREA

............ ............ ...... 2-2 2 2-2 EXAMPLE CALCULATION SPECIATED FUGITIVE EMISSIONS FOR EQUIPMEN

T IN WASTE FEED STORAGE A REA

............ ............ ....... 2-2 4 2-3 SOCMI AVERAGE EMISSION FACTORS

............ ............ ............ . . 2-2 5 2-4 QUALITATIVE EFFECTS OF PHYSICAL & CHEMICAL CONDITIONS ON METHYLATION

............ ............ ............ ............ ........... 2-5 4 2-5 TOXICITY EQUIVALENCY FACTORS FOR COPLANAR PCBs

............ ....... 2-6 4 2-6 SLOPE FACTORS FOR PCBs

............ ............ ............ ............ . 2-6 5 2-7 PCDD/PCDF TOXICITY EQUIVALE NCY FACTOR VALUES

............ ......... 2-6 9 2-8 RELATIVE POTENCY FACTORS FOR CLASS B2 CARCINOGEN PAHs

............ 2-70 3-1 HYPOTHETICAL PARTICLE SIZE DI STRIBUTION DATA TO SUPPORT EXAMPLE CALCULATIONS

............ ............ ............ ............ 3-10 3-2 URBAN LAN

D USE TYPES

............ ............ ............ ............ . . 3-17 3-3 SUR

FAC E ROUGH

NES S HE IG

HTS

............ ............ ............ ....... 3-19 3-4 L VALUES FOR VARIOUS LAND USES

............ ............ ............ ... 3-32 3-5 ALBEDO OF NATURAL GROUND COVERS FOR LAND USE TYPES AND SEASONS

............ ............ ............ ............ ............ ..... 3-34 3-6 DAYTIME BOWEN RATIOS BY LAND USE, SEASON, AND PRECIPI TATION CONDITIONS

............ ............ ............ ............ ............ . 3-36 3-7 ANTHRO POGEN IC H EAT FLU

X ( Q f 

### ) AND NET RADIATION ( Q * 

### ) FOR SEVERAL URBAN AREAS

............ ............ ............ .......... 3-38 3-8 ISCST3 INPUT FILE SECTIONS

............ ............ ............ .......... 3-41 3-9 DRY DEPOSITION VELOCITY ESTIMATES AVAILABLE IN LI TERATURE

........ 3-43 3- 10 ISCST3 AIR PARAMETER OUTPUT

.......................................... 3-59

### Human Health Risk Assessment Protocol

Contents September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xiv TABLES (contd.)
4-1 RECOMMENDED EXPOSURE SC ENARIO S FOR A HU MAN HEALTH RI SK ASSESSMENT

............ ............ ............ ............ ............ . 4-13 6-1 MEAN CONSUMPTION RATES FOR RECOMMENDED EXPOSURE SCENARIOS

.... 6-4 6-2 COOKING -RELATED WEIGHT LO SSES FOR VAR IOUS H OME-PRO DUCED FOODS

............ ............ ............ ............ ............ ....... 6-11 6-3 EXPOSURE DU RATION VAL

UES

............ ............ ............ ........ 6-21

### Human Health Risk Assessment Protocol Contents September 2005 LIST OF ACRONYMS

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

## xv : 

### g Microgram : 

### m Micrometer ACGIH American Conference of Governmental Industrial Hygienists ADD Average daily dose AEFA Average emission factor approach AEGL Acute inhalation exposure guidelines AERMOD American Meteorological Society/EPA Regulatory Model Ah Aryl hydrocarbon AHH Aryl hydrocarbon hydroxylase AIEC Acute inhalation exposure criteria AIHA American Industrial Hygiene Association APCD Air pollution control device APCS Air pollution control system ARE Acute reference exposure Acute REL Acute reference exposure level ASTM American Society for Testing and Materials atm Atmosphere ATSDR Agency for Toxic Substances and Disease Registry AWFCO Automatic waste feed cutoff BaP Benzo(a)pyrene BAF Bioaccumulation factor BBS Bulletin board service BCF Bioconcentration factor BEHP Bis(2-ethylhexyl) phthalate BIF Boiler and industrial furnace BPIP Building profile input program check BSAF Sediment bioaccumulation factor Btu British thermal unit BW Body weight CAA Clean Air Act CALPUFF California Puff Model CARB California Air Resources Board CAS Chemical Abstracts Service CFR Code of Federal Regulations CKD Cement kiln dust CLP Contract Laboratory Program cm Centimeters COPC Compound of potential concern CRQL Contract required quantitation limit CSV Unspeciated chromatographical semivolatiles CWA Clean Water Act

### Human Health Risk Assessment Protocol

Contents September 2005
LIST OF ACRONYMS (contd.)

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xvi DEHP Diethy lhexy lphthal ate dL Decaliter DNA Deoxy ribonuc leic aci d DNOP Di(n)octyl ph thalate DOE Depart ment of En ergy DRE Destruction and rem oval efficiency DW Dry weigh t of soil or plant/anim

al tissue EPACA U.S. Environ mental Protection A

gency Corre lation Approach EQL Estimated quantitati on lim it ERPG Emergency response planning guidelines ESP Electrostatic precipitator
FW Fresh weight (or whole/wet weigh t) of plant or anim

al tissue
g Grams GAQM Guideli ne to Air Quali

ty Mod els GC Gas chromatog raphy GEP Good engineering practice GRAV Unspeciated grav imetric comp ounds H3TD Hierarchy of Huma n Healt h Toxicit y Dat a HEAST Health Effects Assessm ent Summ

ary Tables HI Hazard index HQ Hazard quotient IARC International Agency for Research on Cancer IDL Inst rumen t detect ion lim it IEU/BK Inte grated exposu re uptak e/biok inetic IPM Insoluble polystyrene micros pheres IUPAC Inte rnational Union of Pu

re and A pplied C hemistry IRIS Integrated Risk Information Sy stem ISC -PR IME Indu strial S ource C omplex-Pl ume R ise Mode l Enhan

cemen ts ISCSTDFT Indu strial S ource C omplex Short Term Draft IS CST3 Indus tri al So urce Compl ex Sh ort Ter m 3
K Kelvin kg Kilogram
LADD Lifetime average daily dose L Liter lb Pound LCD Local c limato logica l data a nnual summ

ary with com

parative data

m Meters MACT Maximum ac hievabl e contr ol tec hnology

### Human Health Risk Assessment Protocol

Contents September 2005
LIST OF ACRONYMS (contd.)

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xvii MDL Method d etection limit MEHP Monoeth ylhex yl pht halate mg Milligram Mg Megagram MIR Maximum in dividual risk MJ Megajou le mL Milliliter MPRM Meteorol ogica l proces sor for regula

tory m odels MPTER Air qua lity m odel for mult iple poi nt sourc e gaus sian dis

persion algor ithm with terrain adjustm

ents MRL Minimum risk level NCDC National Climatic D ata Center NC DEHNR North Carolina Departm ent of Environm

ent, Health, and N atural Resources NCEA National Center for Env ironmental Assessm

ent NCP National Oil and Hazardous Substances Pollution Contingency Plan NIOSH Nationa l Institute o f Occup ational Safety and He alth NRC Nuclear Regulatory Comm ission NRC COT Natio nal Res earch Counci l Committe e on Tox icolo gy NTP National Toxicology Program NWS National Weather Service OAQPS Office of Air Quality Planning and S tandards OEHHA Office of Environm ental Health Hazard

Assessment ORD Office of Research and Development OSHA U.S. Occupational Safety and Health Administration OSW Office o f Solid Waste OSWER Office of Solid Waste and Emergency Response PAH Polynuclear arom atic hydrocarbon PCB Polychl orina ted bip henyl PCDD Polychlorina ted dibe nzo(p )dioxin PCDF Polychlorinated dibenz ofuran PCRAMMET Personal computer versi on of the meteorological preprocessor f or the old RAM program PDF Probability density function pg Picogram PIC Product of incom plete combustion PM Particulate matter PMD Portable monitoring device PM10 Particulate matter less than 10 microm eters in diameter POHC Principal organic hazardous constituent ppb Parts per billion ppm Parts per million ppmv Part s per milli on by vo lume ppt Parts per trillion

### Human Health Risk Assessment Protocol

Contents September 2005
LIST OF ACRONYMS (contd.)

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xviii PQL Practica l quanti tation l imit PU Polyurethane QA Quality assurance QAP jP Quality assurance pro ject plan QC Quality control RCRA Resource Conservation and Recove ry Act RfC Reference concentration RfD Reference dose RME Reasonable m aximu m exp osure RPF Relative potency factor RTDM Rough terrain diffusio n model RTDMDEP Rough terrain diffusio n model depos ition

s Second SAMSON Solar an d Meteor ologic al Surfa

ce Obse rvational Net

work SCAPA Subcomm ittee on Consequence A ssessment and Protective Actions SCRAM Suppor t Cente r for Re gulatory Air

Models SF Slope factor SLERA Screening leve l ecological risk assessment SOCMI Synthetic Org anic Chemical Manu facturing In

dustries SQL Samp le quan titation limit SRA Screening rang es approach SVOC Semivolatile organic comp ound SW-846 U.S. E nviron menta l Protection Agency Te st Metho ds for E valua ting S olid Was te TCDD Tetrachlorodiben zo(p)d ioxin TDA Toluenediamine TDI Toluene diisocy anate TEELs Temporary e merg ency e

xposure limit s TEF Toxicity equivalent factor TEQ Toxicity equivalent q uotient TG Terrain g rid TIC Tentatively identified com pound TLV Threshold limit valu e TOC Total organic carbon TOE Total organic emiss ions TSD Treatment, storage,and disposal TTN Technolo gy t ransfer network TWA Time-wei ghted ave rage U/BK Uptak e/biok inetic USCA Unit-Specific C orrelation Approach USDA U.S. D epartm ent of A gricul ture

### Human Health Risk Assessment Protocol

Contents September 2005
LIST OF ACRONYMS (contd.)

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xix U.S. EPA U.S. Environ mental Protection A

gency USGS U.S. Geological Survey USLE Universal soil loss eq uation UTM Universal transverse mercator VOC Volatile organic com pound WHO World Health Organization

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xx Variable Units Definition [Sections] / Equations ( unitless 

### Empirical constant used to gen erate Rp 

### 8 z unitless 

### Dimensionless v iscous sublayer thick

ness 5-41B; 5- 42B; B-4-

20; B-4- 21 

### : a g/cm-s 

### Viscosity of air 5-42B; B- 4-21 

### : w g/cm-s 

### Viscosity of water correspo nding to water tempe rature 5-41B; B- 4-20


### D a g/cm 3 or g/m 3 

### Density of air 5-18; 5-41- B; 5- 42B; B-2- 8; B-3- 8; B-4-20; B-4-21 

### D s kg/L 

### Bed sed iment density used to gen erate 2 bs 

### D soil g/cm 3 

### Solids particle density 5-7a; B-1-6; B-2-6; B-3 -6; B -4-6 

### D w g/cm 3 

### Density of water corresponding to water tempe rature 5-41B; B- 4-20 

### 2 unitless 

### Temperature correction factor 5-40; B-4-19 

### 2 bs unitless 

### Bed sed iment porosit y 5-36B; 5- 37; 5- 47; B-4-16; B-4-25 

### 2 sw mL water/ cm 3

soil 

### Soil volumetric water content [5.2. 4.4] ; 5- 4; 5- 5A; 5-7A; 5-7C; 5-32; 5- 33; B- 1- 3; B- 1- 4; B1-5; B-1-6; B-2-3; B-2-4; B-2-5; B-2-6; B-3-3; B-3-4; B-3-5; B-3-6; B-4-3; B-4-4; B-4-5; B-4-6; B-4- 10; B-4- 11 

### 2 v cm 3 /cm 3 

### Soil void fraction 5-7B; 5- 7C 

### a unitless 

### Empirical intercept coe fficient 5-34; B-4-14 

### A beef mg COPC/kg FW

tissue 

### Concentration of COP C in beef [5.4. 4] ; 5- 22; B-3- 10 

### A chicken mg COPC/kg FW

tissue 

### Concentration of COP C in chicken m eat [5.6. 1] ; 5- 26; B-3-

14 

### ADD mg CO PC/kg

BW -day 

### Average daily dose 6-1 

### ADD infant pg COPC/ kg BW inf ant/ day 

### Avera

ge dai ly dos e for infant exp osed to contam inated breast m

ilk C-3-2 

### ADD mat pg COPC/ kg BW mother/ day 

### Avera

ge dai ly dos e (mother) AEF kg/hr -sourc e 

### Applicable averag e emission factor for the equipment ty

pe A egg mg COPC/kg FW

tissue 

### Concen trati on of COPC in eggs [5.6. 1] ; C-1-3 

### Ah m 2 

### Area planted us ed to es ti mat e Yp 

### Ahi m 2 

### Area planted to i th crop see Ah 

### A I m 2 

### Imperv ious watershed area receiv ing COPC deposition 5-31; 5-32; 5-33; 5- 36C; B-4- 9; B-4- 10

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxi A L m 2 

### Total watershed area receivin g COPC d

eposition 5-32; 5-33; 5-34; 5-

36C; 5- 43; B-4- 10; B-4-11; B-4-14; B-4- 22 

### A milk mg COPC/kg FW

tissue 

### Concen tration of COP C in m

ilk [5.4. 5] ; 5- 24; B-3- 11 

### A pork mg COPC/kg FW

tissue 

### Concen tration of COP C in pork [5.5. 1] ; 5- 25; B-3- 12 

### AT days 

### Avera ging t ime [6.5] ; 6- 1; C- 1-7; C1-8; C -3-1 

### A W m 2 

### Water body surface area [4.1. 2] ; 5- 29; 5- 30; 5-35; 5-36C; 5-43; B-4-8; B-4-12; B-4- 15; B-4- 22 

### b unitless 

### Empirical slope coe fficient 5-34; B-4-14 

### Ba beef day/kg FW tissue 

### Biotransfer factor for beef 5-22 ; [A2.5. 1] ; A- 2- 16; B-3- 10 

### Ba chicken day/kg FW tissue 

### Biotransfer factor for chick en 5-26 ; [A2.5. 3] ; B-3- 14 

### Ba egg day/kg FW tissue 

### Biotr ansfe r fact or for eggs 5-26 ; [A2.5. 3] ; A- 2- 18; B-3- 13 

### BAF fish L/kg FW tiss ue 

### Bioaccumulation fa ctor for fish 5-49 ; [A2.5. 4] ; B-4- 27 

### Ba milk day/kg FW tissue 

### Biotran sfer factor for m ilk 5-24 ; [A2.5. 1] ; A- 2- 17; B-3- 11 

### Ba pork day/kg FW tissue 

### Biotran sfer factor for p ork 5-25 ; [A2.5. 2] ; B-3- 12 

### BCF fish unitless

(mg CO PC/kg FW tis sue )/ (mg COP C/kg dissolved water) 

### Bioconcentration factor for fish 5-48 ; [A2.5. 4] ; B-4- 26



### BD g soil/cm 3 soil 

### Soil bu lk den sity [5.2. 4.2] ; 5- 4; 5- 5A; 5-7A; 5-11; 5-32; 5- 33; B- 1- 1; B- 1- 3; B1-4; B-1-5; B-1-6; B-2-1; B-2-3; B-2-4; B-2-5; B-2-6; B-3-1; B-3-3; B-3-4; B-3-5; B-3-6; B-4-1; B-4-3; B-4-4; B-4-5; B-4-6; B-4-10; B-4-11 

### Br ag unitless 

### Plant-soil biocon centration factor for aboveground

produce 5-20 A; [A2.4. 3] ; A2-14 A; B -2-9 

### Br forage unitless

( : g COP C/ g DW plant)/( : g CO PC /g soil) 

### Plant -soil bi oconce ntrat ion fac tor fo r fora ge 5-20 A; [A2.4. 3] ; A2-14 B; B -3-9

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxii Br grain unitless

( : g COP C/ g DW plant)/( : g CO PC /g soil) 

### Plant- soil bio concent ration f actor for COPC

in grain 5-20 A; [A2.4. 3] ; A2-14 B; B -3-9



### Br rootveg unitless

( : g COPC/g FW plant)/( : g CO PC /g soil) 

### Plant- soil bio concent ration f actor for COPC

in belowground pro duce 5-20 B; [A2.4. 2] ; A2-13; B-2-10



### Bs unitless 

### Soil bioavailability factor [5.4. 4.6] ; 5- 22; 5- 24; 5- 25; 5- 26; B-3- 10; B-3- 11; B-3- 12; B-3-13; B-3-14 

### BSAF unitless 

### Biota-to- sediment accum ulation factor [5.75] ; 5- 50; [A2.5. 4.3] ; B-4- 28 

### Bv ag unitless

(mg CO PC/kg li pid tis sue )/ (mg COP C/kg sedim ent) 

### COPC air-to-plant biotransfer factor for

aboveground

produce ( : 

### g COPC/g DW plant)/( : 

### g COPC/g

air)—unitless 5-18 ; [A2.4. 4] ; A- 2- 15A &B ; B-2 -8



### Bv forage /si lage unitless ( : g COP C/ g DW plant)/( : g COP C/g air) 

### Air-to-

plant biotransfer factor for forage and silage 5-18 ; [A2.4. 4] ; A- 2- 15A &B ; B-3 -8



### C unitless 

### USLE cover managem ent factor 5-33A; B-4-13 

### C a : g/m 3 

### Total COPC air concentration [6.1] ; 7- 1; 7- 5; B-5- 1; C- 2-1; C-2- 2; C3-1 

### C acute 

### Acute air concentration ( μ g/m 3 

### ) 7-9; B -6-1; C -4-1 Can cer Risk i unitless 

### Indi vidua l lifetim e risk throug h indire ct expo sure to COPC carcinogen i 7-3; C -1-7
Cancer Risk inh(i) unitless 

### Individua l lifetime cancer risk

through direct inhalation of COPC carcinogen i C-2-1 

### C BS g sediment /cm 3 water 

### Bed sed iment concen tration (or sedi

ment bulk densi ty) 5-36A; 5-37; 5-43; 5-47; B-4-16; B-4- 22; B-4- 25 

### C d unitless 

### Drag coefficient 5-41B; 5- 42B; B-4- 20; 

### C dw mg C OP C/L

water 

### Dissolved phase w ater concentration [5.7. 4.9] ; 5- 46; 5- 48; 5- 49; B- 4- 24; B4-26 ; B-4 -27; C -1-5 

### C fish mg COPC/kg FW

tissue 

### Concentration of COP C in fish [5.7. 5] ; 5- 48; 5- 49; 5-50 ; B-4 -28; C -1-4 

### Chv μg-s/g-m 3 

### Unitized hourly air concentration from

vapor phase B-6 -1 

### Chp μg-s/g-m 3 

### Unitiz ed hour ly air concent

ration f rom p article phase B-6 -1 

### Chpb μg-s/g-m 3 

### Unitized hourly air concentration from

particlebound phase

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxiii Cs mg C OP C/kg s oil 

### Avera ge soi l conce

ntration over exposu

re duration [5.2. 1] ; 5- 1C&D; 5- 20A&B; 5-22; 5-24; 5-25; 5-26; 5-32; 5- 33; B- 1- 1; B- 2- 1; B2-9; B-2-10; B-3-1; B-3-9; B-3-10; B-3- 11; B-3- 12; B-3- 13; B-3-14; B-4-1; B-4- 10; B-4- 11 

### C sb mg CO PC/kg

sediment 

### Concentration sorbed to bed sediment [5.7. 4.10] ; 5- 47; 5- 50; B-4- 25; B-4- 28 

### CSF (mg/k g-day) -1 

### Cancer slope factor 7-2; [A2.6. 2] ; C-1-7 

### Cs tD mg C OP C/kg s oil 

### Soil concentration at tim e tD [5.2. 1] ; 5- 1E; B-1- 1; B-2-1; B-3-1; B-4-1; C-3-1 

### C wct ot mg C OP C/L

wat er c olu mn 

### Tot al CO PC co ncen tra tio n in w ate r col umn [5.7. 4.8] ; 5- 45; 5- 46; B-4- 23; B-4- 24 

### C wtot g CO PC /m 3 water

body (or mg/L) 

### Total water body CO PC concentration including water column an

d bed sediment [5.7. 4] ; 5- 35; 5- 45; 5-47; B-4-15; B-4- 23; B-4- 25 

### Cyp : g-s/g-m 3 

### Unitized yearly average air c oncentration from particle phase [3.8. 3.2] ; B-5 -1 

### Cyv : g-s/g-m 3 

### Unitized yearly average air c oncentration from vapor phase [3.8. 3.1] ; 5- 18; B-2- 8; B -3-8; B -5-1 

### Cywv : g-s/g-m 3 

### Unitized yearly (water body an

d watershed) average air con

centration from v

apor phase [3.8. 3.1] ; 5- 30; B-4-

12 

### D a cm 2 /s 

### Diffusi vity of COP C in air 5- 7A; 5- 42B; [A2.3. 5] ; A- 2-2A; B-1-6; B-2-6; B-3-6; B-4-6; B-4-21 

### d bs m 

### Depth of upper benthic sediment lay

er 5-35; 5-36A; 5-43;

5-45; 5-47; B-4-15; B-4 -1 6; B- 4- 18; B4-22; B-4-23; B-4- 25 

### D mean 

### Mean particle size density for a particular filter cut si ze 3-1 

### Ds mg CO PC/kg

soil-yr 

### Deposi

tion ter m [5.2. 3] ; 5 -1 C, D&E; 5-36C; B-1-1; B-2- 1; B -3-1; B -4-1 

### d wc m 

### Dept h of w ate r col umn [4.1. 2] ; 5- 35; 5- 36A; 5- 45; 5- 47; B4-15; B-4-16; B-4- 18; B-4- 23; B-4- 25 

### D w cm 2 /s 

### Diffusivity of C OPC in water 5-41 A& B; [A2.3. 5] ; A-2- 2B; B-4- 20

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxiv Dydp s/m 2 -yr 

### Unitized yearly average dry

deposition from particle phase [3.8. 3.2] ; 5- 11; 5- 14; B- 1- 1; B- 2- 1; B2-7; B -3-1; B -3-7 

### Dydv s/m 2 -yr 

### Unitized yearly average dry

deposition from vapor phase [3.8. 3.2] ; 5- 11; 5- 14; B- 1- 1; B- 2- 1; B2-7; B -3-1; B -3-7 

### Dytwp s/m 2 -yr 

### Unitized yearly (water body or watershed) average total (wet and dry) depos ition from particle phase [3.8. 3.2] ; 5- 29; 5- 31; B- 4- 1; B- 4- 8; B4-9 

### Dywp s/m 2 -yr 

### Unitized yearly average wet deposition from particle phase [3.8. 3.2] ; 5- 11; 5- 14; B- 1- 1; B- 2- 1; B2-7; B -3-1; B -3-7 

### Dywv s/m 2 -yr 

### Unitized yearly average wet deposition from vapor phase [3.8. 3.2] ; 5- 11; 5- 14; B- 1- 1; B- 2- 1; B2-7; B -3-1; B -3-7 

### Dytwv s/m 2 -yr 

### Unitized yearly (water body or watershed) average total (wet and dry) depos ition from vapor phase [3.8. 3.2] ; 5- 29; 5- 31; B- 4- 1; B- 4- 8; B4-9 

### d z m 

### Total wa ter body depth 5-36 A; 5- 39; 5 -41A; B-4 -1 6; B- 4- 18; B4-20 

### ED yr 

### Exposure duration 6-1; C-1- 7; C- 1-8; C-3-1 ; C-3-2 

### EF days/yr 

### Exposure frequency 6-1; C-1- 7; C- 1-8; C-3-1 

### ER unitless 

### Soil en richment ratio 5-33 ; B-1 -3; B -2-3; B-3-3; B-4-3; B-4- 11 

### E v cm/yr 

### Average ann ual evapotranspiration 5-5A; B-1-5; B-2-5; B-3 -5; B -4-5 

### f bs unitless 

### Fraction of total water bod y COPC co

ncentration in benthic sedimen

t [5.7. 4.1] ; 5- 36B; 5- 38; 5- 47; B- 4- 16; B4-17; B-4-25 

### F i unitless 

### Fraction of plant typ e i grown on co ntaminated soil and eaten by the animal 5-22; 5-24; 5-25; 5- 26; B-3- 10; B-3- 11; B-3-12; B-3-13B- 3- 14 

### f lipid unitless 

### Fish lipid content 5-50; B-4-28 

### Fw unitless 

### Fraction of CO PC wet deposi tion tha t adhere s to plant surfaces 5-14 ; B-2 -7; B -3-7 

### f wc unitless 

### Fraction of total water bod y COPC co

ncentration in th e wat er co lumn [5.7. 4.1] ; 5- 35; 5- 36A; 5- 38; 5- 45; B4-15; B-4-16; B-4- 17; B-4- 23

### Human Health Risk Assessment Protocol Contents September 2005 INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

## xxv

F

v 

### unitless 

### Fraction of COPC air concentration in vapor phase [3.2] ; 5-11; 5-14; 5- 18; 5-29; 5-30; 5-31; B-1-1; B-2-1; B-2-7; B-2-8; B-3-1; B-3-7; B-3-8; B-4-1; B-4-8; B-4-9; B-4-12; B-5- 1; B-6-1 

### H atm-m 3 

### /mol 

### Henry’s Law constant 5-7A; 5-30; 5-40; [A2.3.4] ; A-2-1; B1-6; B-2-6; B-3-6; B-4-6; B-4-12; B-4- 19 

### HI unitless 

### Hazard index 7-6; 7-7; C-1-11 

### HI j 

### unitless 

### Hazard index for exposure pathway j C-1-10 

### HQ unitless 

### Hazard quotient 7-5; C-1-8 

### HQ i 

### unitless 

### Hazard quotient for COPC i 7-6 

### HQ inh(i) 

### unitless 

### Hazard quotient for direct inhalation of COPC C-2-2; C-2-4 

### I cm/yr 

### Average annual irrigation 5-5A; B-1-5; B-2-5; B-3-5; B-4-5 

### I

i 

### mg/day 

### Daily intake of COPC ( i ) from animal tissue [6.2.2] ; C-1-3 

### k unitless 

### von Karman’s constant 5-41B; 5-42B; B-4- 20; B-4-21 

### K ton/acre 

### USLE erodibility factor 5-33A; B-4-13 

### k

b 

### yr G 1 

### Benthic burial rate constant [5.7.4.7] ; 5-38; 5- 43; 5-44; B-4-17 

### Kd bs 

### cm 3 

### water/g bottom sediment 

### Bed sediment/sediment pore water partition coefficient 5-36B; 5-47; [A2.3.8] ; A-2-8C; B-4-16; B-4-25; 

### Kd ij 

### unitless 

### Partition coefficient for COPC i associated with sorbing material j Kd s 

### cm 3 

### water/g soil 

### Soil-water partition coefficient 5-4; 5-5A; 5-7A; 5- 20B; 5-32; 5-33; [A2.3.8] ; A-2-8A; B-1-3; B-1-4; B-1-5; B-1-6; B-2-3; B-2-4; B-2-5; B-2-6; B-2-10; B-3-3; B-3-4; B3-5; B-3-6; B-4-3; B-4-4; B-4-5; B-4-6; B-4-10; B-4-11 

### Kd sw 

### L water/kg suspended sediment 

### Suspended sediments/surface water partition coefficient 5-36A; 5-39; 5-46; [A2.3.8] ; A-2-8B;B-4-16; B-4-18; B4-24 

### K

G 

### m/y 

### Gas phase transfer coefficient [5.7.4.6] ; 5-40; 5-42A&B; B-4-19; B4-21

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxvi K L m/yr 

### Liquid phase transfer coefficien t [5.7. 4.5] ; 5- 40; 5- 41A& B; B- 4- 19; B4-20 

### K oc mL w ater/g so il 

### Soil organic carbon- water partition coefficient [A2.3. 7] ; A- 2-4; A2-5; A -2-6; A -2-7; 

### K ow unitless

(mg C OP C/L oct anol )/ (mg CO PC /L oc tanol) 

### Octanol-water partition coefficient [A2.3. 6] ; A- 2-4; A2-5; A-2- 6; A- 2-7; A-2- 12A&B; A-2- 14A&B; A- 2-15 A; A-2- 16; A -2- 17; A

2-19 

### kp yr G 1 

### Plant surface loss coefficient [5.3. 1.2] ; 5- 14; B-2- 7; B -3-7 

### ks yr G 1 

### COPC soil loss con stant due to all processes [5.2. 2] ; 5 -1 C, D&E; B-1-1; B-1-2; B-2- 1; B- 2- 2; B- 3- 1; B3-2; B -4-1; B -4-2; 

### kse yr G 1 

### COPC loss constant due to soil erosion [5.2. 2.2] ; 5 -2 A; B1-2; B-1-3; B-2-2; B-2-3; B-3-2; B-3-3; B-4-2; B-4-3 

### ksg yr G 1 

### COPC loss con stant du e to biotic and abiotic degradation [5.2. 2.1] ; 5- 2A; [A2.3. 9] ; A -2 -9 ; B1-2; ; B-2- 2; B-3- 2; B-4 -2 

### ksl yr G 1 

### COPC loss constant due to leaching [5.2. 2.4] ; 5- 2A; 5- 5A ; B-1 -2; B -1-5; B-2-2; B-2-5; B-3- 2; B- 3- 5; B- 4- 2; B4-5 

### ksr yr G 1 

### COPC loss con stant du e to sur face run off [5.2. 2.3] ; 5- 2A; 5- 4;

B-1-2; B-1-4; B-2-2; B-2-4; B-3-2; B-3-4; B-4 -2; B -4-4 

### ksv yr G 1 

### COPC loss constant due to volatilization [5.2. 2.5] ; 5- 2A; 5- 7A; B-1- 2; B-1- 6; B-2-2; B-2-6; B-3-2; B-3 -6; B -4-2; B -4-6 

### k v yr G 1 

### Water column v olatilization rate constant [5.7. 4.3] ; 5- 38; 5- 39; B-4- 17; B-4- 18 

### K v m/yr 

### Overall COPC transfer rate coefficient [5.7. 4.4] ; 5- 30; 5- 39; 5- 40; B- 4- 12; B4-18; B-4-19 

### k wt yr G 1 

### Overall total water b ody dissipation rate c onstant [5.7. 4.2] ; 5- 35; 5- 38; B-4- 15;B-4- 17 

### L m 

### Monin- Obuk hov L ength [3.5. 1] 

### LADD mg CO PC/kg

BW -day 

### Lifetime average daily dose 7-2

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxvii L DEP g/yr 

### Total (wet and dry) pa rticle phase and vap or phase COPC direct deposition load to water body [5.7. 1.1] ; 5- 28; 5- 29; B -4-7; B -4-8 

### L dif g/yr 

### Vapor phase COPC d iffusion load to water bod y [5.7. 1.2] ; 5- 28; 5- 30; B-4- 7; B-4- 12 

### leak rat e kg/hr 

### Emission rate from the individual item

of equipment [2.2. 6.1]


### L E g/yr 

### Soil erosion load [5.7. 1.5] ; 5- 28; 5- 33; B-4- 7; B-4- 11 

### L R g/yr 

### Runoff load from pervious surfaces [5.7. 1.4] ; 5- 28; 5- 32; B-4- 7; B-4- 10 

### L RI g/yr 

### Runoff load from impervious surfaces [5.7. 1.3] ; 5- 28; 5- 31; B -4-7; B -4-9 

### L T g/yr 

### Total COPC load to the water body inclu

ding deposition, runoff, and erosion [5.7. 1] ; 5- 28; B-4- 7; B-4-15 

### LS unitless 

### USLE length- slope factor 5-33A; B-4-13 

### M skin g 

### Mass of a thin (skin) layer of below g round vege table 5-19


### M vegetab le g 

### Mass of t he entir e veg etable 5-19 MF unitless 

### Metabolism factor [5.4. 4.7] ; 5- 22; 5- 24; 5- 25; B- 3- 10; B3-11; B-3-12 MW g/mo le Mo lecular weight [A2.3. 1] ; A-2-1 

### OC sed unitless 

### Fraction of organic carbon in bottom sediment 5-50; B-4-28 

### p° L atm 

### Liquid phase vap or pressure of chem ical A-2- 11 

### p°S atm 

### Solid phase vapor pressure of chem ical A-2- 11 

### P cm/yr 

### Average ann ual precipitation 5-5A; B-1-5; B-2-5; B-3 -5; B -4-5 

### PF unitless 

### USLE supporting practice factor 5-33A; B-4-13 

### Pd mg CO PC/kg

DW 

### Abovegroun d exposed produce co

ncentration due to direct (wet and dry) deposition onto plant surfaces [5.3. 1] ; 5- 14; 5- 23; B-2 -7; B -3-7; C -1-2


### P i mg/

kg DW 

### Total COPC concentration in plant type i

ingested by the animal [5.4. 4.3] ; 5- 22; 5- 23; 5- 24; 5- 25; 5- 26; 5- 27; B- 3- 10; B3-11; B-3-12; B-3- 13; B-3- 14 

### Pr mg CO PC/kg

DW 

### Abovegroun d exposed and protected

produce concen trati on due t o root u ptake [5.3. 3] ; 5 -2 0A&B; 5-23; 5-27; B-2-9; B-3 -9; C-1 -2 

### Pr bg mg CO PC/kg

DW 

### Belowground p roduce concentration due to root uptake B-2 -10; C -1-2 

### Pv mg CO PC/kg

DW 

### Concentration of COP C in plant due to air-toplant transfer [5.3. 2] ; 5- 18; 5- 23; B-2 -8; B -3-8; C -1-2

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxviii Q g/s 

### COPC emiss ion rate 5-11; 5-14; 5-18; 5- 29; 5- 30; 5- 31; B-1- 1; B- 2- 1; B- 2- 7; B2-8; B-3-1; B-3-7; B-3-8; B-4-1; B-4-8; B-4-9; B-4-12; B-5- 1; B -6-1 

### Q i g/s 

### Emission rate of COPC (i) Q i(adj) g/s 

### Adjusted emissi on rate of COPC (i) Qcp i(adj) g/s 

### Adj ust ed emi ssi on ra te of Tab le A-1 carcinogenic COPC (i) Qcp i g/s 

### Emission rate of Table A-1 carcinogenic COPC (i) Q f W/ m 2 

### Anthropogenic hea t flux [3.5. 7] 

### Qp i kg DW /day 

### Quantity of plant ty pe i ingested by

the animal each day [5.4. 4.2] ; 5- 22; 5- 24; 5- 25; 5- 26; B-3- 10; B-3- 11; B-3- 12; B-3-13; B-3-14 

### Qs kg/day 

### Quantity of soil ingested by the anim al each day Q * W/ m 2 

### Net radiation absorbed [3.5. 8] 

### r unitless 

### Inte rception fraction—the fr

action o f mate

rial in rain intercepted

by vegetat

ion and initiall y retained R atm-m 3 /mol-K 

### Universal gas constant 5-7A; 5-3 0; 5- 40; A

2-11; B-1-6; B-2-6; B-3-6; B-4-6; B-4- 12; B-4- 19 

### RCF ( μ g COP C/ g DW

plant)/( μ g CO PC /mL so il water) 

### Root concentration factor 5-20 B; [A2.4. 1] ; A2-12A&B; A- 2-13; B-2-10 

### RO cm/yr 

### Average ann ual surface runoff from

pervious surfaces 5- 4; 5- 5A; 5- 32; B1-4; B-1-5; B-2-4; B-2-5; B-3-4; B-3-5; B-4-4; B-4-5; B-4- 10 

### REL California EPA Air Toxics Hot Spots Prog ram acute re ference

exposu re lev els [7.4. 2]


### RF yr G 1 

### USLE rainfall (or erosiv ity) factor 5-33A; B-4-13 

### RfC Inhalation reference dose 7-5; [A2.6. 1] ; C-2-2 

### RfD mg CO PC/kg

body weight

/day 

### Oral reference dose 7-5; [A2.6. 1] ; C-1-8 

### Rp unitless 

### Interception fraction of the edible portion of plant [5.3. 11] ; 5- 14; B-2- 7; B -3-7 S mg C OP C/L

water 

### Solubility of COP C in water [A2.3. 3] ; A-2-1

### Human Health Risk Assessment Protocol Contents September 2005 INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

## xxix

SD unitless 

### Sediment delivery ratio [5.7.3] ; 5-33; 5-34; 5-36C; 5-43; B-1-3; B-2-3; B-3-3; B-4-3 

### ) 

### Sf unitless 

### Entropy of fusion [ ) 

### S f

### /R = 6.79] A-2-11 

### SF (mg/kg-day) -1 

### Slope factor S T 

### cm 2 

### /cm 3 

### air 

### Whitby’s average surface area of particulates (aerosols) A-2-11


### T

a 

### K 

### Ambient air temperature [3.4.2] ; 5-7A; A-2-11; B-1-6; B-2-6; B3-6; B-4-6 

### T

1 

### yr 

### Time period at the beginning of combustion 5-1D; B-1-1; B-2-1; B-3-1; B-4-1 

### T

2 

### yr 

### Length of exposure duration 5-1C&D; B-1-1; B2-1; B-3-1; B-4-1 

### tD yr 

### Time period over which deposition occurs (time period of combustion) 5-1C, D&E; B-1-1; B-2-1; B-3-1; B-4-1 

### T

m 

### K 

### Melting point of chemical [A2.3.2] 

### Tp yr 

### Length of plant exposure to deposition per harvest of edible portion of plant [5.3.1.3] ; 5-14; 5-16; 5-21; B-2-7; B3-7 

### tp i 

### yr 

### Length of plant’s exposure to deposition per harvest of the edible portion of the i th plant group 5-13

Total Cancer Risk unitless 

### Individual lifetime cancer risk through indirect exposure to all COPC carcinogens 7-3; 7-4; C-1-9
Total Cancer Risk inh 

### unitless) 

### Total individual lifetime cancer risk through direct inhalation of all COPC carcinogens C-2-3 

### TSS mg/L 

### Total suspended solids concentration 5-36A; 5-36C; 5-39; 5-43; 5-46; B-4-16;B-4-18; B-4-22; B4-24 

### T

wk 

### K 

### Water body temperature 5-30; 5-40; B-4-12; B-4-19; 

### t 1/2 

### days 

### Half-time of COPC 5-15 

### u m/s 

### Current velocity 5-41A; B-4-20 

### URF : 

### g/m 3 

### Unit risk factor 7-1; C-2-1 Vf

x 

### m 3 

### /yr 

### Average volumetric flow rate through water body 5-35; 5-36C; 5-43; B-4-15; B-4-22; 

### VG ag 

### unitless 

### Empirical correction factor for aboveground produce (forage and silage) [5.3.2.1; 5.4.2.1] ; 5- 18; B-2-8; B-3-8 

### VG rootveg 

### unitless 

### Empirical correction factor for below ground produce 5-19; 5-20B; B-2-10 

### Vp atm 

### Vapor pressure of COPC [A2.3.3] ; A-2-1 

### W m/s 

### Average annual wind speed [3.4.1] ; 5-41B; 5- 42B; B-4-20; B-4- 21 

### W

b 

### m/yr 

### Rate of burial 5-44

### Human Health Risk Assessment Protocol

Contents September 2005
INDEXED LIST OF VARIABLES (contd.)
Variable Units Definition [Sections] / Equations

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 

## xxx X e kg/m 2 -yr 

### Unit soil loss [5.7. 2] ; 5- 33; 5- 33A; 5- 36C; 5- 43; B-1-3; B-2-3; B-3-3; B-4-3; B-4-11; B-4- 13; B-4- 22 

### Yh kg DW 

### Dry harvest yield Yh i kg DW 

### Harve st yie ld of i th crop Yp kg D W /m 2 

### Yield or standing crop biomass of edible portion of plan t (pro ducti vity) [5.3. 1.4; 5. 4.1. 4] ; 5- 14; B -2-7; B -3-7 

### Yp i kg D W /m 2 

### Yield or standi ng cro p biom ass of t he edib le portion of the p lant (pr

oductiv ity) 5-13


### Z s cm 

### Soil m ixing zone d

epth [5.2. 4.1] ; 5- 4; 5- 5A; 5-7A&B; 5- 11; B-1- 1; B- 1- 3; B- 1- 4; B1-5; B-1-6; B-2-1; B-2-3; B-2-4; B-2-5; B-2-6; B-3-1; B-3-3; B-3-4; B-3-5; B-3-6; B-4-1; B-4-3; B-4-4; B-4 -5; B -4-6 

### 0.01 kg cm 2 /mg-m 2 

### Units conversion factor 10 -6 g/ : g 

### Units conversion factor 10 -6 kg/

mg 

### Units conversion factor 0.31536 m-g -s /cm

- : g-yr 

### Units conversion factor 365 days/yr 

### Units conversion factor 907.18 kg/ ton 

### Units conversion factor 0.1 g-kg/ cm 2 -m 2 

### Units conversion factor 0.001 g/ mg 

### Units conversion factor 100 mg-cm 2 /kg- cm 2 

### Units conversion factor 1000 mg/g 

### Units conversion factor 4047 m 2 /acre 

### Units conversion factor 1 × 10 3 g/kg 

### Units conversion factor 3.1536 × 10 7 s/yr 

### Units conversion factorU.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

### 1-1 

# Chapter 1: INTRODUCTION
What’s Covered in Chapter 1: 1. 1 Objective and Document Organization 1. 2 Background 1. 3 Using this Document 1. 4 Primary Reference Documents 1. 5 Risk Nomenclature

PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. 1.1 OBJECTIVE AND DOCUMENT ORGANIZATION
The U.S. Environmental Protection Agency’s (“U.S. EPA” or “the Agency”) Office of Solid Waste (OSW) has developed an approach for conducting multi-pathway, site-specific human health risk assessments on Resource Conservation and Recovery Act (RCRA) hazardous waste combustors. The approach, also known as the Human Health Risk A ssessment Protocol (“HHRAP” or “protocol”) can be used where the permitting authority determines such risk assessments are necessary. The HHRAP replaces an earlier Peer Review Draft published in July 1998.

Our primary objective in developing the protocol was to offer a user-friendly approach to performing sitespecific combustion risk assessments. We wanted to develop a guidance document that would: • be useful to a diverse group of users: risk assessors, permit writers, risk managers, and community relations personnel;

### Human Health Risk Assessment Protocol Chapter 1: INTRODUCTION September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

### 1-2 

### • provide a logical method for doing risk assessments of facilities that burn hazardous waste; • completely explain the reason for each recommended procedure and parameter value; • provide a comprehensive enough collection of default input parameters to conduct a risk assessment. The collection would also be flexible enough to accommodate regional or site-specific information; and finally • make sufficient tools available to produce transp arent, defensible, and realistic results. When coupled with an ecological assessment (U.S. EPA 1999a), these tools would provide critical information often needed by risk managers when faced with the decision of permitting a hazardous waste combustion facility. The HHRAP brings together information from other risk assessment guidance and method documents prepared by U.S. EPA and state environmental agencies. It also contains the latest advancements in risk assessment science, as well as experience EPA has gain ed through conducting and reviewing combustion risk assessments. This version of the protocol also addresses the comments put forward by the public and external scientific peer reviewers regarding earlier drafts of the HHRAP.
The first volume of the HHRAP contains the main body of the document, providing a detailed explanation of a risk assessment approach that we recommend you consider when conducting a risk assessment. The second volume contains the appendices, including: Appendix A : a collection of chemical-specific information which might be of interest - • A-1 - a compilation (from various EPA sources) of compounds of potential interest; • A-2 - Compound-specific parameter value information. Details the sources of, or equations used to calculate, paramete r values used in fate & transport-, biotransfer-, exposure-, and toxicity -related equations. Parameter values themselves are found in a companion da tabase to the HHRAP, which is also available for download. Appendix B: Equations and recommended default va riable values for estimating media concentrations; and Appendix C: Equations and recommended default vari able values for estimating potential cancer risk and non-cancer health effects.

### Human Health Risk Assessment Protocol Chapter 1: INTRODUCTION September 2005

1 This section summarizes the historical context of re gulatory authority and associated policy regarding hazardous waste combustion site-specific risk asse ssment under the RCRA program. This discu ssion is not intended to update, revise or articulate new guidance or policy. Nor is it intended to update, revise or provide any new interpretations of any statutory or regulatory authority, including those relevant to the RCRA 3005(c)(3 ) “omnibus authority”. In addition, it is not intended to reopen for consideration any statutory or re gulatory interpretations of other related guidance documents, or the MACT rule (64 FR 52828).

2 When combustion sources demonstrate compliance with the Part 63, Subpart EEE MACT standards, they may request that certain RCRA permit conditions (e.g., those based on the national performance standards) be removed from their RCRA permit, because they are no longer applicable, through a cla ss 1 permit modification request with prior agency approval. In some cases, RCRA performance standards ma y be retained in the RCRA permit if they are more stringent than the relevant MACT standard. U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

### 1-3 

### Please Note : Although these guidelines address many types of situations encountered in the field, they cannot encompass every potentia l situation. You should ensure that the recommendations in this guidance are appropria te for the facility, based on site-specific information and/or circumstances. This protocol is a “snapshot” of current risk assessment science, and we encourage you to evaluate updates and alternatives to the recommended parame ters (e.g., toxicological benchmarks; exposure factors) when they become available. If you use alternative values, however, keep in mind how changes in one parameter may affect other parameter values and/or calculations. We may revise the protocol in the future if any of the following become available:
• new research in risk assessment science and/or the combustion field; • new information gathered while conducting site-specific risk assessments; and • new initiatives introduced by the Agency. These types of changes are inevitable in this evolving and highly technical field.

1.2 BACKGROUND 1


### Hazardous waste combustors are required to meet RCRA national performance standards and obtain a permit under 40 CFR Part 264, Subpart O; Part 266, Subpart H; and Part 270. 2 

### In addition, Section 3005(c)(3) of RCRA [codified at 270.32(b)(2)] requires that each permit contain the terms and conditions that the permitting authority considers necessar y to protect human health and the environment. This is commonly referred to as the “omnibus author ity.” The omnibus authority gives the Agency both

### Human Health Risk Assessment Protocol Chapter 1: INTRODUCTION September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

### 1-4 

### the authority and the responsibility to set up site -specific RCRA permit conditions as necessary to “be protective of human health and the environment.” These permit conditions are intended to supplement, not replace those conditions that are already re quired under the national performance standards [See Federal Register 1999 (MACT Rule)].
The RCRA national performance standards for incine rators were published in 1981 (40 CFR Part 264, Subpart O) and for boilers and industrial furnaces in 1991 (40 CFR Part 266, Subpart H). Since then, however, new information on indirect exposure pathways and non-dioxin products of incomplete combustion (PICs) suggests that these standards may not fully address all potentially significant risks.
For example the RCRA national standards were based on estimates of risk only from direct exposure to (i.e. inhaling) stack emissions. New information suggests risks from indirect exposures (e.g. ingesting contaminated soil, food, or water) are also important (Federal Register 1999). Bioaccumulation tends to concentrate some chemicals as they migrate through the environment. These higher concentrations can lead to exposures and risks of concern. For exampl e, Fradkin et al. (1988) linked elevated levels of chemical pollutants in soils, lake sediments, and co w’s milk to atmospheric transport and deposition of pollutants from combustion sources. Also, the 1994 Draft Health Reassessment of Dioxin-Like Compounds (U.S. EPA 1994a), and the 1997 Mercury Study Report to Congress (U.S. EPA 1997c), indicate that indirect exposure pathways can lead to significant risks.
Indirect exposure pathways weren’t directly taken into account by the 1981 and 1991 hazardous waste combustion standards. The regulations also didn’t take into account the uncertainty surrounding the types and quantities of non-dioxin products of incomplete combustion (non-dioxin PICs) or any potential risks posed by these compounds.
To address these concerns, the Agency issued the Hazardous Waste Minimization and Combustion Strategy in 1994. This strategy recommended conducting a site-specific risk assessment for each combustion facility seeking a RCRA permit. Permitting authorities could use the results of an assessment to determine, on a case-by-case basis, if a com bustor operating in accordance with the performance

### Human Health Risk Assessment Protocol Chapter 1: INTRODUCTION September 2005

3 

### The standards for Phase 1 sources (incinerators, cement kilns, and lightweight aggregate kilns) are referred to as Replacement Standards. The Replacement Standards replace the February 13, 2002 Interim Standards that were developed in response to a court decision to vacate challenged portions of the 1999 Phase 1 MACT final standards. Thus, the 2005 final rule establishes MACTstandards for both Phase 1 and Phase 2 (boilers and industrial furnaces) sources. U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

### 1-5 

### standards is protective of human health and the envi ronment. If the permitting authority finds that the combustor operating in accordance with the performance standards is not protective of human health and the environment, the permitting authority would invoke the “omnibus authority” and either add additional conditions to the RCRA permit, or deny the RCRA pe rmit. The permitting authority must explain the reasons for any additional permit conditions in the admi nistrative record of the facility (Federal Register 1999).
In 1999 the Agency updated its earlier site-specifi c risk assessment recommendation, to account for the Phase 1 Maximum Achievable Control Technology (MAC T) standards for hazardous waste incinerators, cement kilns, and lightweight aggregate kilns (see 64 FR 52828). While the Phase 1 MACT standards provide additional protection, we recognize that ther e may continue to be circumstances for which sitespecific risk assessments are appropriate. For ex ample, a site-specific risk assessment might be appropriate if there is reason to believe that ope rating in accordance with Phase 1 MACT standards alone may not be protective of human health and the envir onment. So, in the MACT standards rulemaking, we recommend that the permitting authority evaluate th e need for a site-specific risk assessment on a caseby-case basis. For hazardous waste combustors not subject to the Phase 1 MACT standards, such as boilers and industrial furnaces, we continue to recommend that site-specific risk assessments generally be conducted as part of the RCRA permitting process (see Federal Register 1999).
As part of the September 2005 rule finalizing MACT standards for hazardous waste-burning incinerators, cement kilns, lightweight aggregate kilns, boilers, a nd industrial furnaces, we maintain virtually the same the site-specific risk assessment policy recommendati on as conveyed in the 1999 final rule preamble (see previous paragraph) 3 

### . That policy, which establishes that th e need for an SSRA should be determined on a case-by-case basis, now applies equally to both Phase 1 and Phase 2 sources.

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### In addition, the 2005 final rule codifies additional regulatory language that provides the authority for SSRAs. Although a comparative risk analysis conduc ted for the 2005 final rule concluded that the MACT standards for both Phase 1 and Phase 2 sources are generally protective, there may be instances where we cannot be assured that emissions from each source will be protective of human health and the environment. Because we believe that SSRAs are lik ely to continue to be necessary at some facilities (i.e., mainly those that have not previously conducted an SSRA), we ha ve codified language in §§270.10(l) and 270.32(b)(3) that explicitly provides for the permit authority to require SSRAs on a case-by-case basis and add conditions to RCRA permits based on SSRA results, respectively. The language also reminds permit authorities that the de termination that the MACT standards may not be sufficiently protective is to be based only on fact ors relevant to the potential risk from the hazardous waste combustion unit at the site. Additionally, guiding factors have been identified for permitting authorities to consider in determining whether the MA CT will be sufficiently protective at an individual site. In summary, the 2005 final rule only modifies the statutory authority under which we implement the SSRA policy, while maintaining the same SSRA policy from a substantive standpoint.

1.3 USING THIS DOCUMENT
This document contains our generally recommende d approach for conducting multi-pathway, sitespecific human health risk assessments of RCRA hazardous waste combustors. This document does not provide recommendations on how to:

• Determine if a site-specific risk assessment should be performed ; You can find U.S. EPA’s most recent recommendations for when, or if, a site-specific risk assessment should be performed, in documentation of the MACT rule, published on September 30, 1999 (Federal Register 1999).

• Conduct stack emissions testing for a site-specific assessment ; A separate guidance document entitled Risk Burn Guidance for Hazardous Waste Combustion Facilities EPA 530-R-01-001, July 2001 (U.S. EPA 2001c) contains approaches for collecting emissions data to support site-specific risk assessm ents. This document is on the U.S. EPA OSW website at: http:// www.epa.gov/epaoswer/hazwaste/combust/ pdfs/ burn.pdf

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### • Develop a site-specific ecological risk assessment ; We’d previously published our recommendati ons for conducting screening level ecological combustion risk assessments in a separate, compan ion document to the HHRAP. This companion document, the Screening Level Ecological Risk Assessmen t Protocol for Hazardous Waste Combustion Facilities (SLERAP) Peer Review Draft (U.S. EPA 1999a), is currently undergoing substantial revision. Until revisions are co mplete, we can’t recommend using the SLERAP.

• Use risk assessment results in risk manageme nt decisions, such as setting RCRA permit conditions

. Because this protocol is a technical risk assessment tool, it does not discuss risk management issues, such as how risk managers are to u se the provided information (including uncertainty information), the potential for cumulative risks, or target risk levels. U.S. EPA’s generally recommended risk and hazard targets can be found in Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities (U.S. EPA 1994f). Additionally, EPA Region 6's region-specific risk target recommendations, Region 6 Risk Management Addendum (U.S. EPA 1998b), are available on their website at: www.epa.gov/earth1r6/6pd/rcra_c/protocol/r6add.pdf

. Please Note: the ultimate decision for how to in corporate risk assessment estimates in risk management decisions rests with the permitting authority.
For your convenience, the HHRAP many of th e recommendations found in the above-referenced documents. However, unless we say so explicitly, the HHRAP does not intend to update, revise, or replace any of the information containe d in the above-referenced documents.

The HHRAP does update and replace the following guidance documents: • U.S. EPA, Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes, April 15, 1994 Draft and the October 4, 1994 Errata; • U.S. EPA, Protocol For Screening Level Human Health Risk Assessment at Hazardous Waste Combustion Facilities - Volumes 1 & 2, Internal Review Draft, EPA-R6-096-002 February 28, 1997; • U.S. EPA, Human Health Risk Assessment Protocol, Draft Interim Final, April 1998 (CD-Rom version);

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### • U.S. EPA, Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities - Volume 1-3, Peer Review Draft, EPA 530-D-98-001A, B & C, July 1998 and the August 2, 1999, Errata. We anticipate that risk assessments will be comple ted for new and interim-status facilities, where necessary, when they apply for their RCRA permit. The process we recommend evaluates risks to receptors posed by potential emissions from RCRA-regul ated units. We encourage you to use existing and site-specific information throughout the risk assessm ent process in order to properly evaluate actual regulated operations for any particular combusto r. We generally recommend conservative default assumptions only when they will provide confidence th at ensuing permit limits will be health protective.
Throughout the HHRAP we offer parameter values fo r you to consider. These values are based on a number of elements, such as the best science availa ble and professional judgement. Since this is a national level guidance, the recommended values typi cally reflect national average conditions. The values will be more appropriate for some sites, and l ess so for others. For example, the type of waterbody near a facility (i.e. lake, river, wetland) may affect the methylation rate of mercury in the waterbody, or the type of fish consumed may affect percent lipidcontent used in the assessmen t. So, a value that is reasonable for one facility may be over (o r under) protective at a different facility.
In all cases, though, we give the reason for the sugg ested value. We encourage you to consider our reasoning, in deciding if a more representative estimat e of a site-specific value (or range of values) is available and appropriate. If you use values other than those we recommend, you should explore how, or if, those changes may affect other parameter valu es and calculations used in the assessment. As with values recommended in this guidance, using values other than those recommended here should always be clearly identified and discussed in the risk plan and/ or risk assessment (as appropriate). This will ensure clarity and transparency of the final risk assessment results.
You would need considerable time, effort, and f unding to investigate the representativeness of all the values (or ranges of values) available in the HHRAP. As a result, you might choose to use only readily available site-specific information in an initial assessment. You could then use the results of that

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### assessment to determine where (or if) more site-specifi c risk information should be collected (see Figure 1-1). This allows you to use resources most effi ciently and effectively, by focusing resources on areas that are considered “risk drivers”, rather than areas that do not appreciably affect the risk outcome. For example, if the assessment shows that the primary pollu tant and exposure pathway is mercury in fish, then you could target site-specific data gathering effort s on values related to mercury emissions, surface water concentrations and/or fish consum ption. You would not have to sp end resources collecting site-specific information that may not affect the final resu lts of the assessment (for example, Manganese exposure through ingestion of produce).
You can also use the HHRAP as a screening tool. For example, a facility with a highly variable waste stream might choose to provide the permitting authority with historical data and assume that all compounds will be retained in the risk analysis. Or you might choose to use more conservative assumptions throughout, to make the assessment fit a more classic “screening level” approach. For example, you could choose not to initially investigate the actual land use surrounding a facility, but instead locate all the selected recep tors at the area of greatest contaminant deposition. If estimates don’t exceed the selected risk target, additional ite rations of the assessment may not be necessary. Regardless, every risk assessment is limited by the quantity and quality of: • Site-specific environmental data; • Emission rate information; and • Other assumptions made during the risk es timation process (e.g., fate and transport variables, exposure assumptions, and receptor characteristics).
These limitations and uncertainties are described ex tensively throughout the main document and the appendices, and are summarized in Chapter 8. Y ou should generally make every effort to reduce limitations and uncertainties in the risk assessment pro cess, since they can affect the confidence in the risk assessment results.

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### 1-10 Facility Characterization - Compiling Basic Facility Information (Section 2.1) - Identifying Emission Sources & Estimating Emission Rates (Section 2.2) - Identifying Compounds of Potential Concern (COPC) (Section 2.3) - Estimating COPC Concentrations for Non-Detects (Section 2.4) - Evaluating Contamination in Blanks (Section 2.5)

Air Dispersion and Deposition Modeling - Partitioning Emissions (Section 3.2) - Site-Specific Characteristics Required for Air Modeling (Section 3.3) - Meteorological Preprocessor Data Needs (Section 3.5) - ISCST3 Model Input Files (Sections 3.6) - ISCST3 Model Execution (Section 3.7) - Using Model Output (Section 3.8) - Modeling Fugitive Emissions (Section 3.9) - Modeling Acute Risk (Section 3.10) Exposure Scenario Selection - Exposure Setting Characterization (Section 4.1) - Recommended Exposure Scenarios (Section 4.2) - Selecting Exposure Scenario Locations (Section 4.3)

Estimating Media Concentrations

- Calculating Air Concentrations in Air for Direct Inhalation (Section 5.1)

- Calculating Concentrations in Soil (Section 5.2) - Calculating Concentrations in Produce (Section 5.3) - Calculating Concentrations in Meats, Milk, and Eggs (Sections 5.4 through 5.6) - Calculating Concentrations in Drinking Water and Fish (Section 5.7)
Quantifying Exposure - Inhalation Exposure Pathways (Section 6.1) - Ingestion Exposure Pathways (Section 6.2) - Dermal Exposure Pathways (Section 6.3) - Exposure Frequency (Section 6.4) - Exposure Duration (Section 6.5) - Averaging Time (Section 6.6) Characterizing Risk and Hazard - Quantitatively Estimating Cancer Risk (Section 7.1) - Quantitatively Estimating Noncancer Hazard (Section 7.2) - Target Levels (Section 7.3) - Estimating Acute Exposure from Direct Inhalation (Section 7.4)

Interpreting Uncertainty - Understanding Uncertainty and Limitations of the Human Health Risk Assessment Process (Section 8.1) - Identifying Types of Uncertainty (Section 8.2) - Determining Qualitative Uncertainty (Section 8.3) - Determining Quantitative Uncertainty (Section 8.4) - Discussing Human Health Risk Assessment Uncertainty (Section 8.5)

Deny Permit Collect Additional Site-Specific Information Use Additional Site-Specific Information

To Reevaluate Risk

Issue Permit Develop Protective Operating Permit Risk Acceptable?

YES Risk Assessment Risk Management

NO NO 

### FIGURE 1-1 HUMAN HEALTH RISK ASSESSMENT PROCESS

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### As stated in the U.S. EPA (2002c) “Risk assessments may be performed iteratively, with the first iteration employing protective (conservative) assumptions to identify possible risks. Only if potential risks are identified in a screening level assessment is it necessary to pursue a more refined, data-intensive risk assessment. The screening level assessments may not result in "centr al estimates" of risk or upper and lower-bounds of risks. Nevertheless, such assessments may be useful in making regulatory decisions...” U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 

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### The EPA Information Quality Guidelines (U.S . EPA 2002c) recommend ensuring the objectivity of information found in risk assessments by applying, to the extent practicable and consistent with Agency statutes and existing legislative regulations, the follo wing adaptation of the quality principles found in the Safe Drinking Water Act (SDWA) Amendments of 1996: (A) The substance of the information is accurate , reliable and unbiased. This involves the use of: (i) the best available science and supporting studies conducted in accordance with sound and objective scientific practices, including, wh en available, peer reviewed science and supporting studies; and (ii) data collected by accepted methods or best available methods (if the reliability of the method and the nature of the decision justifies the use of the data). (B) The presentation of information on human health , safety, consistent with the purpose of the information, is comprehensive, informative, a nd understandable. In a document made available to the public, EPA specifies: (i) each population addressed by any estimate of applicable human health risk; (ii) the expected risk for the specific populations affected; (iii) each appropriate upper-bound or lower-bound estimate of risk; (iv) each significant uncertainty identified in the process of the assessment of risk; and (v) peer-reviewed studies known to the Administrator that support, are directly relevant to, or fail to support any estimate of risk and the methodology used to reconcile inconsistencies in the scientific data. How risk results are viewed by the risk manager and other stakeholders is comp lex and can involve other factors besides those included in this document (e.g . public concern). Consequently, interpreting risk assessment results warrants careful consideration. Ri sk management decisions are beyond the scope of the HHRAP, and we don’t provide any guidance on inte rpreting risk results. It should be noted, though, that identifying potentially unacceptable risks does not necessarily signify the end of the risk assessment process. You can view risk assessments as an iterative process 4 

### , with a number of available options once risk estimates are produced. The iterative nature of the risk assessment/risk management interface is graphically represented in Figure 1-1, and the vari ous available options are briefly described below:

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### Example 1 : If the initial risk estimates (coupled with any other related factors) indicate that risks are not expected to pose a concern to human health or the environment, the risk manager and/or permit writer will likely end the site-specific risk assessm ent process and the facility will likely receive a permit. Example 2 : If the initial risk estimates (coupled with any other related factors) indicate that the risks are at or above a level that may pose a risk to hum an health or the environment, then additional information might be added to the risk assessmen t (e.g. site-specific information that’s more representative of the actual exposure settings). Additional iterations of the risk assessment could then be performed. This iterativ e process enables you to determine if the risks identified in the earlier assessment accurately represent the situation at a given combustion facility. Example 3 : If the initial risk estimates (coupled with any other related factors) or subsequent iterations (as detailed in Example 2 above), indicate poten tially unacceptable risk, risk managers and/or permit writers might use the results of the risk assessment to propose revised or additional permit conditions (such as waste feed limits and/or pr ocess operating conditions) to lower the potential risk to acceptable levels. Another risk assessm ent could verify that the proposed permit conditions will enable the combustor to operate in a manner that’s protective of human health and the environment. In some situations, target risk levels might be selected and back-calculations conducted to determine what emission and/or waste feed rate w ould allow the facility to operate in a protective manor. In any case, the acceptable waste feed rate and other appropria te conditions could be incorporated into the RCRA permit. Example 4 : If the initial risk estimates or subsequent ite rations (coupled with any other related factors) indicate potentially unacceptable risk, risk managers and/or permit writers might also choose, where appropriate, to deny the permit. The HHRAP may also be useful when a facility or re gulatory agency decides to perform a pre-trial burn risk assessment. A pre-trial burn risk assessment can ev aluate pre-existing permit limits (e.g. regulatory limits such as MACT or BIF) to determine if more extensive or refined risk-based testing is necessary as part of the trial burn testing program. Also, the pre-trial burn risk assessment can test the parameters used in the initial trial burn sampling and analysis plan. Testing trial burn parameters minimizes trial burn contributions to risk assessment uncertainty, and avoids the expense of multiple trial burn iterations. For example, if the initial detection or quantitation limit for a specific compound (such as a dioxin, furan, or bioaccumulative metal) is too high during trial burn sam pling and analysis, then the final risk estimate may be artificially inflated, especially for indirect exposure pathways. If trial burn sampling and analysis

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### uses a lower detection or quantitation limit, the compound mi ght be found not to add appreciably to the risk results. The pre-trial burn risk assessment can al so determine whether modifications to the sampling collection (such as increased sample volumes) are need ed to achieve lower detection or quantitation limits. Please see Chapter 2 for more detailed information on how risk assessments relate to trial burns.

1.4 PRIMARY REFERENCE DOCUMENTS

One of the main benefits of the HHRAP is that it assembles in one place more than a decade of research and experience regarding practices for conducting risk assessments of hazardous waste combustion facilities. This section describes, in chronological order, the primary guidance documents we used to prepare the HHRAP. Many other important reference materials were also needed to produce a document of this magnitude. We have listed all reference materials used in preparing this document in the Reference chapter.

Some of the documents we used were themselves developed over a period of several years, including revisions. In some cases, revisions to the original document address only specific issues rather than a complete revision of the original document. The following discussion lists and briefly describes each document. Overall, the guidance documents listed belo w reflect a continual refining and enhancing of the risk assessment method.
The following was the first U.S. EPA guidance doc ument for conducting risk assessments at combustion units:
U.S. EPA. 1990e

. Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions, Interim Final . Environmental Criteria and Assessment Office. ORD. EPA-600-90-003. January. Referred to as the “IEM” document, EPA (1990e) outlin es and explains a set of general procedures for conducting risk assessments that includes both the direct inhalation pathway and indirect food chain pathways. The IEM document was subsequently supplemented by the following:

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### U.S. EPA. 1993f

. Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions , Review Draft . Office of Health and Environmental Assessment. ORD. EPA-600-AP-93-003. November 10. Referred to as the “Addendum”, EPA (1993f) outlines recommended revisions a nd added new exposure pathways to the previous U.S. EPA guidance ( 1990e), and has been used by the risk assessment community since its release.
In 1994, we issued several additional hazardous waste combustion risk assessment documents, including:
U.S. EPA. 1994f

. Draft Exposure Assessment Guidan ce for RCRA Hazardous Waste Combustion Facilities . OSWER. EPA-530-R-94-021. April. This document (1994f) is made up of a series of four attachments, all issued around the same time frame (April/May 1994) as separate documents: U.S. EPA. 1994g

. Draft Guidance for Performing Screeni ng Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Expos ure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . April 15. U.S. EPA. 1994h . Table 1, “Chemicals Recommended for Identification,” and Table 2, “Chemicals for Potential Identification.” Attachment A, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . April 15. U.S. EPA. 1994i

. Draft Revision, Implementation Guidance for Conducting Indirect Exposure Analysis at RCRA Combustion Units. Attachment, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . April 22. U.S. EPA. 1994j

. Draft Guidance on Trial Burns. Atta chment B, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . May 2 Combined, these four documents present a generally recommended procedure for sampling the combustor emissions, identifying the compounds of concern, conducting both a direct and indirect risk assessment, and implementing the results of the risk assessment for hazardous waste combustion facilities. We used the methodologies identified in both the ORD “IEM” and “Addendum” documents as the foundation of

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### our hazardous waste combustion risk assessment methodology. The “IEM” and the “Addendum” were broader in scope than our document. We used many , but not all, of the me thods, models and exposure scenarios that are described in the two ORD docum ents. Because the ORD documents contain much of the background information necessary to complete a riskassessment, that information was not repeated in our guidance documents. Shortly after the release of our documents, the trial burn portion and the risk assessment portion were further revised with the following releases:
U.S. EPA. 1994n

. Draft Revision of Guidance on Trial Burns. Attachment B, Draft Exposure Assessment Guidance for RCRA Hazar dous Waste Combustion Facilities . OSWER. June 2. U.S. EPA. 1994p

. Errata, Draft Guidance for Perfor ming Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . October 4. As a follow-up to these documents, we prepared another draft guidance. The following was released for internal review, but never formally or o fficially released as a program-supported document:
U.S. EPA. 1994r

. Revised Draft Guidance for Perfor ming Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . Office of Emergency and Remedial Response. OSW. December 14. In 1997, the state of North Carolina’s Department of Environment, Health, and Natural Resources (DEHNR) developed the following guidance documen t for conducting risk assessments in their state:
NC DEHNR. 1997

. North Carolina Protocol for Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units . January. The NC DEHNR document reiterates U.S. EPA procedur es (1994r), with the addition of a tiered approach that can help the regulatory agency or facility to c hoose approaches that reflect the investment they want to make in conducting risk assessments. For instance, a small, on-site unit with limited waste stream variability may find the first tier assessment (worst-case) in the North Carolina protocol appropriate, whereas a larger facility with a diverse waste feed mi xture may decide to complete a Tier 2 or Tier 3 assessment, which are progressively more site-specific.

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### In 1998, the ORD revised, updated and combined the “IEM” and the “Addendum” documents into one document, entitled:
U.S. EPA 1998

. Methodology for Assessing Health Risks A ssociated with Multiple Pathways of Exposure to Combustor Emissions (U.S. EPA 1998c).
This document is referred to as the “MPE” document. It includes information which was gained from cross-Agency review, EPA’s Science Advisory Board (SAB) and the public on the “IEM” and the “Addendum” documents. It also includes information from the draft dioxin reassessment “ Estimating Exposure to Dioxin-Like Compounds” (U.S. EPA 1994a) and the “ Mercury Study Report to Congress” (December 1997). As with the MPE’s predecessor doc uments, it is considered the foundation of our hazardous waste combustion risk assessment methodology and is frequently referenced in the HHRAP.

In 1999 we released a technical document that de tailed the risk assessment conducted to support the hazardous waste combustion Maximum Achievable Control Technology (MACT) standards:
RTI 1999

. The Background Information Document to the Risk Assessment Support to the Development of Technical Standards for Emissi ons from Combustion Units Burning Hazardous Wastes Final Report. EPA Contract Number 68-W6-0053. To ensure consistency, we considered EPA (1999) throughout the development of the HHRAP.
Finally, in 2001 we updated and finalized the document entitled:
U.S. EPA 2001c

. Risk Burn Guidance for Hazardous Waste Combustion Facilities, July. Referred to as the “risk burn guidance,” EPA(2001c) w as prepared by U.S. EPA Region 4 and U.S. EPA OSW. It details recommendations regarding stack emissions tests which may be performed at hazardous waste combustion facilities to support site-specific risk assessments.
As previously stated, our primary objective in developing the HHRAP was to suggest a user-friendly approach to performing site-specific combustion risk assessments. The HHRAP achieves this goal by

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### offering a comprehensive set of tools. You will no longer need to search through a long list of guidance documents to find an appropriate method and/or value when conducting a site-specific risk assessment of a hazardous waste combustor. Instead, you have one self-contained document with the majority of all the available information needed to complete a risk assessment. With the HHRAP’s extensive reference list, you also have the original source of a method and/or value. This simplifies the process of deciding if the reference is appropriate to use for your specific situation.

1.5 RISK NOMENCLATURE
Unless otherwise stated, the following definitions fo r risk-related terms are from the National Academy of Sciences 1983, Risk Assessment in the Federal Government , and used throughout this guidance:
Risk Assessment The scientific evaluation of potential health impacts that may result from exposure to a particular substan ce or mixture of substances under specified conditions. Hazard An impact to human health by chemicals of potential concern. Risk An estimation of the probability that an adverse health impact may occur as a result of exposure to chemicals in the amount and by the pathways identified. Dose The amount of a substance available for interaction with metabolic processes or biologically significant receptors after crossing the exchange boundary of an organism (U.S. EPA 1998c). Exposure The condition of a chemical contacting the exchange boundary of an organism (U.S. EPA 1998c). Indirect Exposure Resulting from contact of human and ecological receptors with soil, plants, or waterbodies on which emitted chemical has been deposited. For screening level purposes, indirect exposure includes ingestion of above ground fruits and vegetables, b eef and milk, chicken and eggs, freshwater fish and soil. Direct Exposure Exposure via inhalation.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 2-1 

# Chapter 2: Characterizing Facility Emissions What’s Covered in Chapter 2: 2.1 Compiling Basic Facility Information 2.2 Identifying Emission Sources & Estimating Emission Rates 2.3 Identifying Compounds of Potential Concern (COPCs) 2.4 Estimating COPC Concentrations for Non-Detects 2.5 Evaluating Contamination In Blanks

PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. This chapter provides guidance on characterizing th e nature and magnitude of facility emissions. Characterizing includes (1) compiling basic facility information, (2) identifying emission sources, (3) estimating emission rates, (4) identifying COPCs, (5 ) estimating COPC concentrations for non-detects, and (6) evaluating contamination in blanks. You can consider the information listed in the highlighted box at the end of each section the minimum that we recommend to ensure a risk assessment is scientifically sound. However, you may want to consult up front the more detailed discussions found in each section. A more complete understanding of the re levant issues will make sure that all appropriate information is collected simultaneously. This will help minimize the time and effort expended collecting site-specific information.

2.1 COMPILING BASIC FACILITY INFORMATION
If you are a risk assessor, there is basic facility information you should consider while conducting the risk assessment, and include in the risk assessment report. Including this basic facility information in the report will enable reviewers to establish a contextual sense of how the facility relates to other facilities

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### C 

### Description of physical setting C 

### Principal business and primary production processes C 

### Normal and maximum production rates C 

### Types of waste storage and treatment facilities C 

### Type and quantity of wastes stored and treated C 

### Process flow diagrams showing both mass and energy inputs and outputs

< 

### Relevant information from an existing or propo sed permit and/or compliance documents (e.g., Waste Analysis Plan or Feedstream Analysis Plan; Startup, Shutdown, and Malfunction Plan; Certifications of Compliance; etc.) RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT and other hazardous waste combustors. It's also very important to thor oughly understand (and document) any regulatory limits evaluated in the risk assessm ent, because the risk assessm ent report informs the setting of risk-based permit limits. For example, speci fic emissions data might not be collected for a particular unit where waste feeds are controlled in lieu of demonstrating compliance with an emissions limit under the regulations (e.g., Tier I under the BI F rule for certain metals, MTEC under the HWC MACT rule). For transparency, we therefore r ecommend clearly identifying the basis for the assumptions and/or data to be used in the risk assessment, al ong with the rationale for how the information will be used.

2.2 IDENTIFYING EMISSION SOURCES & ESTIMATING EMISSION RATES
Burning hazardous waste typically emits combustion by-products from a stack. In addition to emissions from a combustion stack, types of emissions associat ed with the combustion of hazardous waste may include (1) process upsets emissions, (2) accidental releases, (3) general RCRA fugitive emissions, and if the facility is a cement kiln (4) cement kiln dust (C KD) fugitive emissions. Each of these emission source types is defined below with regards to the context and scope of this guidance.
Stack Emissions - Release of compounds or pollutants from a hazardous waste combustor into the ambient air while the unit is operated as in tended and in compliance with a permit and/or regulation (for interim status).

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### Process Upset Emissions - Release of compounds or pollutants from a hazardous waste combustor into the ambient air while the unit is not being operated as in tended, or during periods of startup or shutdown. Upset emissions usually occur during events and times when the unit is not operating within the limits specified in a permit or regulation. Conditions within the combustion system during the process upset result in incomplete destruction of the wastes, or otherwise promote the formation and/or release of hazardous compounds from combustion stacks. Upset emissions are generally expected to be greater than stack emissions. Accidental Releases - an accidental release is defined in Section 112(r) of the Clean Air Act as an unanticipated emission of a regulated substance or other extremely hazardous substance into the ambient air from a stationary source. Accidental releases are typically associated with non-routine emissions from RCRA facilities, such as the failure of tanks or other material storage and handling equipment, complete failure of com bustion and air pollution control systems (e.g. resulting from explosions, and fires), or transportation accidents. RCRA Fugitive Emissions - Release of compounds or pollutants into the ambient air from RCRA-regulated sources other than hazardous waste combustion stacks. RCRA fugitive emissions are typically associated with the re lease of pollutants from leaks in the combustion chamber (e.g., “puffs”); tanks, valves, flanges, a nd other material-handling equipment used in the storage and handling of RCRA hazardous wastes; residues from the combustion process such as ash or quench water; and other RCRA treatment, storage, or disposal units (e.g., landfills). CKD Fugitive Emissions - Release of pollutants into the ambient air caused by the handling, storage, and disposal of cement kiln dust. We generally recommend that as applicable, all of these emission source types except accidental releases be addressed in the risk assessment. Accidental rel eases aren’t within the scope of this guidance. We generally recommend evaluating accidental releases per Section 112(r) of the CAA and current Agency guidance (U.S. EPA 1996f) or the RMP Offsite Consequence Analysis Guidance , dated May 24, 1996. Despite this general guidance, it is for the permitting authority to decide on a site-specific basis whether the risk assessment will consider accidental releases.
The following subsections contain guidance for estimati ng emissions of the source types to be included in the risk assessment. Guidance on air dispersion modeli ng of stack and fugitive emissions is presented in Chapter 3.
2.2.1 Estimating Stack Emission Rates for Existing Facilities We generally consider it important to determine stack emission rates (in grams per second) of every COPC identified using the procedures outlined in Sec tion 2.3. We anticipate that emission rates for existing facilities (i.e. already built and operational) will be based on direct stack measurements from regulatory performance tests, because permitting authorities generally require performance tests before

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

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### Test Design: Performance vs. Health Criteria Performance testing involves demonstrating compliance with emission standards or performance criteria under any operational circumstance. Facilities typically wish to maximize the flexibility of operating conditions allowed by their permit. This leads to performance tests designed to demonstrate compliance even while operating under extreme conditions (i.e., conditions that may only seldom occur or may only occur for brief durations over the course of a year). Regulatory performance requirements are generally national-scale , technology-based instantaneous limits. Such performance requirements might not consider various health impacts to receptors located near a particular facility . Therefore, data needs to assess potential health risks are typically more comprehensive than those of a performance test. For example, a performance test will provide information to calculate destruction and removal efficiency (DRE) for a principal organic hazardous constituent (POHC) and perhaps measure total particulate matter, but will not typically quantify the various products of incomplete combustion (PICs) in the stack gases, nor establish particle size distribution for gases exiting the stack. Situations have occurred in which some facilities assume that the only way to maximize permit flexibility and satisfy risk assessment data needs is to conduct separate tests. We encourage another interpretation. As mentioned elsewhere, we suggest modifying performance-based test protocols to include risk assessment data requirements as appropriate to evaluate both acute and chronic exposures posed by facility-specific operations that may occur under the terms of the permit. 

### granting a permit to burn hazardous wastes, or in order to demonstrate compliance with emission standards.
As mentioned in the Special Note "How This Do cument Relates to Trial Burns" and elsewhere, we suggest incorporating data collection for a risk assessment into the regulatory performance testing program whenever possible. This will optimize th e use of both facility and permitting agency resources, and minimize expenditures associated with stack testing and subsequent data review, evaluation, and permitting. Incorporating risk assessment data collection into the performance test program can ensure that proper evaluation across test conditions is achieved for optimal data usability and versatility– both engineering considerations relating to unit operations flexibility, and streamlined data collection considerations for characterizing potential emissions.
Experience has shown us that in order to evaluate both acute and chronic reasonable maximum exposure estimates, the potential emissions evaluated in the risk assessm ent need to be based on actual operating scenarios that may occur under the terms of the permit. We acknowledge that proper design of a regulatory test program that includes risk assessment data collection is challenging for facilities that burn highly variable waste and/or have multiple operating conditions. At the same time, inadvertently omitting potential risk drivers from the risk assessment due to improper or oversimplified test design is to be avoided. Therefore, if feed streams differ between the various test conditions in the regulatory test program, we generally recommend providing appropria te rationale for this difference in the test plan, and discussing in the risk assessment report any impacts the diffe rences may have had upon the risk analysis.

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### Test Conditions’ Relation to Permit Conditions The feed and operating conditions demonstrated during the testing will define an operating envelope that not only establishes the working assumptions for the risk assessment, but also the final permit terms. If a facility collects emissions data for the risk assessment under "normal" operating conditions, additional permit limitations may be appropriate to ensure that conditions represented as normal during the test are, in fact, normal over the long-term operation of the facility. 

### In some cases, a facility may elect to focus data collection efforts for a risk assessment into one test condition in the regulatory testing program that demonstrates "normal operations" using feedstreams considered "worst-case" from an operati onal and potential emissions standpoint.
Please Note : We suggest such a test condition only for facilities that can identify and substantiate via historical operating record s the typical (or day-to-day) operating mode for the hazardous waste combustion unit and ancillary equipment, regardless of the type of waste fed. If combining multiple and variable feedstreams into a single "worst-case" feed, the mixture needs to represent those actual waste matrices and constituents that are the most difficult to burn (ensuring that the combustion unit is fairly challenged). A "worst-case" feed also needs to contain the most toxic substances managed in the unit, on a mass basis proportional to that fed at any time (ensuring that all potentially toxic emissions are quantified). Multiple and/or highly variable feedstreams that require different extremes of a wide operating envelope, or feedstreams that are combined on a disproportional mass basis to that fed at any time, may not be representative of actual operations. We're concerned that they might even result in emission estimates that are not sufficiently conservative for the risk assessment. Please see the Risk Burn Guidance for Hazardous Waste Combustion Facilities (U.S. EPA 2001c) for further information on designing a testing program that integrates risk assessment data collection into the regulatory testing of hazardous waste combustors.
We generally recommend including the risk assessor in the early planning efforts of the test program development, so that the test program can be more effectively streamlined while meeting multiple and complex data collection goals. At least three valid runs at steady state are need ed to characterize a test condition. Since steady state conditions are typically ou tlined in the test plan for each test condition and verified by field observations during the test program, resulting emission rates for any particular COPC are likely to be fairly consistent between runs for each test condition. Test reports document any abnormalities in steady state operations for a particular run or test condition. If any one run experiences significant issues that may impact the data quality or comparability with the other runs, the facility and permitting authority might decide during the test to discontinue the problem run and initiate a new run to

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

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### ensure a valid test condition. Test reports also doc ument this occurrence and identify those valid runs of the test condition.
For risk assessments, we generally recommend using th e maximum of the three emission rates identified for each COPC during a particular test condition, adjust ed for process upsets. This approach is consistent with implementing a steady state test designed fo r collecting risk data where the combustor burns representative, yet worst-case or challenging feeds, at operating conditions that are allowable and/or typical under the permit. This approach will also allow consistency in refinements to the final risk analysis that may involve several risk evaluations for different operating scenarios (i.e., across the various test conditions) in order to afford operational flex ibility while maintaining permit provisions that ensure protection of human health.
Please Note : The recommendation to use the highest of the three emission rates is an update to Section 8.1.2 of U.S. EPA (2001c). An alternative to a regulatory performance test is the use of data "in lieu of" testing. Permitting authorities generally consider this type of data on a case-by-case basis. Prior to accepting such data as a surrogate for use in the risk assessment, we reco mmend evaluating the data from both an engineering perspective and a data usability perspective. To ev aluate the similarities between combustors, consider the design and construction of the combustor and asso ciated air pollution control devices, along with the basic operating conditions of the process equipment as tested (e.g., capacity, flow rates, supplemental fuels used, etc.) to ensure compar able emissions. Stack test measurements from a similar combustor are useful if the combustor burns similar waste feed(s) in terms of constituents, type of waste matrix, and amount of waste fed on a mass basis. In addition, we recommend evaluating the methods used to quantify COPCs and associated detection limits achieved during the test, as well as verifying that the data quality documentation is acceptable for risk assessment purposes.

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### SPECIAL NOTE: HOW THIS DOCUMENT RELATES TO TRIAL BURNS We believe that generating defensible emission rates for compounds of potential concern (COPCs) is one of the most important parts of the risk assessm ent process. This requires special consideration when planning a risk assessment. Therefore, we c onsider emissions testing, risk assessment planning, and implementation as interdependent aspects of the hazardous waste combustion site-specific risk assessment process. As described elsewhere in this chapter, traditional regulatory performance tests (e.g., RCRA trial burns designed solely to measure DRE) do not sufficiently characteri ze COPC emissions for performing site-specific risk assessments . We therefore generally recommend that collecting emissions data for a site-specific risk assessment include a thorough understanding of the operating limits to be established in the regulatory permit and the possible emissions that may result under the permitted operations of the unit. Regardless of whet her the emissions data for the risk assessment is collected in a separate test condition or in multip le test conditions that are part of a regulatory performance test program, we recommend that to the extent possible, the planning, regulatory agency review, and collecting of emissions data be conduc ted simultaneously, to ensure consistency in data evaluation across test conditions is achieved a nd actual operations allowable under the permit are appropriately evaluated. This approach also elim inates redundancy or the need to repeat activities and minimizes cost expenditures overall. The guidance documents below relate to the RCRA hazardous waste combustion program. You may find the listed documents useful for developing and conducting trial burns: U.S. EPA. 1989f. Handbook: Guidance on Setting Permit Conditions and Reporting Trial Burn Results. Volume II of the Hazardous Waste Incineration Guidance Series. Office of Research and Development (ORD). EPA/625/6-89/019. January. U.S. EPA. 1989g. Handbook: Hazardous Waste Incineration Measurement Guidance Manual. Volume III of the Hazardous Waste Incineration Guidance Series. Office of Solid Waste and Emergency Response. EPA/625/6-89/021. June. U.S. EPA 1990i. Handbook: Quality Assurance/Quality Control (QA/QC) Procedures for Hazardous Waste Incineration . Office of Research and Development. EPA/625/6-89/023. January. U.S. EPA. 1992c. Technical Implementation Document for EPA’s Boiler and Industrial Furnace Regulations. Office of Solid Waste and Emergency Response. EPA-530-R-92-011. March. U.S. EPA. 2001c. Risk Burn Guidance for Hazardous Waste Combustion Facilities . U.S. EPA Region 4 and OSW. EPA 530/R/01/001. July. Generic Trial Burn Plans and/or Quality Assu rance Plans and Procedures (QAPP) developed by individual EPA regional offices or authorized states.

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### 2.2.1.1 Additional Emissions Testing Considerations
COPC emission rates demonstrated in a traditional regulatory performance test (such as a RCRA trial burn) are expected to be greater than normal emi ssion rates because a facility “challenges” its combustor during a trial burn. These challenges introduce a wide range of conditions for automatic waste feed cutoff (AWFCO) systems. Regulatory performance t ests are usually conducted under two conditions: 1. a high-temperature test, in which the emission rate of metals is maximized, and 2. a low-temperature test, in which the ability of the combustor to destroy principal organic hazardous constituents (POHCs) in the waste feed is challenged. The combination of high POHC feed rates and extreme operating conditions tested during a low-temperature trial burn typically produce higher PIC em ission rates. However, this is not true in all cases. For example, the formation of Polychlorina ted dibenzo(p)dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) doesn’t depend on “POHC incinerability” low temperature conditions. PCDDs and PCDFs can be formed catalytically in the low-temperature regions of the combustion unit or APCS. We recommend basing the decision to test under low, high, or both temperature conditions on the characteristics of the facility as discussed in the preceding section, considering facility-specific unit operation information for the particular types of wastes burned in the combustion unit as well as the particular APCS.

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### C 

### All stack sampling information (current and historical data relevant to the risk assessment) on emission rates from the combustor during normal or day-to-day operating conditions and/or regulatory performance test conditions. C 

### A description of the waste feed streams burne d during the stack sampling. This includes chemical composition and physical properties, which demonstrate that the waste feeds are representative of worst-case wastes relative to producing emissions that may pose a potential risk concern. C 

### Description of the operating conditions under whic h each set of emission rate data being used was developed. * * * NOTICE * * * The permitting authority might not request a risk assessment for every possible metal or PIC from a combustor. This doesn’t imply, however, that it will only ask for targeted sampling for COPCs during regulatory performance tests. Based on permitting experience and discussions with analytical laboratories, we maintain that complete target analyte list analyses conducted when using U.S. EPA standard sampling methods (e.g., 0010 or 0030) don’t subject facilities to significant additional costs or burdens during th e trial burn process. We recommend that stack emission samplers strive to collect as much information as possible to characterize the stack gases generated from the combustion of hazardous waste. Facilities should, then, generally expect that data collected for the risk asse ssment may include the following tests: Method 0010, Method 0030 or 0031 (as appropriate), total organic compounds (using the Guidance for Total Organics, including Method 0040), Method 0023A, Method 26A or 26 (as appropriate), the multiple metals train, and method for par ticle size distribution (e.g., CARB 501 or Method 5 Modified with analysis by Scanning Electr on Microscopy [SEM]). The permitting authority might also determine that using other test methods is appropriate for the performance test, to address detection limit or other site-sp ecific issues. See Table B.1-4 of the Risk Burn Guidance for Hazardous Waste Combustion Facilities (U.S. EPA 2001c) for a complete list of methods. 

### RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT

2.2.1.2 Estimating the Total Organic Emission (TOE) Rate
We recognize that despite all efforts, it might not be possible to identify all the compounds in the emissions from a facility. This data gap has th e potential to underestimate risks and represents a non-conservative uncertainty. Organic compounds that can ’t be identified by laboratory analysis can’t be defensibly treated as COPC’s in the risk calculations. However, these compounds might still contribute significantly to the overall risk, and so it’s reasonabl e to consider them qualitatively in the risk assessment (DeCicco 1995; U.S. EPA 1994i).

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### U.S. EPA developed the total organic emissions (TOE ) test as one approach to account for unidentified organic compounds because pre-existing methods, such as total hydrocarbon analyzers, don’t fully determine the total mass of organics present in st ack gas emissions (Johnson 1996). We anticipate that trial/risk burns will generally include the TOE test, inorder to provide sufficient information to address concerns about the unknown fraction of organic emissions . The TOE test is used in conjunction with the identified organic compounds to calculate a TOE factor. We recommend using the TOE factor to qualitatively evaluate potential risks from the unidentifie d fraction of organic compounds in the stack gas.

The TOE test is the subject of other guidance, such as the Guidance for Total Organics (U.S. EPA 1996d) with additional clarification provided in Section B.7 of U.S. EPA (2001c). Proper use of TOE data depends on a good understanding of the test method a nd how the data is reported. The TOE method defines total organics as the sum of three fractions:
Fraction 1: Total Volatile Organic Compounds (TO VOC 

### ) (referred to as Field GC Component in the TO Guidance) - The fraction of organic compounds with boiling points less than 100°C. This VOC fraction is collected using U.S. EPA Method 0040. U.S. EPA Method 0040 allows for quantification of the total m ass of organic compounds with boiling points less than 100°C, determined by summing the gas chro matograph/flame ionization detector results as described in the TO Guidance. Fraction 2: Total Chromatographical Semivolatiles (TO SVOC 

### ) (referred to as Total Chromatographical Organics Component in the TO Guidance) - The fraction of organic compounds with boiling points from 100°C to a nd including 300°C. This VOC fraction is collected using modified U.S. EPA Method 0010 procedures as defined by U.S. EPA (1996d). The total mass of organic compounds with boiling points 100°C up to and including 300°C is determined by summing the total gas chromatograph/flame ionization detector results as described in the TO Guidance. Fraction 3: Total Gravimetric Compounds (TO GRAV 

### ) (referred to as Gravimetric component in the TO Guidance) - The fraction of organic compounds with boiling points greater than 300°C. This fraction is determined by using modified U.S. EPA Method 0010 procedures defined by U.S. EPA (1996d), which qua ntify the mass, above this fractions boiling point, by measuring the total mass by evaporati on and gravimetry (weighing) for nonvolatile total organics.
Please note that the TO total (TO TOTAL 

### ) is the sum of the sums of each fraction. The sum of the TO fractions is described as follows:

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 2-11 

### Equation 2-1

Equation 2-2 where: TO TOTAL 

### = stack concentration of TO, in cluding identified and unidentified compounds (mg/m 3 

### ) TO VOC 

### = stack concentration of volatile TO, including identified and unidentified compounds (mg/m 3 

### ) TO SVOC 

### = stack concentration of SVOC TO, including identified and unidentified compounds (mg/m 3 

### ) TO GRAV 

### = stack concentration of GRAV TO, including identified and unidentified compounds (mg/m 3 

### ) Use the TOE data in conjunction with the identified data to compute a TOE factor. Previously-computed TOE factors range from 2 to 40. The HHRAP defines the TOE factor as the ratio of the TO TOTAL

### mass to the mass of identified organic compounds, as calculated by the following equation:

where FTOE 

### = TOE factor (unitless) TO TOTAL 

### = total organic emission (mg/m 3 

### ) C i 

### = stack concentration of the i th identified COPC (mg/m 3 

### ) Identifying the organic compounds in the denominator of Equation 2-2 is one of the most critical components of the TOE factor. Although the permitting authority may not request that you analyze the organic compounds with all possible analytical methods, you may wish to consider the effects that gaps in compound-specific identification may have on the computation of the TOE factor. For example, hazardous waste-burning cement kilns have expressed concern about the amount of light hydrocarbons that may evolve from the raw materials processed in the cement kilns, because these light hydrocarbons have not typically been identified in trial burns. If such concerns are significant, you and the permitting authority might choose to use additional test methods in the trial burn in order to speciate the maximum number of organic compounds.
We also generally recommend including tentativel y identified compounds (TICs) in the denominator when computing the TOE factor, so that appropriate cr edit is given to defensible efforts at identifying the

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### maximum number of organic compounds. Finally, we generally recommend that non-detect COPCs be treated consistently between the risk assessment a nd TOE evaluation. That is, if a non-detected constituent is deleted as a COPC (See Section 2.3), then it would not be included in the identified fraction of the TOE equation. COPCs identified per Section 2. 3, but not detected, might be included in the TOE factor equation at the reliable detection limit (non-is otope dilution methods) or the estimated detection limit (isotope dilution methods).
It’s important to carefully evaluate the results of the gravimetric fraction when using the TOE factor. Both regulated industry and U.S. EPA have expressed some concern that the gravimetric fraction may over-report the organic fraction. It’s been suggested that the gravimetric fraction may consist of organic and/or inorganic mass not directly attributable to organic incinerator emissions (U.S. EPA 1997a). The U.S. EPA Office of Research and Development (ORD ) National Risk Management Research Laboratory (NRMRL) recently conducted a series of experiments to i nvestigate this issue. The results indicate that it is indeed possible for inorganic mass to become sol uble and retained in the TOE train methylene chloride extract. More importantly, the ORD/NRMRL resear ch identified and demonstrated techniques for successfully mitigating this problem. Details of the experiments, results, and procedures for mitigating the GRAV bias will be made available in a forthcoming ORD report. Ultimately, these procedures will be contained in the forthcoming TOE guidance currently being revised by ORD. Further information on this topic is also available in U.S. EPA (2001c).
We recommend using the TOE factor in the uncertain ty section of the risk assessment report to evaluate the risks from the unknown fraction of organics. Th e permitting authority can then evaluate the TOE factor and assess to what extent actual risks may be great er than estimated risks. For example, if the risk from the known portion of the emissions show that ri sks may be borderline and/or the TOE method shows that the unknowns are a significant portion of the emission profile, the permitting authority has several options, including: 1. Describe in a narrative form what is known of the unknown portion of the emissions. 2. As a bounding estimate, attribute a risk to the unknown portion of the emissions. An example is presented as a preferred opti on in U.S. EPA (1994f), which assumes that the unknown compounds are similar in toxicity and chemical properties to the known compounds taken as a whole. The re ferenced equation is as follows:

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

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### Equation 2-2A

where Q i,adj 

### = adjusted emission rate of compoundi (g/s) Q i , 

### = emission rate of compound i (g/s) TO TOTAL 

### = total organic emission (mg/m 3 

### ) C i 

### = stack concentration of the i th identified COPC (mg/m 3 

### ) 3. Recommend additional testing to identify a greater fraction of the organic compounds. 4. Specify permit conditions that further contro l total organic emissions or that further control the risks associated with known emissions.
Variations of the TOE factor can be useful to addr ess site-specific concerns. For example, compute three separate TOE factors based on the apportioning provided by the TOE test (i.e., TO VOC 

### , TO SVOC 

### , and TO GRAV 

### ). Then evaluate the unknowns associated with each fraction of unidentified organic compounds separately.
2.2.2 Estimating Emission Rates for Facilities with Multiple Stacks
We generally recommend that the risk assessment c onsider emissions from all combustors burning hazardous waste at a facility, not just the unit cu rrently undergoing the permitting process. As discussed further in Chapter 3, air dispersion modeling fo r each combustor (source) is frequently conducted separately, to evaluate risk on a stack- or sour ce-specific basis. An example case is a chemical manufacturing facility which operates both an on-site incinerator and several hazardous waste-burning boilers. Whether it is the incinerator or the boile rs being permitted, the risk assessment considers the emissions from all the combustors in the estimate of facility risk. In addition to RCRA combustors, emissions from other RCRA treatment, storage, or di sposal units (e.g., open burning/open detonation and thermal desorption) might also be incl uded in the risk evaluation in some cases.
2.2.3 Estimating Stack Emission Rates for Facilities Not Yet Operational
The permitting process for new hazardous waste combustion facilities includes submitting information of sufficient detail for the regulatory authority to eval uate compliance with existing regulations, guidance, and standards of protectiveness. Stack (or other source) locations and dimensions, design flow and

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

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### emission rate estimates, waste feed characteristics, surrounding building dimension data, facility plot plans, and terrain data are frequently reviewed and used in a pre-operation risk assessment. This assists decision-making and designing permit requirements.
We generally recommend reviewing design emission rat es, waste feed characteristics, and other design data, along with supplementary documentation, to make sure they are representative, accurate, and comprehensive. Good engineering practice dictates a check of, and comparison with, data from similar existing units. Stack test reports for facilities of similar technology, design, operation, capacity, auxiliary fuels, waste feed types, and APCSs can be useful in estimating COPC emission rates for new facilities that have not been constructed. In addition to d esign data, particle size distribution data from a similar type unit that is operational may be useful. Estimatedemission rates used to complete pretrial burn risk assessments are frequently compared to the measu red emission rates from actual performance tests completed after the new facility receives a permit, is constructed and operational.
If surrogate data from similar facilities aren’t ava ilable, some state environmental agencies enforce emission rate limits based on state laws. Since th ese limits cannot be exceeded, you could use them to develop emission rate estimates for the risk assessment. A trial or risk burn could then demonstrate that facility emissions are less than those cons idered in the permit and risk assessment.
2.2.4 Estimating Stack Emission Rat es for Facilities Previously Operated
We generally recommend that the risk assessment also consider emissions from the historical operation of other combustors burning hazardous waste at the f acility, not just the unit currently undergoing the permitting process. The permitting authority will determine the appropriateness of this on a case-by-case basis. An example case might be when the emissions from historical operation of a source or sources have already resulted in potential risk concerns at or near the facility. You could model emissions from historical operations as a separate source or, if applicab le, include them in the fate and transport equations by adding the previous years of operation to the an ticipated time period of combustion for an existing or newly operating source. In some cases, you might also include historical emissions from other RCRA treatment, storage, or disposal units at the f acility (e.g., open burning/ope n detonation and thermal desorption) in the risk assessment, in addition to RCRA combustors.

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### C 

### All stack test reports for combustors used to develop emission rate estimates C 

### If using surrogate data to assess a new facility, descriptions of how the combustion data used represent similar technology, design, operation, capacity, auxiliary fuels, waste feed types, APCSs, and particle size distributions C 

### Demonstration that the data used to develop the emission rate estimates were collected using appropriate U.S. EPA sampling and analysis procedures C 

### The range of data obtained, and values used, in completing the risk assessment RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT

2.2.5 Emissions From Process Upsets
It is possible for unburned hazardous waste to be emitted through the stack as a result of various process upsets, such as start-ups, shutdowns, and malfunctions of the combustion unit or APCS. Emissions can also be caused by operating upsets in other areas of th e facility (e.g., an upset in a reactor which vents gases to a boiler burning hazardous waste could trigger a process upset in the boiler, resulting in increased emissions). U.S. EPA (1994i) indicates that upsets aren’t generally expected to significantly increase stack emissions over the lifetime of the facility.

To account for the increased emissions associated with process upsets, we generally recommend that the stack emission rates estimated from trial burn data be multiplied by an upset factor. The upset factor is not applied to non-PIC emission rate estimates where th e total mass of a constituent in the waste feed is assumed to be emitted. When available, site-specific emissions or process data can be useful to estimate the upset factor. You may also want to consider a nd evaluate the following types of data to derive the upset factor: C 

### Data from continuous emissions monitoring systems that measure stack carbon monoxide, oxygen, total hydrocarbon (if re quested), or opacity (if appropriate) C 

### Data on combustion chamber, APCS, or stack gas temperature C 

### Data on hazardous waste residence time C 

### Frequency and causes of automatic waste feed cutoffs (AWFCO) C 

### Frequency of start-up and shut-down events C 

### Ratio of AWFCO frequency a nd duration to operating time

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### C 

### Historical operating data demonstrating the frequency and duration of process upsets C 

### A discussion of the potential cause(s) of the process upsets C 

### Estimates of upset magnitude or emissions C 

### Calculations which describe the derivation of the upset factor. RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT C 

### APCS operating variables like baghouse pressu re drop, liquid scrubber flow rate, or electrostatic precipitator voltage C 

### Stack test data collected while the combustor was operated under upset conditions You might use this information to estimate the magn itude of the increase in emissions and the percentage of time, on an annual basis, that the unit operates at upset conditions. Additional information regarding upset factors for liquid-burning BIFs is available in the Louisiana Chemical Association (LCA) Letter Report on Upset Factors, dated October 27, 1999, available on the U.S. EPA Region 6 web site ( www.epa.gov/region06/ ).
If you don’t have site-specific data, or they are inappropriate for deriving an upset factor, we generally recommend estimating upset emission rates using a procedure based on work by the California Air Resources Board (CARB) (1990). Estimating Emissions from Process Upsets: To represent stack emission rates during process upsets, multiply the emission rate developed fro m the trial burn data by 2.8 for organics and 1.45 for metals. These factors are derived by assuming that emissions during process upsets are 10 times greater than emissions measured during the trial burn. Since the unit doesn’t operate under upset conditions continually, the factor is adjusted to account for only the period of time, on an annual basis, that the unit operates unde r upset conditions. For organic compounds, the facility is assumed to operate as measured during th e trial burn 80 percent of the year and operate under upset conditions 20 percent of the year [( 0.80)(1)+(0.20)(10)=2.8]. For metals, the combustor is assumed to operate as measured during the trial burn 95 percent of the year and operate under upset conditions the remaining 5 per cent of the year [(0.95)(1)+(0.05)(10)=1.45]. Catastrophic process upsets brought about by complete failure of combustion and air pollution control systems (e.g. resulting from non-routine events such as explosions, fires, and power failures) are typically considered accidental releases and conseque ntly aren’t addressed by this guidance.

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### 2.2.6 RCRA Fugitive Emissions
RCRA fugitive emission sources frequently evaluated in site-specific risk assessments include waste storage tanks; process equipment ancillary to the com bustor; and the handling and disposal of combustion system residues such as ash. Fugitive emissions fro m other RCRA treatment, storage, or disposal units (e.g., landfills) may also warrant evaluation in some cases.
This section contains guidance for quantitatively es timating fugitive emissions using procedures outlined in other U.S. EPA guidance. Guidance regarding air dispersion modeling of fugitive emissions is presented in Chapter 3.
2.2.6.1 Quantitative Estimation of RCRA Fug itive Emissions from Process Equipment
We generally recommend the following series of steps to quantitatively estimate RCRA fugitive emissions: (1) identify equipment to evaluate as a fugitive emission source(s); (2) group equipment, as appropriate, into a combined source; and (3) estim ate compound-specific emission rates for each resulting source. We illustrate an example in Figures 2-1 a nd 2-2 and Tables 2-1 and 2-2, to help explain the recommended steps. Figure 2-1 presents the plot plan of a hypothetical facility that includes one RCRA combustion unit (CU-1), two hazardous waste feed storage tanks (WST-1 and WST-2), and ancillary equipment identified in a RCRA Part B permit application.
Step 1: Identify Fugitive Emission Sources - Generally, identify RCRA fugitive emission sources such as waste storage tanks and process equipment that comes in contact with a RCRA hazardous waste. Such equipment is specified in Title 40, Code of Federal Regula tions (40 CFR) Part 265, Subpart BB. Equipment covered under Subpart BB includes: C 

### Pumps C 

### Valves C 

### Connectors (flanges, unions, tees, etc.) C 

### Compressors C 

### Pressure-relief devices C 

### Open-ended lines C 

### Product accumulator vessels C 

### Sampling connecting systems C 

### Closed vent systems

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### C 

### Agitators Note each fugitive emission source on a facility plot map with a descriptor and the location denoted with Universal Transverse Mercator (U TM) coordinates (specify if North American Datum [NAD] of 27 or NAD83).
Step 2: Group Equipment Into a Combined Source - To significantly reduce the effort required to complete air dispersion modeling and the subse quent risk assessment, group equipment in close proximity, and evaluate as a single combined s ource. The speciated emission rates for the group are the summation of the emissions from the grouped individuals. Clearly denote on a facility plot plan or map the area extent of the grouped or combined source, as defined by UTM coordinates (specify if NAD27 or NAD83). Define the area extent of the combined source using the actual locations of the equipment being gr ouped, without exaggeration to cover areas without fugitive sources. It may also be useful to consider how fugitive emission sources are to be defined when conducting the air dispersion modeling (see Chapter 3). Equipment in two areas of the hypothetical facility shown in Figure 2-1 are grouped into combined sources; these consist of the Waste Feed Storage Area and the RCRA Combustor Area.
Step 3: Estimate Fugitive Emissions from Tanks - Obtain fugitive emission rates for waste storage tanks from the facility’s emission inventory or Title V air permit application prepared in compliance with Clean Air Act Amendments of 1990 (see example provided as Figure 2-2). If that information is not available, fugitive emissions from storage tanks can be calculated using U.S. EPA’s TANKS Program or by following the procedures outlined in U.S. EPA (1995a), “Compilation of Air Pollution Emission Factors, January 1995.” The information needed to accurately estim ate fugitive emission rates from storage tanks includes, but is not limited to: C 

### Dimensions of the tanks - Shell height and diameter C 

### Characteristics of the tank roof - Color and shade - Condition (e.g., poor, good) - Type (e.g., cone, dome) - Height - Radius or slope - Fixed or floating C 

### Characteristics of the shell - Color and shade - Condition (e.g., poor, good) - Heated C 

### Settings on breathe vents - Vacuum setting

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### - Pressure setting C 

### Characteristics of the stored liquids - Maximum and annual average liquid height - Working volume - Turnovers per year - Net throughput - Average annual temperature - Vapor pressures of speciated constituents (at annual average temperature) Step 4: Estimate Fugitive Emissions from Process Equipment - Estimate fugitive emissions for each type of equipment listed under 40 CFR Part 265, Subpart BB by using the following four approaches, listed in order of increasi ng refinement and data requirements: C 

### Average Emission Factor Approach (AEFA) C 

### Screening Ranges Approach (SRA) C 

### U.S. EPA Correlation Approach (EPACA) C 

### Unit-Specific Correlation Approach (USCA) These four approaches would generally be applicab le to estimate fugitive emission rates of volatile organic compounds (VOCs) from equipment on any facility. Except for the AEFA method, all of the approaches need screening data collected using a portable monitoring device (PMD). Because data on fugitive emissions at a facility is typically limited, th e AEFA method is expected to be used in most cases, and therefore has been selected for use in the example illustrated in Figure 2-1, and Tables 2-1 and 2-2. However, we recommend using more refined appro aches such as SRA, EPACA, or USCA, if sufficient data is available. U.S. EPA (1995k) provides a de tailed discussion on these three approaches. Additional information on estimating fugitive emission rates is available in U.S. EPA (1995k), “Protocol for Equipment Leak Emission Estimates, EPA-453/R-95-017."

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### FIGURE 2-1 EXAMPLE FACILITY PLOT MAPHuman Health Risk Assessment ProtocolChapter 2: Facility CharacterizationSeptember 2005U.S. EPA Region 6U.S. EPAMultimedia Planning and Permitting DivisionOffice of Solid WasteCenter for Combustion Science and Engineering2-21FIGURE 2-2EXAMPLE EMISSIONS INVENTORYHuman Health Risk Assessment ProtocolChapter 2: Facility CharacterizationSeptember 2005U.S. EPA Region 6U.S. EPAMultimedia Planning and Permitting DivisionOffice of Solid WasteCenter for Combustion Science and Engineering2-22TABLE 2-1EXAMPLE CALCULATIONTOTAL FUGITIVE EMISSION RATES FOR EQUIPMENT IN WASTE FEED STORAGE AREA1 2 3 4 5 6 7 8 9 10FugitiveEmissionSourceWasteStreamType of WasteStream InServiceEquipmentTypeNumber of EachEquipmentType Per WasteStreamEquipment EmissionFactorsTotal VOCWeightFractionOperationalTime Period ofEquipment(days)Total VOCEmissions Rate byEquipment (g/sec)Total FugitiveEmission Rate(g/sec)(kg/hr) (g/sec)WasteFeedStorageAreaProcessAWastesLight Liquid Pumps 3 0.01990 0.00553 0.9 180 0.014930.14926Light Liquid Valves 70 0.00403 0.00112 0.9 180 0.07056Light Liquid Connectors 30 0.00183 0.00051 0.9 180 0.01377Light Liquid Tank WST-1 1 -- -- 0.9 180 0.02Light Liquid Tank WST-2 1 -- -- 0.9 180 0.03ProcessBWastesHeavy Liquid Pumps 2 0.00862 0.00239 0.6 180 0.002870.06857Heavy Liquid Valves 75 0.00023 0.00112 0.6 180 0.0504Heavy Liquid Connector 50 0.00183 0.00051 0.6 180 0.0153Heavy Liquid Tank WST-1 1 -- -- 0.6 0 0Heavy Liquid Tank WST-21 -- -- 0.6 0 0Notes:Column 1 Equipment in the Waste Feed Storage Area was identified and grouped as a combined RCRAfugitive emission source with anarea extent defined by UTMcoordinates (NAD83).Column 2 The waste streams serviced by equipment in the WasteFeed Storage Area can be determined through review of the facility's RCRA Part B Permit Application, AirEmission Standards.Column 3 The type of waste stream in service, defined as lightor heavy for determination ofequipment-specific emission factors, can be determined from review of wastestream vapor pressure.Column 4 Similar types of equipment can be grouped according to the most applicable equipment-specific emission factor and typeof waste stream service (light or heavy)provided in U.S. EPA (1995k).Human Health Risk Assessment ProtocolChapter 2: Facility CharacterizationSeptember 2005U.S. EPA Region 6U.S. EPAMultimedia Planning and Permitting DivisionOffice of Solid WasteCenter for Combustion Science and Engineering2-23Column 5 The number of equipment type (per waste stream) identified in column 3.Column 6 Emission factors specific to each type of equipment canbe obtained from U.S. EPA (1995k), with the exception of storage tanks.Column 7 Weight fraction of total volatile organic compounds wasobtained from dividing the concentration of VOCs (mg/L) by thedensity of the waste stream (mg/L).Column 8 Assumed the equipment is operational for 180 days a year.Column 9 Equipment-specific fugitive emission rates were determinedby multiplying Columns 5, 6, and 7. Emission rates for tanks were obtained from Title V air permitapplication. In the absence of such data, emission rates for tanks can be calculated using U.S. EPA’s TANKS Program or by following the procedures outlined inU.S. EPA (1995a).Column 10 The total fugitive emission rate for each waste streamis determined by summing emission rates for all the equipment.Table 2-2 presents calculations for estimatingspeciated fugitive emissions.

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### TABLE 2-2 EXAMPLE CALCULATION SPECIATED FUGITIVE EMISSIONS FOR EQUIPMENT IN WASTE FEED STORAGE AREA 1 2 3 456

Fugitive Emission

Source Waste Stream Waste Stream Composition Weight Fraction of Each VOC In

Waste Stream (%) Total Fugitive Emission

Rate (g/sec) Speciated Fugitive Emissions (g/sec)

Waste Feed Storage Area Process A Wastes Acetaldehyde 0.20 0.14926 

### 0.0030 Acetonitrile 0.25 0.0037 2-Nitropropane 0.25 

### 0.0037 Nitromethane 0.20 

### 0.0030

Process B Wastes Acetaldehyde 0.20 0.06857 0.0137 Acetonitrile 0.10 0.0069 Methanol 0.20 0.0137 Propionitrile 0.05 

### 0.0034
Notes: Column 1 Equipment in the Waste Feed Storage Area was identified and grouped as a combined RCRA fugitive emission source with an aerial extent defined by UTM coordinates (NAD83). Column 2 The waste streams serviced by equipment in the Waste Feed Storage Area can be determined through review of the facility’s RCRA Part B Permit Application, Ai r Emission Standards. Column 3 The waste stream composition can be determined from analytical data Column 4 Weight fraction of compounds in the waste stream can be determined from analytical data or review of the facility’s Title V Air Permit Application, Emissions Inventory Questionnaire (EIQ) for Air Pollutants (see example in Figure 2-2). Column 5 The total fugitive emission rate for each wa ste stream was obtained from Column 10, Table 2-1. Column 6 Speciated fugitive emissions were obtained by multiplying Column 4 and 5.



### An Example Calculation Using the AEFA Method
Information needed to estimate fugitive emi ssion rates using the AEFA method includes:
C 

### Type of waste stream associated with each equipment type (Columns 2 and 3, Table 2-1) - light liquids are those in which the sum of the concentration of individual constituents with a vapor pressure over 0.3 kilopascals (kPa) at 20°C is greater than or equal to 20 weight percent - heavy liquids are all others liquids not meeting the definition of light liquids as specified above

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### C 

### Number of each equipment type associated with each waste stream (Columns 4 and 5, Table 2-1) C 

### Total VOC weight fraction of each waste stream (Column 7, Table 2-1) C 

### Weight fraction of each VOC in each waste stream (Columns 3 and 4, Table 2-2) C 

### Operational time period of equipment (Column 8, Table 2-1)
In the AEFA method, equipment is grouped by waste streams of similar characteristics and VOC composition (Columns 1 and 2, Table 2-1). Howe ver, the AEFA method doesn’t account for different site-specific conditions such as temperature, vapor pressure, or screening values, among process units within a source category. Site-specific factors can significantly influence fugitive emission rates of leaks from equipment.
U.S. EPA (1995k) presents the average emission factors (Column 6, Table 2-1) for synthetic organic chemicals manufacturing industry process units, refineri es, and natural gas plants. The following table is an excerpt from this guidance document. These emi ssion factors are most valid for estimating rates of emissions from a grouping of equipment over a long time period.

TABLE 2-3 SOCMI AVERAGE EMISSION FACTORS
Equipment type Service Emission factor (kg/hr/source) Valves Gas Light liquid Heavy liquid 0.00597 0.00403 0.00023 Pump seals Light liquid Heavy liquid 0.0199 0.00862 Compressor seals Gas 0.228 Pressure relief valves Gas 0.104 Connectors All 0.00183 Open-ended lines All 0.0017 Sampling connectors All 0.0150 Source: U.S. EPA (1995k)

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### C 

### Summary of the step-by-step process conducted to evaluate fugitive emissions C 

### Facility plot map clearly identifying each fugitive emission source with a descriptor and the location denoted with UTM coordinates (specify if NAD27 or NAD83). C 

### Speciated emission rate estimates for each w aste stream serviced by each source, with supporting documentation C 

### Applicable discussion of monitoring and contro l measures used to mitigate fugitive emissions RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT To calculate the total VOC emissions rate for a specified equipment type, multiply the equipment emission factor by the total VOC weight fraction and the number of each equipment type per waste stream (Column 9, Table 2-1 = Column 6 x Column 7 x Column 5).
Generate the total fugitive emission rate for the waste stream (Column 10, Table 2-1) by summing the total VOC emission rates for each equipment type. Speciated fugitive emissions are then calculated by multiplying the weight fraction of each VOC in the w aste stream and the total fugitive emission rate for the waste stream (Column 6, Table 2-2 = Column 4 x Column 5). This speciated emission rate is the emission rate used in the risk assessment.

2.2.6.2 Fugitive Emissions from Combustor Leaks

We recommend that when appropriate, the risk assessm ent evaluate fugitive emissions resulting from the construction, design, or operation of a hazardous wast e combustor. Examples of fugitive emissions from combustor leaks include:
C 

### Combustors operating under negative pressure may experience temporary positive pressures (“puffing”) that cause fugitive emissions. This condition can occur when a slug of high BTU waste is combusted, causing a rapid expansion in the volume of combustion gases that exceeds the volume of the combustion chamber. C 

### Fugitive emissions resulting from the day-to-day operation of the combustor and APCS. These emissions will typically include (1) leaks that occur due to a positive pressure in the APCS, and (2) routine maintenance activities such as replacement of baghouse collection bags.

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### C 

### Process design information and drawings (if necessary) C 

### Past operating data indicating the frequency, duration, and magnitude of combustor leaks C 

### Information regarding the probable cause of combustor leaks C 

### Summary of procedures in place to monitor or minimize fugitive emissions resulting from combustor leaks RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT Currently, we don’t offer any specific guidance on how to quantitatively estimate fugitive emissions from hazardous waste combustors. However, if no site-sp ecific quantitative methods are available, one option is to address risks associated with leaks in the uncertainty section of the risk assessment. Under such an approach, the permitting authority could review facility -specific data to determine whether or not the design addresses equipment leaks and whether the operational data indicate that equipment leaks may be a problem.

2.2.7 RCRA Fugitive Ash Emissions
Burning hazardous waste may produce flyash. Fugitiv e particle emissions may result from the associated collection, handling, and disposal of the flyash. Ty pically, fugitive emissions of flyash collected from an air pollution control device (APCD) will occur during tr ansfer into covered truc ks or other conveyance mechanisms prior to disposal. Emissions genera ted during the loading process can be controlled by APCDs or other types of equipment. However, some of the flyash may still escape into the atmosphere as fugitive emissions.
We generally recommend the following steps to qua ntitatively estimate RCRA fugitive ash emissions: (1) determine an empirical emission factor, (2) estimat e the flyash generation rate, and (3) account for air pollution control equipment, if applicable. As dem onstrated in the example calculation below, it is then possible to estimate the fugitive ash emission rate by multiplying the empirical emission factor by the flyash generation rate and, if applicable, the contro l deficiency of the air pollution control equipment.

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### Step 1: Determine an Empirical Emission Factor - One approach to estimate particle emissions associated with flyash loading and unloading is to use an empirical emission factor of 1.07 lb per ton flyash. This factor is based on a field testing program conducted at a coal fired power plant equipped with an electrostatic precipitato r (ESP) (Muleski and Pendleton 1986). Because burning coal and hazardous wastes are similar activ ities, flyash generated from similar control devices is expected to behave similarly under the same conditions, with respect to fugitive emissions. In general, particle behavior is dependent more on the physical form of the flyash than on the feed (or waste) stream being burned. The emission factor determined during the empirical study (0.107 lb per ton flyash) can be adjusted by a factor (e.g., 10) to account for the fact that the flyash from burning coal (in the study) was wetted. Depending on the facility, the flyash from the hazardous waste combustion facility may or may not be wetted. Step 2: Estimate the Flyash Generation Rate - Obtain the APCD flyash generation rate from the Part B Permit Application. Obtain the total ash conten t of the “generic” waste streams created from the waste profile. Both values should be approximately the same. Since a major portion of ash fed to the combustor is converted to bottom ash, it is lik ely that this value can be assumed to be a high estimate of the actual flyash generation rate. Step 3: Account for Air Pollution Control Equipment - If an APCD is used for controlling emissions during flyash handling operations, you can genera lly apply an efficiency factor (e.g., 99.5 percent) to the emission rate. An efficiency f actor of 99.5 percent is based on typical collection efficiencies of particulate matter control devices, fo r the particle sizes in the range of 2.5 to 10 um (U.S. EPA 1995a). Example Calculation
Multiply the empirical emission factor (Step 1) times the estimated flyash generation rate (Step 2): [(1.07 lb per ton) * (5,000 tons per year) = 5,350 lbs per year]. To account for the air pollution control equipment, multiply the product of Steps 1 and 2 times one minus the fabric filter efficiency (Step 3) to calculate th e final RCRA fugitive ash emission rate for use in the risk assessment: [(5,350 lbs per year) * (1 - 0.995) = 26.75 lbs per year].
2.2.8 Cement Kiln Dust (CKD) Fugitive Emissions
CKD is the particulate matter (PM) that is remove d from combustion gas leaving a cement kiln. This PM is typically collected by an APCS—such as a cyclone, baghouse, ESP—or a combination of APCSs. Many facilities recycle a part of the CKD back in to the kiln. Current and applicable guidance on evaluating CKD includes (1) the Technical Background Document for the Report to Congress (U.S. EPA 1993g), and (2) the regulatory determination of CKD (60 FR 7366, February 7, 1995).

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### Most CKD constituents (for example, metals) aren’t volatile but could be released to air through fugitive dust emissions as volatile or semivolatile organics. These emissions can be in gaseous form and present in relatively low concentrations, if at all (U.S. EPA 1993a). Dust particles may be suspended in the air by either wind erosion or mechanical disturbances. The extent to which dust is blown into the air by wind erosion depends on several site-specific character istics, including (1) the texture (particle size distribution) and moisture content of the CKD on th e surface of piles, (2) non-erodible elements, such as clumps of grass or stones on the pile, (3) presence of a surface crust, and (4) wind speeds. Mechanical disturbances that can suspend CKD constituents in the air include (1) vehicular traffic on and around CKD piles, (2) CKD dumping and loading operations, and (3) transportation of CKD around a plant site in uncovered trucks. Cement plants may use various control measures to limit the release of CKD to the air. For example, CKD may be pelletized in a pug mill, compacted, wetted, and covered to make the material less susceptible to wind erosion.
To keep the dust down, many facilities add water to CKD before disposal, to agglomerate individual particles. In addition, as CKD sits in a pile e xposed to the elements, occasional wetting by rainfall may form a thin surface crust in inactive areas of the pile. This acts to mitigate air entrainment of particles. However, based on field observations by U.S. EPA (1993g), neither surface wetting nor natural surface crusting eliminates the potential for CKD to be blow n into the air. Wetting the dust before disposal provides incomplete and temporary control because wate r is infrequently applied, and the dust ultimately dries and returns to a fine particulate that is available for suspension and transport. Similarly, a surface crust may develop, but (1) the crust breaks when vehi cles or people move on the pile, and (2) fresh dust is regularly added to the pile, providing a continual, e xposed reservoir of fine particles. Please note that a crust doesn’t always form, for a variety of reasons such as weather and CKD chemistry.

CKD constituents that are released to the air are transported and dispersed by the winds, and are ultimately deposited onto land or water, either by settling in a dry form or by being entrained in precipitation.
2.2.8.1 Composition and Characteristics of CKD
We evaluated the potential direct and indirect ri sks resulting from on-site and off-site management of CKD (U.S. EPA 1993g; 1993h). These studies highlight the limited amount of available information regarding variation in the chemical constituents of CKD generated by facilities burning hazardous waste

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### C 

### Physical data, including particle size distribution and density C 

### Chemical data, including organic and inorganic analytical tests similar to those used for sampling combustion gases C 

### Plant net CKD generation rate (how much CKD per year that is available for disposal) C 

### Ambient air monitoring data C 

### CKD management, transportation, storage, and disposal methods C 

### Containment procedures, including fugitive dust prevention measures and the area of exposed CKD C 

### Meteorological data, including wind speed and precipitation RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT as fuel, and by facilities burning only fossil or nonhazardous waste fuels. There may also be differences in composition between the “as-generated” CKD -- a portion of which is recycled back into the system – and the “as-managed” CKD that is disposed of on or offsite.
The air exposure pathway is generally of concern for CKD, because the dust is a fine PM that is readily suspendable, transportable, and respirable in air. In general, particles that are # 

### 100 micrometers can be suspended in the wind and transported. Within this range, particles that are # 

### 30 micrometers can be transported for considerable distances dow nwind. However, particles that are # 

### 10 micrometers are of primary concern for respiration by humans (U.S. EPA, 1993g). Virtually all of the dust generated at the 15 facilities evaluated by U.S. EPA (1993g) in the Cement Kiln Dust Report to Congress may be suspended and transported in the wind (that is, the vast majority of particles are # 

### 100 micrometers), and over two-thirds of all CKD particles generated may be transported over long distances. Additionally, a significant percentage of the total dust generate d (from 22 to 95 percent, depending on kiln type) comprises respirable particles that are # 

### 10 micrometers.

2.2.8.2 Estimating CKD Fugitive Emissions
In general, the HHRAP doesn‘t address quantitative estimation of risk from fugitive CKD emissions. However, risk assessments of cement manufacturing fac ilities are still able to evaluate the fugitive CKD emissions qualitatively. The Technical Background Document for the Report to Congress (U.S. EPA

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### 1993g), includes methods to estimate the magnitude of fugitive emissions from the handling, storage, and disposal of CKD. Sampling data of CKD collect ed during maximum waste metal feed rate conditions from the trial burn, risk burn and/or certification of compliance tests may also be useful in evaluating CKD fugitive emissions. You can then evaluate it qua litatively by comparing the risks estimated for the kiln stack emissions, to the high end national screening level estimated by U.S. EPA for CKD in U.S. EPA (1993g) and the regulatory determination of CKD (60 FR 7366, February 7, 1995). If the risks are equivalent, the combined risks appear significant, or the risks attributed to the CKD are greater than the risks estimated for the kiln stack emissions, it might be appropriate to evaluate the risk from CKD emissions in a more quantitative fashion. We ge nerally recommend that the permitting authority make sure that any qualitative evaluation includes a comp arison of the conditions at the facility to the conditions at the model facilities we evaluated in U.S. EPA (1993g; 1993h). In addition, an analysis of a specific facility’s compliance with other risk-based environmental statutes and regulations is often an appropriate method to qualitatively evaluate risks associ ated with the handling, storage, and disposal of CKD.

2.3 IDENTIFYING COMPOUNDS OF POTENTIAL CONCERN
Compounds of potential concern (COPCs) are those compounds evaluated throughout the risk assessment. There is no universal list of COPCs, because a compound that’s a COPC for one combustor may not be a COPC for another combustor. COPC s in the emissions from hazardous waste combustors vary widely, depending on the type of
< 

### combustor,
< 

### fuel and hazardous waste feed being burned, and
< 

### APCS used.
COPCs include metals, products of incomplete combus tion (PICs), and/or reformation products. PICs are any organic compounds emitted from a source that are present in the feed stream (even in trace amounts) and not completely destroyed in the combustion process. Reformation products are organic compounds that are formed immediately after combustion, due to interaction of specific constituents in the combustion gasses and specific unit operating conditions relative to a particular combustion process and associated air pollution control equipment.

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### PICs can be formed by trace toxic organic compounds in the waste feed stream. Therefore, we generally recommend evaluating these trace compounds as PIC precursors, in addition to those compounds more prevalent in the hazardous waste feed. Don’t confuse PICs with principal organic hazardous constituents (POHCs). POHCs are compounds in the waste feed stream used during a performance test burn to measure combustor DRE. Unburned POHCs a nd partially destroyed or reacted POHCs are PICs, but PICs are not necessarily POHCs. We’ve typically subdivided COPCs into seven different constituent categories (U.S. EPA 1994g; 1994i; 1994j; 1994n): C 

### Polychlorinated dibenzo(p)dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) C 

### Polynuclear aromatic hydrocarbons (PAHs) C 

### Polychlorinated biphenyls (PCBs) C 

### Nitroaromatics C 

### Phthalates C 

### Other organics C 

### Metals Table A-1 (Appendix A) presents a comprehensive list of compounds typically found (1) in hazardous waste, and (2) in hazardous waste combustion stack gas emissions. Table A-1 identifies the Chemical Abstracts Service (CAS) number for each compound, and states whether the compound has been identified as a carcinogen. Table A-1 also indi cates whether a compound has been identified as a potential COPC by • U.S. EPA and state risk assessment reference documents, • emission test results that have identified the compound in the emissions from hazardous waste combustion facilities, or • other literature that suggests that the risks from the compound may be significant. We provide Table A-1 to help you make sure that the performance test program considers the full range of compounds potentially emitted from a combustor, and the appropriate analytical method. A risk assessment won’t necessarily evaluate every metal, potential PIC, and reformation product listed in Table A-1. Once the performance tests are comp leted, we recommend selecting the risk assessment COPCs from the stack test data and available facility -specific process information, rather than Table A-1.
Identify COPCs from the trial/risk burn data based on their potential to pose increased risk or hazard via one or more of the direct or indirect exposur e pathways. We recommend focusing on compounds that • are likely to be emitted because they (or thei r precursors) are present in the waste feed,

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### • are likely to be emitted because they are likely reformation products, • are potentially toxic to humans, and/or • have a tendency to bioaccumulate or bioconcentrate in food chains.
Appendix A discusses carcinogenic and noncarcinogenic toxicity of specific compounds. The toxicity information provided in the HHRAP Companion Data base is for informational purposes, to help you explain the basis for selecting COPCs. Please keep in mind that toxicity benchmarks and slope factors might change as additional toxicity research is c onducted. We recommend consulting the hierarchy of human health toxicity data (see Appendix A, Secti on A.2.6) before completing the risk assessment, to make sure that you use the most current toxicity data.
We generally recommend the following six-step appro ach (illustrated in Figure 2-3) for identifying the COPCs to evaluate in a site-specific risk assessment (U.S. EPA 1994i). Step 1: Evaluate analytical data from the stack tests performed during the regulatory test burn program, and compounds associated with fugitive emissions ( see Section 2.2.6). Prepare a list that includes all the compounds specified in the analytical me thods performed in the stack tests, and all compounds found in the fugitive emissions evaluation. Also include compounds of concern due to site-specific factors (e.g., community and regulatory concern, high background concentrations), as well as PCDD/PCDFs, PAHs, and PCBs if not otherwise included. Notate whether each compound was detected or not detected. In the recommended approach, a detection in any one of the sampling components (e.g., front half rinse, XAD resin, condensate, Tenax tube), in any run constitutes a detection for that specific compound. Evaluating blank contamination results [included in the quality assurance (QA) data section of the trial burn report] may be relevant when determining the non-detect status of the compounds (see Section 2.5).
Regardless of the analytical methods performed in the regulatory test burn program, we recommend that risk assessments consider PCDD/PCDFs, PAHs, and PCBs (the rationale for including these compounds is discussed in greater detail under Step 3 and in Sections 2.3.1 through 2.3.3).
Steps 2 through 4 are unnecessary for compounds detected in the stack test data analysis or identified in the fugitive emissions evaluation; they may jump to Step 5. All other compounds continue to Step 2.

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concerns



### Trial/risk burn analytes and fugitive emissions,

PLUS compounds: * With related site-specific factors; * Otherwise recommended

Is non-detected compound present in: Waste being burned; OR

other materials fed to unit? Was compound detected?

Does non-detect have a high potential To be emitted as a PIC /Ref. product?

Is toxicological data available? Yes

Yes

Yes No

No List of Tentatively Identified Compounds (TICs) with peaks >= 10% of full scale

DELETE FROM LIST List of COPCs for QUALITATIVE assessment, using surrogate toxicity data from a similar

compound List of COPCs for QUANTITATIVE

human health risk assessment Are there: Related site-specific factors AND is it possibly emitted?

No No Yes

NO

YES 

### STEP 1

STEP 2

STEP 3

STEP 4 STEP 6

STEP 5 

### FIGURE 2-3 COPC IDENTIFICATION

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### Step 2: Evaluate all wastes that the unit will be permitted to burn. Retain for evaluation any non-detected compound present in the waste (Section 2.4 discusses estimating concentrations for non-detects). For example, if a facility is permitted to burn expl osives which characteristically include nitroaromatic compounds, yet the stack test didn’t detect any n itroaromatic compounds, it may be appropriate for nitroaromatic compounds to still be evaluated in the risk assessment. It is prudent to also consider other materials fed to the combustor (e.g. raw materials, or coal in a cement kiln).
Steps 3 and 4 are unnecessary for constituents retained as part of the Step 2 evaluation; they may jump to Step 5. All other compounds, i.e. non-detected compounds that did not satisfy Step 2, continue to Step 3.
Step 3: Retain for evaluation any non-detect with a high potential to be emitted as a Product of Incomplete Combustion (PIC). As defined earlier, PICs are either present in the f eed stream and not completely destroyed, or formed during the combustion process. It’s therefore important to consider combustion chemistry in identifying COPCs. For example, PCDDs and PCDFs may not themselves be found in any feed stream yet still be emitted, because they can form when chlorine-containi ng chemicals react with organic matter in the lowtemperature regions of the combustion unit or AP CS. We therefore generally recommend that PCDDs and PCDFs be assessed. The potential for various PICs to be found in combustor emissions is dealt with in more detail in Sections 2.3.1 through 2.3.13, as well as EPA (2001c).
Identifying/including some compounds (nitroaroma tics, phthalates, hexachlorobenzene, and pentachlorophenol) as PICs in the risk assessment may be warranted, considering waste feed composition and their potential to be emitted (e.g., nitrogenated w astes, plastics, or highly chlorinated organic waste streams) (see Sections 2.3.4 through 2.3.6).
Step 4 is unnecessary for PCDDs/PCDFs, PAH’s, PCB’ s, and other compounds with high potential to be emitted as PICs; they may jump to Step 5. All other compounds, i.e. non-detected compounds that did not satisfy Steps 2 or 3, continue to Step 4.

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### Step 4: Retain for evaluation those compounds that (1) ar e a concern due to site-specific factors, and (2) may be emitted by the combustor. As mentioned in Step 1, site-specific factors may contribute COPCs. For example, if there is community/regulatory concern about high background concentrations of a substance which would not have otherwise been assessed (i.e. it was neither a risk/trial burn analyte, nor found in the fugitive emissions evaluation), and there is reasonable poten tial for it to be emitted, it may be appropriate to include the compound. Also, if a compound found in the trial/risk burn analysis or fugitive emissions evaluation (and therefore included in the COPC list) doesn’tsatisfy Steps 2 or 3, yet is of concern for sitespecific factors and has reasonable potential to be emitte d, it may be appropriate for it to continue to Step 5.
If a compound doesn’t have a reasonable potential of being present in the stack emissions, we generally recommend that the risk assessment report justify this assertion. This information will generally provide the risk manager with sufficient information to concl ude that the facility has not overlooked a serious risk.
Compounds of concern due to site-specific factors with reasonable potential to be emitted continue to Step 5. Delete all other compounds (i.e. non-detect ed compounds that did not satisfy Steps 2 through 4) from consideration in the risk assessment.
Step 5: Research the recommended hierarchy of human health toxicity data (see Appendix A2.6) for available compound-specific health benchmarks. Add compounds with available toxicity data to the COPC list for quantitative assessment. Retain compounds that have no toxicity data on the COPC list for qualitative assessment, and use surrogate toxicity data from a toxicologically similar compound. As detailed in Appendix A, we recommend a hierarchy of sources for toxicity data appropriate to use in the risk assessment. The tox hierarchy represents a library of sources for scientifically defensible, compound-specific human health benchmarks.
We generally recommend that the assessment of CO PCs using surrogate toxicity data not be quantitative but rather qualitative , and be reported in the Uncertainty section of the risk assessment. The definition of a “toxicologically similar compound” will depend on th e original compound, which in turn changes from

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### SPECIAL NOTE: REGARDING FATE & TRANSPORT DATA Step 5 in Identifying COPCs focuses on availability of toxicity data because it tends to be the controlling factor: without toxicity parameter values, quantitative assessment is not possible. Depending on the compound, though, availability of fate & transport parameter values could also be a limiting factor. If these parameter values are available, then it is scientifically reasonable, and in the interest of protecting human health and the environment, to evaluate exposure of receptors to the COPC via various direct and indirect pathways. Howeve r, if the necessary fate & transport properties for a particular exposure pathway aren’t available, then it seems reasonable to exclude that COPC from consideration for the affected pathway (or pathways). For example, if a biotransfer value for milk (see Chapter 5) is not available for a COPC then it can be assumed that, based on current information, the COPC won’t be assessed via the ingestion of milk exposure pathway. This principle holds true for other variables as well. Please note, though, that the lack of fate and transport data doesn’t automatically equate to an absence of potential exposure and risk. We generally recommend that as long as sufficient fate & transport properties are available, the calculations for each exposure pathway be completed, and any uncertainties introduced into the risk assessment described in the uncertainty discussion of the risk assessment report (see Chapter 8). Fate & transport parameter data may be quite limited for somecompounds, and acquiring that data can be a labor-intensive and timeconsuming process. In an effort to streamline the risk assessment process, the fate & transport parameter values needed to follow this Protocol to assess the 200+ compounds most commonly found in hazardous waste combustor risk assessments are made available in a database companion to the HHRAP (available for download from the HHRAP web site). For those compounds not found in the database, the Superfund Chemical Data Matrix ( SCDM) is a good first source to acquire the necessary values. When actual values aren’t directly available, HHRAP Appendix A also lists our recommended methods for estimating parameter values. We generally recommend consulting with the permitting authority on the appropriate level of effort to expend acquiring/estimating fate & transport parameter values. 

### assessment to assessment. We recognize the uncertainties involved in even defining what constitutes “toxicologically similar.” We therefore recommend consulting with the permitting authority when identifying toxicologically similar compounds. It’s also within the permitting authority’s purview to determine that it’s technically appropriate (on a compound-specific basis) to use surrogate toxicity data quantitatively.
Previous guidance on how to qualitatively assess risk is inconsistent. Common practice is also highly variable. One option is to generate quantitative estimates for compounds using surrogate toxicity data. These results, however, aren’t typically reported with the rest of the COPCs, nor do they contribute to risk totals. Instead, the surrogate-based risk results are typically reported in the Uncertainty section of the risk assessment report, to inform risk management decision-makers.
Please Note : The above is only one option. We recommend consulting with the permitting authority regarding the appropriate level of effort in acquiring surrogate toxicity data, and other methods and processes to use in qualitative assessment. Step 6 : Evaluate the tentatively identified compound (TIC) peaks obtained during gas chromatography (GC) analysis, to determine whether any of th e TICs have toxicities similar to the detected

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### compounds. If they do, qualitatively assess using su rrogate toxicity data, as recommended for identified compounds in Step 5. All organic compounds that are identified and quantifie d are ultimately subtracted from the total organic emissions mass value. It is therefore beneficial for the laboratory to identify and quantify the maximum number of compounds, including TICs. Although it’s in your interest to characterize as many TICs as possible, extensive characterization of TICs involv es a significant commitment of time and expertise and can reach a point of diminishing returns. We th erefore generally recommend characterizing TICs when the peak intensity is 10 percent or more of the full chromatographic scale, and obtaining a quantitative estimate of the value using the nearest eluting internal standard and a response factor of 1. Unless the identification of the TIC is confirmed by the analysis of an authentic standard, it may be appropriate to qualify the quantitative value as "estimated."
We recognize that for many compounds, only limited info rmation on potential health effects is available. Also, for those chemicals with iden tified health effects, the relationship between dose and response may be poorly understood. We suggest that the risk assessment use the sum of the available toxicological information and evaluate the uncertainty associated with these issues. As stated previously, toxicity benchmarks and slope factors may change as additiona l toxicity research is conducted. You may wish to consult with the most current versions of the resources found in the tox hierarchy (see Appendix A, Section A2.6) before completing the risk assessment, to make sure that the toxicity data used in the risk assessment is the most current available.
Previous Agency guidance (1989e; 1994j; 1994n; 1998) recommended that the COPC list for indirect exposure analysis consist of only those constituents considered to present the most significant risks. These constituents were selected based on the 1. quantity of the hazardous waste to be burned, 2. toxicity of the hazardous waste to be burned, and 3. potential for the hazardous waste to bioaccumulate. For direct exposure analysis, however, previous guidance recommended including all constituents for which stack emission data and inhalation health be nchmarks exist. We now recommend that a single COPC list apply to both indirect and direct exposure analysis. We believe that, through the use of computer-based calculations, you can efficiently assess all identified COPCs via both direct and indirect exposure pathways. Savings gained through computer-based calculations will provide for an efficient use

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## C Complete evaluation of hazardous wastes to be burned in the combustor C 

### Complete evaluation of any raw materials or primary fuels burned in the combustor C 

### Waste analysis procedures used to monitor th e composition of hazardous waste feed streams C 

### Analytical data and calculations used to complete the COPC identification process RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT of facility and regulatory resources. Assessing the entire list of COPCs - rather than a subset as previously recommended - may help minimize public concern over the exclusion of some COPCs and reduce confusion for those interested in reviewing the results of the risk assessment.

The following subsections provide specific information and guidance on identifying COPCs for each facility—with discussions for specific classes of compounds—that we typically recommend including in risk assessments. Emerging issues surrounding the class of compounds referred to as “endocrine disruptors” are also discussed.
The following subsections also focus on compounds that past experience has shown can drive risk assessments. These compounds include PCDDs/PCDFs, PAHs, PCBs, nitroaromatics, phthalates, hexachlorobenzene and pentachlorophenol, and metals . Volatile organic compounds are also discussed. We also discuss specific issues th at affect the COPC identification process, and evaluating these compounds in the risk assessment.

2.3.1 Criteria Pollutants
Under the Clean Air Act, EPA establishes air quality standards to protect public health, including the health of "sensitive" populations such as people with asthma, children, and older adults. EPA has set national air quality standards (40 C.F.R. Part 40) for six principal air pollutants (also called the criteria pollutants): nitrogen dioxide (NO 2 

### ), ozone (O 3 

### ), sulfur dioxide (SO 2 

### ), particulate matter (PM), carbon monoxide (CO), and lead (Pb). We discuss lead in Section 2.3.5.2, and PM in Section 2.3.7.
Nitrogen dioxide is a reddish brown, highly reactive gas that is formed in the ambient air through the oxidation of nitric oxide (NO). Nitrogen oxides (NOx ), the generic term for a group of highly reactive

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### gases that contain nitrogen and oxygen in varying amount s, play a major role in the formation of ozone, PM, haze, and acid rain. The major sources of man-made NOx emissions are high-temperature combustion processes such as those thatoccur in automobiles and power plants. Short-term exposures (e.g., less than 3 hours) to low levels of NO 2 

### may lead to changes in airway responsiveness and lung function in individuals with preexisting respiratory illnesses. These exposures may also increase respiratory illnesses in children. Long-term exposures to NO 2 

### may lead to increased susceptibility to respiratory infection and may cause irreversible alterati ons in lung structure. NOx react in the air to form ground-level ozone and fine particle pollution, which are associatedwith adverse health effects (U.S. EPA 2005).
Ozone occurs naturally in the stratosphere approximately 10 to 30 miles above the earth’s surface and forms a layer that protects life on earth from the sun’s harmful rays. Ozone is also formed at ground level by a chemical reaction of various air pollutants combin ed with sunlight. The pollutants that contribute to ozone formation are oxides of nitrogen (NOx) and volatile organic compounds (VOCs). “Ground-level” ozone is an air pollutant that damages human health and the environment. Even at relatively low levels, ozone may cause inflammation and irritation of the resp iratory tract, particularly during physical activity. The resulting symptoms can include breathing difficulty, coughing, and throat irritation. Breathing ozone can affect lung function and worsen asthma attacks. Ozone can increase the susceptibility of the lungs to infections, allergens, and other air pollutants. Medi cal studies have shown that ozone damages lung tissue and complete recovery may take several days after exposure has ended (U.S. EPA 2004a).
Sulfur dioxide (SO 2 

### ) belongs to the family of SOx gases. Th ese gases are formed when fuel containing sulfur (mainly coal and oil) is burned at power plants and during metal sm elting and other industrial processes. High concentrations of SO 2 

### can result in temporary breathing impairment for asthmatic children and adults who are active outdoors. Short-te rm exposures of asthmatic individuals to elevated SO 2 

### levels during moderate activity may result in breathing difficulties that can be accompanied by symptoms such as wheezing, chest tightness, or s hortness of breath. Other effects that have been associated with longer-term exposures to high concentrations of SO 2 

### , in conjunction with high levels of PM, include aggravation of existing cardiovascular disease, respiratory illness, and alterations in the lungs' defenses. The subgroups of the population th at may be affected under these conditions include individuals with heart or lung disease, as well as the elderly and children (U.S. EPA 1986d; 2005).
Carbon monoxide is a colorless and odorless gas, formed when carbon in fuel is not burned completely. It is a component of motor vehicle exhaust, whic h contributes about 60 percent of all CO emissions

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### nationwide. Other sources of CO emissions in clude industrial processes, non-transportation fuel combustion, and natural sources such as wildfires. CO enters the bloodstream through the lungs and reduces oxygen delivery to the body's organs and tissues. The health threat from levels of CO sometimes found in the ambient air is most serious for those who suffer from cardiovascular disease such as angina pectoris. At much higher levels of exposure not commonly found in ambient air, CO can be poisonous, and even healthy individuals may be affected. Visu al impairment, reduced work capacity, reduced manual dexterity, poor learning ability, and difficulty in performing complex tasks are all associated with exposure to elevated CO levels (U.S. EPA 2000d).
The permitting authority decides whether to include criteria pollutants in the quantitative risk assessment. For example, as noted in the November 14, 1997, decision of the Environmental Appeals Board in reference to the Ash Grove Cement Company Permit No. KSD031203318 and risks associated with exposure to cement kiln dust controlled through the state solid waste permit, compliance with other environmental statutes (e.g., CAA, CWA) may be an appropriate method to cons ider and control risks from non-RCRA related pollutants (Environmental Appeals Board 1997).
2.3.2 Endocrine Disruptors
Endocrine disruptors are chemicals are thought to mimic natural hormones, inhibit the action of hormones, or alter the normal regulatory function of the immune, nervous, and endocrine systems. Possible human health endpoints affected by these agents include breast cancer and endometriosis in women, testicular and prostate cancers in men, abnormal sexual development, reduced male fertility, alteration in pituitary and thyroid gland functions, immune suppression, and neurobehavioral effects (U.S. EPA 1997g).
Problems were encountered while attempting to cl assify chemical compounds as endocrine disruptors. Only limited empirical data are available to support the designation of specific chemicals as endocrine disruptors, and some of the data are conflicting. Ther e is a lack of clear structure-activity relationship, as well as a lack of unifying dose-response relationship, among the diverse groups of chemicals considered endocrine disruptors. Also, there are multiple m odes of action for chemicals currently considered endocrine disruptors.
Because the information currently available on endocrine disruptors is inconsistent and limited, U.S. EPA has not yet developed a methodology for quantitative assessments of human health risk resulting from

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### exposure to potential endocrine disruptors (U.S. EPA 1996i). However, the methods for addressing endocrine disruptors are developing at a rapid pace. We therefore generally recommend contacting the Economics, Methods and Risk Analysis Division (EMRAD) of the Office of Solid Waste for the latest guidance on how to address endocrine disruptors in s ite-specific risk assessments. Additional information (e.g., U.S. EPA 1997g) is available for review at the web site http://epa.gov/endocrine/pubs.html

. 2.3.3 Hexachlorobenzene and Pentachlorophenol
In past guidance (U.S. EPA 1994g; 1994i; 1994j; 1994r) we recommended always including hexachlorobenzene and pentachlorophenol in risk assessments of hazardous waste combustors. However, we no longer recommend automatically including them. Rather, we generally recommend carefully considering the information and issues presente d below before deciding whether to include hexachlorobenzene and pentachlorophe nol as COPCs for quantitative assessment.
Hexachlorobenzene is an impurity in pentachlo rophenol, while pentachlorophenol is formed from hexachlorobenzene in the body as well as in some factories (ATSDR 1994a; ATSDR 1994b). Hexachlorobenzene and pentachlorophenol, like all chlori nated aromatics, are synthesized by the reaction of elemental chlorine with a parent aromatic (Deichmann and Keplinger 1981; Grayson 1985). The addition of the first chlorine atom to the benzene or phenol molecule is rapid, but further chlorination becomes progressively more difficult, requiring ferric chloride or another Lewis acid catalyst to complete the reaction (March 1985). Therefore, these chlori nated compounds are difficult to make even under controlled conditions. Hexachlorobenzene, but not pentachlorophenol, has been reported in emissions from the combustion of municipal solid waste and from other processes (such as the chlorination of wood pulp) that also produce PCDDs and PCDFs (ATSD R 1994a; ATSDR 1994b). The combustion properties of these chlorinated compounds indicate that they aren’t likely to be formed as PICs if they aren’t present in the waste feed stream.
We consider it prudent to include hexachlorobe nzene and pentachlorophenol as COPCs for combustors that burn waste feeds containing hexachlor obenzene and pentachlorophenol, wood preservatives, pesticides, or highly variable waste streams such as municipal solid waste. However, we don’t recommend precluding these compounds from analytical testing during the trial burn based only on process knowledge and waste feed characteristics. Because PCDDs and PCDFs can be formed from fly ash-catalyzed reactions between halogens and und estroyed organic material from the furnace, other

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### Agency guidance (U.S. EPA 1994i; 1998c) recommends including potential precursor compounds in the risk assessment and trial burn (see Section 2.3). These precursor compounds might include chlorinated phenols (such as pentachlorophenol) and chlorinated ar omatics (such as hexachlorobenzene). Also, the toxicity and uncertainties associated with combusti on chemistry suggest that stack gas testing always confirm the absence of these compounds from stack emissions.
2.3.4 Hydrogen Chloride/Chlorine Gas
Hydrogen chloride (which becomes hydrochloric acid when dissolved in water) and chlorine are major products of the chemical industry, with uses too numer ous to list. When chlorine gas dissolves in water (whether during drinking water treatment or when some one inhales chlorine), it hydrolyzes to form equal amounts of hydrochloric acid and hypochlorous acid; the adverse effects of which are similar but not identical (Stokinger 1981; ACGIH 1991).
Hydrochloric acid has many uses. It is used in the production of chlorides, fertilizers, and dyes, in electroplating, and in the photographic, textile, and rubber industries. Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes. Acute (shor t-term) inhalation exposure may cause eye, nose, and respiratory tract irritation and inflammation and pulm onary edema in humans. Acute oral exposure may cause corrosion of the mucous membranes, esophagus , and stomach and dermal contact may produce severe burns, ulceration, and scarring in humans. Chronic (long-term) occupational exposure to hydrochloric acid has been reported to cause gastritis, chronic bronchitis, dermatitis, and photosensitization in workers. Prolonged exposur e to low concentrations may also cause dental discoloration and erosion (U.S. DHHS 1993).
Chlorine is a potent irritant to the eyes, the upper respiratory tract, and lungs. Chronic (long-term) exposure to chlorine gas in workers has resulted in respiratory effects, including eye and throat irritation and airflow obstruction (Cal EPA 2000). Depending on the exposure con centration, acute (short-term) exposure to chlorine elicits reac tions ranging from tickling of the nose and throat (Calabrese and Kenyon 1991) to chest pain, vomiting, dyspnea, and cough (U.S. DHHS 1993). Chlorine is also extremely irritating to the skin and can cause severe burns in humans (U.S. DHHS 1993).

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## C Waste feed, raw material, and secondary fuel stream analytical data C 

### Metal emission rate sampling data or assumptions based on waste feed data C 

### Explanations for excluding specific metals from evaluation during the risk assessment RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT 2.3.5 Metals
Previous guidance (U.S. EPA 1994g; 1994i; 1998c ; NC DEHNR 1997) recommends including the following inorganic substances in the risk assessmen t: antimony, arsenic, barium, beryllium, cadmium, hexavalent chromium, lead, mercury (elemental and diva lent), nickel, selenium, silver, thallium, and zinc. All of these substances, except nickel, selenium, and zinc, are regulated by 40 CFR Part 266, Subpart H (the BIF regulations). We recommend evaluating nick el and selenium, to determine whether additional terms and conditions may need to be incorporated into the permit, pursuant to 42 USC § 6925(c)(3) and 40 CFR Part 270.32(b)(2)–i.e., U.S. EPA’s “omni bus” authority. In addition, U.S. EPA (2001c) recommends also characterizing the metals alumi num, copper, manganese, a nd vanadium. Another potential option is applying the BIF regulation Tier I or MACT MTEC assumptions, which assume that all metals in the waste feed pass through the combus tion unit and APCS to the emission stream (U.S. EPA 1992c).
Please Note: It may be appropriate to include metals in the risk assessment even if they aren’t present in the combustor’s feed streams. Although metals cannot be formed as PICs, we are aware of combustors with metal emissions resulting from leaching from stainless steel feed piping.

The following subsections provide additional inform ation on our recommended procedures for evaluating four metals—chromium, lead, mercury, and nickel. When evaluating stack emissions for the risk assessment, we highly recommend considering how each of these metals may be affected by the combustion process, including possible in teractions with other constituents.

2.3.5.1 Chromium

The oxidation state of chromium is a crucial issue in evaluating the toxicity of this metal, and the risks associated with exposure. Hexavalent chromium (Cr +6 

### ) is the most toxic valence state of chromium and

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### has been shown to be a human carcinogen through inhalation exposure (U.S. EPA 2005i). Trivalent chromium (Cr +3 

### ) is a commonly found, less-oxidized form of chromium. Trivalent chromium has not been shown to be carcinogenic in either humans or laboratory animals (U.S. EPA 2005i). U.S. EPA (1990a; 1990b) has indicated that chromium emitted from a combustor is not likely to be in the hexavalent form. However, there is not suffici ent evidence to reliably estimate the partitioning of chromium emissions into these two valence states. In addition, we recognize that chromium may exist partially or in some cases entirely as trivalent chromium in various media. For example, Amdur et al. (1991) states that: “Trivalent chromium is the most common form found in nature, and chromium in biological materials is probably always trival ent. There is no evidence that trivalent chromium is converted to hexavalent forms in biological systems. However, hexavalent chromium readily crosses cell membranes and is reduced intracellularly to trivalent chromium..” We generally consider it best to use measured, speci ated emissions data in the risk assessment. If sitespecific speciated emissions data is unavailable, y ou may generate a default speciation. We generally recommend using the following method (developed by us through interpretation of data available in the MACT database, as documented in Appendix D) to generate a default speciation: • When the measured amount of total chromium is <10 : 

### g/dscm, we recommend a default of 5 : 

### g/dscm hexavalent chromium. • When the measured amount of total chromium is in the range of 10 : 

### g/dscm to 100 : 

### g/dscm, we recommend assuming 45 percent is hexavalent chromium. • When the measured amount of total chromium is >100 : 

### g/dscm, we recommend assuming 30 percent is hexavalent chromium.
2.3.5.2 Lead
We generally recommend that risk assessments eval uating lead as a COPC use the IEUBK model when soil concentrations are calculate d to be above the benchmark.
The Integrated Risk Information System (IRIS) doesn ’t currently list an RfD or RfC for lead, because a threshold level for exposure to lead has not been estab lished. While the Agency has characterized lead as a probable human carcinogen, it has not developed a qua ntitative estimate of cancer risk due to a number of uncertainties, some of which may be unique to lead (U.S. EPA 2005b). The Agency has typically relied on the neurological effects observed in children as the sensitive endpoint for evaluating lead toxicity. Consequently, the Agency developed the integrated Exposure Uptake Biokinetic (IEUBK)

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### Model for Lead in Children. Developed through the e fforts of U.S. EPA (1990c) and Kneip, et al. (1983), this model evaluates potential risks based on predicte d blood lead levels associated with exposure to lead (U.S. EPA 1994e). The IEUBK model integrates several assumptions about the complex exposure patterns and physiological handling of lead by the body, and it has been validated at several sites at which lead exposure data and human blood lead levels are available (U.S. EPA 1990c). The U.S. EPA Science Advisory Board (U.S. EPA 1992b) and the U.S. EPA’s Technical Review Workgroup for Lead have both reviewed and recommended the IEUBK model.
The Agency has developed a computerized version of the IEUBK model that predicts blood lead levels and distributions for children 0 to 7 years of age (U.S. EPA 1994e). The IEUBK model is available for download at http://www.epa.gov/superfund/programs/lead/products.htm . The IEUBK computer model cannot predict potential blood lead levels in adults. The Agency has developed an Interim Approach to Assessing Risks Associated with Adult Exposures to Lead in Soil (U.S. EPA 1996r). This interim model is intended for “assessing adult lead risks associated w ith nonresidential [industrial] exposure scenarios.” However, in general, children are more susceptible to lead exposures than adults because of higher soil ingestion rates and greater absorption by the gut, in addition to nutritional variables and lower body weight. In fact, The Agency’s interim approach for assessing adult exposures to lead is based not on limiting adult toxicity, but rather on limiting fetal t oxicity by limiting indirect fetal exposure through direct maternal exposures to lead (U.S. EPA 1996r).
As stated before, we generally recommend that risk assessments evaluating lead as a COPC use the IEUBK model when soil concentrations are calculate d to be above the benchm ark. We don’t generally recommend evaluating carcinogenic risks or noncarcinogenic hazards of lead. When run with standard recommended default values (these generally represen t national averages, or “typical” values), the Agency’s IEUBK model predicts that no more than 5 percent of children exposed to a lead concentration in soil of 400 mg/kg will have lead concentrati ons in blood exceeding 10 μg/dL (U.S. EPA 1994e and 1994o).
2.3.5.3 Mercury
We generally recommend that the risk assessment eval uate exposure to three mercury species via varied pathways: 1. Assess elemental mercury only through direct inhalation of the vapor phase;

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### 2. Assess divalent mercury through both direct inhalation and indirect exposure to vapor and particle-bound mercur ic chloride; and. 3. Assess methyl mercury only through indirect exposure. Air emissions of mercury contribute to local, re gional, and global deposition. The U.S. Congress explicitly found this to be the case and required the Agency to prioritize maximum achievable control technology (MACT) controls for mercury (U.S. Congress 1989).

The Mercury Study Report to Congress (U.S. EPA 1997c) found that anthropogenic mercury releases are thought to be dominated on the national scale by i ndustrial processes and combustion sources that release mercury into the atmosphere. A portion of these an thropogenic releases is in the form of elemental mercury, and a portion in the form of mercuric chlo ride. Coal combustion is responsible for more than half of all mercury emissions from U.S. anthropogenic sources. The fraction of coal combustion emissions in oxidized form (i.e. mercuric chloride) is thought to be less than the fraction in oxidized form from other combustion emission sources (including waste incineration).
Stack emissions include both vapor and particulate form s of mercury. Most of the total mercury emitted from the stack is in the vapor phase, although exit streams containing soot or particulates can bind up some fraction of the mercury. Vapor mercury emissions are thought to include both elemental (Hg 0 

### ) and oxidized (e.g., Hg +2 

### ) chemical species. Particulate mercury emissions are thought to be composed primarily of oxidized compounds, due to the relativel y high vapor pressure of elemental mercury (U.S. EPA 1997c).
The methods for analyzing mercury speciation in emission plumes are being refined, and there is still controversy in this field. The speciation of mercury emissions is thought to depend on the fuel used, flue gas cleaning, and operating temperatures. True speci ation of mercury emissions from the various source types is still uncertain and thought to vary not onl y among source types, but also between individual plants (U.S. EPA 1997c). Total mercury exiting the st ack is assumed to consist entirely of elemental and divalent species, with no emissions of methyl mercury. The exit stream is thought to range from almost all elemental mercury to nearly all divalent mercury. Much of the divalent mercury is thought to be mercuric chloride (HgCl 2 

### ) (U.S. EPA 1997c), particularly in the combustion of wastes containing chlorine. The divalent fraction is split between vapor and particle-bound phases (Lindqvist et al. 1991).

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### Please note that data on mercury speciation in stack emissions is very limited. Also, the behavior of mercury emissions close to the point of release has not been extensively studied. It is possible for chemical reactions to occur in the emission plume. This results in a significant degree of uncertainty implicit in modeling mercury emissions. Additional examples of uncertainties include the precision of measurement techniques, estimates of pollution contro l efficiency, limited data specific to source class and activity level. U.S. EPA (1997c) discusses uncerta inty, and sensitivity analyses of several of the assumptions used in the modeling of mercury emissions. Additional discussions and examples of mercury modeling can be found in the proceedings of the IT3 conference (Kaleri 2000).
Site-Specific Mercury Sampling
If site-specific mercury sampling information is availa ble, one option is to estimate the oxidation state and phase distributions. We recommend basing the estimates on the concentration of mercury in various components of the Agency’s multiple metals samp ling train (i.e., U.S. EPA Method 29 or Method 0060) using the following guidelines: • Mercury found in the acidic potassium permanga nate impingers would be expected to be the elemental form of mercury (Hg 0 

### ). • Divalent mercury (HgCl 2 

### ) is soluble in water and would be expected to be found in the dilute nitric acid/hydrogen peroxide impinges. This is also referred to as the ionic portion. • Mercury found in the probe and filter can be assumed to be vapor-phase mercury adsorbed onto particulate matter or a solid-phase compound. This fraction is referred to as Hg(PM). We understand that these methods can be biased by high SO 2 

### and trace Cl 2 

### in the feed. This bias results in the over-reporting of ionic vapor (or divalent form) and the under-reporting of elemental vapor mercury. For risk assessment purposes, we consider this protective.
Default Phase Allocation and Speciation of Mercury Exiting the Stack
As discussed above, stack emissions are thought to be speciated into both divalent and elemental mercury, and include both vapor and particle -bound forms. Vapor-phase divalent mercury is thought to be more rapidly and effectively removed by both dry and we t deposition than particle -bound divalent mercury. This is a result of the reactivity and water solubility of vapor-phase divalent mercury (Lindberg et al. 1992; Peterson et al. 1995; Shannon a nd Voldner 1994). Also, divalent mercury emitted either in the

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### vapor phase or particle-bound, is thought to be subject to much faster atmospheric removal than elemental mercury (Lindberg et al. 1992; Peterson et al. 1995; Shannon and Voldner 1994). A small fraction (about one percent) of vapor-phase elemental mercury ma y be atmospherically transformed into divalent mercury by tropospheric ozone and adsorbed to partic ulate soot in the air and subsequently deposited in rainfall and snowfall (U.S. EPA 1997c).
Based on review of mercury emissions data presen ted for combustion sources in U.S. EPA (1997c) and published literature (Peterson et al. 1995), estimates for the percentage of vapor and particle-bound mercury emissions range widely from 20 to 80 percent. Therefore, unless site-specific mercury sampling information is available, we generally recommend a protective approach that assumes phase allocation of mercury emissions from hazardous waste combustion of 80 percent of total mercury in the vapor phase and 20 percent of total mercury in the particle-bound phase. As illustrated in Figure 2-4, of the 80 percent total mercury in the vapor phase, 20 percent of the to tal is in the elemental form and 60 percent of the total is in the divalent form (Peterson et al. 1995) . Of the 20 percent of the total mercury that is particle-bound, 99 percent (assumed to be 100 percent in Figure 2-4) is in the divalent form. This allocation is: C 

### Consistent with mercury emissions speci ation data for hazardous waste combustion sources reported in literature (Peterson et al. 1995); and C 

### Believed to be reasonably protective, since it results in the highest percentage of total mercury being deposited in proximity to the source, and therefore, indicative of the maximum indirect risk.Human Health Risk Assessment ProtocolChapter 2: Facility Characterization September 2005U.S. EPA Region 6U.S. EPAMultimedia Planning and Permitting Division Office of Solid WasteCenter for Combustion Science and Engineering 2-50FIGURE 2-4PHASE ALLOCATION AND SPECIATION OF MERCURY IN AIR20% is Hg0vapor[2.00g]60% is Hg2+vapor[6.00g]20% is Hg2+particle-bound[2.00g]Fv(Total Mercury) = 0.8LEGENDHg0- Elemental MercuryHg2+- Divalent Mercury[ ] - Example Mass Allocation1% Deposited as Hg0vapor99% Enters Global Cycle as Hg0vapor68% Deposited as Hg2+vapor32% Enters Global Cycle as Hg2+vapor36% Deposited as Hg2+particle-bound64% Enters Global Cycle as Hg2+particle-bound[0.02g][1.98g][4.08g][1.92g][0.72g][1.28g]Without Considering Global Cycle:•20% of Total Mercury Emittedis deposited as Hg0[2g / 10g]•80% of Total Mercury Emittedis deposited as Hg2+[(6g + 2g) / 10g]Calculated Fv:•Fv(Hg0) = [2g / 2g] = 1.0•Fv(Hg2+) = [6g / (6g+2g)] = 0.75Considering Global Cycle:•0.2% of Total Mercury Emittedis deposited as Hg0[0.02g / 10g]•48% of Total Mercury Emittedis deposited as Hg2+[(4.08g + 0.72g) / 10g]Calculated Fv:•Fv(Hg0) = [0.02/(0.02 + 0)] = 1.0•Fv(Hg2+) = [4.08/(4.08 + 0.72)] = 0.85Compound-Specific Emission Rate (Q)•Actual Q (Hg0) = 0.2% * Q (Total Mercury)•Actual Q (Hg2+) = 48% * Q (Total Mercury)Total Mercury Emissions Exiting Stack Into Air[10.0g]80% is in Vapor Phase[8.00g]20% is in Particle-Bound Phase[2.00g]

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### The Mercury Global Cycle
According to information in U.S. EPA (1997c), a vast majority of mercury exiting the stack doesn’t readily deposit, but is vertically diffused to the fr ee atmosphere, transported outside the study area and into the global cycle. Regardless of the source of ph ase and speciation distribution values (i.e. either sitespecific sampling data or default values), we ge nerally recommend using the following fractions from U.S. EPA (1997c): • A vast majority of the vapor-phase elemen tal mercury (over 99 percent) doesn’t readily deposit, but becomes part of the global cycle; • Of the mercury emitted as vapor-phase divalent mercury, about 68 percent deposits and about 32 percent diffuses vertically to the global cycle; and • 36 percent of the particle-bound divalent me rcury deposits, and the rest diffuses vertically to the global cycle. Deposition and Modeling of Mercury
Based on information in U.S. EPA (1997c) and as shown in Figure 2-4, we generally assume that deposition to the various environmental media is almost entirely divalent mercury in either the vapor or particle-bound form. Without considering the globa l cycle, 80 percent of total mercury would be deposited as divalent mercury and the remaining 20 percent would be deposited as elemental mercury.
We generally recommend using the percentages provi ded in U.S. EPA (1997c) to account for the global cycle. Using these figures, the percentage of tota l mercury deposited would be reduced to a total of 48.2 percent (40.8 percent as divalent vapor, 7.2 pe rcent as divalent particle-bound, and 0.2 percent as elemental vapor). As discussed in Appendix A-2, th ese speciation splits result in fraction in vapor phase ( Fv) values of 0.85 (40.8/48.0) for divalent mercury, and 1.0 (0.2/0.2) for elemental mercury. Also, to account for the remaining 51.8 percent of the total me rcury mass that is not deposited, the deposition and media concentration equations (presented in Appe ndix B), multiply the compound-specific emission rate ( Q ) for elemental mercury by a default value of 0.002; and divalent mercury by a default value of 0.48.
Methylation of Mercury The net mercury methylation rate (the net result of me thylation and demethylation) for most soils appears to be quite low; with much of the measured me thyl mercury in soils potentially resulting from wet deposition (U.S. EPA 1997c). Based on the information in U.S. EPA (1997c), We assume that 98 percent

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### of the deposited mercury remains divalent mercury, and two percent speciates to organic mercury (methyl mercury) in soil. A significant and important excep tion to mercury methylation rate being low in soils appears to be wetland soils. Wetlands appear to c onvert a small but significant fraction of the deposited mercury into methyl mercury; which can migrate to nearby water bodies and potentially bioaccumulate in the aquatic food chain (U.S. EPA 1997c). Therefore, we assume the percentage of methyl mercury in wetland soils is higher than the 2 percent assumed fo r non-wetland soils. However, wetlands soils aren’t specifically considered in any of the exposure pa thways represented in the recommended human health exposure scenarios (see Chapter 4).

Both watershed erosion and direct atmospheric deposition can be importa nt sources of mercury to a water body (U.S. EPA 1997c). There appears to be a great deal of variability in the processing of mercury among water bodies. As a result, you can generally e xpect different water body types to have different ranges of methylation, with wetlands generally expect ed to have higher percentages of methyl mercury than lakes, and lakes subsequently more than rive rs or streams (Driscoll et al. 1994; Hurley et al. 1995; Krabbenhoft et al. 1999; Watras et al. 1995). Studies have also shown that rivers or lakes with wetland components (particularly riparian wetlands) have an increased methyl mercury content (Hurley et al. 1995; Krabbenhoft et al. 1999; St. Louis et al. 1996). Th e percentage of the water body that constitutes a riparian wetland also contributes (i.e., the highe r percentage - the higher the methyl mercury concentration). The watershed is also an important factor in determining the methyl mercury concentration of the water body. Waterbodies that ar e surrounded by agricultural or forested land tend to have higher methylation fractions. Waterbodies th at are surrounded by mining activities have high amounts of inorganic mercury in the water, and therefore have a lower methylation efficiency (Krabbenhoft et al. 1999). As briefly discussed later in this section, this variability in methylated mercury concentrations is primarily due to the characteristica lly wide range of chemical and physical properties of water bodies. Additionally, mercury entering the wa ter body can be methylated predominantly through biotic processes (U.S. EPA 1997c).
In the absence of site-specific measurements to s upport evaluation of water body properties and biotic conditions relevant to mercury methylation, we generally recommend assuming that 85 percent of total mercury in surface water is divalent mercury, and the remaining mass is methyl mercury. This percentage (i.e., 15 percent as methyl mercury) is based on the average of reported values for the fraction of total mercury that is methyl mercury in surface water (Akagi et al. 1979; Bloom and Effler 1990; Bloom et al. 1991; Gill and Bruland 1990; Kudo et al. 1982; Lee and Hultberg 1990; Parks et al. 1989; Watras and Bloom 1992). These literature sources were origina lly presented in the SAB Review Draft of the

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### Mercury Study Report to Congress (U.S. EPA 1996s). The final Mercury Study Report to Congress (U.S. EPA 1997c, Volume III; Appendix D) also presents litera ture values for the fraction of methyl mercury in the water column. However, the data are specific to the epilimnion and hypolimnion. For the epilimnion, reported values range from 4.6 percent to 15 percent, with a point estimate of 7.8 percent. For the hypolimnion, reported values range from 27 percent to 44 percent, with a point estimate of 36 percent.
We are modifying our previous recommendation for applying the default mercury speciation (85 percent divalent mercury and 15 percent methyl mercury) to each calculated water body loading. Instead, we recommend that a dissolved water concentration first be calculated for total mercury using the fate and transport parameters specified for mercuric chloride . Then, the dissolved total mercury concentration should be apportioned based on an 85 percent divalent and 15 percent methyl mercury speciation split in the water body. Appendix B (Table B-4-24) presen ts the equations we recommend for applying the speciation assumptions.
For most environmental systems, the literature suggests that various physical and chemical conditions may influence the methylation of mercury. In some cases you might need to consider these conditions, and the magnitude of their potential impact, to assess the potential for over- or under-predicting mercury methylation in media and subsequent biotransfer up the food chain. There is extreme variation between modeled environmental systems, and at times disagr eement in the literature regarding the quantitative influence of specific conditions on methylation. Table 2-4 summarizes the qualitative effects that some physical and chemical conditions, as reported in literature, may have on methylation. We therefore generally recommend conducting extensive research of literature specific to the conditions prevalent at the site, before deviating from the protective assumptions recommended above.
More recent advances in scientific understanding of the physical, chemical, and biological processes controlling mercury speciation and partitioning in water bodies are summarized in U.S. EPA (2005g).

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### TABLE 2-4 QUALITATIVE EFFECTS OF PHYSICAL & CHEMICAL CONDITIONS ON METHYLATION Physical or Chemical Condition Qualitative Influence on Methylation Referenced Literature Low dissolved oxygen Enhanced methylation Rudd et al. 1983; Parks et al. 1989 Decreased pH Enhanced methylation in wa ter column Xun 1987; Gilmour and Henry 1991; Miskimmin et al. 1992 Decreased pH Decreased methylation in sedi ment Ramlal et al. 1985; Steffan et al. 1988 Increased dissolved organic carbon (DOC) Enhanced methylation in se diment Chois and Bartha 1994
Increased dissolved organic carbon (DOC) Decreased methylation in water column Miskimmin et al. 1992
Increased salinity Decreased methylation Blum and Bartha 1980 Increased nutrient concentrations Enhan ced methylation Wright and Hamilton 1982; Jackson 1986; Regnell 1994; Beckvar et al. 1996 Increased selenium concentrations D ecreased methylation Beckvar et al. 1996 Increased temperature Enhanced methylatio n Wright and Hamilton 1982; Parks et al. 1989 Increased sulfate concentrations Enhanced methylation Gilmour and Henry 1991; Gilmour et al. 1992 Increased sulfide concentrations Enhanced methylation Beckvar et al. 1996 

### The deposition and media concentration equations that we generally recommend (presented in Chapter 5 and Appendix B) have been modified specifically to account for the methylation and subsequent biotransfer of mercury, assuming steady-state cond itions. The HHRAP companion database provides the parameter values specific for methyl mercury, and Appendix A-2 includes additional discussion and reference on their origin.
As noted above, methylation can be highly variable be tween environmental systems. This results in a significant degree of uncertainty implicit in the m odeling of mercury methylation. To expand on the qualitative information presented in Table 2-4, and to better understand conditi ons that may influence mercury methylation specific to a site, we recommend reviewing the related information presented in U.S. EPA (1997c; 2005).

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### We generally recommend using the equations and protective assumptions presented in this guidance to estimate risks associated with mercury. If estimated risks exceed target levels, it may be appropriate to use more extensive site-specific data (if available) and subsequently a more rigorous modeling effort, to further evaluate points of potential exposure. For exampl e, if sufficient site-specific data is available, it could be used in a model that predicts transformation of chemical forms and biotransfer of mercury. One such model is the SERAFM (Spreadsheet Ecological Risk Assessment for the Fate of Mercury) model developed by EPA's Office of Research and Deve lopment, National Exposure Research Laboratory, Ecosystems Research Division. SERAFM updates th e IEM-2M mercury fate and transport algorithms described in detail in U.S. EPA (1997c) by in corporating more recent advances in scientific understanding of the physical, chemical, and biological processes controlling mercury speciation and partitioning in water bodies. The SERAFM enhancements to IEM-2M are summarized in U.S. EPA (2005g).
SERAFM is written in an easy-to-implement Microsoft Excel format so that all manipulations, parameters and equations are readily available to the user . By specifying only a few additional water body parameters beyond those already utilized in this guidance (i.e., water body pH, dissolved organic carbon and color), the user is able to model specific water body mercury transformation processes instead of using the default speciation assumptions (i.e., 85 per cent divalent/15 percent methyl). In the SERAFM model, mercury species are subject to several tran sformation reactions incl uding photo-oxidation and dark oxidation of elemental mercury in the water co lumn, photo-reduction and methylation of divalent mercury in the water column and sediment layers, and photo-degradation and demethylation of methyl mercury in the water column and sediment layers. For hazardous waste combustion sources, it is recommended that, watershed soil concentrations and water body loadings due to source deposition be calculated externally to SERAFM using the equations presented in Chapter 5 (Equations 5-1E and 5-28) and then linked to the appropriate SERAFM wo rksheets for calculation of speciated mercury concentrations in the water body.
The decision to use more complex mercury models in a risk assessment is not precluded just because they are different from the model we recommend in the HHRAP. It is for the permitting authority to decide whether the assessment will use more complex mercury models. If you use more complex mercury models, we recommend ensuring that sufficient and relia ble site-specific data is readily available, and then carefully identifying and evaluating the models ' associated limitations, and clearly documenting the evaluation in the Uncertainty section of the risk assessment report.

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### Conclusion
We encourage all facilities to implement a combin ation of waste minimization and control technology options to reduce mercury emission rates on an ongoi ng basis. Realistic expectations for mercury emission reduction efforts may be established by c onsidering various technology-based mercury emission limits that apply to waste combustors (for exampl e, standards for European combustors, the MACT standards for hazardous waste combustors, or the MACT standards for municipal waste combustors). We acknowledge that site-specific risk assessments as currently conducted may not identify the entire potential risk from mercury emissions. Mercury that doesn’t deposit locally will ultimately enter the global mercury cycle for potential deposition elsewhere.

2.3.5.4 Nickel
We generally recommend evaluating nickel as an inhalation carcinogen using the inhalation unit risk factor for nickel refinery dust. We generally reco mmend evaluating nickel for other effects using the oral RfD for nickel soluble salts, the only available nickel-related RfD (see Appendix A-2 and the HHRAP companion database).
Nickel refinery dust is identified as a potential human inhalation carcinogen (U.S. EPA 2005i). Major components of nickel refinery dust include nickel s ubsulfide, nickel oxide and nickel sulfate. IRIS classifies nickel subsulfide - the primary component (roughly 50%) of nickel refinery dust - a Class A human carcinogen (U.S. EPA 2005e). However, all components responsible for the carcinogenicity of nickel refinery dust have not been conclusively established (U.S. EPA 2005c). Because the component (or components) of nickel refinery dust causing it to be carcinogenic have not been conclusively established, we consider it appropriate to evaluate nickel emissions as a potential carcinogen via the inhalation pathway. In addition, nickel oxides can be reduced to nickel sulfates (some of which are carcinogenic) in the presence of sulfuric acid (Weast 1986). Hazardous waste combustors which burn wet wastes containing significant amounts of nickel and sulfur may need to be especially concerned with nickel emissions.
We generally recommend evaluating nickel as an inhalation carcinogen because some forms of nickel—including nickel carbonyl, nickel subsul fide, and nickel refinery dust—are considered carcinogens (U.S. EPA 2005c,d,e). This is contrary to the Agency’s previous analysis of the toxicity of

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### nickel emissions from hazardous waste combustors. These forms of nickel were not considered in developing the BIF regulations, because the BIF regul ations assumed that nickel can only be emitted as nickel oxide, which by itself is not cons idered to be a carcinogen (U.S. EPA 1991a).
If the permitting authority has information at points of potential inhalation exposure that demonstrate the absence of nickel refinery dust components, or the presence only of noncarcinogenic nickel species, it may be appropriate to use this information as th e basis for supplemental noncarcinogenic calculations. For exposure pathways other than inhalation, nick el has not been shown to be carcinogenic (U.S. EPA 2005i).

2.3.6 Nitroaromatics
We generally recommend carefully considering the information in the following paragraphs before deciding the appropriateness of including nitroaromatic organic compounds in the risk assessment. It is reasonable to include nitroaromatics as COPCs if the combustor feed streams include nitroaromatic compounds or close relatives (TDA and TDI).
Please Note : In earlier guidance (U.S. EPA 1994g; 1994i; 1994j; 1994r) we recommended that risk assessments always include nitroaromatic organic compounds, including 1,3-dinitrobenzene; 2,4-dinitrotolue ne; 2,6-dinitrotoluene; nitrobenzene; and pentachloronitrobenzene. We no longer recommend automatically including nitroaromatic organic compounds in risk assessments. Nitroaromatic organic compounds such as 1,3-dinitrobe nzene; 2,4-dinitrotoluene; 2,6-dinitrotoluene; nitrobenzene; and pentachloronitrobenzene (or close relatives such as toluenedia mine [TDA] and toluene diisocyanate [TDI]—derivatives of dinitrotoluene) are typically associated with explosives and other highly nitrogenated hazardous wastes. Dinitrotoluene is used to make two products: trinitrotoluene and TDA. TDA is, in turn, used to make TDI. TDI read ily reacts with water, and is therefore very unstable at ambient conditions. TDI is typically reacted with a polyol to form polyurethane (PU) plastics.
Combustion properties of these nitroaromatic compounds indicate that they won’t be formed as PICs if they aren’t present in the waste feed stream, mainly because of the thermodynamic and chemical difficulty of adding a nitro group to an aromatic. The process requires that (1) nitronium ions be generated, and (2) an aromatic ring react with the n itronium ion, with the nitronium ion attaching to the ring. This reaction process is not likely to occur in a hazardous waste combus tor because (1) the reaction is typically carried out by using a “nitrating acid” solution consisting of three parts concentrated nitric

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### acid to one part sulfuric acid, and (2) nitronium ions aren’t usually formed in a combustor environment (if they are, a thermodynamically more favorable reacti on will occur, thereby eliminating the nitronium ion) (Hoggett, et al 1971; Schofield 1980; March 1985).
Combustion conditions most likely to result in nitrogenated PICs are associated with premature quenching of the primary flame—resulting from low temperature or excess air in the primary combustion chamber of the unit (U.S. EPA 1994j). Under such conditions, sampling for hydrogen cyanide is also recommended (U.S. EPA 1994j).

2.3.7 Particulate Matter
We don’t recommend evaluating PM as a separate CO PC in the risk assessment. However, PM is generally quite useful as an indicator variable, becau se it can be measured in real time and is sensitive to changes in combustion conditions.
Particle pollution is a mixture of solid particles a nd liquid droplets found in the air. Some particles are emitted directly from a source, while others form in co mplicated chemical reactions in the atmosphere. In general, particle pollution c onsists of a mixture of larger material s, called "coarse particles," and smaller particles, called "fine particles." Coarse particl es have diameters ranging from about 2.5 micrometers ( : 

### m) to more than 40 : 

### m, while fine particles, also known as known as PM2.5, include particles with diameters equal to or smaller than 2.5 : 

### m. EPA also monitors and regulates PM10, which refers to particles less than or equal to 10 : 

### m in diameter. PM10 includes coarse particles that are "inhalable" - particles ranging in size from 2.5 to 10 : 

### m that can penetrate the upper regions of the body's respiratory defense mechanisms (U.S. EPA 2004b).
Exposure to particles can lead to a variety of serious health effects. Scientific studies show links between these small particles and numerous adverse health e ffects. Long-term exposures to PM, such as those experienced by people living for many years in ar eas with high particle levels, are associated with problems such as decreased lung function, development of chronic bronchitis, and premature death. Short-term exposures to particle pollution (hours or da ys) are associated with a range of effects, including decreased lung function, increased respiratory symp toms, cardiac arrythmias (heartbeat irregularities), heart attacks, hospital admissions or emergency r oom visits for heart or lung disease, and premature death. (U.S. EPA 1982c; 2004c).

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### Ambient PM is a complex mix of constituents derived from many sources, both natural and anthropogenic. Hence, the physicochemical compositi on of PM generally reflects the major contributing local and regional sources arising locally as well as regiona lly. It stands to reason that the contribution of any given component within the mix may not be equi valent in value or potency, but may well be highly dependent on other physicochemical attributes (e.g., co - constituents, specific bioavailability, or chelates), as well as the health status of the exposed individua l. Evidence collected to date indicates that the discovery of a uniquely responsible physicochemical attribute of PM is not likely to occur (U.S. EPA 2004c).

2.3.8 Phthalates
We generally recommend carefully considering the information in the following paragraphs before deciding the appropriateness of including phthalates in combustor risk assessments. At the same time, due to their toxicity and bioaccumulative potentia l, don’t automatically discount the evaluation of phthalates in the risk assessment. If phthalates are included as COPCs in the risk assessment, we generally recommend using a metabolism factor (MF ) of 0.01 for BEHP, and 1.0 for all other COPCs.
Please Note : In earlier guidance (U.S. EPA 1994g; 1994i; 1994j; 1994r) we recommended always including BEHP and DNOP in every risk assessment. We no longer recommend automatically including phthalates in risk assessments. Phthalates such as bis(2-ethylhexyl)phthalate (BEH P) and di(n)octyl phthalate (DNOP) are synthesized by reacting alcohol with phthalic anhydride in the presence of an acidic catalyst in a nonaqueous solvent (ATSDR 1993; ATSDR 1995b). Among all phthalate plasticizers, BEHP—also referred to as di(2-ethylhexyl)phthalate or dioc tyl phthalate—is produced in the largest volume; it is used in the manufacturing of polyvinyl chloride, the most widely produced plastic. DNOP is a plasticizer that is produced in large volumes, and is used in the manufacture of plastics and rubber materials. Because plastics have become so widely used in society, phthalate plasticizers such as BEHP and DNOP have become widely distributed in food, water, and the atmosphere (Howard 1990). The general public’s exposure to phthalate-contaminated food averages 0. 3 μg/day/individual, with an estimated maximum exposure of 2 mg/day/individual (ATSDR 1992). Phthalate plasticizers are commonly found in the environment and are practically impossible to avoid, especially at the trace concentrations that modern analyses can detect.

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### Phthalates and their predecessors are readily burned, as indicated by their flash points of 150 to 225 o 

### C (NIOSH 1994). There is no apparent mechanism for phthalate PICs to be formed by burning other chemical compounds. Therefore, phthalates are very unlikely to be emitted from a combustor, although some degradation products, such as PAHs, are likely to be emitted when phthalates are included in the waste feed. However, facilities that burn plastics or materials with phthalate plasticizers should carefully consider the potential for phthalate plasticizers to exist in the stack gas emissions due to incomplete combustion. Also, the uncertainties associated with combustion chemistry suggest that stack gas testing confirm the absence of these compounds from stack em issions, rather than relying on process knowledge or waste feed characterization data.
Based on the findings of long-term animal carcinogeni city studies, the Agency has classified BEHP as a “probable human carcinogen” (class B2) (NTP 1982). Because of its octanol-water coefficient ( K ow 

### ) value, BEHP has been presumed to have a high te ndency to bioaccumulate (Mackay, Shiu, and Ma 1992; Karickoff and Long 1995). Considering its ubi quity, B2 classification, and high tendency to bioaccumulate, BEHP is on most Agency lists of ta rget chemicals (see Table A-1), including the Contract Laboratory Program (CLP) semivolatile organics analysis list; the Groundwater Monitoring List (40 CFR Part 264, Appendix IX); and the Hazardous Substa nces and Reportable Quantities List (40 CFR Part 302.4).
Evidence indicates BEHP is more readily metaboli zed and excreted by mammalian species than other contaminants (ATSDR 1987). As stated above, we generally recommend using an MF of 0.01 for BEHP, and 1.0 for all other COPCs. An MF represents the estimated amount of COPC that remains in fat and muscle. Based on a study by Ikeda et al. (1980), the Agency (EPA 1995h) used a COPC-specific MF to account for metabolism in animals and humans. Cons idering the recommended values for this variable, MF has a quantitative effect on animal and human con centrations only for BEHP. No information could be found on the metabolism or disposition of DNOP in the peer-reviewed literature. However, disposition data were found for an isomer of DNOP , diisooctyl phthalate (DIOP), a branched-chain phthalate (Ikeda et al., 1978). Based upon its similarity in structure, it may be assumed that DNOP would behave comparatively to DIOP and BEHP, and ther efore, may be over estimated by approximately a factor of 100.

The MF applies only to mammalian species, including beef cattle, dairy cattle, and pigs. It does not relate to metabolism in produce, chicken, or fish. In add ition, since exposures evaluated using this guidance are

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### intake driven, only apply a metabolism factor to eval uating indirect human exposure via ingestion of beef, milk, and pork. In summary, using an MF doesn’t apply for direct exposures to air, soil, or water, or to ingestion of produce, chicken, or fish. Using an MF is further discussed in Section 5.4.4.7 and Appendix B, Tables B-3-10, B-3-11, and B-3-12.
2.3.9 Polychlorinated Biphenyls

Because of evidence that PCBs can be emitted from co mbustion sources regardless of feed characteristics, and considering the significant toxicity of PCBs , we recommend conducting stack testing for PCBs to support the risk assessment. We also recomme nd automatically including PCBs as COPCs for combustors that burn PCB-contaminated wastes or waste oils, highly variable waste streams such as municipal and commercial wastes (for which PCB cont amination is a reasonable assumption), and highly chlorinated waste streams. Due to the toxicity a nd uncertainties associated with combustion chemistries, we generally recommend that stack gas testi ng confirm the absence of these compounds from stack emissions.
The most commercially useful property of PCBs is that they are chemically stable in relatively adverse conditions, such as temperatures of several hundred degrees in an oxygen-containing atmosphere. The more chlorinated congeners are more resistant to reaction. PCBs were produced commercially by the reaction of the aromatic hydrocarbon biphenyl with chlorine gas in the presence of a suitable catalyst, generally ferric chloride or another Lewis aci d (ATSDR 1995d). The degree of chlorination was controlled by manipulating the reaction conditions, in cluding temperature, pressure, and the ratio of the reactants (Erickson 1992; Grayson 1985). The uses and distribution of polychlorinated biphenyls (PCBs) were severely restricted in the United States in the late 1970s—with additiona l bans and restrictions taking effect over the next decade (ATSDR 1995d).
Due to their stability in adverse conditions, destru ction of PCBs by burning generally requires contact with high temperatures (at least 1,200 o 

### C) for an extended period of time (more than 2 seconds), under conditions with adequate oxygen (E rickson 1992). Waste combustors can contribute significantly to total emission inventories of PCBs (Alcock et al. 1999; U.S. EPA 1997e). An increasing body of information supports the likelihood that PCBs may be emitted as by-products of burning, regardless of PCB contamination in the combustor feed.

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### It is possible that PCBs can be formed by the sam e types of reactions that produce dioxins and furans, including gas-phase formation, heterogeneous formation from organic precursors, and de novo synthesis from flyash-bound carbon. Lemieux et al. (1999) hypoth esized that if PCBs and dioxins and furans are formed by similar mechanisms, then emissions of P CBs should correlate with emissions of dioxins and furans. This hypothesis was tested by reviewing data where both PCBs and dioxins and furans were measured. An apparent trend was indeed found showing increased PCB emissions with increased emissions of dioxins and furans. In most cases, PCBs were found in the stack even when there were no PCBs in the combustor feed. Overall, PCB emissions exceeded dioxin and furan emissions by approximately a factor of 20, and this trend appearedto hold over five orders of magnitude in dioxin and furan emissions.
In addition, there is some limited data, from both la boratory and field studies, showing that PCBs may be formed from burning hazardous waste. Stack tests performed in U.S. EPA Region 10 on a boiler and an incinerator burning waste with 0.07 and 1.4 percen t chlorine, respectively, confirmed the presence of PCBs in the stack gases (Kalama Chemical, Inc. 1996; Idaho National Engineering Laboratory 1997). The concentration of detected coplanar PCBs (as defi ned in Section 2.3.9.1) found in the boiler stack gas was 0.55 ng/dscm @ 7% O 2 

### at low temperature conditions (1,357° F) and 1.12 ng/dscm @ 7% O 2 

### at high temperature conditions (1,908° F). The concentration of total PCBs detected in the incinerator stack gas was 211 ng/dscm @ 7% O 2 

### at low temperature conditions (1,750 °F) and 205 ng/dscm @ 7% O 2 

### at high temperature conditions (2,075° F). PCBs with more th an four chlorines comprised 51 percent of the total PCBs in the low temperature test and 59 percent of the total PCBs in the high temperature test.
Other laboratory studies suggest the possible formation of PCBs as PICs from burning hazardous waste with a high chlorine content. Bergman et al. (1984) heated samples of two chlorinated paraffins (CP) in conditions similar to incinerator conditions. A CP containing 70 percent chlorine did produce PCB (up to 0.3 percent of the amount of CP), as well as chlorinate d benzenes (up to 0.5 percent), chlorinated toluenes (up to 0.6 percent), and chlorinated naphthalenes (up to 0.2 percent). Similar treatment of a CP containing 59 percent chlorine produced only chlorina ted benzenes (up to 0.1 percent of the amount of CP, based on a detection limit of 0.0005 percent for each individual compound) and almost all of those (about 90 percent) were monochlorobenzene (Bergman 1984). This study indicates that burning highly chlorinated wastes (60 percent or greater chlorine) can produce PCBs. Also, in an experiment involving 4 percent charcoal, 7 percent chlorine, and 1 percent copper catalyst heated to 300° C, PCBs were formed

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### at levels approaching 300 ppb for the penta hom ologue, 200 ppb for the hexa homologue, 150 ppb for the hepta homologue, and less than 50 ppb for th e tetra homologue (Stieglitz et al. 1989).
2.3.9.1 PCB Carcinogenic Risks
In earlier guidance (1994g; 1994i; 1994j; 1994r) we recommended that risk assessments treat all 209 PCB congeners as a mixture having a single carcinogenic potency. This recommendation was based on the Agency drinking water criteria for PCBs (U.S. EPA 1988a), which used available toxicological information with the following limitations: C 

### Aroclor 1260 was the only PCB for which a cancer SF had been developed; there was no agreed upon procedure for applying this SF for similar mixtures with less chlorine content. C 

### Available physical, chemical, fate-and-transport, and toxicological information on individual congeners was limited (primarily because separation and synthesis of pure congeners can be technically difficult). C 

### The number of tests conducted with various PCB mixtures and specific congeners to demonstrate similar toxicological effects was very limited. Research on PCBs has continued since the compilation of U.S. EPA (1988a),. The most important finding of this research is that some of the moderately chlorinated PCB congeners can have dioxin-like effects (U.S. EPA 1992e; 1994a; 1996q; ATSDR 1995d). This sub-category includes PCB congeners with four or more chlorine atoms and few substituti ons in the ortho positions ( positions designated 2, 2', 6, or 6'). They are sometimes referred to as “coplan ar” PCBs, because the rings can rotate into the same plane if not blocked from rotation by ortho-substituted ch lorine atoms. In this configuration, the shape of the PCB molecule is very similar to that of a PCDF molecule. Studies have shown that these dioxin-like congeners can react with the aryl hydrocarbon receptor; the same reaction believed to initiate the adverse effects of PCDDs and PCDFs. The World Health Organization (WHO) used various test results to derive interim toxicity equivalency factors (TEFs) ranging from 0.1 to 0.00001 for the dioxin-like coplanar PCB congeners (WHO 1998).

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### TABLE 2-5 TOXICITY EQUIVALENCY FACTORS FOR COPLANAR PCBs CAS Number Chemical Structure WHO 1998 TEFs (unitless) 32598-13-3 3,3',4,4'-tetrachlorobiphenyl 0.0001 70362-50-4 3,4,4',5-tetrachlorobiphenyl 0.0001 32598-14-4 2,3,3',4,4'-pentachlorobiphenyl 0.0001 74472-37-0 2,3,4,4',5-pentachlorobiphenyl 0.0005 31508-00-6 2,3',4,4',5-pentachlorobiphenyl 0.0001 65510-44-3 2',3,4,4',5-pentachlorobiphenyl 0.0001 157465-28-8 3,3',4,4',5-pentachlorobiphenyl 0.1 38380-08-4 2,3,3',4,4',5-hexachlorobiphenyl 0.0005 69782-90-7 2,3,3',4,4',5'-hexachlorobiphenyl 0.0005 52663-72-6 2,3',4,4',5,5'-hexachlorobiphenyl 0.00001 32774-16-6 3,3',4,4',5,5'-hexachlorobiphenyl 0.01 39635-31-9 2,3,3',4,4',5,5'-heptachlorobiphenyl 0.0001 Source: World Health Organization (1998) 

### Additional congeners are suspected of producing sim ilar reactions, but there is not yet enough data to derive TEF values for them. Since available analytical methods can now quantify most if not all individual PCB congeners, we genera lly consider it reasonable for the permitting authority to request that additional congeners be reported. For instance, 2,2',4,4',5,5'-Hexachlorobiphenyl (CAS No. 35065-27-1) is the most prevalent PCB congener found in human milk and fat (McFarland and Clark 1989). Work is currently underway to develop a separate slope fact or for this particular compound (not a coplanar congener). However, until that work is complete , this compound can only be qualitatively assessed in the risk assessment.
We generally recommend estimating risks from coplan ar PCBs by computing a toxicity equivalency quotient (TEQ) for PCBs, and then applying a slope factor for dioxin. High resolution gas chromatograph test methods, available at most commercial laboratories with dioxin/furan analytical capabilities, are able to identify the specific concentration of individual coplanar PCBs in stack gas.

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### In addition to the coplanar (dioxin-like) PCB c ongeners, We also generally recommend evaluating the remaining PCBs in the risk assessment. After c onsidering the accumulated research on PCBs, especially a recent carcinogenesis study of Aroclors 1016, 1242, 1254, and 1260 and a number of studies of the transport and bioaccumulation of various congeners, USEPA (1996q) derived three new SF s to replace the former single SF for PCBs. These new SF s became effective in IRIS on October 1, 1996. These SF s are subject to revision as additional information from continuing research becomes available. The SF s and the criteria for their use are as follows (U.S. EPA 1996q):

TABLE 2-6 ORAL SLOPE FACTORS FOR PCBs Slope Factor (milligrams per kilogram-day) -1 Criteria for Use 2 Food chain exposure Sediment or soil exposure Early-life (infant and child) exposure by all routes to all PCB mixtures Congeners with more than four chlorines comprise more than 0.5 percent of the total PCBs 0.4 (Not Typically Used) Ingestion of water-soluble (l ess chlorinated) congeners Inhalation of evaporated (less chlorinated) congeners 0.07 Congeners with more than four chlorines comprise less than 0.5 percent of the total PCBs Source: U.S. EPA 1996q



### An SF of 2 (milligrams per kilogram-day) -1 

### is typically used in most circumstances when conducting a risk assessment. An SF of 0.07 (milligrams per kilogram-day) -1 

### is generally scientifically defensible for adult exposures, when congener-specific analyses of em issions demonstrate that at least 99.5 percent of the mass of the released PCB mixture has fewer than five chlorine atoms per molecule (U.S. EPA 1996q). Acceptable congener-specific analyses include hi gh-resolution gas chromatography/mass spectroscopy (or similar means) for total PCB concentrations for each mono- through deca-isomer group. We don’t expect that the 0.4 SF will be widely used in combustion risk assessments, because the PCB mixture will usually contain 0.5 percent or more PCB congeners with more than 4 chlorines.

2.3.9.2 Potential PCB Non-Cancer Effects

In addition to cancer risk associated with all PCBs, we generally recommend determining noncancer hazard for those Aroclors having RfD s. IRIS specifies RfD s for Aroclor 1254 and Aroclor 1016 (U.S. EPA 2005i). The RfD for Aroclor 1254 (2x10 -5 

### milligrams per kilogram-day) will typically be used in

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### most circumstances when conducting a risk assessment. We consider this approach reasonable because approximately 77 percent of Aroclor 1254 is composed of PCB congeners with more than 4 chlorines (Hutzinger et al. 1974). The RfD for Aroclor 1016 (7x10 -5 

### milligrams per kilogram-day) is scientifically defensible for each homologue group de monstrating that at least 99.5 percent of the mass of the released PCB mixture has more than four chlorine atoms pe r molecule (U.S. EPA 1996q). We generally consider this approach reasonable because approximately 99 percent of Aroclor 1016 is comprised of PCB congeners with 4 or fewer chlorines (Hutzinger et al. 1974).
We also recommend evaluating th risks to infants fro m exposure to coplanar PCBs in human breast milk. Please see Section 2.3.10.2 for information on comparing estimated levels of coplanar PCBs (along with dioxins and furans) to background. More informati on on the breast milk pathway is in Chapter 4, and Tables C-3-1 and C-3-2.
2.3.9.3 Fate & Transport of PCBs
When evaluating coplanar PCB congeners, or PCB c ongener mixtures of which greater than 0.5 percent contain more than 4 chlorines, we recommend using the fate and transport properties for Aroclor 1254. When assessing risks and hazards from PCB congener mi xtures of which less than 0.5 percent contain more than 4 chlorines, we recommend using th e fate and transport properties of Aroclor 1016.
2.3.10 Polychlorinated Dibenzo(p)dioxins and Dibenzofurans
As was the case with previous Agency guida nce (U.S. EPA 1994i, 1994j, 1994n, 1994r, and 1998c), we recommend including PCDDs and PCDFs in the risk assessment. Information in U.S. EPA (2000b) suggests that there is adequate evidence that expos ure to PCDDs and PCDFs results in a broad spectrum of cancer and noncancer effects in animals, some of which may occur in humans.

PCDDs and PCDFs were first discovered as ther mal decomposition products of polychlorinated compounds, including (1) the herbicide 2,4,5-T, (2) hexachlorophene, (3) PCBs, (4) pentachlorophenol, and (5) intermediate chemicals used to manufacture these compounds. One mode in which PCDDs and PCDFs form is in dry APCSs, where fly ash cat alyzes reactions between halogens and undestroyed organic material from the furnace. In recent years, as chemical analytical methods have become more sensitive, additional sources of PCDDs and PCDFs ha ve been identified, including (1) effluent from

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### paper mills that use chlorine bleaches, and (2) com bustion sources such as forest fires, municipal waste and medical incinerators, and hazardous waste combus tors. Duarte-Davidson et al. (1997) noted that burning chlorine-containing materials in municipal solid waste is responsible for about two-thirds of the total annual emissions of newly formed TCDDs and TCDFs in the United Kingdom. In the United States, U.S. EPA (1998a) estimated that emissions of dioxin TEQs from municipal solid waste incinerators accounted for 37 percent of all emissions of dioxins into the environment in 1995. The current Agency draft dioxin sources inventory suggests that open barrel burning is the largest current single source of release of these compounds (U.S. EPA 2000).
PCDDs and PCDFs are formed at these combustion sources from the reaction of chlorine-containing chemicals and organic matter. Predicting the forma tion of PCDDs and PCDFs in a specific situation is difficult because dechlorination, which produces PAHs from PCDDs and PCDFs, occurs under similar conditions. Recent studies (Addink et al. 1996; Envi ronment Canada 1987; Fröese and Hutzinger 1996a, 1996b; Gullett et al.1994; Kilgroe et al. 1991; Luijk et al. 1994; and Shriver 1994) have explored some of these complexities, including (1) the formation of PCDDs and PCDFs from simple organics (such as ethane) and complex organics (such as dibenzofuran), and (2) the catalysis of these reactions by various common metals, such as copper. Wikström et al . (1996) found that the form of chlorine—whether organic, as with chlorinated solvents, or inorga nic, as with bleach and salts—has little effect on the quantity of PCDDs and PCDFs formed. However, their study found that the total concentration of chlorine is important. In particular, if the wast e being burned exceeds 1 percent chlorine, the PCDD and PCDF formation rate increases significantly. In contrast, Rigo et al. (1995) analyzed over 1,700 test results with varying chlorine feed concentrations and found no statistically significant relationship. The formation rate of PCDDs and PCDFs may also depend on the physical characteristics of the waste feed stream. Solid waste streams or high-ash-content liqui d waste feed streams may increase particulate levels in the combustion system between the combustion un it and the APCS. The increased particulate levels provide additional surfaces for catalysis reactions to occur.
A review of currently available dioxin data for combustors reveals that total PCDD/PCDF emission rates vary by more than 28-fold between different faciliti es, even though they use similar combustion units and APCSs (U.S. EPA 1996b). Site-specific emission data ar e therefore needed to complete a more refined risk assessment of each combustor.

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### In evaluating fate-and-transport, it is important to consider the chemical and physical properties of dioxins. In soil, sediment, and the water colu mn, PCDDs and PCDFs are primarily associated with particulate and organic matter because of their high lipophilicity and low water solubility. Ambient air monitoring studies, in which researchers studied the partitioning of dioxin-like compounds between the vapor and particle phases, suggest that the highe r chlorinated congeners (the hexa through octa congeners) principally sorb to airborne particulates. The tetra and penta congeners significantly, if not predominantly, partition to the vapor phase (U.S . EPA 2000b). These findings are consistent with vapor/particle partitioning as theoretically modeled in Bidleman (1988). Dioxin-like compounds exhibit little potential for significant leaching or volatilization (U.S. EPA 2000b).
The following subsections clarify the procedur es we recommend using (in conjunction with the procedures described in Chapter 7) to estimate risk s associated with PCDDs and PCDFs. Also, we’re aware of growing concern regarding the risks resulting from exposure to (1) fluorine- and bromine-substituted dioxins and fu rans, and (2) sulfur analogs of PCDDs and PCDFs. Research regarding these compounds is ongoing. Until such time as new information is released, though, you can consider the following subsections as our guidance on how to evaluate fluorine, bromine, and sulfur PCDD/PCDF Analogs as potential COPCs in hazardous waste combustor risk assessments.

2.3.10.1 PCDD/PCDF Cancer Risks
We recommend using the TEF method to assess carcinogenic risk on the basis of toxicity relative to 2,3,7,8-TCDD, which is the most toxic dioxin.
There are 210 individual compounds or “congeners” of PCDDs and PCDFs. Seventeen of these 210 congeners are considered to have "dioxin-like" t oxicity. In the TEF method, each of these 17 congeners is assigned a value, referred to as a toxicity equivale ncy factor (TEF), which compares its toxicity to that of 2,3,7,8-TCDD. 2,3,7,8-TCDD then has a TEF of 1.0, and other dioxin- like congeners have TEFs between 0.0 and 1.0. TEF values for these 17 congeners are listed in the Table 2-7.

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### TABLE 2-7 PCDD/PCDF TOXICITY EQUIVALENCY FACTOR VALUES Dioxin Congener TEF (unitless) Furan Congener TEF (unitless) 2,3,7,8-Tetrachlorodibenzo(p)dioxin 1.0 2,3,7,8-Tetrachlorodibenzofuran 0.1 1,2,3,7,8-Pentachlorodibenz o(p)dioxin 1.0 1,2,3,7,8-Pentachlorodibenzofuran 0.05 1,2,3,4,7,8-Hexachlorodibe nzo(p)dioxin 0.1 2,3,4,7,8-Pentachlorodibenzofuran 0.5 1,2,3,6,7,8-Hexachlorodibenzo(p)dioxin 0.1 1,2,3,4,7,8-Hexachlorodibenzofuran 0.1 1,2,3,7,8,9-Hexachlorodibenzo(p)dioxin 0.1 1,2,3,6,7,8-Hexachlorodibenzofuran 0.1 1,2,3,4,6,7,8-Heptachlorodibe nzo(p)dioxin 0.01 1,2,3,7,8,9-Hexachlorodibenzofuran 0.1 1,2,3,4,6,7,8,9-Octachlorodi benzo(p)dioxin 0.0001 2,3,4,6,7, 8-Hexachlorodibenzofuran 0.1 1,2,3,4,6,7,8-Heptach lorodibenzofuran 0.01 1,2,3,4,7,8,9-Heptach lorodibenzofuran 0.01 1,2,3,4,6,7,8,9-Octach lorodibenzofuran 0.0001 Source: World Health Organization (1998) Van den Berg et al (1998).


### To estimate the exposure media concentrations for PCDDs and PCDFs, we recommend using the congener-specific emission rates from the stack. Then , model the fate and transport of each of these 17 congeners to the exposure site to estimate conge ner-specific exposure media concentrations. The HHRAP companion database includes congener-specific fate and transport parameter values, and the media concentration equations are provided in Appe ndix B. After estimating congener-specific exposure media concentrations, we recommend using the TEFs to estimate a "toxic equivalent" (TEQ) exposure media concentration, and an overall TEQ exposure and cancer risk, as follows: 1. convert the exposure media concentrati ons of an individual congener to a TEQ concentration for that congener by multiply ing the congener’s media concentrations by the congener’s TEF; 2. sum the TEQ concentrations of the individua l congeners to get an overall exposure media concentration; 3. estimate the lifetime average daily dose (LADD) for the TEQ concentration; and 4. assess the cancer risk on a TEQ basis using the cancer slope factor for 2,3,7,8-TCDD, in combination with the TEQ-based LADD. Please see Chapter 7 for a more complete discussi on of the steps included in the TEF method.

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### 2.3.10.2 PCDD/PCDF Noncancer Hazards
We generally recommend comparing PCDD and PCDF oral exposure estimates to national average background exposure levels, usi ng 1 pg TEQ/Kg/day for adults and 60 pg TEQ/kg/day for nursing infants. The pertinent exposure estimate would be the ADD, or Average Daily Dose, experienced over the course of the exposure duration, rather than th e LADD, which is this ADD averaged over a lifetime.
The Agency typically evaluates noncancer effects of chemicals by comparing exposure levels to healthbased reference doses or reference concentrations. Ho wever, for reasons discussed in the Agency’s Draft Dioxin Reassessment (U.S. EPA 2000b), the Agency has not developed these non-cancer benchmarks for any of the PCDD or PCDF congeners, or for TEQ concentrations/doses.
One approach the Agency has taken to evalua te whether PCDDs and PCDFs emitted from hazardous waste combustion facilities are likely to cause significan t noncancer health effects is to compare estimated TEQ exposures to national average background exposur e levels (1 pg TEQ/kg/day for adults and 60 pg TEQ/kg/day for nursing infants). The average bac kground level of PCDD/PCDFs and co-planar, dioxinlike PCBs in breast milk is 25 parts per trillion (ppt) of 2,3,7,8-TCDD TEQ (EPA 2000b). The 25- ppt 2,3,7,8-TCDD TEQ is the sum of the average breast milk concentration of 18-ppt TEQ from PCDD/PCDFs and 7-ppt TEQ from co-planar, dioxin- like PCBs (EPA 200b). After normalization for infant body weight, this breast milk concentration of 25 ppt TEQ results in an average, background intake for the infant, ADIb-inf, of 93 picograms per kil ogram per day (pg/kg-day) of 2,3,7,8-TCDD TEQ. If exposures due to the facility’s emissions during the exposure duration of concern are low compared to background exposures, then the emissions aren’t e xpected to cause an incr ease in noncancer effects.
In the future, the Agency may develop alterna tive approaches to evaluate noncancer effects from exposures to PCDDs and PCDFs. In that case, those approaches may be included in future risk assessments.
2.3.10.3 Fluorine, Bromine, and Sulfur PCDD/PCDF Analogs
We generally recommend deciding on a site-specifi c basis whether to evaluate these compounds, in consultation with the permitting authority. Consideri ng that neither the likelihood of the formation, nor

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### the toxicity of these compounds is well understood, th e permitting authority is not likely to request a quantitative toxicity assessment of fluorine, bromine, and sulfur analogs.
The Agency is currently evaluating the potential for the formation of (1) fluorine- and brominesubstituted dioxins and furans, a nd (2) sulfur analogs of PCDDs and PCDFs (U.S. EPA 1996h; 1996m). Available information indicates that fluorinated dioxins and furans aren’t likely to be formed as PICs; although the presence of free fluorine in the combusti on gases may increase the formation of chlorinated dioxins (U.S. EPA 1996h). We aren’t aware of any studies conducted to evaluate this relationship.
Available information indicates that there is potential for brominated or chlorobrominated dioxins to form (U.S. EPA 1996i). The Agency has not assigned TEF values for brominated dioxins or furans (U.S. EPA 1994k). However, the toxicity of bromo- and chlo robromo-substituted dioxin analogs is comparable to that of chlorinated dioxins in short-term toxicity assays (U.S. EPA 1996m).
Although chlorinated dibenzothiophenes (the sulfur an alogs of dibenzofurans) have been reported to form, no information is available indicating the form ation of chlorinated dioxin thioethers (the sulfur analogs of dibenzo[p]dioxins) (U.S. EPA 1996h) . This may be because the carbon-oxygen bond is stronger than the carbon-sulfur bond, and the compound furan (which is part of the dibenzofuran structure) is more stable than thiophene (which is part of the dibenzothiophene structure) (U.S. EPA 1996c). Another possible reason that chlorinated dioxin thioethers have not been observed is the potential instability of these compounds. Chlorinated dioxin th ioethers contain two carbon-sulfur bonds in the central ring of the structure (U.S. EPA 1996h). Please Note : There is currently no U.S. EPA-approved method for the sampling or analysis of these dioxin analogs. We generally recommend using the TOE method (see Section 2.2.1.2) to account for the potential presence of these compounds. The Uncertainty secti on of the risk assessment report (See Chapter 8) could then discuss the potential for the formation of these analogs.

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## C Description of any combustor-specific operating conditions that may contribute to the formation of dioxins C 

### Any facility-specific sampling information regarding PCDD and PCDF concentrations in air, soil, water, or biota C 

### Information regarding the concentrations of su lfur, fluorine, and bromine in the combustor feed materials RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT

2.3.11 Polynuclear Aromat ic Hydrocarbons (PAHs)
As is the case in previous Agency guidance (U.S. EPA 1994i, 1994j, 1994r, 1998c), we recommend evaluating PAHs as COPCs. The following are commonly detected PAHs: • benzo(a)pyrene (BaP); • benzo(a)anthracene; • benzo(b)fluoranthene; • benzo(k)fluoranthene; • chrysene; • dibenz(a,h)anthracene; and • indeno(1,2,3-cd)pyrene. The Agency considers all of these compounds to be carcinogenic. However, an IRIS oral cancer slope factor is only available for benzo(a)pyrene.
PAHs are readily formed in combustors by either (1) dechlorination of other PAHs (such as dioxins) present in the waste feed or emissions stream, or (2 ) the reaction of simple aromatic compounds (benzene or toluene) present in the waste feed or emissions stream. PAHs are well-known as the principal organic components of emissions from all combustion sources, including coal fires (soot), wood fires, tobacco smoke ("tar"), diesel exhaust, and refuse burning (Sandmeyer 1981). They are generally the only chemicals of concern in particulate matter (Man ahan 1991), although the presence of metals and other inorganics in the waste feed can add other contam inants of concern. Based on the toxicity and combustion chemistry of PAHs, we generally recommend that stack gas testing confirm the absence of these compounds from stack emissions.

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### At present, BaP is the most studied PAH and the only one for which a 2-year feeding rodent bioassay has been conducted (U.S. EPA 1991c). The studies av ailable for the other carcinogenic PAHs were conducted by injection, dermal or gavage. Multiple animal studies in rodent and nonrodent species demonstrated BaP to be carcinogenic following administration by oral, intratracheal, inhalation, and dermal routes. BaP also produced positive results in several in vitro bacterial and mammalian genetic toxicity assays, in addition to numerous in vivo tests for deoxyribonucleic acid (DNA) damage. BaP metabolizes to reactive electrophiles that are capable of binding to DNA (U.S. EPA 1990h). Therefore, U.S. EPA (1993d) used various nonbioassay results to determine relative potency factors (RPFs) for the class B2 carcinogen PAHs. RPFs for these seven PAHs are listed in Table 2-8.

TABLE 2-8 RELATIVE POTENCY FACTORS FOR CLASS B2 CARCINOGEN PAHs Compound RPF Benzo(a)pyrene 1.0 Benz(a)anthracene 0.1 Benzo(b)fluoranthene 0.1 Benzo(k)fluoranthene 0.01 Chrysene 0.001 Dibenz(a,h)anthracene 1.0 Indeno(1,2,3-cd)pyrene 0.1 Source: U.S. EPA (1993d)


### Obtaining test data for an individual chemical from a standard carcinogenesis bioassay that might be used to develop a cancer slope factor requires: 1. at least 1 kilogram of relatively pure chemical (greater than 98 percent purity is the most common specification), 2. $500,000 to $1,000,000, and 3. 5 to 6 years. However, an alternative to the fu ll carcinogenesis bioassay is to use in vitro studies to compare various PAHs. In vitro studies, such as those conducted by Knebel et al. (1994) and many other groups, require a few milligrams of each chemical, a few weeks, and about $1,000 per chemical. Because of these

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### differences, we wouldn’t anticipate that many full car cinogenesis bioassays of PAHs will be carried out in the near future.
As with previous guidance (U.S. EPA 1994g), we generally recommend evaluating PAHs using an approach similar to the BaP-RPF method. We generally recommend using the fate-and-transport properties of specific PAHs (versus those of benzo[ a]pyrene) to estimate exposure concentrations. Then following the BaP-RPF method, you adjust the concentrations of the individual PAHs and sum them to obtain an equivalent total concentration of BaP. Multiply this summed concentration by the BaP cancer SF to estimate total risk from all carcinogenic PAHs.
We don’t currently recommend a metabolism factor (MF) for PAHs. A published study (Hofelt et al. 2001), however, highlights the uncertainty in the HHRAP’s approach and presents an alternative metabolism factor for use. If this alternative metabo lism factor is used, you may wish to consider the following site-specific points: 1. If the PAHs under consideration are metabolized in the animal (beef, pork, etc) has it been determined that the degradation produc ts/metabolites aren’t persistent in the meat/and or milk? (This concern has been raised because it is the degradation products of PAHs that cause the toxicity.); 2. Is the extrapolation from the rat to larger animal appropriate?; and 3. If the metabolism factor is appropriate, shoul d it be used equally for all the PAHs being evaluated? Using an MF is discussed further in Sec tion 5.4.4.7 and Appendix B, Table B-3-10.
In addition to carcinogenic effects, noncarcinogenic hea lth effects are associated with exposure to PAHs. However, RPFs for noncarcinogenic effects of PAHs (similar to those developed for carcinogenic effects) have not been developed. The uncertainties asso ciated with attempting to quantify the potential noncarcinogenic effects of PAHs without RfDs or Rf Cs is typically considered greater than the uncertainty associated with not evaluating these potential effects. However, if site-specific emissions data indicate that significant amounts of noncarcinogenic PAHs are emitted, we generally recommend that the potential to underestimate the noncarcinogenic health effects associated with exposure to PAHs be discussed in the Uncertainty sec tion of the risk assessment report.

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### 2.3.12 Radionuclides
Radionuclides exist in naturally occurring materials su ch as coal and other rocks, and as radioactive by-products of industrial processes. The HHRAP doesn ’t consider the naturally occurring concentrations of radioactive materials such as uranium and thoriu m (and their decay elements), based on Agency policy and technical limitations for measuring such low levels . However, radioactive wastes and materials, as defined by the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE), are subject to evaluation through interagency agreem ents on this subject. The U.S. NRC considers “radioactive waste” as waste that is, or contains, by-product material, source material, or special nuclear material (as defined in 10 CFR Part 20.1003). The U.S. NRC considers “mixed waste” as waste that contains both radioactive waste and hazardous waste ( as defined by U.S. EPA). Both radioactive and mixed wastes must be handled in accordance with a ll relevant regulations, including U.S. EPA and U.S. NRC (10 CFR Part 20.2007) regulations. In particular, U.S. NRC licensees must comply with 10 CFR Part 20.2004—“Treatment or Disposal by Incine ration”—and applicable U.S. EPA regulations.
We generally recommend evaluating the burning of mi xed waste and radioactive material if those substances are components of the combustor feed. We also generally recommend including a radionuclide as a COPC if it is in the combustor’s f eed, and has an available toxicity value (e.g., slope factor). Slope factors for over 300 radionuclides are available in HEAST. The slope factor for a particular radionuclide is multiplied by the intake (pCi ) or soil concentration and years of exposure (pCi/g times years of exposure) to estimate cancer risk.
Radionuclide exposure pathways typically evaluated in human health risk assessments include inhalation, ingestion of food products (e.g., meat, milk, vegetables) , incidental soil ingestion, external exposure from ground surface deposits, and external exposure from air c oncentrations (air submersion). The submersion exposure pathway may be of particular concern for radionuclides that emit high-energy beta particles.
Environmental transport and subsequent human exposure are commonly evaluated through the use of radionuclide “dose” codes or computer code/spread sheet combinations. A dose code combines air dispersion/deposition modeling with terrestrial tr ansport models, human exposure parameters, and pre-calculated dose conversion factors [ e.g., from Federal Guidance Report No. 11 (U.S. EPA 1988c) and Federal Guidance Report No. 12 (U.S. EPA 1993j)] to obtain dose and/or risk. The following are several available dose codes for evaluating ra dionuclides from mixed waste combustion facilities:

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### C 

### CAP-88 (Clean Air Act Assessment Package - 1988) C 

### GENII (The Hanford Environmental Radiation Dosimetry Software System) C 

### MEPAS (Multimedia Environmental Pollutant Assessment System) C 

### ISCST3 (Industrial Source Complex Dispersion Model) C 

### CALPUFF (California Puff Model)
To calculate air concentrations and ground deposition rates of radionuc lides, we generally recommend the ISCST3 air dispersion model using the exponential d ecay option. Intake can then be calculated with appropriate exposure scenario equa tions and parameters. ISCST3 is a good choice for facilities with multiple sources, complex terrain, building downwash , and wet/dry deposition requirements. A second option is to use the air concentration and ground deposition rate output from another dose code (e.g., CAP-88 if the facility has completed its NESHAPs analysis).
We generally recommend that equations for fate and transport of radionuclides in soil and water be consistent with those presented for non-radionuclid es, while factoring in decay (and ingrowth if applicable). The recommended food chain biotransfer parameters used to determine food concentrations are available in the user’s guides for most of the do se codes listed previously. However, a comprehensive reference for obtaining these values is the Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments; IAEA Technical Report Series No. 364 (International Atomic Energy Agency 1994).
Decay and ingrowth of radionuclides is a special cons ideration for integrating radioactive materials into risk calculations. Most radioactive materi als undergo radioactive decay through a series of transformations rather than in a single step. Until the last step, these radionuclides emit energy or particles with each transformation and become othe r radionuclides. As radioactive decay progresses, the concentration of the original radionuclides decreases, while the concentration of their decay products increases and then decreases as the decay products themsel ves transform. The increasing concentration of decay products and activity is called ingrowth. We recommend that the assessment consider decay over both the air transport time and the surface exposure duration. Ingrowth may be important, and we generally recommend the assessment use radionuclide slope factors that include contributions from decay elements (“+D” slope factors). Ingrowth that invol ves change of physical state is another situation

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### needing special attention in the fate and transpor t modeling. For instance, solid radium-226 decays to gaseous radon-222, which then decays through solid polonium-218 to further decay elements.
Options for estimating cancer risks from exposure to radionuclides include using the slope factor methodology presented in the Agency’s Estimating Radiogenic Cancer Risks (U.S. EPA 1994s), or using estimates of the relationship between radiation dose a nd cancer risk to convert dose to risk. Federal Guidance Report No. 13 (U.S. EPA 1999d) contains recent estimates of cancer risk for given radiation dose, based on low-dose, low-Linear Energy Tran sfer uniform irradiation of the body. For these conditions, radiation dose equivalent(rem) and absorbed dose (rad) are approximately equivalent. The Report provides risk estimates in terms of mortality and morbidity. It is important to use the estimate appropriate to the site and assessment in question.
The dose-conversion approach uses a single factor to conve rt dose to risk. It is limited, then, in that it doesn’t take into account variations among radionuclid es in the relationship between dose and risk. In general, though, this approach is protective. Th e slope factor approach generally provides a better estimate of risk. Limitations of the slope factor conversion methodology, however, include:
C 

### It assumes a single chemical form, which is not necessarily site-specific or most protective; C 

### External radiation slope factors are only provided for soil contaminated to an infinite thickness, which will over-estimate exposure from radionuclide concentrations near the surface; C 

### Slope factors aren’t available for the s ubmersion in water exposure pathway; and C 

### Slope factors include decay chains for a limited number (18) of parent radionuclides (although these are the most significant decay chains)
Some radioactive materials, such as uranium, also present a non-carcinogenic hazard that it is possible to evaluate. We generally recommend also assessing these non-carcinogenic hazards. We also recommend that the risk summary table in the risk assessm ent report present the cancer risk from radiological contaminants alongside the risks from non-radiological contaminants.
To enhance transparency, we generally recommend that results include a discussion of additivity and the uncertainties of additivity when combining risks from radiological and non-radiological contaminants. There are fundamental differences between the slope factors for chemical and radionuclide carcinogens.

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### Most notably, the slope factors for chemical carcinogens generally represent an upper bound or 95 th 

### percent confidence limit value, while radionuclide sl ope factors are best estimate (50% confidence) values.
Please Note : A prescriptive method for calculating risk from combustion facilities burning mixed waste is beyond the scope of the HHRAP. The above information is provided to outline the method we recommend. 2.3.13 Volatile Organic Compounds
U.S. EPA (1990e) reported that volatile organics listed as probable PICs (based on Freeman 1988 and 1989) produced by burning hazardous waste include: • benzene; • chloroform; • tetrachloroethylene; • 1,1,1-trichloroethane; • toluene; and • methylene chloride. However, the validity of evaluating volatile orga nic COPCs through the various indirect exposure pathways (see Chapter 4) is subject to debate. One argument to exclude these COPCs from evaluation is that there is no empirical evidence that VOC emi ssions pose a hazard via indirect pathways. We’re similarly not aware of any such evidence, but we’r e also unaware of any evidence to the contrary.
Another argument to exclude VOCs from evaluation is based on the conclusion that 1. volatile organic COPCs released into the air ar e expected to remain in the gas phase unless or until they are transformed into low-volatility compounds, and 2. this transformation (or atmospheric chemical reaction), and the subsequent removal of the reaction products, makes irrelevant the toxic ity of the parent volatile organic COPC. We disagree with both aspects of this argument. Fi rst, we’re not aware of any information or research documenting the fate-and-transport of volatile organic COPCs from hazardous waste combustors. Second, although we agree that the toxicity of the parent COPC is irrelevant following transformation, this argument ignores the potential toxicity of the r eaction products. We’re not aware of any available quantitation methods that could be used to predict at mospheric chemical reactions of this nature. We therefore generally believe that evaluating the fa te-and-transport (and toxicity) of the parent COPC

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### remains the best available method for protectively accounting for the potential reaction products to which receptors are ultimately exposed.
Finally, another argument to exclude VOCs from evaluation is the assertion that there is no firm technical basis for assessing the rate of deposition of VOCs to so ils or uptake by plants (discussed in detail in Appendix A-2). Although we agree with the basic prem ise of this issue, we’re unaware of any other method for evaluating the potential indirect exposure to volatile organic COPCs or their atmospheric reaction products (empirical data aren’t available).
To summarize, we agree in principl e that the science regarding the fate-and-transport of volatile organic COPCs in the environment is poorly understood. However, because the poten tial risks associated with indirect exposure to these COPCs is also poorly unders tood, we believe that evaluating volatile organic COPCs via the indirect exposure pathways—with th e proper explanation of the uncertainties associated with this process—generally provides the most r easonable (based on current science) and protective estimate of these potential risks. We also believe th at the risk equations generally address this issue because a calculation cannot be completed unless there ar e sufficient fate and transport properties values for each COPC.
Finally, current sampling and analytical methods aren ’t always able to positively identify all individual organic compound in stack emissions. We recommend accounting for the mass of unidentified organic compounds in stack emissions on the basis of TOE from the hazardous waste combustor. The methodology for using TOE in a risk assessment is discussed further in Section 2.2.1.2.

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### 2.4 ESTIMATING COPC CONCENTRATIONS FOR NON-DETECTS
One particularly difficult issue in a risk assessment is how to treat data that are reported as below the “detection limit” (i.e. “Non-detects”). The following subsections:
1. define commonly reported detection limits; 2. describe the use of non-detect data in the risk assessment; 3. describe statistical distribution techniques applied to address this issue; 4. summarize our recommendations on quantifying non-detects for use in risk assessments; and 5. clarify use of data flagged as estimated maximum possible concentration (EMPC) in the risk assessment. 2.4.1 Definitions of Commonly Reported Detection Limits
Generically, a “detection limit” is the lowest level of an analyte that can be detected using a particular analytical method. The Agency’s commonly-used definition for the detection limit for non-isotope dilution methods is the method detection limit (MDL ), as promulgated in 40 CFR Part 136, Appendix B (U.S. EPA 1995i). A level above the MDL is the level at which reliable quantitative measurements can be made; generically called the “qua ntitation limit” or “quantitation leve l.” In practice, numerous terms have been created to describe detection and qua ntitation levels. We have summarized below the significance and applicability of the levels most widely reported by analytical laboratories. These levels—listed generally from the lowest lim it to the highest limit—include the following:
C 

### Instrument Detection Limit (IDL) : The smallest signal above background that an instrument can reliably detect, but not quantify. Also commonly described as a function of the signal-to-noise (S/N) ratio. C 

### Method Detection Limit (MDL) : The minimum concentration of a substance that can be measured (via non-isotope dilution methods) and reported with 99 percent confidence that the analyte concentration is greater than zero. It is determined from analysis of a sample in a specific matrix type containing the analyte. The MDL is considered the lowest level at which a compound can be reliably detected. The MDL is b ased on statistical analyses of laboratory data. In practice, MDLs are determined on analytical reagents (e.g., water) and not on the matrix of concern. However, a laboratory may contract to do a matrix-specific “MDL Study” for a particular project or a particular facility’s w aste matrix when needed. However, routine MDL determinations (water reagent) are conducted on at least an annual basis or whenever equipment changes occur. MDLs for a given method are laboratory- and compound-specific.

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## Equation 2-3 To determine the MDL as specified in 40 CFR Part 136, Appendix A, for example, at least seven replicate samples with a concentration of the co mpound of interest near the estimated MDL are analyzed. The standard deviation among these analyses is calculated and multiplied by 3.14. The result of the calculation becomes the MDL. The factor of 3.14 is based on a t-test with six degrees of freedom and provides a 99 percent confid ence that the analyte can be detected at this concentration (U.S. EPA 1995i). Please Note : 40 CFR Part 136 is specific to the Clean Water Act, and it identifies the use of water as the matrix for the MDL determinati on. The MDL was promulgated in 1984, and is incorporated in more than 130 Agency anal ytical methods for determining several hundred analytes. C 

### Reliable Detection Level (RDL) : A detection level recommended by the National Environmental Research Laboratory in Cincinnati. It is defined as 2.623 times the MDL (U.S. EPA 1995i). C 

### Estimated Detection Limit (EDL) : A quantitation level defined in SW-846 that has been applied to isotope dilution test methods (e.g., SW-846 Method 8290). A variation of the SW-846 defined EDL is also commonly reported by commercial la boratories, however, with the addition of a multiplication factor that generally elevates the EDL value by 3.5 to 5 times that of the SW-846 definition. Commercial laboratories sometimes report EDLs for non-isotope dilution methods, even though an EDL is not defined by the methods. As defined in SW-846: The EDL is defined in SW- 846 (presented in various methods, e.g., Method 8280A) as the estimate made by the laboratory of the concentration of a given analyte required to produce a signal with a peak height of at least 2.5 times the background signal level. The estimate is specific to a particular analysis of the sample and will be affected by sample size, dilution, etc. The presented equation defining EDL is as follows:

where EDL = Estimated detection limit (ng/L) 2.5 = Peak height multiplier (unitless) Qis = Nanograms of the appropriate internal standard added to the sample prior to extraction (ng) H

n 1 

### and H n 2 

### = The peak heights of the noise for both of the quantitation ions of the isomer of interest H

is 1 

### and H is 2 

### = The peak heights of both the quantitation ions of the appropriate internal standards D = Dilution factor - the total volume of the sample aliquot in clean solvent divided by the volume of the sample aliquot that was diluted (unitless) V = Volume of sample extracted (L) RF n 

### = Calculated relative response factor from calibration verification (unitless)

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## Equation 2-4 Common commercial laboratory practice: The EDL generally reported by commercial laboratories is defined as the detection limit reporte d for a target analyte that is not detected or presents an analyte response that is less than 2.5 times the background level. The area of the compound is evaluated against the noise level measured in a region of the chromatogram clear of genuine GC signals times an empirically derived f actor. This empirical factor approximates the area to height ratio for a GC signal. This fact or is variable between laboratories and analyses performed, and commonly ranges from 3.5 to 5. The equation is as follows:

where EDL = Estimated detection limit 2.5 = Minimum response required for a GC signal Q $ 

### = The amount of internal standard added to the sample before extraction F = An empirical factor that approximates the area to height ratio for a GC signal H = The height of the noise D = Dilution factor W = The sample weight or volume RRF F 

### = The mean analyte relative response factor from the initial calibration A $ 

### = The integrated current of the characteristic ions of the corresponding internal standard

C 

### Practical Quantitation Limit (PQL) : A quantitation level that is defined in 50 FR 46908 and 52 FR 25699 as the lowest level that can be relia bly achieved with specified limits of precision and accuracy during routine laboratory operati ng conditions (U.S. EPA 1992g; 1995i). The PQL is constructed by multiplying the MDL, as deri ved above, by a factor (subjective and variable between laboratories and analyses performed) usually in the range of 5 to 10. However, PQLs with multipliers as high as 50 have been reported (U.S. EPA 1995i). The PQL has been criticized because of the am biguous nature of the multiplier and because the resulting levels have been perceived as t oo high for regulatory compliance purposes (U.S. EPA 1995i). C 

### Target Detection Limit (TDL) : A quantitation level constructed similar to the PQL. C 

### Reporting Limit (RL) : A quantitation level constructed similar to the PQL. C 

### Estimated Quantitation Limit (EQL) : A quantitation level constructed similar to the PQL. C 

### Sample Quantitation Limit (SQL) : A quantitation level that is sample-specific and highly matrix-dependent because it accounts for sample volume or weight, aliquot size, moisture content, and dilution. SQLs for the same co mpound generally vary between samples as moisture

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### content, analyte concentration, and concentra tions of interfering compounds vary. The SQL is generally 5 to 10 times the MDL, however, it is often reported at much higher levels due to matrix interferences. C 

### Contract Required Quantitation Limit (CRQL) /Contract Required Detection Limit (CRDL) : A quantitation pre-set by contract, which may incorporate SW-846 methods, Office of Water methods, or other methods deemed necessary to meet study objectives. These limits are typically administrative limits and may actually be one or two orders of magnitude above the MDL. 2.4.2 Using Non-Detect Data In the Risk Assessment
In collecting waste feed or emissions data for use in risk assessments, or in setting regulatory compliance levels, a permitting authority is often faced with data quality objectives that require analyses near or below analytical detection or quantitation levels. In such situations, permittees often argue that the detection levels should be set with a large factor of certainty in order to be confident that measurements are reliable. Environmental groups frequently argue th at a level of zero, or a level at which a single researcher can demonstrate that the compound can be detected, should be used as the set level. Measurements made below analytical detection a nd quantitation levels are associated with increased measurement uncertainty, so it is important to unde rstand the impact they may have when they are applied.
Because of the quantitative differences between the various types of detection levels, “non-detected” compounds pose two questions: 1. Is the compound really present?, and 2. If so, at what concentration? The first question is generally hard to answer, a nd is dependent mainly on the analytical resources available. The answer to the second question is “so mewhere between true zero and the quantitation level applied.” In earlier guidance (U.S. EPA 1994i) we recommended applying emission rates of one-half the “detection limit” for non-detects. However, which detection limit to use was not explicitly defined or presented in quantitative terms.

For waste feed data (e.g., used as a surrogate when emi ssions data is not available), we generally recommend using the SQL, since waste feeds are typically highly concentrated organic or inorganic matrices that require special analytical clean-up proce dures and dilutions of the sample. This approach is consistent with that used in other program offices for highly contaminated media requiring quantification

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### specifically for risk assessment purposes. However, in dealing with stack emissions data, concentrations of constituents are typically found only at trace levels (assuming good combustion). Therefore, to increase consistency and reproducibility in dealing with non-detects for emissions data , we generally recommend using the MDL-derived RDL to quantify non-detects for COPCs analyzed with non-isotope dilution methods, and using the method-defined EDL to quantify non-detects for COPCs analyzed with isotope dilution methods. The procedures are as follows: For COPCs Analyzed With Non-isotope Dilution Methods: Quantify non-detects by using an MDL-derived RDL. 1. Require the laboratory to report the actual MDL as specified in the chosen SW-846 analytical method. The laboratory should report MDLs for every non-detect compound analyzed, in addition to the commonly used reporting limit, such as an EDL, EQL, or PQL. Commonly used SW-846 non-isotope dilution methods such as Method 8260 (volatiles), and Method 8270 (semivolatiles) don’t themselves define the MDL. They reference 40 CFR Part 136 instead. Though specified in the Method, some laboratories do not always report MDLs as defined in 40 CFR Part 136. This would apply to the analysis of each individual component of multiple-component samples (e.g., front half rinse, XAD resin, condensate, Tenax tube). Note: Laboratories typically produce MDLs specific to each non-isotope dilution method performed by the laboratory on an annual basis. 2. Calculate an MDL-derived RDL for each COPC non-detect by multiplying the MDL by 2.623 (interim factor) (U.S. EPA 1995i). Another option is to request that the labor atory derive the RDLs for you (per the definition above), as part of the analys is. Good quality assurance/quality control (QA/QC) suggests you check to make sure the RDLs have been generated properly. 3. Adjust the RDL, as appropriate, to account for sample-specific volumetric treatments (e.g., splits and dilutions) that differ from those used in the Part 136 MDL determinations. Again, an option is to have the laboratory perform the adjustments for you. We recommend you check to make sure the adjustments have been done properly. For COPCs Analyzed With Isotope Dilution Methods: Quantify non-detects using the EDL as defined by the analytical method, without the use of empirical factors or other mathematical manipulations specific to the laboratory. Commonly used isotope dilution methods include SW-846 Methods 8290, 1624, and 1625, as well as CARB 429. Methods for Metals Analysis: Quantify non-detects for metal analysis in the risk assessment by using the IDL as defined by the analytical method, without the use of empirical factors or other mathematical manipulations specific to the laboratory.

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### Please note this recommendation is an update to the information provided in U.S. EPA [2001c] Risk Burn Guidance for Hazar dous Waste Combustion Facilities. ) The MDL definition used in 40 CFR Part 136 addresses erro rs of the first type (i.e. false negatives). The 99 percent confidence limit states that the MDL has only a 1 percent chance the detects will be misidentified as negative, when the compound of con cern is actually present. Errors of the second type (false positives) aren’t addressed. By not addressing fal se positives, the statistically-defined default value becomes 50 percent. In other words, where 40 CF R did not address false positives, the system required that 50 percent of the detects at the MDL would be false positives. This is a very protective approach, and biased toward not missing any compounds of potential concern that may be present. The MDL-derived RDL, and to a lesser extent the ED L, somewhat indirectly addresses the false positive issue. As described in defining the RDL (see Secti on 2.4.1), by the time the standard deviation has been multiplied by 8, the possibility of false positives is usually less than 1 percent.
2.4.3 Statistical Distribution Techniques
Many statistical distribution techniques are availabl e for calculating a range of standard deviations to quantify non-detect concentrations of COPCs. These include random replacement scenarios, such as (Cohen and Ryan 1989; Rao, Ku, and Rao 1991): • the uniform fill-in (UFI) method, in which each LOD value is replaced with a randomly generated data point by using a uniform distribution; • the log fill-in (LFI) method which is the same as UFI, except using a logarithmic distribution; • the normal fill-in (NFI) method which is the same as UFI, except using a log-normal distribution; and • the maximum likelihood estimation (MLE) technique.
Also, if the permitting authority determines it to be applicable, a Monte Carlo simulation might be used to determine a “statistical” value for each non-detect concentration.
2.4.4 Our Recommendations on Quantifying Non-Detects
Using non-detects in a risk assessment depends on the an alytical method(s) used to produce the data. In most cases, the Agency estimates emission rates fo r undetected COPCs (see Section 2.3) by assuming that COPCs are present at a concentration equivale nt to the MDL-derived RDL for non-isotope dilution

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### methods, or to the method-defined EDL for isot ope dilution methods. We consider these methods reasonable, and believe they represent a scientifica lly sound approach that supports maximum protection of human health and the environment while rec ognizing the uncertainty associated with analytical measurements at very low concentrations in a real wo rld sample matrix. We also recognize that there are subjective components and limitations to each of the non-detect methodologies presented in this and previous guidance, including the recommended methods.
Some risk assessors have expressed the desire to obt ain and use non-routine data (e.g., uncensored data) of defensible quality in risk assessments, as a way to deal with non-detect issues. The HHRAP doesn’t address what forms or how such data might be used . The decision to use non-routine data in a risk assessment is not precluded just because it is diffe rent. Neither does the HHRAP necessarily endorse using non-routine data. We generally recommend consulting with the permitting authority on the appropriateness of using non-routine data. If non-rou tine data is used, we generally recommend carefully identifying and evaluating the limitations associated w ith the data, and clearly document this discussion in the Uncertainty section of the risk assessment report.
As stated previously, a pretrial burn risk assessment can help to make sure that the trial burn test will achieve the desired quantitation limit (and, therefor e, DREs and COPC stack gas emission rates).
2.4.5 Estimated Maximum Possible Concentration (EMPC)
The EMPC as defined in SW-846 is in most cases only used with the isotope dilution methods. An EMPC is calculated for dioxin isomers that: • have a response with a signal to noise ratio of at least 2.5 for both the quantitation ions; and • meet all the relevant identification criteria sp ecified in the analytical method, except the ion abundance ratio. Ion abundance ratios are affected by co-eluting in terferences that contribute to the quantitative ion signals. As a result, one or both of the qua ntitative ions signals may possess positive biases.

An EMPC is a worst-case estimate of the concentrati on. An EMPC is not a detection limit and should not be treated as a detection limit in the risk assessment. We generally recommend using EMPC values as detections without any further manipulation (e.g., dividing by 2). However, because EMPCs are worst-

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## C Actual MDLs for all non-detect stack emissions data, non-isotope dilution methods 

## C EDLs for all non-detect stack emissions data, isotope dilution methods 

## C SQLs for all non-detect waste feed or feedstream data used C 

### Description of the method applied to quantify the concentration of non-detects RECOMMENDED INFORMATION FOR THE RISK ASSESSMENT REPORT case estimates, you may wish to consult with the permitting authority on techniques to minimize EMPCs when reporting trial and risk burn results. This is especially true when the EMPC values result in risk estimates above regulatory levels of concern. So me techniques to minimize EMPCs include performing additional cleanup procedures (as defined by the analytical method) on the sample or archived extract, and/or reanalyzing the sample under different chromatographic conditions.
Please Note : using alternative quantitation i ons might be acceptable, if the signal-to-noise ratio of the ion signal is at least 2.5 and if the tune data indicate that the mass spectrometer is operating within specifications. Such actions to reduce the EMPC are expected to be more cost effective than the additional sample cleanup and/or reanalysis.

2.5 EVALUATING CONTAMINATION IN BLANKS
Blank samples are intended to provide a measure of any contamination that may have been introduced into a sample: 1. in the field while the samples were being collected, 2. in transport to the laboratory, or 3. in the laboratory during sample preparation or analysis. Blank samples are analyzed the same way as the site samples from the trail burn. To prevent including non-site related compounds in the risk assessmen t, we generally recommend comparing the concentrations of compounds detected in blanks to concentrations detected in site samples collected during the trial burn. Four types of blanks are defined in the Risk Assessment Guidance for Superfund

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### (U.S. EPA 1989e): trip blanks, fi eld blanks, laboratory calibration blanks, and laboratory reagent or method blanks. Detailed definitions of each are provided below. Trip Blank - A trip blank is used to indicate potentia l contamination due to migration of volatile organic compounds from the air on the site or in sample shipping containers, through the septum or around the lid of sampling vials, and into the sample. The blank accompanies the empty sample bottles to the field as well as with the site samples returning to the laboratory for analysis. The blank sample is not opened until it is analyzed in the lab with the site samples, thus making the laboratory “blind” to the identity of the blanks.
Field Blank - A field blank is used to determine if field sampling or cleaning procedures (e.g., insufficient cleaning of sample equipment) result in cross-contamination of site samples. Like the trip blank, the field blank is transported to the field with empty sample bottles and is analyzed in the laboratory along with the site sam ples. Unlike the trip blank, however, the field blank sample is opened in the field and recovered in the same manner as the collected samples. As with trip blanks, the field blanks’ containe rs and labels may be the same as for site samples and blind to the laboratory.
Instrument Blank - An instrument blank is distilled, deionized water injected directly into an instrument without having been treated with reagen ts appropriate to the analytical method used to analyze actual site samples. This type of blank is used to indicate contamination in the instrument itself. Laboratory Reagent or Method Blank - A laboratory reagent of method blank results from the treatment of distilled, deionized water with all of the reagents and manipulations (e.g., digestions or extractions) to which site samples will be subj ected. Positive results in the reagent blank may indicate either contamination of the chemical r eagents or the glassware and implements used to store or prepare the sample and resulting solutions. Although a laboratory following good laboratory practices will have its analytical processed under control, in some instances method blank contaminants cannot be entirely eliminated. Water Used for Blanks - For all the blanks described above, results are reliable only if the water comprising the blank was clean. For example, if the laboratory water comprising the trip blank was contaminated with VOCs prior to being taken to the field, then the source of VOC contamination in the trip blank cannot be isolated. Blank data is generally compared to the results withwhich the blanks are associated. However, if the association between blanks and data can’t be made, blank data is compared to the results from the entire sample data set.
U.S. EPA (1989e) makes a distinction between bla nks containing common laboratory contaminants and blanks containing contaminants not commonly used in laboratories. Compounds considered to be common laboratory contaminants are

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 2-89 

### • acetone, • 2-butanone (methyl ethyl ketone), • methylene chloride, • toluene, and • the phthalate esters. If compounds considered to be common laboratory contam inants are detected in the blanks, then sample results are usually not considered to be detected unless the concentrations in the sample are equal to or exceed ten times the maximum amount detected in the applicable blanks. If the concentration of a common laboratory contaminant in a sample is less th an ten times the blank concentration, then the compound is usually treated as a non-detect in that particular sample.
In some limited cases, it may be appropriate to cons ider blanks which contain compounds that aren’t considered by the Agency to be common laboratory contaminants. In these limited cases, sample results aren’t considered to be detected unless the concen trations in the sample exceed five times the maximum amount detected in the applicable blanks. If the c oncentration in a sample is less than five times the blank concentration, then the compound would be treated as a non-detect in that particular sample.
Carefully consider the evaluation of blank data in the overall context of the risk assessment and permitting process. We generally expect issues re lated to non-laboratory contaminant blanks to be minimal, because data collection and analysis efforts in support of trial/risk burns are expected to be of high quality and in strict conformance to QA/QC plan s and SOPs. Carefully evaluating the trial/risk burn data will avoid the potential for contaminated blanks to compromise the integrity of the data. It will also help prevent the need for retesting to properly address data quality issues.
We highly recommend practicing caution in applying bla nk results to correct or qualify sample results for any purpose, as blanks are provided in minimal quantiti es (e.g., one per test condition or one per test) and therefore are at best qualitative indicators of the validity of a data set. Blank correction can reduce accuracy and often represent a non-conservative uncer tainty. Consequently a permit authority might dedice not to allow blank correction as a conservativ e assumption (consistent with a screening level risk assessment).
When considering blank contamination in the CO PC selection process, we recommend that permitting authorities ensure that:

### Human Health Risk Assessment Protocol Chapter 2: Facility Characterization September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 2-90 

### (1) The facility or data gatherer has made every reasonable attempt to ensure good data quality and has rigorously implemented the QA/QC Plan and good industry sampling and testing practices. (2) Trial/risk burn data has not been s ubmitted to the permitting authority as “blank corrected.” Rather, the permitting authority has the full opportunity to review the data absent additional manipulation by the data gatherer. (3) The effect of the blank correction on the overall risk estimates, if such an effect is considered, is clearly described in the un certainty section of the risk assessment report. (4) The risk assessment report lists emissions rates both as measured, and as blank corrected, in situations where there is a signi ficant difference between the two values.U.S. EPA Region 6 U.S. EPA

Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-1 

# Chapter 3 Air Dispersion and Deposition Modeling

What’s Covered in C hapter 3: 3.1 Background

on Air Dispersion Mod

els for Risk Asses sment 3.2 Partitioning Em

issions 3.3 Site-Specific Ch

aracteristics Required for Air Mo deling 3.4 Meteorological Data Prim er 3.5 Meteorological Preprocessor Data Needs 3.6 ISCST3 Model I

nput Files 3.7 ISCST3 Model E xecution 3.8 Using Model Outp ut 3.9 Modeling Fugitiv e Emissions 3.10 Modeling Acute Risk

PLEASE NO TE : for the purposes of this guidance, “we” refers to the U.S. E PA OSW. The “you” to which

we speak in this chapter is the air m odeler: the person (or persons) who will actually put the recomm ended air modelin

g methods

into practice. The burning of m

aterials produces residual am ounts of pollution that cou ld be released to the environment. Knowledge of atm ospheric pollutant concentrations and deposition rates in the areas around the com

bustion facility is an in

tegral part of estim

ating potential hum

an health risks associa

ted with these releases. A

ir concentrations and depos ition rates are usually e stimated using air dispersion models. Air dispersion models are mathem atical constructs that attem pt to describe the effects of physical processes that occur in the atmo sphere on rates of dispersion of emissions from a source (suc h as the s tack o f a com

bustor) . These mathe

matic al const

ructs ar e coded into compute

r prog rams to facilitate the computation al process.

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-2 

### This chapter prov

ides g uidance on criteria to c onsider

when s electing

an air m odel to use to s

upport a risk assessmen

t. It also d

escribes the developm

ent and use of the U .S. EPA air dispe rsion model—the Industrial Source

Complex Sh

ort-Term Model (ISCST3)—which best addresses the selection c riteria for most risk as sessments. Although the air dispe rsion modeling

methods presente d in the HHRAP focus on use of I SCST3, other a

vailab le mo dels m

ay be more appropr

iate if t hey b etter m

eet the selection criter

ia due to study- specific objectives or assessm ent area characteristics. Of particular interest is the Am erican Meteorological Society- Env ironmental Protection Agency R egulatory Model (AERMOD), which has been proposed by

EPA as a replacem

ent for the IS CST3 model for C lean Air Act regu latory purposes. More details about AERMO D and other alternative models are provided in Section 3 .1.1.

The Guideline on Air Qu ality Models (GAQM) (U.S. E PA 1996k; 19 99b; Federal Register 2000) is a primary referenc e for all US EPA and state agencies o n using air m

odels for regulatory

purposes. The GAQM is Appendix

W of 40 CFR P art 51. The Office of A ir Quality Planning

and Support (OAQ PS) provides the GAQM and extensive information on up dates to air dispersion m odels, meteorolog

ical data, data preprocessors, and user’s guides on the Support Center for Re gulatory Air Models (SCRAM) web site at www.e

pa.gov/scra

m001 /index. htm . We sugg est you review this web site periodically to check for updates and chang es to the recomm ended model. General questions regarding air m odeling, or information on the web site may be addressed to atk

inson.dennis@epam

ail.epa.gov. Specific questions on the use of this g

uidance may

be addressed to the ap

propriate permitting

authority. Please

refer to the respecti ve m odels U ser’s Man

ual for:

< 

### a more in- depth discussion on the physical assum ptions embodied in the ISCS T3 or other air dispersion mode l that may be considered; as well as

< 

### concept s of atm

ospheri c proce sses tha

t are em bodied in dispe

rsion m odels in gener al. Discussions in Section 3 .1 focus on a back ground of available models, an d selection criteria to consider when deciding w

hich air model to use in a risk assessm ent. The remainder of the chapter provid es information on I SCST3 input data needs, and output file development. Chapter sections include:

• Partitioning em

issions (Section 3.2)

• Site-specific characteristics needed for air mo deling (Section 3.3 )

- Surrounding terrain (S ection 3.3.1)

- Surrounding land use (Section 3.3.2)

- Facility building characteristics (Section 3.3.4)

• Meteorological data (Section 3.5)

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-3 

### If you aren’t familiar with the types of data use d in air concentration and deposition models, Section 3.4 provides a short tutorial on the types o f meteorologic al data needed, and p otential data sources. Section 3.5 describes the data n

eeds of the preprocessor c omputer prog ram we recom

mend using

to prepare, organize, and

format m eteorological data for u se in the IS CST3 model. Section 3.6 describes the structure and format of ISCST3 inp ut files. Section 3.7 describes limitations to consider in executing ISCST3. S ection 3.8 describes how model outputs are used in the risk assessment com

putations. Section 3.9 discusses air m

odeling of fugitive emissions. Section 3.10 discusse s air modeling for acute exposure.

3.1 DESCRIPTION OF AIR M ODELS
This section gives a brief backgro und on air dispersion m

odels for risk assessm

ent. This section also introduces some d

ata preprocessing prog

rams develo

ped to aid in preparing

air model input files (these preproc essing

progr ams a re descr ibed in more detail in

Section s 3.3. 3 and 3 .5).

3.1.1 Background on Air Dispersion Models for Risk Assessment

Before 1990, the Ag ency a nd the r egula ted com munit y used sever al air di spersion mod

els. The se mo dels were of limited u sefulness in risk assessm ents because they considered only air concentration, and not the dep osition of conta

minan ts to lan d. The o rigina l Age ncy g uidance on com pleting risk a ssessm

ents (U.S. EPA 19 90e) identified two m odels that were explicitly formulated to acc ount for the effects of deposition:

• COMPLEX I, from which a new model—C OMPDEP—resulted

• Rough Terrain Diffusion Model (RTDM), from which a new model—RTDMDEP—resu lted An updated vers ion of the IS CST model in us e at the time, C OMPDEP included b uilding wake

effects. Subseq uent Agency g

uidance (U.S. EPA 1 993f an

d 1994g ) recom mend ed usin g CO MPDEP for air deposi tion mode ling. U.S . EPA (199 3f) spe cifie d COMPDEP Versi on 93252 , and U.S. EPA (199 4g) specified COMPDEP Version 93340. When thes e recomm endations were m

ade, a combin

ed ISC- COMPDEP m

odel (a merg er of the ISC ST2 and COMPLEX I model) was still under developm ent. The merged m

odel became k

nown as I SCSTDFT. U.S. EPA guidance (1994r) recomm ended using the IS CSTD FT model . Af

ter r evi ews a nd ad justm ents , thi s mo del was re leas ed as IS CST3 . The

IS CST3 model contains alg

orithms for dispersion

in simple, interm

ediate, and com

plex terrain; dry depo sition; wet deposition; and plum e depletion.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-4 

### Operating the CO MPDEP, RTDMDEP, and ISC ST models is described in more detail in

the following User’s Manuals. Please

note, thoug

h, that all models except the

current versi on of I SCST3 a

re considered obsolete:

• Environmen

tal Research and Technolog y (ERT). 1987. User’s Guide to the R ough Terrain Diffusion Model Re vision 3.20 . ERT Docum ent P-D535 -585. C oncord, Massachusetts.

• Turner, D.B. 1986

. Fortran Computer C ode/User’s Guide for C

OMPLEX I Version 86064: An Air Q

uality Dispersion Model in S ection 4. Additional Mod els for Regulatory Use. Source File 31 C ontained in UNAMAP (Version 6). National Technical Inform

ation Service (NTI S) PB86-2 22361/AS.

• U.S. EPA. 1 979. Industrial Source Co mplex Dispersion Model U ser’s Guide, Volume I. Prepared by the H .E. Cramer Company . Salt Lake C ity, Utah. Prepared for the Office of Air Quality Plannin

g and Standards. Research Triangle P ark, North Caro lina. EPA 450/4-79/030. NTIS PB 80-133044.

• U.S. EPA. 1 980b. User’s Guide for MPTE R: A Multiple Point Ga ussian Dispersion Algorithm with Option al Terrain Adjustment . Environm ental Sciences Research Labo rat ory. R esea rch T ria ngle Park, Nort h Car oli na. EP A 600 /8-80 /016 . NTIS PB80-1973 61.

• U.S. EPA. 1 982a. MPTER-DS: The MPT ER Model Including Dep osition and Sedimentation . Prep ared by the Atm ospheri c Turbule

nce and Diffusi on Labo

ratory (NOAA). Oak

Ridge, Tennessee. Prepared for the En vironmental S ciences Research Labo rat ory. R esea rch T ria ngle Park, Nort h Car oli na. EP A 600 /8-82 /024 . NTIS PB83-1142 07.

• U.S. EPA. 1987b. On-Site Meteorological Program Guidance for Re gulatory Modeling Applications . Offic e of Air Qualit y Planni ng and Sta ndards . Resear ch Tri angle Pa rk, North Carolina.

• U.S. EPA. 1995f. User’s Guide for the In dustrial Source Comp lex (ISC3) D ispersion Models, Volum es I and

II. Office of Air Qua

lity Planning and Standards. Em issions, Monitoring, and A

nalysis Division . Research Triangle Park, North C arolina. EPA 454/B- 95/003 a. Septembe r.

Four air models in curr ent regulatory use, or pr oposed by OAQPS, include ISCST3, AERMOD, CALPU FF and ISC -PR IME. However, we gene rally r ecom mend using the late st version of ISC ST3 in most situations to c onduct air dispersion and deposition modeling for use in a risk assessment. This recommen

dation is based on I SCST3's status as the:

• Model most used by regional, state and local agenc ies; and

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-5 

### • Model satisfying the most of the fo llowing criteria:

< 

### Has bro ad reg

ulatory accepta nce and experie nce in e valua ting t he im pacts of air contaminants em

itted from va

rious industrial sources (e.g ., short and tall stack heigh ts, fugitive e

missi ons from

proces s and st

orage areas);

< 

### Can ev

aluate i mpac ts attrib

utable t o a sing le sourc e, with

capabi lity to

evalu ate multiple sources;

< 

### Can ev

aluate c ompo

unds em itted as vapor or par

ticulate phase w ith consideration of deposition a nd remova

l processes based on the

physical characteristics of the com pound;

< 

### Accepts placemen t of grid nodes at any location within the applicable range of the air m odel;

< 

### Can conduct stepwise evaluation of hourly meteorologic al conditions for multiple years of data producing short-term (acute) and long-

term (chronic) averages as o

utputs; and

< 

### Can evaluate buildin g downwash effects.
The othe r three a ir mo dels are

propos ed by

OAQP S as ref

ined reg ulatory air models in

the rev isions t o the Guideline on Air Q

uality Models (U.S. EPA 1996k ; 1999b). Of particula r interest is AERMOD. AERMO D is pro

posed t o replac e IS CST3 as the recommended a ir quali ty m odel for most regul atory applications (Federal Register 2000). AERMO D has been evaluated extensively by the air m

odeling
commun ity for improv

ements ove

r the ISCS T3 algorithms for vertical contamin ant distribution from sources with tall stacks, terrain effects in areas w ith terrain elevations above the top of em ission source stacks , and e

nhanced night time d ispersion in urb an areas . However, AERMOD currently has minim

al regula tory experience. AE

RMOD w ould be an im portant consid eration for risk

assessm ents if:

• it gains broad reg ulatory acceptance,

• the ass essment area co ntain s signif icant terra in fea tures (i.e., terra in ele vation s above emission source stacks) OAQPS prom

ulgated the California Puff Model (CALPUF F) model for us e on a case- by-case basis, for long- range transport (gre ater tha

n 50 k ilometers), a s well a s the sp ecial condition s of v ery lig ht or ca lm winds ( less t han 1 mete r per se cond). CALPUFF may be a n import ant con sider ation when model ing:

• chem

ical tran sformation of

highl y reactive c ontam

inants;

• long r

esidenc e time s during

extend ed perio ds of li ght winds or calm conditi ons;

• transport over long distances;

• recircul ation of

contam inants d ue to lo cal wind effect s; or

• hilly terrain and river valleys.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-6 

### Also, the proposed OAQPS revisions to the GAQM recom mend using

the version of I SCST with the new downwash algo

rithm, I SC-PRI

ME, for applications where aerodynam

ic building down

wash is critical (Federal Register 200 0). The necessary information and inp uts to evaluate the e ffects of building downwash are further d

iscussed in Section 3.2. 4. We generally recommend determining the need for the improved b

uilding downwa sh calculation on a case- by-base basis.

Althou gh air dispers ion m

odeling meth ods pre sented i

n this g uidance use I SCST3, you m

ay wa nt to evaluate othe

r mod els (such as I SC- PRIME, AERMOD, or CAL PUFF, if the r

evised GAQM adopts them), to see w

hether they m

ore substantially m

eet the selection criteria. Sp ecific to its ability to m eet the sele ction cr

iteria li sted above, the IS CST3 m odel is technic ally c apable of eva luating :

• Gaussian dispersion rates in vertical and horiz ontal plume cross- section;

• Urban and rural dispersion coefficients;

• Terrain effects;

• Source characterization a s a discrete point, two- dimensional area, or three-dim ensional volume;

• Short-

term a nd long -term

avera ges (1 -hou

r and an nual);

• Surface meteorolog y data includes ho

urly observation s of wind speed (neare st 1/10th mile p er secon

d), win d direct ion (nea rest deg ree), st ability class (6 categ ories), and tem perature (nearest degr

ee);

• Mixing

heigh t data in terpolat ed from twice d aily u pper air soundi ngs co rrespon ding t o each hour of surface data;

• Deposition processes for co nservation of m

ass with particle wet and dry deposition and removal, a

nd vapor wet d

eposition and rem

oval (dry v

apor deposition im

plemented within the air m

odeling ; see Se ction 3. 6.1);

• Hourly precipitation am ount and type act on wet deposition an d removal; and

• Single first order expo nential decay rate.

In a ddition , emi ssion so

urces ca n be de fined in

ISC ST3 with

either stack d

imens ions at a discre

te point , as a two -dim

ensiona l area so urce, or in thre e dimensions as a volume

source . Theref

ore, I SCST3 o ffers the flexibility

to mo del sou

rces bas ed on s ource ty

pe (i.e. , stack

or fugitive a

rea).

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Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-7 

### 3.1.2 Preproce ssing Pro grams

ISCST3 needs the help of additional com puter program s, referred to as “preproces sing” program s. These programs format available information reg arding surrounding buildings and m

eteorological data into a format that I SCST3 can read. C urrently, these prog

rams include:

• Building Profile I nput Program

(BPIP) ca

lculates the maxim

um crosswind widths of buildings, which ISCST3 then uses to estimate the effects on air dispersion. These effec ts by sur roundi ng build ings are typical ly refe rred t o as bui lding do wnwash o r wake effects. The BPI

P User’s Guide contain s detailed information for preparing the nece ssar y bu ildin g di men sion s (lengt

h, h eig ht, a nd width ) and loca tion s for the I SCS T3 mode l (U.S. EPA 1 995c).

• Meteorol ogica

l Proces sor for Regul atory Models (MPRM) prepares meteorologi cal data for ISCST3. MPRM merg es hourly m easurements of surfac e parameters (e.g ., precipitation, wind speed, and wind direction) into rows and colum

ns of information that ISC ST3 can read. The MPRM U ser’s G uide contains i

nstructi ons for using

on- site meteorological data to prepare the necessa ry meteorolog

ical input file for I SCST3 (U.S. EPA 1996j; 1999c). The Addendum to the MPRM User’s Guid

e describes the additional data needed in the m

eteorological input file for ISCST3 to m odel dry deposition of vapors (U.S . EPA 1999c). We generally

recom mend using MPRM to

proces s the m

eteorolo gical data, b ecause MPRM pr ovide s all the meteorological parameter values that ISC ST3 needs to function. The peer review draft o f the HHRAP described the per sonal computer version of the meteorological pre processor for the old RAM program (P CRAMMET). Unfortunately , PCRAMMET doesn’t provide the param eters needed for evaluating dry

vapor deposition in ISCST3. Therefore, we no longer recomm end using PCR

AMMET.

When sufficient

site- specific

data is avail able on

the loc ation, size a

nd shap e of stru

ctures i n the v icinity of the emissions s ources, you can use the BPI

P program

to prepare the I SCST3 input file to conside r the effects of building do

wnwash on pollutant transport. If sufficient site-specific d ata is not available to run BPIP, then

you w ill not b e able t

o addre ss build

ing do wnwash in air m odeling efforts . Prior

to perfo rming the air dis persi on modeli ng, we rec ommend that you consu lt wit h the ap propr iate p artie s (e.g. regulatory autho

rity and facility) o

n the decision to include or omit nearby structures.

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Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-8 

### 3.2 PARTITIONING EMISSIO NS

COPC em

issions to the environ

ment occur in either vapor or particle p hase. In general, you

can assume:

• most meta

ls and organic C OPCs with very low vo latility (fraction of COP C in vapor phase [Fv ] less than 0.05, see Appendix A- 3) occur only in the particle phase;

• highly v

olatile organic COP Cs occur only in the vapor phase (Fvof 1.0 , see A ppendix A-3); and

• the remaining

organic COPC s occur with a portion of the vapor cond ensed onto the surface of particulates (i.e. p article-bound).
For m odeling COPC s releas ed only

as part iculates , the m

ass fractions al located

to each particle size a re different than the m

ass fractions used for m

odeling organ

ics released in both the v apor and particle-bound p

hases.

Due to mode l limitations, y ou need to run I SCST3 multiple tim es to generate estim

ates of vapor phas e COPCs, particle pha se COPCs, and particle-bound C OPCs. An example is the risk assessment for the WTI incinerator located in East Liverpool, Ohio. The study used three runs; a vapor phase run for organ ic COP Cs, a p article r

un with mass weig hting of the p article p

hase m etals an d orga nic CO PCs wi

th very low v

olatility, and a particle run with surface area weighting of the particle-bound organic COPC s.

3.2.1 Vapor Phase Modeling
Vapo r pha se ai

r mo deli ng r uns d o not need a pa rticl e size dis tribu

tion in the I SCS T3 in

put f ile. IS CST3 output for vapor p

hase runs are vapo

r phase ambient air concentration, dry vapor deposition, and wet vapor deposition at receptor grid nodes based on the unit em ission rate.

3.2.2 Particle Phase Modeling (Mass Weighting )

ISC ST3 uses

algor ithms to com pute the rate at which d

ry and wet rem oval p rocesse s depos it partic le phase C OPCs onto the Earth’s surface . Parti cle siz e is the main determ inant of the fate of part icles in air flow, w hether d ry or wet. The key

to dry particle deposi tion rate is the

termi nal, or falling , velo city o f a parti cle. Pa rticl e termin al veloc ity is ca lcula ted main ly from the parti cle si ze and par ticle densit y. Large parti cles f

all more rapidl y than smal l part icles , and are deposi ted cl oser t o the st ack. Small parti cles ha ve low terminal v

elocities. Very sm

all particles remain susp ended in the air flow. Wet particle deposition

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Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-9 

### also dep ends on

particle size a s larg er parti cles are more easily removed, or scav

enged , by f

alling liquid (rain) or frozen (snow

or sleet) precipitation. To estim ate particle phase deposition rates, ISCS T3 needs an initi al estim

ate of the partic le size

distribution, broke

n out by part

icle dia meter

.
The diameters of sm

all particles contained in stack emissions are usu

ally measured

in microm

eters. The distribu tion of particle

diameters will diffe

r from one combus tion pro cess to another , and i s grea tly depend ent on t he:
1. Furnace

type; 2. Combustion chamber desig n; 3. Feed fuel com

position ; 4. Particu

late rem oval e fficiency; 5. APCS design ; 6. Amount of air, in excess of stoichiom etric amounts, that is used to sustain com bustion; and
7. Combustion tem

perature. The particle size distribution ca nnot be calculated, but only directly m easured or inferred from

prior data. Unfo rtu nat ely, few s tudi es ha ve bee n per for med to dire ctl y measu re pa rti cle size dist rib uti ons f rom a variet y of s tationar

y com bustion source s (U.S . EPA 1986a).

We recom

mend that existing

faciliti es perform sta

ck tests to ide

ntify particle

size d istribut ion. We further recom

mend that th ese data

represe nt actua l operat ing condition s for the com bustion unit an d air pollu tion co ntrol device ( APCD) th at remove p artic ulate from the s tack gas. A table o f part icle s ize distribu tion dat a may be prep ared us ing st

ack te st data in the f

ormat simil ar to the exam

ple illu strated in Table 3-1.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-10



### TABLE 3-1 HYPOTH ETICAL PARTICLE SIZE DISTRIBUTION DATA TO SUPPORT EXAMP LE CALCULATIONS

1 2 3 4 5 6

Mean Par

ticle Diameter a (μm) Particle

Radius (μm) Surface

Area/ Vol ume (μm-1 ) Fraction of

Total Mass b Proportion

Availa ble Surface Area Fraction

of Total Surface Area > 15.0 7.50 0.400 0.128 0.0512 0.0149 12.5 6.25 0.480 0.105 0.0504 0.0146 8.1 4.05 0.741 0.104 0.0771 0.0224 5.5 2.75 1.091 0.073 0.0796 0.0231 3.6 1.80 1.667 0.103 0.1717 0.0499 2.0 1.00 3.000 0.105 0.3150 0.0915 1.1 0.55 5.455 0.082 0.4473 0.1290 0.7 0.40 7.500 0.076 0.5700 0.1656 < 0.7 0.40 7.500 0.224 1.6800 0.4880
a Geometric m

ean diameter in a distribution from U.S. EPA (1980a), as presented in U.S. EPA (1998c) b The ter ms m ass and w eight are used interc

hangeably

when using

stack t est data



### We expect that actual stack test data will be different from the hy pothetical values presen

ted in Table 3- 1. This is because actual stack samplin g will use particle “c

ut size” for the differen

t cascade impactor filters (or Coulter counter- based distributions). The test m ethod will drive the range of particle sizes that are presented in the results o f the stack test. However, I SCST3 needs mean particle diameter for each parti cle si ze distr ibuti on, and t he stac k test da ta ide ntifi es only t he mass (“ weight” ) of par ticle s in a ra nge bounde d by t

wo spec ific diam

eters. To addre ss this, we recommend tha t stack test da ta be converte d into
a mea n partic le diam

eter wh ich approximates the

diameter of a

ll the p articles

within a defined range. We
recom mend using the fol lowing

equation to cal culate t

he me an parti cle diam

eter:

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-11 

### Equa tio n 3-1

where D mean 

### = Mea n par tic le di amete r for the p art icl e siz e cat egor y (μm) D 1 

### = Lowe r bou nd cu t of t he pa rti cle size cate gory ( μm) D 2 

### = Uppe r bou nd cu t of t he pa rti cle size cate gory ( μm)

For exa mple, the mean part icle d iameter of 5.5 μm in Table 3-1 is cal culat ed from a l ower bo und cut size (assuming a cascade impactor is used to collect the sam ple) of 5.0 μm

to an upper bound cut size of 6.15 μm. In this exam

ple, the mean particle diameter is calcu lated as:

From Table 3- 1, the mean particle diameter is 5. 5 μm. The m ass of particulate from

the 5.0 μm

stack test data is then assigned

to the 5.5 μm

mean particle diam

eter for the purpose of computing the “fraction of total mass.”
Typically, eig

ht to ten mean particle diameters are av ailable from stack

test results. Howev

er, as determined from

a sensitivity an

alysis conducted by

The Air Group- Dallas under contract to U .S. EPA Region 6 (

http://www.epa.g ov/region06 ), a minim um of three particle size categories (> 10 microns, 2 -10 microns, and <

2 microns) detected during stack testing are ge

nerally the m

ost sensitive to air m

odeling with ISCS T3 (U.S. EPA 19 97f). For facilities with stack test results which indicate mass am

ounts lower than the detecta ble lim it (or the filter weigh

t is less after sa mplin g than before) , a sing

le me an parti cle size d iamet er of 1. 0 micron may be used to represe nt all m ass (e.g ., part

icle dia meter of 1.0 micro n or a particle mass fraction of 1. 0) in the partic le and p article- bound m odel runs. Bec ause ru

dimen tary methods for stack

testing may

not detect the very

small size or amounts of C OPCs in the particle p hase, the use of a 1. 0 micron par ticle size will a

llow these sm

all parti cles to be inclu

ded pro perly as parti cles in the risk assessm ent exp osure p athway s while dispers ing an

d depos iting in the a

ir mo del sim

ilar in behavior to a v

apor. Consequently , we recomm end that a minim

um of three particle size categories b e used in the air mode ling e ffort.
After calculating the m

ean particle diameter (Column 1), you can com pute the fraction of total m ass per mean particle siz e diameter (Colum n 4) from the stack test results. F or each mean p article diameter, the

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-12 

### stack test data prov

ides an associated particulate m ass. Calculate the fraction of total mass for e ach mean particle diameter by

divid ing the assoc iated pa

rticulate mas s for that diam eter by the total partic

ulate mass in the sam

ple. In m any cases, the fractions of total mass will not sum to 1.0 because of round ing errors. In these instances, we adv ocate forcing the total mass to 1.0 by adding the remaining mass fraction into the largest mean particle diam eter mass fraction.

Direct measurem

ents of particle-size distributions may not be available a

t a proposed new facility . You will need to supply

ISCST3 w

ith an assumed particle distributions. I n such instances, y

ou may use a representative distribution. We recomm end that the com

bustor on which the representative distribution is based be as s imilar

as practicable to the proposed comb ustor.
ISCST3 uses the mass-based particl e size distribut ion to apportion the mass of particle ph ase COPCs (metals and organics with F v 

### values less than 0 .05) according to particle size. The I SCST3 input file uses the data in Colum

n 4 of Table 3- 1 (as developed from actual stack test data) to perform

a particulate run with th e part icle p hase COP Cs appor tione d per mass weighti ng.

3.2.3 Particle-Bound Modeling (Surface Area Weighting)
Use a surface area weig

hting of particles, inste ad of mass weighting, in separate particle runs of I SCST3. Surface area we ightin

g approximates the

situatio n where a porti on of a semiv

olatile o rganic contam inant, volatilized in the high tempe rature environm

ent of a combustion system, condenses to the surface of particles entrained in the com bustion gas after the gas cools in the stack. Apportion ing emission s by particle diameter becom

es a function of the surfac e area of particles ava ilable for chemical adsorption (U.S. EPA 19 98c).

The first step in apporti oning COPC emis sions by surf

ace area is to ca lculate the prop ortion o f avai lable surface area of the particles. If particle dens ity is held constant (such as 1 g/cm 3 

### ), the proportion of available surface area o f aerodynam ically spherical particles is the ratio of surface area ( S ) to volum

e ( V ), is estimated as follow s:

• Assume aerody

namically spherical particles.

• Specifi c surfac e area o f a sphe rical pa rticle with a rad

ius, r— S = 4 B 

### r

2



### • Volume of a s

pherica l particl e with a

radius, r— V = 4/3 B 

### r 3

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-13 

### • Copies of all stack test data used to determ ine particle size distribution

• Copies of all calculations m ade to determine particle size distribution, fraction of total mass, and fraction of total surface a rea RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT • Ratio o f S

to V

—S/V = 4 B 

### r

2 

### / (4/3 B 

### r 3 

### ) = 3/ r
The following exam

ple uses the hypothetical particle size distribution in Table 3-1 to

apportion the emiss ion rate

of the p article-

bound p ortion o f the CO PC bas ed on surface a rea. We gener ally recommend follo wing thi s proce dure fo r appor tioni ng actua l emissi ons to t he actu al par ticle size distribution measured at the stack.

In Table 3- 1, a spherical particle hav ing a diam

eter of 15 μm (Column 1) ha s a radius of 7.5 μm (Column 2). The proportion of available surface area (assum ing particle density

is constant) is S/V = 3/7.5 = 0.4, which is the value in Column 3. Column

4 shows that particles w

ith a mean diam

eter of 15 μm con stitute 12.8 percent of the total mass. Multiply ing Colum

n 3 by Colum

n 4 yields the v

alue in Column 5 of 0.0512. This v alue is an approxim

ation of the relative p

roportion of total surface area, based on the percent o f particles that are 15 μm in diameter. Totaling Column 5 yields the total surface area of all particles in the pa rticle size distribution. In this exam ple, the sum is

3.4423. Colum

n 6 is the fraction of tota l surfac e area r

epresen ted by the spe cific pa

rticle di amete

r in the distrib ution. Colum

n 6 is calculated by div

iding the relative proportion of surface area (C olumn 5) for a specific diameter by the total relative proportion o f surface area (3.4423 sq uare microm

eters [μm

2 

### ]). In the example of the 1 5 μm-dia meter particle, the fraction of total surface area av ailable for adsorption is 0.0 149 (0.0512/3.4423). This procedure is then repeated for all particle sizes in the array.

ISCST3 uses the surface area-b ased particulate size distribu tion to apportion m

ass of particle-bou

nd COPCs (mo st organics) according to particle size. The ISCST3 input file uses Column 6 of Table 3-1 (as developed from actual st ack test data) to per form a particulate run for the parti cle-bound COPCs apport ioned accord ing to su rface area we ightin g.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

1 

### UTM is a map coordinate projection of geo graphic coordinates.
U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-14 

### 3.3 SITE-SPECIFIC INF ORMATION NEEDED FOR AIR MO DELING
We generally

recom mend that th e site- specific

inform ation for the fac ility a

nd surro unding area us ed in air disp ersion m

odeling include : 1. the elevation of the surrounding land su rface or terrain; 2. surrounding land u ses; and 3. characteristics of on- site buildings that m ay affect the dispersion

of COPCs into the surrounding env

ironment.
You can often obtain some of the site- specific information ne eded for air dispersion m odeling by review ing av ailable maps and other gra phical d ata on t he area surroun

ding t he facil ity. The first step in the air m odeling proces s is rev

iewing these r esource s. Usi

ng U. S. Geo logica

l Survey (U SGS) 7 .5-m

inute topographic m

aps (1:24,000) extending to 10 kilom

eters from the facility , and USGS 1 :250,000 map s exten ding out to 50 kilo meters, you can id entif y much of the follo wing:

• site location,

• nearby terrain features,

• waterbodies and watershe ds,

• ecosystems,

• nearby residences, and

• land use. Aerial p hotog raphs a re frequ ently availa

ble to s upplem ent the depictio

n of the area. An accu

rate fac ility plot plan—showing buildings, stack s, property and fence lines—is also needed. Facility inform ation includi ng sta ck and fugit ive so urce loc ations, buildin

g corners, pla

nt prop erty, and fence lines , in Univ ersal Tran sverse M erca

tor ( UTM 1 

### ) grid

coordin ates in meters east a

nd nort h mig ht be av ailable in both US GS refe

rence systems . Theref

ore, k nowled ge of the horizonta

l datum of the geogra

phic coordinates from w

hich the UTM coordinates we re projected is required. We generally recom mend consult ing with pers onnel experienced and know ledge able in the intr

icacies of these

types of coor dinate systems, an

d the various software programs used to conduct con

versions.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-15 

### • All site-specific m aps, photographs,or figures used in developing the air modeling approach

• Mapped identification of facility information includin

g stack and fugitive source locations, locations of facility buildin gs surrounding

the emission sou

rces, and property boundaries of the faci lity RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT Most USGS paper 7. 5-minu te topographic m

aps are published in the North American Datum sy stem established in 1927 (NA

D 27). Howev

er, most digital elevation data (e.g ., USGS Dig ital Elevation Mapping) is in the 19 83 revised sy stem (NAD 83). We recomm end taking s

pecial care not to m

ix source data based on NAD

27 with data based on NAD 83. Also, we recom mend obtaining

emission source inform ation in the ori ginal units fr

om the facilit

y data , and c onver

t it to m etric un its for a ir mo deling , if necessary. You

can get digital terrain data from U SGS, or another so urce.
The following subsection s describe the specific inform ation we generally

recomm end collecting. Entering this inform

ation into the I SCST3 input files is described in Section 3.6.

3.3.1 Surrounding Terr ain Information

Terrain is important to

air modeling

becaus e air concentra

tions an d depos ition ra

tes are g reatly influenced by the height of the plum e above local g

round level. Terrain is characterized by elevation relative to stack height. For air modeling p urposes, terrain is referred to as “complex” if the elevation of the surrounding land

within the assessm

ent area—typically d

efined as anywhe

re within 50 kilom

eters of the stack—is above the top of the stack evaluated in the a

ir modeling analysis. Terrain at or b elow stack top is r eferred to as “s imple .” I SCST3 i mplem ents U. S. EPA

guida nce on the prop er appli cation o f air mode ling m

ethods in all te

rrain if you in

clude te rrain el evation for ea

ch receptor gr

id node and sp ecify the appropriate control param eters in the input file.

Even small

terrain feature s may

have a larg e imp act on t

he air d ispersion and d

epositio n mod eling results and, ul timate ly, on the ri sk est

imate s. We generally

recom mend that air mode ling i

nclude terrain elevations for every receptor grid node. Som

e exceptions may

be those sites characteriz ed by very flat terrain where t

he perm itting authori ty has sufficie nt expe rience t o comfortably

defer the use of

terrain data be cause the terrain ’s historical eff ect on a ir mo deling

results have been m

inima l.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-16 

### • Description of the terrain data used for air dispersion m odeling

• Summ

ary of any a ssumptions m

ade regarding

terrain data

• Description of the sou rce of a ny ter rain dat a used, includi

ng an y proc edures used to manipulate terrain data for use in air dispersion m odeling RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT We generally recommend including electronic cop ies of the digital terrain data used to extract receptor grid n ode elevation s in the

risk a ssessm

ent repo rt. One way

to obta in receptor gr

id node eleva tions is using digital terrai

n data a vailab le from

the US GS on the I

nternet at web site htt p:/ /ed c.us gs.go v/gui des/ dem.h tml . For most locations, an acceptable de gree of accuracy is provided by the USGS “One Degree” (e.g., 90 m eter data) data available as “DEM 250" 1:250, 000 scale for the entire United States free of charge. For area s requiring m ore accurate terrain, USG S 30-m eter (1:24,000 scale) d ata m ight b e consid

ered, th ough it is not

unive rsally avail able. E ither 90 -meter or 3 0-m eter dat a is suffic ient for

most risk a ssessm

ents wh ich util ize 10 0 met

er or g reater g rid spac ing. Digit

al terrai n data is also av

ailable for purc

hase from a v

ariety of com merci al ven

dors, w ho ma y requ ire vendor-p rovided progra

ms to extract the data. You can also manually extract the elevation of each receptor grid node from USGS topographic m aps.

3.3.2 Surrounding Lan d Use Information

Land use inform

ation is needed in the risk assessment for air dispersion modeling , as well as identify ing and selecting exposu

re scenario locations (see Chapter 4). Land use analysis for air dispe

rsion modeling usually occursout to a radius

of 3 k ilometers fro m the

centroi d of the

stacks from

which emiss ions are being mode led. C ertain la

nd uses , as de fined by

air modeling

guida nce, af fect the selectio n of air dispersion modeling

variables. These v

ariables are known as dispersion coefficients and surface roughne ss. You t ypical ly use USGS 7.5-minute topogra phic maps , aeria l photo graphs, or visua l surveys to define the air dispersion modeling lan d uses.

Land use inform

ation is also important for selecting expo sure scenario locations, bu t at a radius further (50 ki lomet

ers) from the

emis sion source(s), to ma ke sur e all rec eptors t

hat may be impacted are identified . In most cases, though, air modeling performed out to a ra dius of 10 kilometers all ows

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-17 

### adequat e characteriza

tion for evalu ating exposu

re scena rio loca tions. If y

ou are e valua ting a facility with multi ple stacks or emiss ion sou rces, we gene

rally r ecom mend extend ing the radius

from the cen troid of a polygon draw

n connecting the various stack c oordinates.

3.3.2.1 Land U se for Di spersio n Coefficie nts
You need to specify

the appropriate dispersion c oefficients for ISC ST3 to run properly. Land uses need to be defined in order to

specify dispersion co efficients. We generally recommend using the A

uer method specified in

the Guideline on A

ir Quality Models (40 CFR Part 51, A ppendix W) (U.S. E

PA 1996k; 1999b) to

define land use. L and use categories o f “rural” or “urban” are tak en from Auer (1978). Areas typically defined as rural include reside nces with grass law

ns and trees, large estates, metropolitan parks and g olf courses, agricultural areas, undeveloped land, and water surfa

ces. Auer typ ically defines an area as “urban” if it has less than 35 percent vegetation cov erage or the area falls into one of the following use ty

pes:

TABLE 3-2

URBAN LAND USE TYPES
Urban Land

Use Type Use and Structures Vegetation I1 Heavy industrial Less tha n 5 percent I2 Light/moderate industrial Less tha n 5 percent C1 Commercial Less tha n 15 percent R2 Dense si

ngle/m ulti-fam ily Less tha

n 30 percent R3 Multi-fam

ily, tw o-story Less tha n 35 percent


### In general, the Auer m

ethod is described as follow s: Step 1 Draw a radius of 3 kilometers from the center of the stack

(s) on the site ma

p. Step 2 Inspect the m

aps, and define in bro ad terms whethe r the area within the radiu s is rural or urban, according to Auer’s definitions. Step 3 Classif

y sm aller are as with

in the r adius as either r ural or urban, based o

n Auer’ s definitions. (It may be prudent to overlay a grid [for exam

ple, 100 by 1 00 meters] and identify each square as primarily ru ral or urban) Step 4 Count t

he num ber of r ural squ ares; if more than 50

percen t of the total sq uares ar e rural, the area is rural; otherwise, the area is urban.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-18 

### • Description of the methods used to determ ine land use sur roundin g the facility

• Copies of any m

aps, photographs,or figures used to determine land use

• Description of the source of any com puter-based m

aps used to determ

ine land use RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT Alterna tively , dig ital land

use dat abases may

be used in a compute

r-aid ed draft ing system to perform th

is analysis.

3.3.2.2 Land Use for Surface Ro ughness Height (Length )
Surface roughness height—also referred to as (aerodynam

ic) surface roughness length—is the heig ht above the g

round at which the w

ind speed goes to

zero. Surface roughness affects the height above local ground level that a particle mov es from the am

bient air flow above the ground (for example in the p lume) into a “ capture d” depo sition r egion near the grou

nd. Tha t is, I SCST3 a ssume s the pa rticle is deposi ted to the ground at som

e point above the

actual land surface, base d on surface roug hness height. S urface roughness heig

ht is defined by in

dividual elements on the landscape, such as trees and building s.

There are several m

ethods for compu

ting surface roug

hness. One uses measureme nts of hourly surface roughness based o

n wind direction (fetch). Another uses the change in wind speed w ith height in the surface layer, as m

easured on an instrum

ented tower operated at the site. We recom mend deciding

which method to use to characterize surface rou ghness based on the variability of surface features and seasonal values for the site. In lieu of any other m ethod, the paragrap

hs below describe our recommen dations for computing surface roughness.

In order to b e consistent with the recom mended m

ethod for determinin

g land use for d

ispersion coefficients (Section 3.3.2. 1), the land use within 3 kilome ters generally is acceptable for determin ing surface roughness. Surface roughness height value s for various land use types are as fo llows:

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-19



### TABLE 3-3 SURFACE ROUGHNESS HEIGHTS
Surface Roughn ess Heights for Lan d Use Types and Seasons (m

eters) Land Use Type Spring Summ er Aut umn Winter Water surface 0.0001 0.0001 0.0001 0.0001 Deciduous forest 1.00 1.30 0.80 0.50 Coniferous forest 1.30 1.30 1.30 1.30 Swamp 0.20 0.20 0.20 0.05 Cultivated land 0.03 0.20 0.05 0.01 Grass land 0.05 0.10 0.01 0.001 Urban 1.00 1.00 1.00 1.00 Desert s hrubland 0.30 0.30 0.30 0.15 Source: Shei

h, et al. (1979) 

### If a sign ificant number of b

uildings are located in

the area, higher surface roughness heights (such as those for trees) may

be appropriate (U.S. EPA 1995g ). Previous g

uidance documen

ts do not recom

mend a specific method for determining average surfac e roughness heig ht. If y ou are using N ational Weather Service surface m

eteorological data, w

e generally recommend setting the surface roug hness height for the measurem

ent site at 0.10 m

eters (grassland, sum

mer). I f you intend to p

ropose a different valu

e for the measurem

ent site, we recom

mend using

the following pro cedure to determine the value: Step 1 Draw a radius of 3 kilometers from the center of the stack

(s) on the site ma

p. Step 2 Inspect the m

aps, and use profession

al judgment to c lassify the area within the radius accordi ng to land us e type

(for ex ample

water, grass land, c

ultiva ted land , and f

orest); a site visit may

be necessary to verify som e classifications. Step 3 Divide the circular area into 12 angular sectors of 30 degree s. Step 4 Identify a

single representative surface roughness height for each sector, based on an area-weig hted average of the land use ty pes within the sector usin g the categories identified above. Step 5 Input the area-

weighted surface rou

ghness heigh

t value representative of each of the 12 sectors into MPRM for preproc essing the m eteorological data file.
Site- specific

conditi ons m

ight b e such t

hat yo u consi der methods other than thos e descri bed above m

ore appropr iate for determ ining surface rough

ness he ight. In such in stances , we re comm end cle arly identifying and discussing the alternativ e methods with the appropriate parties (reg ulatory authority or facility) prior to use.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-20 

### 3.3.3 Information on Facility Building Char acteristics
Building wak

e effects, also referred to as “building downwash,” have a sig nificant impact on the concentration and deposition of COPCs near the stack. Build ing wake effects are flow lines that cau se plumes to be forced down to the g round much so oner than they would if the building was not there. The ISCST3 m

odel contains algorithm

s for evaluating

this phenomeno

n. We recomm

end that the downwash analysis consider all nearby structures with heights at least 40 p ercent of the height of the shortest stack to be modeled. The 40 percent value is based on Goo d Engineering Practice (GEP) stack

height of 2.5 times the heig

ht of nearby structures

or buildings (stack

height divide d by 2.5 is e qual to 0.40 m ultiplied by the stack height [40 CFR Part 51 Appendix W]). BPIP uses Building d

imensions and lo cations, and stack heigh

ts and l ocation s, to id

entify the pot ential fo r buildi ng downwash . BPI

P and t he BPI P User’ s Guide are available for download from the SCRAM web

site ( http://www.epa.g ov/scram001 / ) to address specific ques tions. The BPIP output fil e is in a format that can be copied and pasted i nto the source (SO) pathwa y of the IS CST3 inp

ut file. We ge

nerally recom mend the fol lowing

proced ure to i dentify buildings for input to

BPIP: Step 1 Lay out facility

plot plan, with buildin

gs and stack

locations clearly identified (building heights identified for eac h building); for buildin

gs with m ore than one heig

ht or roof line, id entify each he ight (BPIP refers to each heigh t as a ti er). Step 2 Iden

tify the buildi

ngs to be incl uded in the BP IP a

nalysi s by c ompa

ring b uilding heigh ts to stack heigh

ts. The building heig

ht test specifies that only buildings at least 4 0 percent of the height of a potentially affected stack be included in the B PIP input file. For exam ple, if a com

bustion unit sta ck is 5 0 feet h

igh, only b

uilding s at least 20 feet tall (0.40 multiplied b

y 50 feet) will affect air flow at stack top . Any build ings shorter than 20 feet need not be in

cluded in the BPI

P analysis. The bu

ilding height test is performed for ea ch stac k and each buildi ng. Step 3 Use the building distance test to check each building to b e included in BPI P from the buildin g heig ht test. For the buildi

ng distance te st, onl

y buil dings

“nearby” the

stack will affect air flow at stack top. “Nearby” is defined as “five tim es the lesser of building height or crosswind

width” (U.S. E

PA 1995c). A simplified distance test may be used by cons ide rin g only the b uil ding heigh t rat her t han t he cr ossw ind w idt h. Wh ile some buildin gs wi th more heig

ht than width w

ill be in cluded unneces sarily

using this simplification, BPI

P will identify correctly

only the building

dimensions requ

ired for ISCST3. An example, hypothetical plot plan identifies a 25-foot tall building that is 1 15 feet from the 50-foot tall combustion unit stack center to the clo sest building corner. The building dista nce tes t, for t his bui lding on ly, is fi ve times th e build ing heigh t, or 12 5 feet (five mult ipl ied by the buil ding heigh t, 25 feet ). Th is bu ild ing wo uld b e inc lude d in t he BP IP analy sis, be cause it

passes the buil ding height test and buildin g dist ance test.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-21 

### Step 4 Repeat steps 2 and 3 for each building and each stack, identifying all bu ildings to be included in the BPI

P. If the number of buildin gs exceeds the B PIP lim

it of eight buildings, consider combining buildings, m odifying BP IP code for more building s, or using third- party comm

ercial s oftware

which imple

ments BPIP. I f two building s are closer than the heigh

t of the taller building,the two building s may be combined. For example, two buildings are 40 fee t apart at their closest points. One building is 25 feet high, and the other building is 50 feet high. The buildin gs could be com

bined into one buildin g for input to

BPIP. For

input t o BPI P, the corners

of the c ombin

ed build ing ar e the outer corners of the tw o buildings. F or unusually shaped buildings with m

ore than the eig ht corne rs allowed by

BPIP, approximate the buildin g by using the eig ht corne rs that best represent the extrem e corners of the building . The BPIP User’s Guide contains additional description and illustrations on combinin g buildings, and BPIP

model limita tions (U .S. EPA 1995 c). Step 5 Mark off the facility plot plan with UTM g rid lines. Extract the U

TM coordinates of each bu ildin g corner and eac h stack c enter to be inc luded in BPIP inpu t file . Althou gh BPIP allow s the us e of “pl ant coordinates ,” we r ecom mend that all inputs to the a

ir model be prepare d using UTM coordinate s (meters) for consisten cy. UTM coordinates are rectilinear, oriented to true north, and needed in metric units for I SCST3 modeling

. Almost all air m

odeling will need to use USGS topo graphic data (digital and maps) for receptor elevations, terrain grid files, locating

plant property, an

d identifying surroun ding s ite featu

res. The refore, using

an abso lute coordinate system will enable you to check inputs at each step of the ana lysis. Also, the meteorolo gical data are oriented to true north. Significant errors will resu lt from I SCST3 if incorrect stack or building locations are used, plant north is inco rrectly rotated to true no

rth, or incorrect base ele vation s are us ed. Wit

h com puter ru n times requ

iring many

hours ( up to 4 0 hours for one deposition run w

ith depletion), verify

ing locations at each step while preparing mode l inputs

will pr event the nee d to rem

odel.

We recommend observing several precautions a

nd guidelines wh

ile preparing input files for BPIP:

• Graphically confirm ing the correct location s before BPI P is run. One m

ethod is to plot the buil ding s and stac k loca tio ns us ing gr aphi cs so ftwa re. S ever al co mmerci al pr ogra ms incorporating BPI

P provide g

raphic displays of B PIP inputs.

• In addition to using UTM coordinates fo r stack locations and building corners, also use meters as the

units f or heig ht.

• Careful ly inc lude the stack base el evation and b

uilding base el evations according to BPIP U ser’s Guide instructions.

• Note that the BPI P User’s Guide (rev

ised February 8, 1995) has an error on page 3- 5, Table 3-1, und

er the “TIER(i,j)” description , which incorrectly identifies tier height as base elevation.

• BPIP mix es the u se of “r eal” and “integ er” va

lues in the inpu

t file. To prevent pos sible errors in the input file, note that integers are use d where a count is re quested (for example, the n

umber of building s, number of tiers, number of corners, or num ber of stacks ).

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-22 

### • Make the stack identifiers (up to eight characters) in BPI P identical to those used in the ISCST3 input file, or ISC ST3 will report errors. For most sites, BPIP exec utes in less than 1 m

inute. The array of 36 building heig hts and 36 building widths (one for each o f 36 10-deg ree direction sectors) are input into the ISC ST3 input file by cutting and pasting f

rom t he BPI P outpu t file. We recom

mend deletin g the five b lank s

paces precedin

g “SO ” in the BPIP output file, so that the “S O” begins in the first column of the ISCST3 inp ut file.

One use of BPI

P is to design stac

k heights for new facilities. Another is to determine w hat stack heigh

t increases are necessary to avoid building influence on air flow, which may cause high conc entrations and deposition near the facility . The output for BPI P provides the G

EP heights for stacks. Sign ificant decreases in concentrations an d deposition rates will beg in at stack heig

hts at least 1.2 tim

es the building height, and further decreases occur at 1.5 times building height, with co

ntinual decreases of up to 2.5 times building

height (GEP stack height) w here the building n

o longer influences stack gas.

3.4 METEOROLOGICAL DATA PRIMER
Air disp ersion a

nd depo sition m

odeling is extre mely comp licated, and us es data potenti ally u nfami liar if your expertise lies ou

tside meteorolog

y and air m

odeling. Section 3.4 is an introduction to the types of meteorological data used by air dispersion and deposition models, as well as information on potential data sources. Section 3.5 continues this introdu ction into the specific data p arameters required by MPRM, t he data prepro cessor f

or the I SCST3 a

ir mo del.
Generally speak

ing, air concentration and deposition m odels attempt to ch

aracterize the effects of atmospheric forces o

n a mass of C OPC found in the air. These forces can be d ivided between:

• those w

hich tra nsport t he COP C (the d

omina nt factor is win

d);

• those which disturb the straight flow of the COPC away from the source (also known as mixing, examples include b uilding downwa sh effects, and atm ospheric stability); and

• those actors which rem ove, or conditions

which encourag e the removal of, the COPC from the atm

osphere (An ex ample

of a rem oval a ctor wo uld be r ain, whereas an

exam ple “condit ion” wo uld be t he poin t above the g

round a t which windsp eed slow s to ze

ro).
Air concentrati on and deposit ion m odels need a v

ariety of me teorolo gical inform

ation, at diffe

rent lev els of tempor al def

initi on. The ISCST3 model requir es the f ollowi ng:

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-23 

### • Iden

tification of all

source s of meteorolo gical data RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT • Hourly value s (also know as “surface data, as they describe conditions closer to ground level) a. Wind direction (degrees from true north) b. Wind speed (m/s) c. Dry b

ulb (am bient ai r) tem perature (K) d. Opaque cloud cov er (tenths) e. Clou d cei lin g heig ht (m) f. For dry particle dep osition: i. surface pressur

e (mil libar) ii. solar ra

diation (watts/ m2 

### ) g. For wet particle deposition: i. Precipitation amount (inches) ii. Precipitation type (liquid or frozen)

• Daily values (also called “upper air data” as they describe con ditions higher in the atmosphere) a. Mor ning mixin g heig ht (m) b. Afte rnoo n mixi ng hei ght ( m) The following subsection s describe important characteristics of the needed d ata.

3.4.1 Wind Direction and Wind Speed Wind direction and speed a re two of the m

ost critical parameters in air modeling. The wind direction promote s higher concen trati on and de posit ion if it pers ists f

rom one di recti on for l ong peri ods dur ing a year. For ex ample , a pred omina ntly s outh wi

nd, suc h as on the Gu lf Coas t of Texa s, will

contrib ute to high c oncentr

ations a nd depo sitions north o f the fac ility. Wind sp eed is i nvers ely pr

oportional to concent ration predicted

using air modeling : The hi gher t he wind speed, the lower the c oncentr ation will be. I f wind speed d

oubles, the con

centrati on and deposit

ion wil l be red

uced by one-half. A

ir mo dels need wind speed and

wind direction at the sta

ck top. Most air modeling is performed using governm ent sources of surface data. Wind data are typically measured by

National Weather Serv

ice (NWS) stations at a hei ght of

10 meters. Howev

er, sinc e some stations have wind speed r ecorded at a dif ferent height,
we recomm

end always v

erifying the ane

mometer height, and that the correct value is inpu

t into the meteorological data preprocessing pro gram. I SCST3 uses a wind s peed profile to calculate win d speed at stack top. Th

is calcu lation exponen

tially increase s the m

easured wind s peed from the

meas ured he ight t

o

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-24 

### a cal cul ate d win d spe ed at stac k heig ht. ISC ST3 assu mes th at wi nd di rec tio n at s tac k heig ht is the s ame as that measured at the NWS station heig ht (U.S. EPA 1995c).

3.4.2 Dry Bulb Temperature Dry bulb tem

perature, or ambie

nt air temperature, is the same tem perature reported on the telev ision and radio stations across the cou ntry each day . Dry bulb (ambient) tem perature contributes to describing the surface conditi ons tha

t vary from hour to hour in the measured

mete orological dat

a neede d for ai

r modeling. It therefore has a dire ct effect on the modeling results, as desc ribed below.
Dry b ulb tem perature is typ ically

meas ured at 2 met

ers abo ve g

round l evel. ISC ST3 uses air tem perature in the buoyant p lume rise equations developed by Briggs (U .S. EPA 1995 f). The model resu lts are not very sensiti ve to air tem

perature , except at extr

emes. However, b

uoyan t plum e rise is very sensiti ve to the stack gas temperature. Bu oyant plum

e rise is mainly

a result of the difference b etween stack gas temperature and am

bient air temperature. Conceptually, it is similar to a hot air balloon: The higher the sta ck gas tempe rat ure, and l ower the a mbien t temp era tur e, th e high er wi ll be the p lume r ise . High plume heights result in low

concentrations and depo sitions as the COPCs travel further and are diluted in a larger volum e of am bient ai r before reachin g the surface. A large vari ation in ambi ent tem

perature will affect buoyant plum

e rise, but not as m

uch as variations in stack gas tem perature. The fact that the stack gas temperatu

re is constant (for m

ost modeling

analyses) is the v

ery point for noting

that it is the chang es in the dry bulb te

mperature that creates the temperature differential affecting plume rise in the air m odel (see also Section 3.6.2 .2 regarding selection of stack gas exit temperature). The temperature is m easured in K, so a stack gas temperature of 4 50°F is equal to 505 K, an amb ient temperature of 9 0°F = 305 K, an d 32°F = 273 K.

When determin

ing values for dry bulb tem perature (or am bient ai r temp erature) , it is i

mport ant not to appear to be ‘data shopp ing’ by artificially selecting a period of meteorological data that has either average or above- average amb ient tem perature s that w

ill redu ce plum e rise. The sk

ewing of resu lts in one dire ction or

anothe r may over- estimate concentrati ons nea r the so urce, b ut unde r-est imate concentrations and deposition s away from the source where m

ore sensitive receptors m ay be located (see Chapter 4 for m

ore on Exposure Sce

nario location) . Attem

pts to increase protective ness by apply

ing such approaches m

ay not achieve the desired result.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-25 

### If the meteorolog

ical dat a sets y ou use, and your cho ice of d ry bul b tem perature are not consist ent with the HHRAP, we recommend cle arly id entify ing an d discu ssing them in the r isk pl an and/

or cost estimate (as appropriate) to ensure clarity and transparency of the final risk assessm ent results.

3.4.3 Opaque Cloud Cover
Observ ations o f opaque cloud

cover are use d to cal culate t

he stabi lity o f the atm

osphere . Stab ility determ ines the dispers ion, or

dilution, rate of COP Cs in the atmosphere . Rapi d diluti on occu rs in unstable air conditions, w hile stable air results in very little mixing , or dilution, of the e mitted COPC s.

With c lear s kies dur ing the d ay, the su n heats the Ear th’s s urfac e, whic h heats the air immediate ly above it. The w arm a ir rises and overturns with the coole r air above it. Durin

g this “unstab le” condition, while layers of air are m

oving throug

h one another, the stack plume mixes as the air m ixes.

A cool surface occurs at nig ht beca use of r adiative loss o f heat on clear nights . With a cloud c over, surface heating during

the day and heat loss at night are reduced, resulting in moderate m ixing rates, or neutral stability.
Opaque cloud cov

er is a measure o f the transparency of the clouds. For exa mple, a com

pletely overcast sky with 1 0/10ths cloud cove r may hav

e only 1/10th op aque cloud cover if the clouds are hig h, translucent clouds that do n ot prevent sunlig

ht from reaching

the Earth’s surface.

3.4.4 Cloud Ceiling Height
ISCST3 needs cloud ceiling heig ht to calculate stability. Specifically, the he ight of the cloud cover affects the heat balance at the Earth’s surface.

3.4.5 Surface Pressure The MPRM preprocessor for I SCST3 requires station (i.e. surface) pressure. MPRM u ses station pressure to compu

te Monin-Obuk

hov Length

and Friction Velocity, two boundary lay er parameters that ISCST3 needs to perform dry particle deposition. I SCST3 is not very sensitive to surface p

ressure.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-26 

### 3.4.6 Incoming Short-wave Radiation\L eaf Area Index Solar radiation affects the respirato ry activity of leaf surfaces, which a ffects the rate of dry vapor deposit ion. We recom mend using the method d

escribed in Sect ion 3.6 .1 to address t

he effects of dr

y vapor deposi tion. S pecify

a single val

ue in the IS CST3 inp

ut file f or dry vapor depos ition velocity for all hours. Even

thoug h incom ing so lar radi ation an

d leaf a rea index are not used w

hen spe cifyin

g the dry vapor deposition v

elocity, the I SCST3 model w ill not run properly if values for these two data fields aren’t included in the m

eteorological input file.
Though we don’t re commend it, ISCS T3 is able to compu te the hourly dry

vapor deposition velocity by combining hourly incom

ing short-wave (solar) radiation with the user-s pecified, site-specific leaf area index. The default value specified in the Add endum to the MPRM User’s Guide (U .S. EPA 1999 c) may be used for leaf area index when site- specific data is not available.

3.4.7 Precipitation Amount and T ype
In order to c alculate wet deposition of vapor and particles, ISCST3 requires that MPRM process precipitation amount and type into the ISCST3 m eteorological file. Prec ipitation is measured at 3 feet (roughly 1 m

eter) above gro

und level. The am

ount of precipitation will directly influence the am ount of wet deposition at a spec ific location. Particles and vapor are both captured by falling precipitation, known as precip itation scavenging

.
Scave nging coeffic ients ar

e neede d as inp

uts to I SCST3 f

or vap ors, wi

th a rate specifi ed each

for liqu id and frozen precipitation. The precipitation type in a SAMSON weather report (see Section 3. 4.9 for more inform

ation on SAMSON) will identify to I SCST3 which event is occurring for a ppropriate use of the scavenging

coefficients entered (see Section 3.6.2.6). MPR M can also read supplem ental precipitation files from NCDC, and integ rate the data with CD -144 data in the ISCST3 m eteorological file. We discuss the im

portance of precipitation to I SCST3 results further in Section 3.4.9 ( Potential Data Sources).

3.4.8 Upper Air Da

ta (Mix ing Heig ht) Upper air data are neede d to run the I SCST3 model. MPRM uses mea surements of m orning and afternoon (twice daily) upper air data to calculate a n hourly m

ixing height using interpolation m ethods

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-27 

### FIGURE3-1 SOURCES OF METEOROLO GICAL DATA Meteorological Data Proc essing - Governme nt Sources (U.S. EPA 19 96j). We recom mend that on ly years wi

th com plete up per air d ata be u sed as i

nput for air modeling. It is im

portant that the years you select for uppe r air data match the years you select for surface data. I f matching years of data are n ot available from

a single upper a

ir station, we recom

mend another upper air station be used for comp leting the five y ears. We also recom

mend discussing

your choic e of rep resen tative data wi th the a ppropr iate a uthor ities prior to perf orming ai r modeli ng.

3.4.9 Potential Data Sources
As shown in Figur e 3-1, thes e data a re avail able f rom severa l diff

erent source s. For most air model ing,
we recommend five years of dat a from a repre sentativ

e NWS s tation. However, i n some instan

ces whe re the clos est NWS data is

clearly not representat

ive of site- specific

mete orological con

ditions,and the

re is insuffic ient tim

e to col lect 5 y

ears of onsite d

ata, y ou mi ght us e 1 ye ar of on site meteorolo gical data (consistent with GAQM) to complete the risk assessment. We recommen d clearly identifyin

g and discussing you

r choice of representative meteorological data with the appropria te parties (e.g. perm

itting autho rity or facil ity) pr ior to air model ing.

### Human Health Risk Assessment Protocol Chapter 3: Air Dispersion and Deposition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 3-28 

### MPRM On-Site Surface NCDC Mixing Height

NCDC Precipitation Data ISCST3 Meteorological File Required if not included incommercial on-site source data 

### Surface Data Upper Air Data 

### Meteorological Data Processing - Commercial Sources

Hourly data, also know as “surface data” because it tends to characterize meteorology nearer the surface, can be obtained from the National Climatic Data Center (NCDC) web site at address ( http://lwf.ncdc.noaa.gov/oa/ncdc.html ). We recommend data in the SAMSON format (available on CD-ROM). SAMSON data are available for 239 airports across the U.S. for the period of 1961 through 1990. SAMSON data contain all of the needed i nput parameters used by ISCST3 to compute concentration, dry and wet particle de position, and dry and wet vapor deposition.
You could also get hourly surface data from NCDC in TD-3280 format, then reformat it to CD-144format for input to MPRM. Precipitation data in TD-3240 format is also available from NCDC. TD3240 formatted data is processed by MPRM to supplement the hourly surface data.

National Climatic Data Center Federal Building 37 Battery Park Avenue Asheville, NC 28801-2733 Customer Service: (704) 271-4871 File type: File name: Hourly precipitation amounts NCDC TC-3240 Hourly surface observations withprecipitation type NCDC TD-3280 Hourly surface observations with precipitation type NCDC SAMSON CD-ROM (Vol. I , II, and/or III) Twice daily mixing heights from nearest station NCDC TD-9689 (also available on SCRAM web site for 1984 through 1991)

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-29 

### Currently, MPRM is the most appropriate Agency meteorological preprocessor program for preparing the surface and upper air data into an ISC ST3 meteorological input file. Most air m odeling analyse s will use MPRM to process the Na tional Weather Service da ta.

We recommend using the m ost recent 5 years o f complete m eteorological data av

ailable on SAMSON (or more recent sources ) for the air mod eling. I t’s desirable, but not m

andatory, that the 5 years be consecutive.
Each year of the 5 years of data sh ould be comple

te before being proc essed by MPRM. If data gaps exist, we recom

mend filling in all missing data. The procedures we recomm end for filling m

issing surface and upp er air da

ta are d ocumented on the S CRAM web site under the meteorolog ical dat a section. If the missing d

ata are not addressed by

the Agency

objective procedures, then with the approval of the permitting

authority, y

ou can develop a subjective method for filling in m

issing data. I f conditions
occur such tha

t: 1. missing v

alues are not able to be replaced; and 2. the permitting authority approves the use of the m eteorological data in tha

t condition
then specify the MSGPRO keyword in the COntrol pathway of the I SCST3 input file. Note that the DEFAULT keyword can't be used with MSGPRO

. If you wish to use less than 5 years of m eteorological data, we recomm end clearly identify

ing and discussing this with all appropriate parties (e.g . permitting authority, or facility ).
To pre vent the need to repeat air model ing acti vities , we reco mmend that your choi ces of r epres entat ive upper a ir and s urface d ata be c learly

identif ied and discuss ed with

the app ropriate parties (e.g. regul atory authori ty, fa cility)before you b egin p reproce ssing and air mode ling. Also, we recommend com pletely documenting

all processing of m

eteorological data, inclu

ding sources of d

ata, selection criteria, consideration for precipitation am ounts, preprocessor option s selected, and filled m issing data. I f your choices of meteoro logical data (e.g . selection of upper air d ata, or determination

of dry bulb tem

perature) are inconsistent with this g uidance, we further recommend clearly identifying and discussing these choices in the risk p lan and/or cost estim ate (as appropriate) to ensure clarity and transparency of the final risk assessm

ent results.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-30 

### • Electronic copy of the ISCST3 inp ut code used to enter m

eteorological inform

ation

• Description of the selection criteria and process used to identify representative years used for meteorologi cal data

• Identification of the 5 years of m

eteorological selected

• Summ

ary of the pro cedures

used to comp ensate f

or any miss ing da

ta RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT

3.5 METEOROLOGICAL PREP ROCESSOR DATA NEEDS
After selecting the app

ropriate surface and upper air data using the p rocedures outlined in Section 3.4, you still need to p

ut the data into a form

that ISCS T3 can use. As stated ab ove, we recom mend using

the meteorologi cal preprocessor MPRM t o do this. The followi

ng Se ction de scribes the data MPRM it self requires in order to perform the preprocessing. Agency approval is recom

mended in the selection of MPRM parameter v

alues.

We recommend preparing an ISCST3 m eteorological file that can be used to calculate either concent ration or depos ition (w

hat MPR M term s an “I SCGAS W” file). All ne cessary param eters will then be avail able to ISC ST3 for a ny su bsequen t conce ntration or depo sition m

odeling . For examp le, if only the concentration

option is selected in I SCST3 for a specific run, ISCST3 will ig nore the precipit ation v alues in the meteorolo gical file. F or subs equent air depo sition m odeling , IS CST3 wi ll access the precipitation data from the same prepro cessed meteorolog ical file.

MPRM includes extensive QA/QC to check for values that are out of rang e. MPRM also check s for missi ng da ta and s umm arizes value s that re quire ed

iting to fill m

issing data. After a comp lete sur face file passes the quality checks, it is processed with NCDC u

pper air data.

MPRM ne eds the followi ng inp ut param eters re present ative of the m

eteorolo gical measu

remen t site (typic ally the nearest repres entative National Weat her Stat ion):

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-31 

### • Minimu

m Mon in-O bukhov leng

th

• Anemom

eter height

• Surface roughness length (at measurement site)

• Noon-tim

e albedo

• Bowen

ratio

• Anthropogenic hea t flux

• Fraction of net radiation abs orbed at surface
MPRM also needs the follow ing input param

eter representative of the application site (e.g.,source location ):

• Surface roughness length (at application site)

The MPRM User’s Guide contains detailed informa tion for preparing the ISCST3 m eteorological input file (U.S. EPA 1 996j). The parameters listed are briefly described in the following subse ctions. These data are not included in the surface or mixing height d ata files obtained from

the U.S. EPA

or NCDC. We recommend taking s

pecial care, while using

the tables in the MPRM U ser’s Guide or reference literature, to select values representative of the m eteorological m

easurement site and the site to be mode led. We

recom mend clearly identif ying and dis cussing

the sel ected v

alues with the appropr

iate parties (e.g. perm

itting authority, or facility) before processin g the mete orological data.

3.5.1 Monin-Ob ukhov Length

The Monin-Obuk

hov length (

L ) is a measure o f atmospheric stability . It is ne gative during the day, when surface heating

causesunstab le air. It is positiv e at nig ht, when the s

urface i s cooled

and the atmo sphere
more stable. In urban a

reas du ring s table condition s, the e stima ted va lue of L may not adequately reflect the less stable atmos

phere associated with the mechanical m ixing generated by buildings or structures. However, MPR

M needs an input for m

inimum u rban Monin-Ob

ukhov leng

th, even if the are a to be analy zed by ISC ST3 is ru

ral. A nonz ero va

lue for L must be entered to run MPRM. We recommend using a val ue of 2. 0 met

ers for L when the land use surrounding the site is rural (see Section 3.3. 2.1). For urban a reas, H anna an

d Chan g (199 1) suggest t

hat a m inimu m v alue of L be set f

or stabl e hours

to

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-32 

### simul ate buil ding- induced instabi lity. The follo

wing are ge

neral example s of L values for various land use classifications:

TABLE 3-4 L VALUES FOR VARIOUS LAND USES Land Use Classificat ion Mi nimu m L Agric ultural (open) 2 meter s Residential 25 meter s Compact residential/industrial 50 meter s Commercial (19 to 40-story buildings) 100 meter s Commercial (>40-story buildings) 150 meter s



### MPRM will use t he min imum L value in calc ulating urban stability

param eters. These urb an val

ues wil l be ignored by

ISCST3 durin

g the air m

odeling analyse s for rural sites.

3.5.2 Anemometer Height

ISCST3 m

odel results are very

sensitive to sm

all variations in wind

speed. The heigh

t of the wind speed
measu remen ts is ne eded by

ISC ST3 to ca

lculate wind sp eed at stack t op. The wind s ensor (a

nemometer

) height for eve

ry National Weather S ervice station is identified in the station history section of the Local Climatological Data Summ ary available from

NCDC. Sin

ce 1980, mo st National Weather Serv ice stations meas ure win d speed at the height of 10 m

eters. Howev

er, som e stations oper

ate at o ther hei ghts or have data at m

ore than one heig

ht. We generally

recomm end verifying

the correct measu

rement heigh

t for each year of data prior to

proces sing w

ith MPR M and ru nning the I SCST3 m

odel.

3.5.3 Surface Rough ness Le ngth at Measur ement Si

te
Surface roughness length (or heig ht) is a measure of the height of o bstacles to wind flow. It is im portant in ISCST3 be cause it determines how close a particle m ust be to the grou

nd before it is “captured” for deposit ion on the gr

ound. Sligh

t varia tions in surface rough ness ca n lead t o dram atic diff erences in ISC ST3 resu

lts. For surfac e meteorolog ical dat a from a National Weat

her Stat ion, w e typi cally
recom mend using a val ue of 0. 10 me

ters for the “m easurem ent site .” Sur

face rou ghnes s is pro

portional, but not equal, to the p

hysica l heig ht of the obstac les. Tab le 3- 3 (in Se ction 3. 3.2.2)lists av ailable roughness heig

ht values. These v

alues are based on the general land use in the vicinity of the

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-33 

### measureme

nt site. We recom

mend considering

these values in d

iscussions with the approp riate parties prior to air mod eling.

3.5.4 Surface Rough ness Le ngth at Applic ation S ite

MPRM also needs the surfac e roughness leng th at the facility (application site) in order to prepare the ISC ST3 me

teorolo gical file. I SCST3 m odel res ults are very sensiti ve to the va

lue used in MPR M for thi s parameter. Ta

ble 3- 3 in Se ction 3. 3.2.2 is also applica ble to t he appl ication site. C ompu te a sin gle surface rough

ness value representat

ive of the site by us ing the met

hod des cribed i

n Sectio n 3.3. 2.2. W e
recommen

d clearly identifyin

g and discussing

the computed surface roughness len gth for the application site, along with m

aps or photograph s illustrating land use, with the appropriate parties (e.g. perm itting authority or facility) prior to use.

3.5.5 Noon-Time Albedo

“Noon-tim

e albedo” is the fraction o f the incoming solar radiation that is reflected from the g round when the sun is directly overhead. Albed o is used in calculating

the hourly net heat balance at the surface. Net heat balance at the surface is th en used in calcula ting hourly values of Monin -Obukhov length. MPRM automatically ad

justs for the variation in albed o with solar elevation

angle. Expe

rience suggests that ISC ST3 mo deling

results are not sensiti ve to the va

lue sele cted for

this pa ramet er. Tabl e 3- 5 prese

nts typical albedo values. Albedo v alues vary from

0.10 to 0.20 on water surfaces from summe r to winter. Cultivated far

mland value s vary

the m ost, from 0. 14 duri

ng spring w

hen land is till ed to ex

pose da rk earth, to 0.60 in w

inter when areas are snow-covered.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-34



### TABLE 3-5 ALBEDO OF NATURAL GROUND COVERS FO R LAND USE TYPES AND SEASONS

Land Use Type Season a Spring Summ er Aut umn Winter Water surface 0.12 0.10 0.14 0.20 Deciduous forest 0.12 0.12 0.12 0.50 Coniferous forest 0.12 0.12 0.12 0.35 Swamp 0.12 0.14 0.16 0.30 Cultivated land 0.14 0.20 0.18 0.60 Grass land 0.18 0.18 0.20 0.60 Urban 0.14 0.16 0.18 0.35 Desert s hrubland 0.30 0.28 0.28 0.45 Source—Iqbal

(1983)

a The various seasons are defined by Iqbal (1983) as follows: Spring: Periods whe n veget ation is em

erging or partially green; t his is a tr ansitional s ituation that applies f or 1 to 2 months afte r the last kil ling frost i n sprin g. Summ er: Periods whe

n veget ation is lush and healthy ; this is ty pical of mid-sum

mer, but also of othe

r seasons in which f rost is le ss com

mon. Autum

n: Periods whe

n freez ing conditions are com

mon, deciduous trees are lea fless,crops are

not yet planted or are already har

vested ( bare soil e

xposed), g

rass surf aces ar e brown, a

nd no snow is present. Winter : Periods whe n surfac es are c overed by snow and t

empera tures are below f reezing . Winter albedo depends on whether

a snow c over is pr

esent conti

nuously, int

ermitt ently, or seldom. Albedo ra

nges f rom about 0.30 for bare

snow cov

er to about 0.65 f

or continuous cov

er.



### Based on the inform

ation in Table 3-5,rural area albedo estim ates vary from

0.14 to 0.20 for cultivated land, and from

0.18 to 0.20 for grassland. For urban areas without snow , values va ry from 0. 14 to 0.18. For pra ctical p urposes , it is d

esirable to proc ess a complet

e year of me teorolo gical data wi

th a sin gle value for noon-tim

e albed o. For exam ple, the sing le val

ue of 0. 18 ma

y be a ppropri ate to process a

ll meteorological data for an urban site. For rural sites, a sing le albedo value of 0.18 for grassland and cultivated land m

ay be appropriate fo

r areas without sign

ificant snow cover during winter m onths. For desert shrubland, a sing

le value of 0.28 may be

appropriate. A sing

le value of 0.12could be representative of forested areas. We recomm end discussing the proposed values w ith the permitting autho rity pr ior to air model ing.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-35 

### 3.5.6 Bowen Rati o

The Bowen ratio is the ratio of the sensible heat flux to the evaporative or latent heat flux at the ground surface. The presence of m oisture affects the heat balance through evap orative cooling, which, in turn, affects the hourly Monin-Obuk hov length calculated by MPRM. Surface moisture is highly v ariable. Daytime B owen ratios are presented in Table 3-6.

Bowen ratio v alues v ary th roughout the country . For examp le, in u rban are as wher

e annua l rainfa ll is less than 20 inches, a single Bowen ratio value of 4.0 may be representative. For rural areas, a Bowen ratio value of 2.0 m

ay be appropr

iate for grass land and cultiv

ated lan d. For areas w here an nual rai nfall is greater than 20 inches, we recom mend a single Bowen ratio value of 2.0 for urban areas; and 0.7 for rural for est s, gra ssl ands , and cult ivat ed la nds. You ca n ref ine the B owen rati o est imat es pr ovid ed in Tab le 3-6 by using site- specific precipitation and wind speed data. We recom

mend clearly identifying and discuss ing the propo sed va lues wi th the a ppropri ate part

ies (e.g . perm

itting authori ty or f acility ) prior t o
use. TABLE 3-6

DAYTIME BOWEN RATIO S BY LAND USE, SEASON, AND PRECIPITATION CONDITI ONS

Land Use Season a Spring Summ er Aut umn Winter Dry Conditions Water ( fresh a

nd salt) 0.1 0.1 0.1 2.0 Deciduous forest 1.5 0.6 2.0 2.0 Coniferous forest 1.5 0.6 1.5 2.0 Swamp 0.2 0.2 0.2 2.0 Cultivated land 1.0 1.5 2.0 2.0 Grass land 1.0 2.0 2.0 2.0 Urban 2.0 4.0 4.0 2.0 Desert s hrubland 5.0 6.0 10.0 2.0 Average Conditions Water ( fresh a

nd salt) 0.1 0.1 0.1 1.5 Deciduous forest 0.7 0.3 1.0 1.5 Coniferous forest 0.7 0.3 0.8 1.5 Swamp 0.1 0.1 0.1 1.5 Cultivated land 0.3 0.5 0.7 1.5

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-36



### TABLE 3-6 (contd.)

Land Use Season a Spring Summ er Aut umn Winter Grass land 0.4 0.8 1.0 1.5 Urban 1.0 2.0 2.0 1.5 Desert s hrubland 3.0 4.0 6.0 6.0 Wet Conditions Water ( fresh a

nd salt) 0.1 0.1 0.1 0.3 Deciduous forest 0.3 0.2 0.4 0.5 Coniferous forest 0.3 0.2 0.3 0.3 Swamp 0.1 0.1 0.1 0.5 Cultivated land 0.2 0.3 0.4 0.5 Grass land 0.3 0.4 0.5 0.5 Urban 0.5 1.0 1.0 0.5 Desert s hrubland 1.0 5.0 2.0 2.0 Source—Paine (1987)

a The various seasons are defined by Iqbal (1983) as follows: Spring: Periods whe n veget ation is em

erging or partially green; t his is a tr ansitional s ituation that applies f or 1 to 2 months afte r the last kil ling frost i n sprin g. Summ er: Periods whe

n veget ation is lush and healthy ; this is ty pical of mid-sum

mer, but also of othe

r seasons in which f rost is le ss com

mon. Autum

n: Periods whe

n freez ing conditions are com

mon, deciduous trees are lea fless,crops are

not yet planted or are already har

vested ( bare soil e

xposed), g

rass surf aces ar e brown, a

nd no snow is present. Winter : Periods whe n surfac es are c overed by snow and t

empera tures are below f reezing . Winter albedo depends on whether

a snow c over is pr

esent conti

nuously, int

ermitt ently, or seldom. Albedo ra

nges f rom about 0.30 for bare

snow cov

er to about 0.65 f

or continuous cov

er.



### 3.5.7 Anthropogenic Heat Flux
Anthropogenic hea

t is the surface heating

caused by hum

an activity, in

cluding autom

obiles and heating systems. It is used t o calcu late h ourly L value s (Monin-Obukhov lengt hs). Tab le 3- 7 prese

nts anthropogenic heat flu

x (Q f 

### ) values for several urban areas around the world (U.S. E PA 1995g). In rural areas, we recommend usi ng a v alue 0. 0 Watts/m 2 

### for the Q

f 

### . A value of 20.0 Wa

tts/m 2 

### is appropriate for large urban areas, based on the annual v alue for Los Ang eles.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-37



### TABLE 3-7
ANTHROPOGENIC HEAT F LUX ( Q f 

### ) AND NET RADIATION ( Q * 

### ) FOR SEVERAL URBAN AREAS

Urban Area (Latitude) Population

(Millions) Population

Density (Pe rson s/km 2 ) Per Capita

Energy Use (MJ x 10 3 /year) Q f (Watts/m

2 ) (Season) Q *

(Watts /m2 )
Manhattan (40° North) 1.7 28,810 128 117 (Annual) 40 (Summ

er) 198 (Winter) 93 (Annual)

Montreal (45° North) 1.1 14,102 221 99 (Annual) 57 (Summ

er) 153 (Winter) 52 (Annual)

92 (Summ

er) 13 (Winter) Budapest (47° North) 1.3 11,500 118 43 (Annual) 32 (Summ

er) 51 (Winter) 46 (Annual)

100 (Summ

er) -8 (Winter

) Sheffi eld (53° North) 0.5 10,420 58 19 (Annual) 56 (Annual)

West Be rlin (52° North) 2.3 9,830 67 21 (Annual) 57 (Annual)

Vancouver (49° North) 0.6 5,360 112 19 (Annual) 15 (Summ

er) 23 (Winter) 57 (Annual)

107 (Summ

er) 6 (Winter) Hong Kong (

22° North) 3.9 3,730 34 4 (Annual) 110 (Annual)
Singapore (1° North) 2.1 3,700 25 3 (Annual) 110 (Annual)
Los Ang eles (34° North) 7.0 2,000 331 21 (Annual) 108 (Annual)

Fairban ks (64° North) 0.03 810 740 19 (Annual) 18 (Annual)

Source—Ok

e (1978)



### 3.5.8 Fraction of Net Radiation A bsorbed at the Ground
Also used for calculating hourly valu

es of Monin-O

bukhov len

gth, fraction of net radiation absorbed at the gr ound is the las t com

ponent of radia

tive heat bala

nce. B ased on :

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-38 

### • the net radiation ( Q * 

### ) values presented in Table 3-7, an

d

• recommend ation s prese nted in the MPR M User’ s Manua l, thems elves ba sed on Oke (1982),

we recommend v alues of 0.15 f or rural areas a nd 0.2 7 for ur

ban are as (U.S . EPA 1995g).

3.6 ISCST3 MODEL INPUT FILES

The ISC3 U ser’s Guide, Volume I (U.S. EPA 1995f) offers a thorough instruction on how to prepare the ISCST3 input files. The User’s Guide is available for downlo ading from the SCRAM at http://www.epa.gov/scram001 . We provide an example ISCST3 input file in Figure 3-2. This example illustrates a s ingle year run (1984), for particle phase COPC em

issions from a sing

le stack. The run is used to com

pute acute (1-h

our average) a

nd chronic (annual av

erage) values. It prov

ides single year results in a one

hour an d annua l aver age pl ot file f

or post- process ing. Specify

ing a terrain grid file in t he TG pa thway is optio nal. Y ou ge

nerally only conside

r it for m odeling dry v apor de position in highly variable terrain. Each air m odeling analysis

has unique issues and

concerns that we recom

mend you addr ess in t he ris k assess ment rep ort. We recommend u sing an a ir model ing method ology consistently throug

hout, f rom d ata coll ection a

nd mo del set-

up, to mode l outpu

t. This w ill assist both you and the pe

rmitting authority

in interpreting and commun icating mode l results. A transparent and scientifically defensible risk assessment report will identify consistent m ethods while docum

enting each section of the I SCST3 input file.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-39 

### FIGURE3-2 EXAMPLE INPUT FILE F OR “PARTICLE PHASE”

CO STARTING CO TITLEONE Example input file, particle phase run CO TITLETWO 1984 met data, Baton Rouge Surface, Boothville Upper Air CO MODELOPT DFAULT CONC DDEP WDEP DEPOS DRYDPLT WETDPLT RURAL CO AVERTIME 1 ANNUAL CO POLLUTID UNITY CO TERRHGTS ELEV CO RUNORNOT RUN CO SAVEFILE 84SAVE1 5 84SAVE2 ** Restart incomplete runs with INITFILE, changing '**' to 'CO' ** INITFILE 84SAVE1 CO FINISHED SO STARTING SO LOCATION STACK1 POINT 637524. 567789. 347. SO SRCPARAM STACK1 1.0 23.0 447.0 14.7 1.9 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 SO BUILDWID STACK1 14.02 15.51 16.53 17.05 17.05 16.53 15.51 14.03 SO BUILDWID STACK1 12.10 14.02 15.51 16.53 17.05 17.05 16.53 15.51 SO BUILDWID STACK1 14.02 12.10 14.02 15.51 16.53 17.05 17.05 16.53 SO BUILDWID STACK1 15.51 14.02 12.10 14.02 15.51 16.53 17.05 17.05 SO BUILDWID STACK1 16.53 15.51 14.02 12.10 SO PARTDIAM STACK1 0.35 0.70 1.10 2.00 3.60 5.50 8.10 12.5 15.0 SO MASSFRAX STACK1 0.22 0.08 0.08 0.11 0.10 0.07 0.10 0.11 0.13 SO PARTDENS STACK1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 SO PARTSLIQ STACK1 7E-5 5E-5 6E-5 1.3E-4 2.6E-4 3.9E-4 5.2E-4 6.7E-4 6.7E-4 SO PARTSICE STACK1 2E-5 2E-5 2E-5 4E-5 9E-5 1.3E-4 1.7E-4 2.2E-4 2.2E-4 SO SRCGROUP ALL SO FINISHED RE STARTING RE ELEVUNIT METERS RE DISCCART 630000. 565000. 352. RE DISCCART 630500. 565000. 365. RE DISCCART 631000. 565000. 402.

... (ARRAY OF DISCRETE RECEPTORS)

... RE DISCCART 635000. 570000. 387. RE FINISHED ME STARTING ME INPUTFIL 84BTR.WET ME ANEMHGHT 10.0 ME SURFDATA 13970 1984 BATON_ROUGE ME UAIRDATA 12884 1984 BOOTHVILLE ME FINISHED TG STARTING TG INPUTFIL TERRAIN.TER TG LOCATION 0.0 0.0 TG ELEVUNIT METERS TG FINISHED OU STARTING OU RECTABLE ALLAVE FIRST OU PLOTFILE 1 ALL FIRST BTR841.PLT OU PLOTFILE ANNUAL ALL BTR84A.PLT OU FINISHED

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-40 

### • Electronic and hard copies of ISCS T3 input file for all air m odeling runs RECOMMENDED INFORMATI ON FOR THE RISK ASSESSMENT REP ORT As discussed in Section

3.2, IS CST3 requires separate runs to model vapor phase COPC s, particle phase COPCs, and pa

rticle-bound pha se COPCs, for a total of three runs per CO PC source (stack or fugitive). The ISCST3 “Co

ntrol Secondary Key

words” used for these three runs are: Vapor Phase: CONC DDEP WDEP DEPOS 

### Particle Phase: CONC DDEP WDEP DEPOS 

### Particle-Bound Phase: CONC DDEP WDEP DEPOS 

### ISCST3 needs site-specific inputs fo r source parameters, receptor locations, m eteorological data, and terrain features . Prep are the mode l for ex ecution by cr eating an inpu t file. The inpu

t file is structured in five (or six , if a terrain grid file is used) sections, or path ways, desig

nated by two- letter abbreviations:

TABLE 3-8 ISCST3 INPUT FILE SECTIONS
Secti on Abbreviat ion Contr ol CO Source SO Recept or RE
Meteoro logy ME
Terra in G rid (O

ption al) TG Output OU


### The following subsection s describe how to spe cify the param eters for each pathway

in the ISC ST3 input file.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-41 

### 3.6.1 COntrol Pathway

Your choice of m

odel options ( MODELOPT 

### ) in the COntrol pathway will direct I SCST3 in the types of computations to p erform. We g enerally recom mend specify

ing the DFAULT parameter for particle and particle-bound p

hase runs, so that I SCST3 will implem ent the following re gulatory default options:

• Use sta

ck-tip dow

nwash ( except for Sch

ulman-Sci

re down wash).

• Use buo

yancy -ind uced di spersion (exce

pt for S chulm

an-S cire dow

nwash)

.

• Do not use fina

l plum e rise (except fo

r buildi ng downwash

).

• Use the calms processing routines.

• Use upper-b ound concentration estim ates for sources influenced b y building d

ownwash from super- squat buildings.

• Use default wind speed profile exponents.

• Use default vertical potential temperature g radients.
The CONC parameter specifies c alculation of air concentrations. The DDEP and WDEP param eters specify dry an

d wet deposition. The DEPOS specifies computation of total (wet and dry

) deposition flux. DRYDPLT and WETDPLT are use d for pl ume d epletion resultin g from dry a nd wet remov

al. We
recommen

d the following command lines for the vapor and two particle runs (thes e are for rural areas; substitute URBAN for urb an areas ): Vapor: CO MODELOPT TOXICS CON C DDEP WDEP DEPOS DRYD PLT

WETDPLT RUR

AL CO GASDEPVD

0.01 Particle Phase: CO MODELOPT DFAULT CON C DDEP WDEP DEPOS DRYD PLT

WETDPLT RUR

AL Particle-Bound: CO MODELOPT DFAULT CON C DDEP WDEP DEPOS DRYD PLT

WETDPLT RUR

AL Note that for vapo

r phase model runs, the DFAULT option is replaced by the TOXICS option . This directs ISC ST3 to execute the dry vapor deposi tion algorithm

in addi tion to the reg

ulatory default parameters. Yo

u need to add an a

dditional COntrol com

mand line for the

vapor phase run , to provide the

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-42 

### single value of the d ry v apor de

position veloc ity. In order to set a sin gle dr y va por dep osition veloc ity in ISCST3, use the following option s:

• Remove the

DEFA ULT ke yword from the CO MODEL OPT card . (This o ption is incompatible with the TOXICS option .)

• Add the TOXICS keyword on the CO MODELOPT card. (This option is needed when using dry v

apor deposition.)

• Add the key

word CO GAS DEPVD<Uservd>, where Uservd in the dry vapor deposition veloc ity (m

eters/se cond).

We recom

mend a dry vapor depos ition velocity of 0.5 centim

eter per second (cm/s ) for organic contaminants, chlo

rine, and HCl. We recommend a dry vapor deposition velo city of 2.9 cm /s for divalent
mercu ry. The recom

mend ed dry vapor depos ition velocity value of 0.5 cm/s

for organic contami

nants is consistent with the rang e specified for pesticides (0.0 1 - 1.1 cm/s) and dioxins and furans (0.27 - 0.78 cm/s) (U.S. EPA 2000b). A recent review of dry deposition (Wesely and Hicks 20 00) demonstrates considerable uncertainty about dry deposition even for well-

measured species s

uch as ozone an

d sulfur dioxide . Unce

rtainty is gre ater for

organ ic com pounds , with very

few m easurem ents av ailable to supp ort defensible values (see following table). TABLE 3-9 DRY DEPOSITION VELO CITY ESTIMATES AVAILABLE IN LITERATURE

Chemical Dry Deposition V elocity (cm/s) Reference Acetic acid 0.64 - 1.0 Hartma nn et al. (1991) 1 0.7 Sanheuza e t al. (1992) 1 Formic a cid 1.1 Sanheuza e t al. (1992) 1 Chlordane 0.01 - 0.04 Bidlema n (1988) Arochlor 1242 0.02 - 0.1 Arochlor 1254 0.08 - 0.2 p,p’-DDT 0.1 - 0.7 TCDD 0.5 Trapp and Ma tthies (1995) 0.5 McLachlan et al. ( 1995) 0.27 - 0.78 Smith and Heinhold (1995) PCDD/Fs 0.19 (0.06-0.60) Koester a nd Hites (1992)
1 As cit ed in Wes ely a

nd Hicks (

2000)

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-43 

### The modeling reported in the Mercury Study Report to Congress (U.S . EPA 1997c) u sed a value of 0.3 cm /s for n ightti me dr y dep osition of divalent m ercury , but u sed day

time v alues ra nging from 0.20 t o 4.83 cm/s dep ending upon atm ospheric stability and la

nd-use category. The day time values were based on data developed

from nitric acid d

ata, not from m

easurements of div

alent mercury. U.S. EPA (1997c) used an averag e ISC m

odel-calculated dry

deposition velocity

of 2.9 cm/s for divalent m ercury vapor and 0.06 cm/s for elemental m ercury. Hig

her values were ex

pected for chemicals with greater reactiv ity than acetic acid or formic acid, but no m easured values were

identified for any o

rganic comp ounds higher than 1.1 cm/s. As a result, we recommen d the default of 2.9 fo

r divalent mercury.
U.S. EPA (19 97c) also calculates site- or contaminant- specific dry vap or deposition velocities based on variou s parame ters i nclud ing molecu lar di ffusi vity, a sol ubili ty enhan cement f actor , pollu tant r eacti vity, mesophyll re sistance, and Henry ’s law constant. I f you are assessing a facility surrounded by land uses other than pine forest (for in stance urban, agricu ltural lands, or wetlands), you may wish to consider how a site- specific

value for this param eter cou ld be ca lculated . Two im

portant param eters ar e the st ability class (from the air m

odeling) and the lan

d use surrounding

the facility. The follow

ing information

can be found in Section 5.1. 2.3 (Dry Dep osition of Vapors), pag e 5-12, in the technical backg round documen

t of the MAC T rule: " Human Health an d Ecological Risk Asses sment Support to the Development of Technical Standards for Emissions from Com bustion Units Burning Hazardous W astes: Background Document, Final R eport (F-1999-RC 2F-S0014) ", which expla ins that : To calculate the weighted dry deposition v

elocity, it is recom

mended that land

use be obtained from 1:250,000

scale quadrangles o f land use and GI RAS spatial data obtained from EPA website and placed in a

n ARC- INFO form

at (U.S. EPA, 1994b). Table B- 6 of Appendix B of the MACT rule backg

round documen

t shows the land use data for the sites that were detailed in the MACT rule. In

the MACT rule, the fraction of time in each stability class was base d on 5-y ear hourly meteo

rological files used in the ISCST3 m odeling. Table B- 8 of Appendix B in the MACT rule backg

round documen

t shows the weig

hted dry deposition velocity for div alent mercury v

apor at the mod

eled facilities. Dry deposition of eleme ntal mercury was not included in the MACT analysis, which is consistent with the 1997 Mercury R eport to Congress. Site-specific dry

deposition velocity

for divalent m

ercury vapor can be calculated by weighting land use and stability

class. Values for dry

deposition velocity

for each land use categ

ory and stability class can be fo

und in the " Mercury Study Report to C ongress Volume III: F

ate and Transport of Mercury in th e Environment, December 1997, EPA -452/R-97-003" in Table 4-3 an

d Table 4-4, respectiv

ely. I t is recomm

ended that these va

lues be averag ed to annualized v alues. Generally, nig

ht time dry deposition velocities can be treated as constant acro ss all stability.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-44 

### As more research

to measure dep osition velocities of m ore organic com

pounds under a v

ariety of conditi ons bec omes availa ble, it may

be appropriate

to develop sit

e- an d chem ical-specifi c defau

lt dry deposit ion of v apor velocitie s. I

t is im portant to note that alt hough we recomm

end inp utting the dry vapor deposition v

elocity directly into

ISCST3, y

ou might instead elect to execute the dry gas dep osition algorithms w

ithin ISCST3 to calculate a deposition velocity. Howe ver, we caution you to read Section 3.1.2(Prepro cessing

Prog rams)and Se ction 3. 4.6 (So lar Rad iation), which note ad

ditiona l data needs and potential lim

itations to ISC ST3 calculating deposition velocities. Hav ing ISC ST3 calculate a deposition velocity

may also require that you c onduct compou nd-specific air m

odeling runs, dev

iating from the unit em

ission rate approach as ou tlined in this guidance . This may significantly increa se the number of air m

odeling runs neede d.

Note that for each of the three runs for each em ission source, 5 com

plete years of off- site (e.g., Nation al Weather Servic e from

SAMSO N) me teorolo gical data are

used. For sit

es with mete orological dat

a collecte d on- site, w e recom mend that th e perm

itting authori ty be notified

of the d ata peri od need

ed for a risk ass essment . Specif

y ‘ ANNUAL ’ for the averaging times (A VERTIME) to com

pute chronic (annual average) healt h risk, a nd/or ‘1’ to c ompute ac ute hea lth ri sks base d on the maximum 1-hour a verage concentrations over the

5-year period (see Section 3.10 ). We generally recommend repeating each phase run five time s (one f

or each year, or a tot

al of 15 ISC ST3 runs ) to com plete a set of 1 5 runs f

or the f ull five years of meteorological data.

Alterna tively , you

can com bine the 5 yea rs of m eteorolo gical data int

o a sing le meteorolo gical data file and complete only 3 runs for ea ch emission source (on e run for each phase ). Section 3.5.1.1 of th e ISC3 User’s Guide (U.S. EPA 1995f), inclu des a complete d

iscussion of comb ining multiple years of meteorological data into a single file prior to running I SCST3. You m ay select the ‘ ANNUAL ’ averaging time for all risk

assessment runs, regardless of the n umber of y

ears in the meteoro logical data file. The incorrect selecti on of ‘ PERIOD ’ will not comp ute the correct deposition rates needed by the risk
asse ssment e quat

ions(ref er toSect ion 3 .2.3 of the I SC3 User Guid e, Vo lume I ). N o add

ition al I SCS T3 model execution time is needed to obtain 1-y ear or 5-y ear air modeling

values.

ISCST3 also a

llows you to sp ecify COPC h alf-life and decay

coefficients. Unless clearly identified and discussed with the appro

priate parties (regulatory

authority or facility

), we don’t recom

mend using

these

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-45 

### keywords w

hen conducting air modeling fo r risk assessm

ents. You typ ically use the TERRHGTS keyword w

ith the ELEV

parameter to m

odel terrain elevations at receptor grid nodes. The FLAGPOLE keyw ord spe cifies re ceptor g

rid nod es abov e local groun

d leve l and is

not ty pically used for mos t air modeling to

perform im

pacts at ground lev

el.

We als o recommend using SAVEFIL to resta rt IS CST3 in the event of a comp uter or power f

ailure during long runs. SAVEFIL is best used by spec ifying

two sa ve file s, each

with a differen

t name. We
recommen

d that the save interv

al not be longer th

an 5 days for large runs. If two save files are used, and a failure occurs during

writing to the sav

e file, no more than 10 days w ill be lost. Use the INITFILE command to restart the runs after the failure, as shown in the following exam ple:

CO SAVEFILE SAVE1 5 SAVE2 ** INITFILE SAVE1



### ISCST3 will sa

ve the results alternately

to SAVE1 and SAVE2 every 5 d ays. I f the run fails after successfully writing

to SAVE1 , you can restart the ISCST3 ru n by replacing

the two asterisks (*) in the INITFILE line with CO and running I SCST3 again. The run will begin after the last day in SAVE1

. Note that you d

on’t use the MULTYEAR

keyword for computing

long-term

averages, and it should not be specified.

The following is an ex ample of the C Ontrol pathwa

y com puter co de for a

singl e-year I SCST3 p article
run:
CO STARTING

CO TITLEONE Example input file, particle phase run, 1 year CO TITLETWO 1984 met data, Baton Rouge Surface, Boothville Upper Air CO MODELOPT DFAULT CONC DDEP WDEP DEPOS DRYDPLT WETDPLT RURAL CO AVERTIME 1 ANNUAL CO POLLUTID UNITY CO TERRHGTS ELEV CO RUNORRUN RUN CO SAVEFILE 84SAVE1 5 84SAVE2 ** Restart incomplete runs with INITFILE, changing ‘**’ to ‘CO’ ** INITFILE SAVE1 CO FINISHED


### The corresponding CO

ntrol pathway com

puter code for a single-year I SCST3 vapor run is:

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-46 

### • Input values with supporting documentation fo

r each parameter id

entified in Section 3.7.2 RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT CO STARTING CO TITLEONE Example input file, vapor phase run, 1 year CO TITLETWO 1984 met data, Baton Rouge Surface, Boothville Upper Air CO MODELOPT TOXICS CONC DDEP WDEP DEPOS DRYDPLT WETDPLT RURAL CO GASDEPVD 0.01 CO AVERTIME 1 ANNUAL CO POLLUTID UNITY CO TERRHGTS ELEV CO RUNORRUN RUN CO SAVEFILE 84SAVE1 5 84SAVE2 ** Restart incomplete runs with INITFILE, changing ‘**’ to ‘CO’ ** INITFILE SAVE1 CO FINISHED 

### Additional runs

for the other 4 years are set up with

the sam e COnt rol path way, except

for the title description and SAVEFILE filenames.

3.6.2 SOurce Pathway

As discussed in Section

3.8, IS CST3 normally

uses a unit em

ission rate of 1.0 g

/s. Additional source characte ristics t he mo del nee ds (ty

pically found in the P art B pe

rmit a pplicati on and trial bu

rn report) inclu de the f

ollowi ng:

• Source type (point source for stack em issions; area or volum

e for fugitive e

missions)

• Sour ce lo cat ion ( UTM coor dina tes , m)

• Source base elevation

• Emission rate (1.0 g/s)

• Stac k heig ht (m)

• Stack

gas te mpera ture (K)

• Stack gas ex

it velocity (m

/s)

• Stac k insi de di amete r (m)

• Buil ding heigh ts an d wid ths (m)

• Particle

size d istribut ion (per cent)

• Particle density (g /cm 3 

### )

• Particle and gas scav enging coefficien

ts (unitless)

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-47 

### 3.6.2.1 Source Location

The lo catio n keyword of

the SOur ce path way (SO LOCATION) 

### identifies the:

• source type,

• location, and

• base elevation. The sour ce typ e for an

y stack is re ferred t

o as a “ point” s ource in

ISC ST3. Fu

gitive sourc e emi ssions a re discussed in section 3.9. The source location m ust be entered into I SCST3. We recom mend entering source locations in UTM coordin ates. The easterly and northerly coordinates are entered to the nearest meter; for exam

ple, 637524 m

eters UTM-E, or 4 567789 meters UTM-N (no com mas are used). Enter the base elevation of eac

h stack in m

eters. Sources for base elevations include U SGS topograph ic maps, facility plot plans or U SGS digital data bases.
An example in

put for the location k

eyword on the SOurce pathway includes source typ e, location, and base ele vation in the f ollowin g form at:
SO LOCATION STACK1 POINT 637524. 4567789. 347.



### 3.6.2.2 Source Parameters

The so urce pa rameter s keyword o f the SOu rce pat hway (SO SRCPARAM) 

### identifies the:

• emission rate,

• stack height,

• stack temperatu

re,

• stack velocity , and

• stack diameter. Enter the unit em

ission rate as 1.0 g

/s. Stack heig

ht is the height above plant base elev ation on the SO LOCATION keyword. Stack gas exit temperature is the most critical stack parameter for influencing concentration and deposition. High stack gas te mpera tures re sult in h

igh bu oyant plume rise, which, in turn, lowers concentration and deposition rates. We recommen d basing stack

gas temp eratures on stack

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-48 

### sampling tests for existing stacks. For new or u ndefined stacks, y

ou might use manufacturer’s d ata for similar equipm

ent. Calculate stack

gas exit ve locity from a

ctual stack gas flow rates and stack diameter. Actual stack g as flow rates can be m easured during existing

stacks during

stack sam

pling. You can get representative value s for new or undefined sources from m

anufacturer’s data on sim ilar equipment. Stack diameter is t

he insid e diam eter of t he stack at exit.
We highly recom

mend using

a site- or un

it-specific stack

temperature (low, average, h igh). Sim ilar to the Chapter 2 discussion on

emissions testing , we recomm end choosing the stack gas tem perature based on the objectives of the risk

assessment. F or example, if p ermitting is the objective, ‘typical’ ope rating temperatures with all control devices operatin g mig ht be a possible testing

condition to select. O

n the other hand, you

might select low or high o perating temp eratures because of the potential for emitting certain COPCs , or the

production of specific

PIC s, reg ardless of plum e rise co nsidera tions. We
recommen

d avoiding the practice of alway s choosing the lowest stack tem perature, in order to decrea se buoya ncy an d thereb y incr ease concentra

tion and deposi tion nea r the so urce. Th is is a g ross oversimplification of cond

itions. Increas es in concentration and d eposition near the source m ay underestimate

concen trations and de position rates aw ay from the

source where more critical receptors may be loca ted (see Chapte r 4).

Foll owin g is an examp le of the s ourc e par amete r inp ut in the S Ourc e pat hway f or emi ssi on ra te (g rams per second), stack height (meters), stack temp erature (K), stack velocity (meters per second), and stack diame ter (meters):

SO SRCPARAM STACK1 1.0 23.0 447.0 14.7 1.9



### 3.6.2.3 Building Parameters

The bu ildin g height an d width keywords o f the SOu rce pat hway (SO BUILDHGT; SO BUILDWID 

### ) identify the building

dimensions that most influence the air flow for each of the 36 10-deg ree directions surrounding a stack . Calculate the dim ensions using BP IP software, as described in Section 3 .2.4.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-49 

### The BPIP ou

tput file is transferred into the I SCST3 SOurce pathway as follows:

SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29
SO BUILDWID STACK1 14.02 15.51 16.53 17.05 17.05 16.53 15.51 14.03 SO BUILDWID STACK1 12.10 14.02 15.51 16.53 17.05 17.05 16.53 15.51 SO BUILDWID STACK1 14.02 12.10 14.02 15.51 16.53 17.05 17.05 16.53 SO BUILDWID STACK1 15.51 14.02 12.10 14.02 15.51 16.53 17.05 17.05 SO BUILDWID STACK1 16.53 15.51 14.02 12.10



### 3.6.2.4 Particle Size Distribution

ISCST3 needs a particle size distribution for determining deposition velocities. We recomm end using site-specific stack

test data for existing sources.
The following exam

ple is an IS CST3 input for a particle phaserun. From Table 3-1, the distribution for 9 mean diam

eter sizes includes the data needed for the k eywords of the S Ource pathway (SO PARTDIAM; SO MASSFRAX) 

### . The PARTDIAM 

### is taken from Column 1 (Mean Particle Diameter). The MASSFRAX 

### is tak

en from Colum n 4 (Fra ction of Total Mas s).

SO PARTDIAM STACK1 0.35 0.70 1.10 2.00 3.60 5.50 8.10 12.5 15.0 SO MASSFRAX STACK1 0.22 0.08 0.08 0.11 0.10 0.07 0.10 0.11 0.13 

### The example for the ISCST3 input for the particle-bound run is described below . From Table 3 -1, the
PARTDIAM 

### is the same. The MASSFRAX 

### is tak en from Colum n 6 (Fra ction of Total Su rface A rea).

SO PARTDIAM STACK1 0.35 0.70 1.10 2.00 3.60 5.50 8.10 12.5 15.0 SO MASSFRAX STACK1 0.49 0.17 0.13 0.09 0.05 0.02 0.02 0.01 0.02


### 3.6.2.5 Particle Density

ISCST3 also n

eeds particle density in order to model the air concentration and de position rates of particles. We recomm

end determining

site-specific m

easured data on particle den sity for all m odeled
sourc es when possib le. For new or un defin ed sour ces re quiri ng air mode ling, we recommend u sing a default particle density o f 1.0 g/cm 3 

### . Particles from combustion source s, however, m ay have de

nsities that are less than 1.0 g

/cm 3 

### (U.S. EPA 1 994d), which wou ld reduce the mo deled deposition flux.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-50 

### Follo wing is an example o f the pa rticl e densi ty porti on of th e SOurc e pathw ay (SO PARTDENS) 

### for the 9 mean particle size diameters of the previous exam ple:

SO PARTDENS STACK1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0


### 3.6.2.6 Scaven ging C oefficients

ISCST3 calculates wet deposition flux by multiplying

a scavengin

g ratio times the vertically integ rated concentration. The scavenging ratio is the product of a scav enging coefficien

t and a precipitation rate. Studies show that best fit values for the scav enging coefficien

ts vary with particle size. For v apors, wet scavenging

depends on the prop erties of the COPCs involved. However, not enough data are n ow availa ble to a dequate ly dev

elop CO PC- specific

scave nging coeffic ients. Therefore , assum e that v apors are scavenged

at the rate of the sm

allest particles, with behav ior in the atmosphere that is influenced more by the molecular proce sses that affect vapors than by the physical processes that m ay domina

te the behav ior of la rger p articles

(U.S. EPA 1 995f).
Wet deposition only o ccurs during precipitation . To use the wet dep osition option in I SCST3, input scavenging

coefficients for each particle size and a file that has ho urly precipitation data. For wet deposition of vapors , we sugg est using a scav enging coefficien

t for a 0.1- μm particle, to sim ulate wet scavenging

of very sm

all (molecular) particles. ISCST3 w ill also accept site-s

pecific measured washout data, or a value calculated based on Hen ry’s Law constant. If y

ou choose an option other than the coeffici ent for a 0.1- μm pa rticle, we recommend cle arly id entify ing an d discu ssing it with the appropriate parties (e.g. perm

itting authori ty, or facilit

y) pri or to analysis . You can est ablish s caven

ging coeffic ients for each particle size from the best fit of the curves presented in the ISC3 User’s Guide (U.S . EPA 1995f). The curves are based on the work of Jindal and Heinh old (1991). The curves are limited to a maximum

particle size of 10- μm. Assum e that all scavenging coefficients for particle sizes greater than or equal to 10- μm are equal. This assumption follow s research on wet scav enging of p articles (Jindal and He inhold 1991).

The IS CST3 m

odel dif ferentia tes between frozen and liquid s caven ging coeffic ients. Researc

h on su lfate and nitrate data shows that frozen precipitation sca venging coefficients are about one- third of the values of liquid precipitation (Scire et al. 1990; Witby 19 78). It is protective to assum e that the frozen scavenging

coefficients are equal to the liquid scavengin g coefficients (Pei and

Cramer 1986). If desired, you may input separate scave

nging coefficients for frozen precipitation.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-51 

### The following is an example of the particle liquid (rain) and froz en (sleet or snow) scav enging coeffici ents inp

ut in the SOurc e pathway for 9 me an parti cle siz e diam eters, a ssumi

ng pa rticles a re scavenged by frozen precip itation at 1/3 the rate of liqu id precipitation:
SO PARTSLIQ STACK1 7E-5 5E-5 6E-5 1.3E-4 2.6E-4 3.9E-4 5.2E-4 6.7E-4 6.7E-4 SO PARTSICE STACK1 2E-5 2E-5 2E-5 4E-5 9E-5 1.3E-4 1.7E-4 2.2E-4 2.2E-4


### The complete SOurc e pathway for the example particle phase

input file is as follows:

SO STARTING SO LOCATION STACK1 POINT 637524. 4567789. 347. SO SRCPARAM STACK1 1.0 23.0 447.0 14.7 1.9 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 18.29 18.29 18.29 18.29 SO BUILDHGT STACK1 18.29 18.29 18.29 18.29 SO BUILDWID STACK1 14.02 15.51 16.53 17.05 17.05 16.53 15.51 14.03 SO BUILDWID STACK1 12.10 14.02 15.51 16.53 17.05 17.05 16.53 15.51 SO BUILDWID STACK1 14.02 12.10 14.02 15.51 16.53 17.05 17.05 16.53 SO BUILDWID STACK1 15.51 14.02 12.10 14.02 15.51 16.53 17.05 17.05 SO BUILDWID STACK1 16.53 15.51 14.02 12.10 SO PARTDIAM STACK1 0.35 0.70 1.10 2.00 3.60 5.50 8.10 12.5 15.0 SO MASSFRAX STACK1 0.22 0.08 0.08 0.11 0.10 0.07 0.10 0.11 0.13 SO PARTDENS STACK1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 SO PARTSLIQ STACK1 7E-5 5E-5 6E-5 1.3E-4 2.6E-4 3.9E-4 5.2E-4 6.7E-4 6.7E-4 SO PARTSICE STACK1 2E-5 2E-5 2E-5 4E-5 9E-5 1.3E-4 1.7E-4 2.2E-4 2.2E-4 SO SRCGROUP ALL SO FINISHED


### When m odeling air vapors using I SCST3, the following is an example of the SOurce pathway input for wet vapor scav

enging coefficien

ts that replaces the PAR

TDIAM, MASS FRAX, PARTDEN S, PARTSLIQ

and PARTSI CE lines in the abov e example:

SO GAS-SCAV STACK1 LIQ 1.7E-4 SO GAS-SCAV STACK1 ICE 0.6E-4


### 3.6.3 REceptor Pathway
The REceptor pathway

identifies sets or arrays of receptor grid nod es (identified by UTM coo rdinates) for whi ch I SCST3 generates estimates of air para

meters includ

ing:

• air concentration,

• dry and wet de

position, and

• total deposition.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-52 

### Previous U.S. EPA guidanc e (1994l) recomm ended using a p olar receptor grid to id entify maxim

um value s. Pol ar grids prov

ide cov erage over l arge a

reas wi th fewe r recept or gri d nodes

than ot her gr id types,thereby

reducin g com puter ru n times. However , U.S. EPA R egion 6 expe rience i ndicate s that, although polar g

rids may red

uce computer run

times, air m

odelers typically choose a different option. The bene fit of re duced r

un tim e is offs et by difficul

ties in i dentify

ing po lar gri d locati ons in a bsolute UTM coor

dinates for (1) extracti

ng ter rain values fr

om di gital t

errain f iles, an d (2) se lecting

exposu re scenario locations (see Chapter 4). Using a Cartesian grid is a n alternative to a po lar grid.

One method of obtaining a C artesian grid with terrain elevations is to open both the grid array

and the USGS DEM file in a graphics prog ram (e.g. , SURFER ® 

### ). The software sam

ples the DEM file at the user-sp ecifi ed loca tions (i.e. t he grid n odes) , each de fined as the i nters ectio n of eas t (x) an d north (y) values. The software extracts terrain elevation (z ) from the DE

M file associated with the des ired location. These x, y , and z values are saved as a text file with one recepto r grid node per line. Use a text editor to prefix each line w ith “ RE DISCCART ,” to spec ify a dis crete

rece ptor gri d nod e in I SCS T3 format. Commercial softwa re is ava ilabl e that generat es the r ecommende d recep tor gri d node ar ray and extracts terrain eleva tions fr om the USGS DEM download ed files , or an

y terra in file i n x- y- z form

at.
The following is an example of the R Eceptor pathway for discrete receptor grid nodes at 500-meter spacing that includes t

errain e levati ons (in meters):

RE STARTING RE ELEVUNIT METERS RE DISCCART 630000. 3565000. 352. RE DISCCART 630500. 3565000. 365. RE DISCCART 631000. 3565000. 402. 

### 9 RE DISCCART 635000. 3570000. 387. RE FINISHED



### We recommend that air mod eling for each risk

assessment include , at a minim um, an array

of receptor grid nodes cov

ering the area within

10 kilom eters of the facility. Locate the origin o f the grid at the centroid of a polygon formed by the locations of the stack emission sources. This receptor grid no de array may consist of a Cartesian g

rid with grid node s spaced 100 m eters apart extending from the centroid out to 3 kilometers. For

the dis tances f

rom 3 kilom

eters ou t to 10 kilom

eters, t he receptor gr

id node spacing can be increased to 500 m eters. The single g

rid node array con

tains both grid nod

e

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-53 

## • Summary

of all information regarding the coordinates and placem ent of the receptor g

rid node array used in air m

odeling

• Copies of any m

aps, figures, or a

erial photographs use d to develop the receptor grid node array

• Map presenting UTM locations of receptor grid no des, along with other facility inform ation. RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT spacing s. I

nclude the sam

e recept or gri d node array in the R Eceptor pathwa y for all I SCST3 r

uns for all years of meteorological data and for all emission sou rces.

We recom

mend specify ing in dividu al terrai n elevations f

or all re ceptor g

rid nod es. Se veral metho ds are availa ble for assign

ing te rrain el evations to g

rid nod es using digital terrai

n data. The 1:2 50,000

scale DEM dig ital data are av ailable for dow

nload a t the US GS I

nternet site ( htt p:/ /ed c.us gs.go v/gui des/ dem.h tml ). This data has horizontal spacing betwe en digital terrain values of approx imatel y 90 meters , which p rovide s suff icien t accur acy for a ir model ing.
During the risk assessm ent, se lect air parameter (concentra tion and deposi tion) values for a single receptor grid node to

evaluate a specific exposure scenario location. You can also com pute an area average o f air pa rameter values a cross multipl e recep tor gri d nodes , to rep resen t the ave rage concentration or deposition over a watershed o r water body (see Chapter 4). However, depending on site-specific consideratio ns, a different receptor g

rid node array m

ay be m ore appropriate.

In addition to the receptor grid nod e array evaluate d out to 10 kilometers, yo u might c onsider additional grid n ode arra ys for evalu ating water b odies an

d their watersheds loca

ted bey ond 10 kilom

eters. We
recom mend a grid node s pacing of 500mete

rs betw een nod

es for a rrays that are

more than 10 kilom eters from the em

ission source. An e qually spaced g rid node array facilitates subsequent comp utation of area averages for d

eposition rates onto waterbo dies and their associated watersheds.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-54 

### 3.6.4 MEteorological Pathway
The file containing m

eteorological data is spe cified in the MEteorological pathway. MP RM creates indivi dual fil es for e ach of t he 5 years as ASCII fil es. I SCST3 u ses them to com pute ho urly concentrations and deposition rates. You can e ither specify a single year of m eteorological data in ea

ch ISCST3 run, or combine the total period of mete orological data into a single meteoro logical file, which ISC ST3 will

proces s in a si

ngle 5 -year run. When c ombin ing m eteorolo gical files, we caution you to consi der the follo wing:

• Preprocess each yea r separately using

MPRM into an ASC II format

• Combine the y

ears into a single file (using a text editor o r DOS COPY

comma nd)

• ISCST3 com

pares the first line (header) of the combined file to the Surface and Up per Air Station ID

numbers specified

in the input file ME pathw ay

• ISCST3 reads the headers of subsequen t years unless they ’re deleted in the com bined file. If subseq

uent year head

ers are i ncluded in the c ombin

ed file, ISC ST3 will

comp are the station IDs

to the input file station I

D. Your analysis m

ight use m

eteorological data from

more than one surface station or upper air station (e.g., the upper air station is m oved after the third y

ear of the period and assigned a new station ID by the National Weather Serv ice). If this is the case, delete the headers for subsequent y ears in the comb ined file.

• For sites where the anem ometer heigh

t is changed during

the 5 year period

(e.g., during the period 1984- 1988, the anem ometer was relocate d on Decemb er 15, 1985, chan ging the height from

20 feet to 10 m

eters), we recom

mend running

each year separately . Use the anemom

eter height in the I SCST3 input file ME pathway which correspo nds to that year’s meteoro logical data.

We recommend completing each year in the file with a full year of data (365 days , or 366 days for leap years). Verify the anemome ter height for the surfa

ce station from L ocal Climate Data Summ ary records, or other sources, such as the state climatolog ist office. We recom

mend identify

ing the correct
anemomete

r heig ht ANEMHGHT for the

wind s peed m easurem ents at the surf

ace stat ion befo re air modeling. Details of specifying the meteorolog

ical data file are in the I SC3 User’s Guide, Section 3.5.1.1.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-55 

### The fo llowi ng is an ex ample in put sec tion f or the M Eteor ologic al pat hway, usi ng the 198 4 Baton Rouge file, with an anem

ometer heigh

t of 10 meters a

nd station identification num bers:

ME STARTING ME INPUTFIL 84BR.WET ME ANEMHGHT 10.0 ME SURFDATA 13970 1984 BATON_ROUGE ME UAIRDATA 12884 1984 BOOTHVILLE ME FINISHED


### 3.6.5 Terrain Grid (TG ) Pathway
Computing

dry plum e depletion is sensitive to terrain elevation. In the absenc e of a terrain grid file, ISCST3 autom

atically assumes

that the terrain slope between the stack base and the receptor grid node elevation is linear. In concept, this assumption m ay underestim

ate plume deposition. Howeve r, based on experience, the m

agnitude of the differen

ces in computed concentrations and deposition rates is nominal. Since includin g a terrain grid file in the TG pathway signific antly increases model execution time, we sugg est that

a terrai n grid file m ay no t be nec essary

for all sites. If a terrain grid f ile is de sired for a specific site ba sed on highly

varia ble terr ain over short

distanc es, the

format of the TG file

is ava ilable in the ISC3 User's Guid

e.

The lo catio n keyword of

the TG p athway ( TG LOCATION 

### ) identifies the x and y values to be ad

ded to the source and receptor g

rid to align with the terrain file coordinates. If the source and receptor grid nodes are in relative units suc

h that the source is at loc ation 0,0, the location keywords in the TG pathway would be the UTM coordin ates of the source. We recommen d specifying all emission sources and receptor grid nodes in UTM coordinates (note NA D27 or NAD83 format), and that the TG file, if used, be in UTM coordinates. Therefore,the location of the orig in of the TG file relative to the source location will be 0,0. A

lso, we recom mend presen ting t he terra in elev ations i n the TG file in meters. Fol lowing is an exampl e of the TG path way:

TG STARTING TG INPUTFIL TERRAIN.TER TG LOCATION 0.0 0.0 TG ELEVUNIT METERS TG FINISHED

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-56 

### 3.6.6 OUtput Pathway

ISC ST3 outp

ut com es in two basic file ty

pes: the mand atory “output

summ ary fil e” typ e (ma

ndatory because ISC ST3 automatically creates the file), and num erous optional file form

ats. As part of its inp

ut file structure, ISC ST3 requires the nam e of the output sum

mary file (Se e Section 3.8.2). Using text and tables, this file sum

marizes the I SCST3 run results, includin g repeating b ack all input data (e. g., sources with parameters, control pathways, grid node list, m odel options selected), and results summ

aries for each an nual and 1- hour av

eragin g peri od. I

t also s tates if the run finished succes sfully . The su

mmary file also alerts you to special meteorological conditions that were fou nd during runtim

e (e.g. num

ber of calm hours, an

d relationships between so urce base elevation a

nd grid node elev

ations). It p

rovides impacts for the hig

hest grid node v

alues, not the results at ev ery grid nod

e required to perform

the methods found in the remainder o f the HHRAP. We recomm end using the ou

tput summ

ary file for quality checking , to mak

e sure the run executed successfully and correctly.

ISC ST3 prov

ides nu merou s option

al outpu t file formats

in addi tion to the resu

lts in the outpu

t sum mary file, as specified in receptor tables (RECTABLE). The “plot files” format is the most useful option for facilitating post-

processing of the air parameter valu es in the model output. For this reason , though “plot files” are optional in executing ISCST3, they are necessary for HHRAP m

ethods. There are two p lot files for each I SCST3 r

un on a singl e sourc e – the ‘annual ’ and ‘1 -hou r’ plot f iles. The 'an

nual' plot fil e contains all air mod

eling results at each g

rid node, for the annu

al average of five years of met data. The '1- hour' plot fil e conta

ins the air mo deling

results at each grid n ode for the 'highe st 1-hour'

impa ct for al l five years. The file presents data in tabular fo rm, with im

pacts at every grid node.
The plot file lists the x and y coordinates, and the c oncentration or deposition rate values for each averaging period. Data are listed

in a format that can easily be pulled into a post-p

rocessing prog

ram (e.g. spreadsheet). Note that the I SCST3-ge nerated plot

file is not the sam

e format as the I SCST3- generated post

file. We recomm

end using the plot file, not the post file.
Following is an example OUtp ut file specification for single-year run of 1-hour and annual average plot files:
OU STARTING

OU RECTABLE ALLAVE FIRST OU PLOTFILE 1 ALL FIRST BTR841.PLT OU PLOTFILE ANNUAL ALL BTR84A.PLT OU FINISHED

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-57 

### The second line directs I SCST3 to create a table of values for each receptor grid node for a ll averaging periods in the m odel run (1-h our and annual). The t

hird line direct s IS CST3 to create a separat e plot f ile (named BTTR841.PLT) of the 1-hour average results fo r all emission source s in the run using the first highest (e.g. , maxim

um) value for all hours of results during the year for each receptor grid node. The fourth line directs I SCST3 to create another sep arate plot file (named BTR84A.PLT) of the ann ual average results fo

r all sources in the run fo r each receptor grid node.

3.7 ISCST 3 MODEL EXEC UTION

Consid er mo del exe cution t

ime needs for each a

nalysi s. A c omple

te air m odeling run—inc luding

air concentration, wet and dry deposition, an d plume depletion

—may require 10 times the run time for the
same source and rec eptor g rid nod es for a ir conce ntration only. You c an avo id wasted mo deling effort and analysis tim

e by verify

ing input param

eters and conducting

test runs prior to executing ISCST3.
Long run tim

es result mainly

from two algorithms—plume depletion and terrain g rid file. ISC ST3 run times increas e as m

uch as t enfold f or runs apply

ing pl ume d epletion . We be lieve that con stituent mass is conserved between

suspended concentration and deposition rate by allowing for dep letion of deposited mass from

the plume con

centration in IS CST3. The overestim ate of plume con

centration, and the subsequent overestim

ate of deposition which results when plum e depletion is not allowed , is too protecti ve. A t the sa me tim e, we d on’t bel ieve t

he nom inal benefits of includi

ng a t errain g rid file justify the add ed run t imes. Therefore, we recom mend that pl ume d epletion alway s be inc luded. We don ’t
recommen

d terrain grid files.

3.8 USING MODEL OUTPUT

ISC ST3 outp

ut (air c oncentr

ations a nd depo sition r

ates) ar e usuall y prov ided on a unit e missi on rate (1.0 g/s) basis from

the combustor or emission source,and aren’t COPC- specific. This is to preclude having to ru

n the model for each individual CO PC. Use the C OPC-specific emission rates from the trial burn (see Chapter 2) to adjust the unitized concentration and deposition output from I SCST3. The resultin g CO PC- specific

air concentrati ons and

deposi tion rates will be used

in the e stima

ting m edia concentration equations (see Chapter 5). Conce ntration and deposition are directly proportional to the unit emission rate u sed in the IS CST3 modeling . However, there migh t be some instan

ces where the risk

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-58 

### assessor will need to con vert modeled

output to COPC -specific output fo r the risk assessm

ent. For
exam ple, the risk

assessor may

want to comp are modeled COPC concent rations in am

bient m edia to concentrations actually m easured in the field.

For facilities with m

ultiple stacks or other emission sources, we recomm end that each source be

modeled separate ly. Th

is is be cause m

odeling mult iple sou rces at o ne tim e result s in an inabilit

y to e stima

te
source- specific

risks . This li

mits t he abili ty of a perm itting agenc y to e valua te which sourc e is respons ible for

the resulting

risks . Such

ambi guity

mak es it im possibl e for the agen

cy to specify protective, com

bustion unit-spec ific permit lim its. If a facility

has two or m

ore sources with identical characteristics (emissions, stack parame ters, and nearby locations), it may be appropriate to m

odel them with a single set o f runs. We recom mend getting

the approval of the permitting authority prior to such multi-sou rce model ing. TABLE 3-10 ISCST3 AIR PARAMETER OUTPUT

Air Parame

ter Description Units (Used for most soil-based exposure pathways) Cyv Unitized yearly ave rage air concentration from vapor phase μg-s/g -m3 Cyp Unitized yearly ave rage air concentration from particle phase μg-s/g -m3 Dydv Unitized yearly ave rage dry deposition from vapor phase s/m 2 -yr Dywv Unitized yearly ave rage wet deposition from vapor phase s/m 2 -yr Dydp Unitized yearly ave rage dry deposition from particle phase s/m 2 -yr Dywp Unitized yearly ave rage wet deposition from particle phase s/m 2 -yr (Used for fish and drinking water ingestion exposure pathways) Cywv Unitized y early (wate r body or w

atershed) averag e air conc entration from vapor phase μg-s/g -m3
Dytwv Uni tiz ed yea rly ( wate r bo dy or water she d) a vera ge to tal (wet and dry)

deposition from vapor phase s/m 2 -yr
Dytwp Uni tiz ed yea rly ( wate r bo dy or water she d) a vera ge to tal (wet and dry)

deposition from particle phase s/m 2 -yr (Us ed fo r eva lua tio n of

acut e ris k via dir ect i nha lat ion expo sur e pat hway) Chv Unitized hourly air concentration from vapor phase μg-s/g -m3 Chp Unitized hourly air concentration from particle phase μg-s/g -m3 Chpb Unitized hourly air concentration from particle-bound phase μg-s/g -m3

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-59 

### Equa tio n 3-2

Equa tio n 3-3 3.8.1 Unit Rate Output vs.COPC-Specific Output
The relationship between the u nit emission rate and

the unit air param

eter values (air concen

trations and deposition rates) is linear. S imilarly, the relationship between the C OPC-specific emission rate ( Q ) and the CO PC- specific

air para meter value s (air concentra

tions an d depos ition ra

tes) is a lso line ar if

the COPC-sp ecific emission rate is used in the air m odel.

In th is Secti on we d

iscuss u sing t

he unit emiss ion rate . We als o adv ance th e rationale that you should
use a un it emi ssion ra

te inste ad of the COPC -spe cific em ission r ate. U sing a

unit em ission r ate preclud es hav ing to run I SCST3 s eparatel

y for each individu

al COP C. We a

dvoca te using a unit emiss ion rate

in the a ir mo deling

becaus e you

can dev elop a c omm

on ratio relation ship between t

he unit emission rate and the COPC- specific emission rate. The ratio is based on the fact that both indiv idual relationships are linear in the a ir model. This ratio relationship is expressed by the following equ

ation:

To use th is equat ion, y ou mu st know three

of the v ariables . IS CST3 provides the modeled output air concentration (or deposition ra te). The unit emission is 1.0 g/s. You can get the COPC- specific emission rate directly from

stack or source test data.

3.8.1.1 Determining the COPC-Specific Emission Rate ( Q )

The COPC-s

pecific emission rate from the stack, prior to any a pplicable adjustments (e.g ., upset emissions scaling , revisions based on hours of operation, feed rate adjustments, etc. ) is a function of the stack gas flow

rate and the stack gas concentration of each COPC. I t can be calculated from

the following equation:

where Q = COPC-sp ecific emission rate (g /s) SGF = Stack gas flow rate at dry stand ard conditions (dscm

/s)

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-60 

### Equa tio n 3-4 SGC = COPC stack gas concentra tion at 7 perce

nt O 2 

### as me asured in the t rial bur n ( : 

### g/ds cm) CFO2 

### = Correction factor for conv ersion to actual stack gas concentration O 2 

### (unitless) 1 x 10 6 

### = Unit convers ion fact or ( : 

### g/g)
Guidan ce for adjus ting COPC -specif ic emiss ion rat es, as we ll as de termini ng emissi on rate s for fu gitive emiss ion sou

rces, is avail able in Chapte

r 2. Also, it is som

etime s neces sary t

o derive the C OPC- specific emission rate from

surrogate data, su

ch as for a new facility

that has not yet been constructed and trial burned (see Chapter 2)

.
3.8.1.2 Converting Unit Outp ut to COPC-Specific Output

Once th ree of the four v

ariables in Equation 3- 1 are k

nown, you c an deriv

e the C OPC- specific

air concentrations and deposition rates by m

ultiplying as follows:

For exa mple, if COP C A is emitte d at a ra te of 0. 25 g/s , and t

he I SCST3 m

odeled concent

ration a t a specific receptor grid

node is 0.2 μg /m 3 

### per the 1.0 g/s unit emission rate, the concent ration of COPC A at that r eceptor grid n ode is 0 .05 μg

/m 3 

### (0.25 multi

plied by 0.2). Calcul ating deposit ion is s imilar

ly proportional to the em

ission rate of each COP C. You are rem inded once again that the process of converting m

odeled unitized outp

ut into COPC- specific output is taken directly into account in the estimating m

edia concentration equations in Chapter 5 and A ppendix E.

3.8.2 ISCST3 Model Outpu t

It is important that the ri sk ass essor un derstand how t

o read t he I SCST3 o

utput st ructure,in orde

r to ensure accurate use of m

odeled output in the risk

assessment. The output from each ISCST3 m odel run is written to two separate file formats. The ‘outp ut summ ary file’ is specified by

name at run time in the execution comm

and. Typical com

mand line nom

enclature is:
ISCST3 inputfile.INP outputfile.OUT

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-61 

### where

ISCST3 

### : specifies executing the ISCST3 m odel inputfile.INP 

### : is the input file nam e you (the m

odeler) select outputfile.OUT 

### : is the output sum mary file nam

e you select, ty

pically the sam

e as the input file name (bu

t with a different suffix)
For example, the following I SCST3 input line would run the input file (PAR

T84R.INP) c

reated by the mode ler for p articula

te em issions using

1984 m eteorolo gical data on

the rec eptor g

rid. I SCST3 w

ill automatically w

rite the output sum

mary file (PA

RT84R.OUT) during execution.

ISCST3 PART84R.INP PART84R.OUT 

### You specify the second file format, the output ‘plot file,’ in the ISCST3 inpu

t file OUtput pathway

. ISCST3 creates it during the run (see Section 3.6.6). The “ plot file” is typically

then imported in

to a post-processing

program (e.g. a spreadshe et) before entry into the risk assessm ent computations.
Vapor phase and Particle- bound phase runs pro duce similar plot files. The plot files for the vapor phase runs will include average concentrations an d wet deposition rates. The plot files for the particle and particle-bound p

hase runs will include av erage concentrations, dry depositions, w et depositions and total depositions. You ca

n average the

1-year values at each receptor grid node for a 5-year value at each node, unless a single five-y ear ISCST3 run

using a com

bined meteorolog

ical file is used. I f you use the 5-year c ombined file, the risk assessor can use the results from the ISCST3 plo t file directly in the risk
assessm ent with out averagin

g over the fi

ve years. A

ll valu es are u sed in t

he estim ating media concent ration e quation s (see Chapter 5 ).

3.8.3 Using Model Output to Estimate Media Concentratio ns

Section 3.2 discussed how partitioning of the COPCs affects the development of ISCS T3 modeling ru ns. The choices of which m

odeled air parameter values (air concentrations and deposition rates) to use in the estimat ing media c oncent ratio n equat ions is based on this sa me parti tioni ng theor y.

3.8.3.1 Vapor Phase COP Cs
ISCST3 g enerates the following output for vapor p hase air modeling

runs:

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

2 These two PA Hs have vapor pha se fracti ons, Fv, less than fi ve percent


### . U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-62 

### • vapor phase air concentrations (unitized Cyv and unitized Cywv ),

• dry vapor d

eposition (unitized Dydv ), and

• wet vapor depos itions (unitized Dywv and unitized Dywwv ) for organic COP Cs at receptor grid nodes based on the u nit emission rate. These values are used in the estimating media

concen tration equations for a

ll COP C org anics except the polyc yclic aroma

tic hydrocarbons (PA

Hs) dibenzo(a,h)an

thracene and indeno(1,2 ,3-cd)py rene 2 

### . The air concentration (unitized Cyv ), dry vap or deposition (unitized Dydv ), and wet vap or deposition (unitized Dywv ) from the vapor phase run is also used in the estim ating media concentration equations for m ercury. You select values for these CO PCs from the vapor phase run because the mass of the COPC em itted by the comb ustor is assum ed to ha ve eit her all o r a port ion of i ts ma ss in the vapo

r phase (see Ap pendix A-3 ).

3.8.3.2 Particle P hase COPCs
ISCST3 g enerates the following output for particle phase air modeling ru ns:

• air concentration (unitized Cyp ),

• dry deposition (unitized Dydp ),

• wet deposition (unitize d Dywp ), and

• combined depos ition (unitized Dytwp )

for inor ganic s and re lative ly non-volatile o rganic COPC s at rece

ptor g rid nod es base d on th e unit emission rate. These values are used in the estimating media concentration equations for all COPC inorganics (except m

ercury, see Chapter 2 and Appendix A-3) and p olycyclic arom atic hydrocarbons with fraction of vap or phase, Fv , less than 0.05 (e. g., dibenz o(a,h)anthracene and indeno(1,2,3- cd)pyrene). Yo u choose values for inorganic and rela tively non-

volatile COPCs from the particle phase run because the all the mass o f the COPC is assu med to be in the particulate phase (see Append ix A-3). Th e mass is a pport ioned across the par ticle size dis tribu tion ba sed on mas s weight ing.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-63 

### 3.8.3.3 Particle- Bound COPCs

ISC ST3 part

icle- bound r uns g enerate the foll owing output :

• air concentration (unitized Cyp ),

• dry deposition (unitized Dydp ),

• wet deposition (unitize d Dywp ), and

• combined depos ition (unitized Dytwp )
for organic COP Cs and mercury (see Chapter 2 and Appendix A- 3) at each receptor g rid node. Use these values in the “estim

ating media concentration” equations to account for the portion of the vapor condensed onto particulate surfaces. Select va lues for these COPC s from the particle- bound run because the mass of the COPC em itted by the com

bustor is assumed to have a portion of its mass cond ensed on particulates (see Appendix A-3). I SCST3 uses surface area weighting to ap portion the particle-

bound mass across the p article size distribution.

3.9 MODELING FUGITIVE EMISSIO NS
The procedures presented in th is chapter for mod

eling stack sou

rce emissions are als o effective for modelin g fugitive source emissio ns, as de fined in Chapt er 2. Howe ver, you ca n repre sent f ugitive emissions in the I SCST3 input file SOurce pathway as either “area” or “volum e” source types. Model fugiti ve em issions of vol atile organics on ly in t he vap or phas e. Mode l fugi tive emissi ons of a sh only in the particle and particle-

bound phases, not v

apor phase.

As disc ussed in Chapte r 2, fug itive e missi ons of v

olatile o rganic vapors are as sociated

with combus tors that i nclud e stor age vesse ls, pip es, valve s, seal s and fl anges. En ter th e horizo ntal a rea of the fugi tive source into the I SCST3 input file according to the instructions found in the ISC3 User’s Guide, Volum e I (U.S. EP A 1995f) . You can ge t the ho rizont al are a from the facil ity plot plan. T he heigh t of the fugiti ve source is defined as the to p of the vertical exten

t of the equipme

nt. If the vertical extent isn’t k nown, you can use a default heig

ht of ground lev

el (release height of zero). This provides a protective estima te of potential impacts. The ISCST3 m odel run time is faster for volum e source types than

for area source types. We ge

nerally recom mend consid ering the vo lume source type f or mo st appli cations . We

### Human Health Risk Assessment Protocol Chapter 3: Air Dispersion and Deposition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 3-64 

### B1
F1 B2

F2 

# Plot Plan ISC3 Volume F1A F1B F1C

F1D 

### recommend following the methods in the ISCST3 U ser’s Guide to define the input parameters representing the fugitive source.
The following example is for organic fugitive emissions only (modeling only vapor phase emissions) modeled as a volume source type. The example includes a facility with two stack emission sources (B1, B2) and two fugitive emission sources (areas F1, F2). A total of four runs for each year (or 5-year combined file) of meteorological data is needed.

Perform one run for each of the two stacks as point s ources. Perform one run for each of the two fugitive areas as volume sources (Note: or you could model as area sources). Since the emissions are fugitive volatile organics, model only the vapor phase. The verti cal extent of the pipes, valves, tanks and flanges associated with each fugitive emission area is 15 feet (about 5 meters) above plant elevation. To define the sources for input to ISCST3, specify the release heightas 2.5 meters (1⁄2 of vertical extent of fugitive emissions). Specify the initial vertical dimension as 1.16 meters (vertical extent of 5 meters divided by 4.3, as described in the ISC3 User’s Guide).
The initial horizontal dimension is the side length of th e square fugitive area (footprint) divided by 4.3. If fugitive area F2 has a measured side of 30 meters, the initial horizontal dimension is 6.98 (30 meters divided by 4.3). For fugitive area F1, subdivide the area on the plot plan (ISC3 Volume) to create square areas for input to ISCST3. The four areas depictedrepresent subdivision into square areas. Fugitive source F1 is input into a single ISCST3 run as four separate volume sources (F1A, F1B, F1C, F1D). The initial horizontal dimension for each volume source is the side of the square divided by 4.3.
It is very important to allocate the unit emission rate (1.0 gram per second) proportionately among the subdivided areas. For example, if the areas of the subdivided squares in the ISC3 Volume figure results in F1A equal to F1B each with 1/8th the total area, the proportion of the unit emissions allocated to each

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-65 

### of these volum

e sources is 0.125 g

rams per second. The remaining two areas are each 3/8 ths of the total area of fugitive F1, so that 0.375 grams per second is specified for the emission rate from each source. The total emissions for the four volum e sources sum to the unit emission rate for the F1 fugitive source (0.125 + 0.125 + 0.375 + 0.375 = 1.0 g/s).
If y ou tell ISC ST3 to in

clude a ll sourc es in the mod

el resul ts (SO SRCGR

OUP A LL), the mod

el will approp riate ly combine all fou r volume so urce su bdivis ions in to combi ned impac t resu lts fo r fugit ive source F1. You can use the resulting air parameter values in the plot files directly in the risk assessm

ent equations, the sam

e as if the emissions were mode led as a single po int source. The initial vertical dimension is define d the same as F2, using the vertical extent of 5 m eters divided by

4.3 and a release height of 2.5 m

eters (1⁄2 vertical extent). For volum e sources, the location is specified by the x and y coordinates of the center of each square area.
The COntrol parame

ters can follow the recom mendations for setting

up a vapor p

hase computation.

CO CONC WDEP 

### Fugitive em

issions of ash particles are from the storage piles ass ociated with com bustion units. Enter th

e horizontal area of the storage pile into the ISCST3 input file according to the ISCST3 User’s Guide, Volume I (U.S. EPA 19 95f). The height of emissions is the top of the pile. I f you don’t k now the vertical extent, y

ou could use gro

und level (or z ero height). Yo u’ll typically m

odel fugitive ash as area source type. H owever, the perm itting authority m

ight consider volume source ty pe prior to air mo deling. We generally recommend following the m ethods in the I SCST3 User’s Guide w hen defining the in

put parameters to represen

t the ash release as an a

rea source.

We recommend the COntrol param eters follow the recom

mendations for setting

up a particulate phase computation.

CO CONC DDEP WDEP DEPOS 

### We recommend documenting the emissions characterization and source type.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-66 

### 3.10 MODELING ACU TE RISK
It mig ht be important for you to evaluate the acute, or short- term, effects due to the direct inhalation of vapor phase, pa

rticle phase and particle-

bound phase COP Cs in the risk ass essment. We recommend consi derin g site- or un it-spec ific f actor s such a s unit o perat ing cond ition s durin g emissio ns test ing, emission rates to b e used in the acute scree n, exposure scenario loc ations, etc. (see Sections 2.2.1, 4.2, 4.3, and 7.5) prio

r to conducting air modeling fo r an acute evaluation

. Since only am

bient air concentrations are inc luded in the direct inhalation pathway, You can compute the air parameters needed

for a screening ac

ute assessment in the same I SCST3 runs (i.e., sam e input values for meteorological data, stack gas exit temperature a nd velocity, etc.) that compute the air parameters for the long-term chronic effects. However, as with chronic m

odeling, a non- steady state dispersion model (e.g. , CALPUFF) mig

ht prov ide a m ore repr esentati ve est imate of conc entration and d

epositio n. This is because of differences in m ethodology fo

r modeling time-v

arying em

issions and time-

and space-v

arying meteorological fields.

Methods outlined in this section focus on supporting

a screening ty

pe acute assessmen

t using the existing air modeling runs executed for the chro nic risk assessm

ent. However , it is i

mport ant to n ote that while this approach provid

es some obv

ious efficiencies with reg ard to air modeling , you might need to execut e separate air modeling runs . For exam ple, you m

ight consider site-

or unit-specific characteristics (i.e., conditions of m

ost concern for a short term or acute release scenario) in order to provide the most protective or appropriate acute assessment. As discussed in Section 3.1, site- specific conditions and assessment objectives might result in your choosing

a different air mod

el for the acute portion than for the chro nic asse ssmen

t.

In air model ing for a n acute type ass essment , the goal is typic ally to compute t he highe st 1-hour average air conc ent rat ion f

or ea ch ph ase ( part icl e-bou nd, e tc) for e ach s ourc e, fo r the enti re pe rio d of a nal ysis . In most cases, this period is the five y ears of meteorolog

ical data. For I SCST3 to identify the highest one-hour av

erage concentration at each grid node, we recomm end makin

g two specifications in the ISCST3 input files.

### Human Health Risk Assessment Protocol

Chapter 3: Air D ispersion and Depo sition Modeling September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 3-67 

### First, you m

ust specify the 1-

hour average as one of the averaging tim es in the COntrol path

way. The example of this sp ecification is included in Section 3.6.1. The I SCST3 input file includes:

CO AVERTIME 1 ANNUAL 

### where “1" specifies the 1- hour averaging

time I SCST3 computes for each hour of m eteorological data.

Rememb er that the ‘ ANNUAL ’ is specified for the chronic effects.

Second , we re comm

end tha t the OU tput pat hway include the spe cificatio

n of a 1 -hou

r aver age pl ot file which c ontains

the hig hest 1- hour concentra

tion at each rec eptor g

rid nod e for all the hou rs eva luated i n the ISCST3 ru

n. For a single year run, the 1-hour conce ntration reported in the plot file is the highest value comp

uted at each x, y

grid node location

for the total hours in the

year (8760, or 8784 for leap years) . The ac

ute risk assessm ent nee ds the h

ighest 1-hour concentrati on for t he 5-year p eriod. We
recommen

d reviewing each of the five sin gle year v alues to identify the highest for all five years at each receptor grid node. However, if you run a com bined 5-y ear meteorological input file, the resulting plot file will already identify

the highest value for the 5-year period at each grid node with n o additional proce ssing ne eded. T he OUtpu t pathw ay instr uctio ns to cr eate t he plot file f or one-ho ur avera ge concentrations are:

OU PLOTFILE 1 ALL FIRST BTR841.PLT 

### where 1: specifies the 1-h our averaging

period, ALL: instructs ISCS T3 to include all sources in the run, FIR ST: instructs the model to include only the first highest va

lue at each receptor grid node, and BTR8 41.P LT: is the name for the plot file. The plot file name is unique for the run and the one-hour averaging period results.
The highest air concentration for the 1-ho

ur averaging

period is input as the air parameters, Chv , Chp, and Chpb in the a

cute risk asse ssmen

t equati ons (see

Section 7.5 an d Appe ndix B,Table B- 6-1)

.U.S. EPA Region 6 U.S. EPA

Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-1 

# Chapter 4 Exposure Scenario Identification What’s Covered in Chapter 4: 4.1 Characterizing the Exposure Setting 4.2 Recomm

ended Exposure Scen

arios

- Farmer

- Farme

r Child

- Resident

- Residen

t Child

- Fisher

- Fisher C

hild

- Acute Receptor 4.3 Selecting Exposure Scenario Locations

PLEASE NO TE : for the purposes of this guidance, “we” refers to the U.S. E PA OSW. The HHRAP is written

for the benefit of a v

aried audience, including risk assessors, regula tors, ri sk m

anage rs, and comm unity relation s person

nel. H owev er, the “you” to which we speak

in this chapter is the perfo rmer of a risk

assessment: the p erson (or persons) who will actually put the recomm

ended methods into practice. The purpose of this chapter is to provide g uidance on identifying

“exposure scenarios” to evaluate in the risk a ssessm

ent. E valua ting exposure

scenari os will estimate the type a nd ma gnitud e of hum an expo sure to COP C em

issions from hazard

ous waste com

bustors (includ ing fu gitive emi ssions) . In

this do cume

nt, identify ing ex posure scenario s consists of :

• characterizing the exposure setting,

• identifying recom mended exposu

re scenarios, and

• selecting exposure sce nario locations. Characterizing the exposure setting in cludes defining the dimensions of the assessment area (or “study area”). It also

includes identifying

the current and potential human activ ities and land uses within those boundaries. Within the co ntext of the exposure setting , an exposure scenario is a combination of “exposure pathway s” to which a “receptor” may be subjected.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-2 

### For this guidance, we define a receptor a s a human be ing potentially exposed to COPCs emitted to the atmosphere from

a hazardous waste combustion fac ility. An expo sure “route” is the particular m eans of entry into the body. For the pur poses of the HHRAP, recept ors come into contact with COPCs via two primary exp osure routes: either directly —via inhalation; or indirectly—via COP C deposition and subsequent ingest ion of water, soil , vegetation, and animals that have been contaminated by COPCs through the food chain.
An exposure “pathwa y” is the course a chemical t akes from its source to the person being exposed. An exposure pathway

consists of four fundam

ental components: 1. a sourc e and m

echanism of C OPC re lease (s ee Chapter 2); 2. a retention medium, or a transport m echanism and su

bsequent retention m

edium in cases involving media transfer of COPCs (see Chapter 3 for air transport of C OPCs, and Chapte r 5 for b ioaccum

ulation of COP Cs in th

e food c hain); 3. a point of potential hum an contact with the con

taminated m

edium; and 4. an exposure route. Exposure to COPC s can occur via n umerous exposu

re pathways, suc

h as ingestion of diary products and home grow n produ ce (see Section

4.2).

The HHRAP identifies a

number of generic exposure scenarios (F armer, Farm er Child; Fisher, Fisher Child; Resident, and Resident Child). U sed as presented, these standardized scenarios s hould be reprodu cible across m

ost site s and la

nd use areas. We inten

d these scenario s to be appropr iate for a broad range of situa

tions, rather than to represen t actual scenarios. We believ e that the recomm

ended exposure scenarios and as sociated assumptions are reasonable. They

represent a scientifically s ound approach that is protective of human health and the environment, while recognizing the uncertainties associated with evalu

ating real world exp osures. For exam ple, the scenarios are desig ned with a level of protecti venes s intend

ed to ad dress potential r

eceptors not di

rectly evalu ated, such as p opulati ons wit h somewhat hig

her exposures than the general public. At the same time,you can easily alter these scenario s to m

ore clos ely re flect sit

e-sp ecific c onditions. To b e transp arent, w e recom mendwelldocumenting , supporting and discussing any

changes (i.e. d

eletions, additions, or m

odifications) to a recommend ed expo sure sc enari o or sce nario locat ion wit h the ap propr iate p artie s (regul atory age ncy, facility , intere sted com

munit y membe rs).

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-3 

### Selectin g exp osure sc enario l ocation s invo lves i dentify ing the phy sical po sitions of the exposure scenario s within

the stu dy are a. For

exam ple, y ou can position

scenari os base d on cu

rrent or future human activ

ities or land use. Altern

atively, y ou can position scenarios artificially, as part of a screening assessment. You could, for exam ple, locate all selected receptors at the area of gre atest contaminant deposition, to m

aximize poten

tial exposure. The HHR

AP focuses on placem

ent based on actual or potential activities and lan d use.
The following sections d escribe how we recom

mend 1. characterizing the exposure setting, 2. identifying wh

ich of the recomm

ended exposure scenarios are appropriate for the risk assessment, and 3. selecting the exposure scenario locations.

4.1 CHARACTERIZING THE EXPOSURE SETTING
The purpose of characterizin g the exposure se

tting is to identify

the human rec eptors, their land uses an d activities, which m

ight be imp acted by exposure to emissions from the facility being

assessed. The exposure setting m

ight include m

ultiple sources (e.g.,multiple stacks, fugitive em issions), as well as terrain both inside and ou tside the facility bound

ary (or “fenceline”). We believe both currentand reasonable potential

human activ

ities or land uses are relev ant, when determ

ining which recom

mended exposu re scena rios are appropriate for the risk asse ssmen t (see S ection 4 .2).
Experience has shown

us that most sig

nificant deposition occurs w ithin a 10 km

radius, as mea sured from the centr oid of a polygon ce ntere d on the stacks o f the fa cilit y being ass essed . Conseq uentl y, resources for characterizing the exposure setting

might initially

be focused within this area. Also, m ost
recommen

ded exposure scenarios ap propriate for the assessm ent will likely be located within this area. It m ay be prudent , howe

ver, t o also character

ize the expos

ure sett ing be yond the 10 k

m rad ius, to determine if condition s exist which warrant ad ditional exposure scenarios. Such conditions m ight include (but are not lim

ited to) recomm

ended exposure scenarios or special populations (see S ection 4.1.3) not found w

ithin the 10 km

area, or topograp

hic features - su

ch as hills - that tend to increase potential deposition. A

50 km radius is the recog

nized limit of the ISCST3 air dispersion model, and can be used as the outer b oundary for characteriz ing additional exposu

re settings (See Chapter 3 for

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-4 

### information on air modeling b eyond a 50 k m radius). A

ll affected parties (i.e. reg ulators, facilities, interested comm

unity mem

bers) can then discuss if a dditional scenarios need to be assessed, and if so, their locations.
The study area m

ight include land u se and water bodies b oth inside and outside the facility fenceline. It’s imp ortant to understand that some of the recom mended scenarios might m ost appropriately be p laced within facility bounda

ries. For exam

ple, some facilities lo cated on substantial property rent portions of the property to the public for farming , ranching, or recreational purposes (e.g ., fishing).
When characterizing the exposure setting, we highly recommend considering

• current and reasonable pote ntial future land use,

• waterbodies and their assoc iated watersheds, and

• special populations. The following subsection s provide inform ation on these aspects.

4.1.1 Current and Rea sonable Potential Future Lan d Use

Land us e is an i

mport ant fact or in characterizing

the exp osure se

tting. When la

nd use is ove

rlaid wi th the air d ispersion mod

eling results, the com

bination will d

emon strate w

hich rec omm

ended exposure scenarios (and their locations) a re most relevant for the risk assessment. We recom mend considering both cu rrent an d reasonable p otential

future land us e (i.e. “future land us e”), be cause ri sk ass essme nts typica lly ev aluate t he pote ntial risks from fac ilities over long pe riods of time (great

er than 30 ye ars).
One can typically

identify current land use, and indications of future land use, by reviewing h

ard copy and/or electronic version s of Land Use/Land Cover (LUL C) maps, top ographic m aps, and aerial photog raphs. We list s ome s ources below, and g eneral i nformation as sociated

with se veral potenti al data and map resourc es. Also, as noted in Chapter 3, we

recommend verifying

that all mapping

information you use is in the

same Univ

ersal Transverse Mercator (UTM) coordin ate system fo

rmat (NAD27or NAD83), to ensu

re consistency and prevent erroneous geo-referencing of locations and areas.
Land Use/Land C

over (LULC) Maps

- you can down

load LULC m

aps directly from

the United States Geological S urvey (USG S) web site (htt p:/ /mapp ing. usgs .gov/ inde x.ht ml ), at a scale of 1:250, 000, in

the GI RAS fi le form

at. LU LC maps are also av

ailable from the EPA

web si te

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-5 

### ( ftp://ftp.epa.gov/p

ub ), at a scale of 1:250, 000, in an Arc/I nfo export format. Within your study area, we recom

mend verify

ing the exact bou

ndaries of polygons defining land use areas using available topogra

phic maps and aerial photographs. Topographic Maps

- Topogr aphic m aps are readily

avail able in both ha

rd copy and ele ctronic forma t directl y from the US GS or n

umero us othe r vend ors. The se ma

ps are c omm

only a t a scale of 1:24 ,000, an d in TIFF f ile fo rmat wit h a TIFF Wo rld Fil e incl uded fo r georef erenc ing. Aerial Photographs

- You ca n purchase hard

copy aerial p hotog raphs d irectly from the US GS in a variety of sc ales and coverag es. Electronic form at aerial photographs or Digital Ortho Q uarter Quads (DOQQs) are also available for p urchase directly from

the USGS, or from an increasing number of com

mercial sources. Properl y ge oreferen

ced DO QQs covering

a 3- km or mo

re radiu s of the

assessm ent area , com

bined w ith overlays of the

LULC m ap coverage and the ISC ST3 modeled receptor grid node array , provide an excellen t referen ce for id entify ing la nd use areas an

d justify ing y our cho ices of exposu

re scena rio locations. The inform

ation above does not represent the universe of data available on human activ ities or land use. They are, however, readily available fo r little or no cost from

a number of governm

ent
sources , often

via the In

ternet.
If feasible, we recomm

end verifying

the accuracy of la

nd use information

with a site visit. Also, organizations ex

ist that routinely collect a nd evaluate land u se data (agricultural exten sion agencies, U.S. Departm

ent of Agriculture, natural resource and park agencies, and lo cal governm ents). You m

ay find discussions with these organizations he lpful in updating cu rrent land use inform

ation or providing information reg arding future land u se. Local planning and zoning

authorities are also potential so urces of information on reasonable potential future land use. These authorities hav e information on the level of developmen

t allowed under current re gulations, and w hat developm

ent may b e expected in the future. The gen eral p ublic is anot her exc ellen t sourc e of inf ormatio n about land us e in the area. Co nduct ing a public w orksh op early in the d ata ga thering proces s for the risk

assessm ent can provi de val

uable information on land

use, crops, special p opulations, etc. as we ll as starting a positiv e dialogue with the
comm unity. For ex ample , by c omm unicatin g with local tr ibes you mi ght fi

nd that certain location s hold special significance for cu ltural or religious activ

ities.

You can also use site- specific data on phy siographic features (e.g ., plant types, soil characteristics, land use, etc.) to verify

the land uses identified u sing the resources listed above. Yo

u can readily determ

ine the pres ence, t

ype, and ext

ent of physio graph

ic featu res from the fol lowing

source s:

• USGS topog

raphic maps,

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-6 

### • Soil Conservation Service reports,

• county and local land use maps, and

• information from state departments o f natural resources or sim ilar agencies. A study area m

ight include m

ultiple land uses, with d

iffering current or poten

tial human activ

ity/land use characteristics. Your activ ity/land use analy sis could identify m ultiple population centers (e.g ., comm unities, residen

tial dev elopments, or rural r

esidenc es), far

ms an d ranches, or other lan

d use ty pes in the study area that would support recom mended exposu

re scenarios. For exam

ple, if a study are a include s a farm

and a small r

esident ial com munit y, y ou coul d consi der both

areas a s possib le expo sure scenario locations (see Section s 4.2 a nd 4.3 ).
Once you’ve identified current land uses,we generally recommend also identifying areas with different
reasona ble pote ntial future

land use characteristics. F or example, if a study area includes

undeveloped property which co

uld be converted to a residential com munity in the future, you m ight consider both of these land use type s (i.e. undevelop ed property, and residential comm unity) in the risk

assessment (see Sections 4.2 and 4. 3). We recom mend considering

only potential future land uses which m ight reasonably be expe cted to occur. For example: 1. A rural area currently characterized as undev eloped open fields, cou

ld reasonably be expecte d to bec ome f

armla nd if it is able to supp ort ag ricultur al activ ities; 2. A rural

area cu rrently charact erized by op en field s and in

termit tent housing, could reasonably be expe cted to become a residential subdivision; and 3. An area currently c haracterized as a tidal swamp would not reasonably b e expected to become farm

land. For transparency an

d clarity, we recommend describing any current or reasonably

expected future land use in the risk asses sment report. O f all the land use areas y ou identify, we generally recom mend focusing on those areas that could be im pacted by the C OPC emission s you’re evalu ating in the risk
assessm ent.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-7 

### C Iden

tification and/or map

ping o f current

land uses in the area, a description of the use,the area of the land

describ ed by

the use , and t

he sour ce of the inform

ation. You m

ight choose t

o focus initially on those

land use areas im

pacted by em

issions of COPCs.

C 

### Iden

tification and/or map

ping o f the rea sonable

potenti al future

land use areas, a de scription of the u se, the

source or rationale on

which the desc

ription is based . You

mig ht choo se to focus initially on those

land use areas im

pacted by em

issions of COPCs. RECOMMENDED INFORMATI ON FOR RISK ASSESSMENT REP ORT

4.1.2 Water Bodies and Their Associated Watersheds

Surface water bodies and their associated watersheds are important factors in evaluating some of the
recommen

ded exposure scenarios. Specifically, water bodies can be im portant sources of fish for the fish ingestion pathwa

y, or sources of water for the drinkin g water pathway

(see Section 4.2). Your careful consideration is warrante d when identifying which water bodies in the study area to assess. For the Fisher scenario, an appropriate water body (and/or its associated watershed) would receive deposition from the em

ission source, and be able to sustain a fish pop ulation harvested by

humans. F or the drinking water ingesti on path way, an ap propr iate wa terbo dy (and/ or its associ ated wa tersh ed) wou ld rec eive deposition from the

emission source, and be used as a direct drinking water source (i.e. not processed by a drinking water treatment facility ). We recomm

end considering both current and potential hu man uses of water bodies found within the study a rea. In ad

dition to identifying

the human u ses of water bodies,
we recomm

end defining the su

rface areas and exact location s of the water bodies, and their associated watersheds. S ee Sect

ion 4.3 for a fu

rther di scussion of sel ecting exposu re scena rio loca tions an d their associated water bodies.
You can typically

identify the use, area, and location of water bodies and their associate d watersheds by reviewing the same hard copy and /or electronic versions of LULC m aps, topographic maps, and aeria l photographs used to identify land uses. We present sources and general inform ation associated with each of these data types or maps in Se ction 4.1.1.
You mig ht also get inform

ation on water body

use from local authorities (e.g., sta te environme

ntal agencies, fish and wildlife agencies, or local water control districts). This might includ e information about viability to

support fish populations and drinking water sources. Surface water bodies that are used

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-8 

### As drin king water s ources in the a ssessm ent area are g enerally

evalu ated in the risk

assessm ent. Wh ile water bodies closest to the facility will gen

erally have hig

her deposition rates, risk

estimates are also affected by other ph

ysical paramete

rs (e.g. the size of the water body and the associated wa

tershed) and by the properties of the COPCs being emitted.

Once you ’ve sele cted a wa ter b ody , we

recomm end i dent ifyi ng t he ar ea ex tent (def ined by UTM coordinates) of its watershed. Watershed runoff can be a significant contributor to overall water bod y COPC loading s. Media concentration e quations use the extent o f pervious and im pervious areas in the watershed, as well as COPC concentrations in watershed soil, to calc ulate the water body

COPC concentrations (see Chapter 5 and Appendix B ). We therefore recom mend clearly identifying and discussing the area extent of the watershed w ith the interested parties (both p ermitting authority and facility).
You g enerally

define the area

extent of a wa

tershed by id entify ing to pogra phic hig hs that result in downsl ope dra

inage into the water

body . We rec omm

end ens uring that the

watershed and

it’s contribution to the water b ody are defined relativ e to the exposure scenario location associated with the water body (e.g . location on the wa ter body of the d

rinking water intake, fishing pier, etc.), and subse quent risk est imates. Please keep in mind that th e tota l water shed ar ea can b e very ext ensive relative to the area that is impacted from facility emission s.

For exa mple, if facil ity em

issions princip ally im

pact an area of land w hich dra ins into a speci fic tribu

tary of a large river system and immediate ly upstream of a private drink ing water intak

e point, you m

ay wish to cons ider e valuat ing an “e ffect ive” wat ershe d area r ather than th e enti re wate rshed area of the lar ge river system . For such a large river system, the watershed area ca n be on the order of thousands of squar e kilomet ers and can inc lude nu merous t ribut aries draini ng into t he river at poin ts tha t would have no net i mpac t on the

drink ing w ater inta

ke or on the w

ater bod y CO PC concentrati on at the expos ure point o f intere st.

To use the HHRA

P as rec omm

ended, you w

ill need the fol lowing

water b ody a

nd wate rshed p arame

ters (on an a verag e annua

l basis) :

• Water body surface area

• Watershed surface area

• Imperv

ious watershed area

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-9 

### • Identification and/or mapping of water bodies and as sociated watersheds potentially impacted by facility em

issions of COPCs, including surface area of the water body and area extent of the contributing watershed, defined by UTM coordinates

• Rationale for selecting or excluding water bodies within the assessm ent area from ev

aluation

• Informa

tion on water body

use that may

justify including or excluding the wate r body from evaluation

• Documentation o f water body area,watershed area, im pervious area, v

olumetric flow rate, current velocity, depth of water colum n, total suspended solids

(TSS), and the USLE rainfall/erosivity factor

• Description of assum ptions made to limit the watershed area to an “effective” area

• Copies of all m

aps, photographs,or figures used to define water body

and watershed characteristics RECOMMENDED INFORMATI ON FOR THE RISK ASSESSMENT REP ORT • Avera

ge wa ter body volum etric flow rate

• Water bo dy cu

rrent velocity

• Dept h of w ate r col umn

• Total suspended solids (TSS)

• Universal Soil Los s Equation (USLE) rainfall/erosivity factor

The im pervio us wate rshed a rea is g enerally

a funct ion of u rbaniz ation within the watershed, a nd is typically presented

as a percentage o f the total watershed area. Volumetric flow rate a nd water body current velocity are typically ann ual average v

alues. State or local geologic surveys often keep records on flow rate and curren

t velocity of larger water bodies. Yo u can calculate the v

olumetric flow rates for smaller stream s or lakes by multiplying

the watershed area by

one-half of the local averag e annual surface runoff. Lack

ing si te-sp ecific d

ata, y ou can calculat

e curren t velo cities by div

iding the vo lumet

ric flow rate by the cross-sectional area ( NOTE : current velocities are n ot used in the equations for lakes). State or local sources som etimes have information on the depths of water bodies available. Discussio ns on determining the USLE rainf all/erosi vity factor are inclu ded in Chapter 5 and Appen dix B.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-10 

### 4.1.3 Special Population Cha racteristics
Special popula tions ar e hum an receptors or segm

ents of the pop

ulation that m ay be at hig

her risk due to increase d sensit

ivity and/or increase d expos

ure to C OPCs. Fetuse s, infan ts and children , and t

he elde rly are examples of h

uman life stages (i.e. populations) w hich might be more sensitiv e to COPC expo sure. You mig ht consider some tribal groups a special population because their ing estion of fish at rates hig

her than the gener al publi c increa ses thei

r expos ure to chemic als that

bioacc umula te. Su bsistence resid

ents are also likely to have higher expo sures fr om in gestion of m

eat (loc ally harvest

ed gam e), pro duce (w

ild berries and oni ons, for exam ple), an d soil. There m

ay be special location s where cultura l activ ities are conducted, or that are s acred to the tribes, and we encourage ev aluating exposures at these locations.
We’ve developed

the assumptions specified in this guidan ce – such as the protective nature of the
recom mend ed expo sure sce

narios ( see Section 4. 2), and the use of RfD s which

have been de

velop ed to account for toxicity t

o sensit ive re ceptors

– to als o protect the he alth of special populat ions. Howev er, you may also need to specifically

address populations that are located in impa cted areas because of unique characteristics of the ex posure setting or to address particular com munity con

cerns. For exam

ple, a day care center o

r hospital may

be located in an area that is directly im pacted by the facility

stack emissions. Re ceptors at these locations m ay be especially

sensitive to the adv

erse effects and/or the exposu re settin g is p articula

rly conducive to exp osure. Conseq uently , due t

o site- specific

exposu re characteristics, exposure to ch ildren at the day ca

re center, or to the sick

in the hospital, m

ight need to be specifically evaluated . Section 4.2 provides additional discuss ion on evaluating potential exposure of special populations, as pa rt of evaluating recommen ded exposure scenarios. Additionally, the Agency has a st ated po licy fo cused on consi stently and ex plicitly evalu ating enviro

nmen tal heal th risks to inf

ants and chi ldren in

all risk assessm ents (U .S. EPA 1995

j).

Concer ns abou t specia l popul ations c an arise

at any time in the p ermitt

ing pr ocess. We there fore
recommen

d identifying s

pecial populations as part o f characterizing the exposure setting. You can identify special populations in the assessm ent area based on the location of schools, hosp itals, nursing homes, day

care centers, parks,commu nity activity

centers, etc. I f available inform ation indicates that there are chi ldren exhibi ting pic a behavi or (def ined fo r risk as sessmen t purpo ses as “ an abno rmally hi gh soil ingestion rate”) in the assessment area, these children could also represent a special population (see Section 6.2.3 .1).

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-11 

### C Identification and/or mapping of the locations of special p opulations at potentially higher risk from exposu

re to fac ility s ources (anticip ated to be loca ted in a reas im pacted by fac ility emissions); focusing

on the characteristics of the exposure setting to e nsure that selected exposure scenario locations are protective of the s pecial populations. RECOMMENDED INFORMATI ON FOR THE RISK ASSESSMENT REP ORT

4.2 RECOMME NDEDEXPOSU RE SC ENAR

IOS

We recom

mend evalu ating the foll owing

exposu re scena rios when they

are con sistent with sit

e-sp ecific exposu re settin gs (al so see Ta

ble 4- 1):

C 

### Farmer

C 

### Farme

r Child

C 

### Resident

C 

### Residen

t Child

C 

### Fisher

C 

### Fisher C

hild

C 

### Acute Receptor

C 

### Nursing I

nfant (Covered as exposure pathway under adult exposure s cenarios)

These are the same exposure scenarios recom mended by

earlier OSW guidan

ce, with the exception of the Farmer Child, Fisher Child, and acu te receptor. The Farm

er Child scenario was in

troduced into the indirect screeni ng pro cess in the risk

assessm ent com pleted t o support the proposed

Haza rdous Wa ste Combustion R

ule and by NC

DEHNR (1997 ). We include the Fishe r Child scenario in order to be consistent with

the adu lt/child pairing s we rec omm

end for the Re sident a

nd Farm er scena rios. W e include the acute receptor sc enario to ensure that the a ssessment evaluates all receptors that m ay be significantly expo sed to emissions from facility so urces.

In a ddition to the r ecom mend ed expo sure sce

narios l isted ab ove, we recommend evaluating , where appropriate, special population s (as defined in Section 4.1.3) and com munities of concern . Do this by identifying their lo cations, and determ ining whether they

are located in areas with exposure setting characteristics that are particularly conducive to C OPC impacts from facility em issions. Exam

ples of additional exposure scenarios include hunters, trespassers, workers (see below ), recreational fishers, etc.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-12 

### You could evalu

ate some populatio

ns using a com

bination of a recom

mended exposu

re scenario expected to overestimate exposure compare d to the populations, a nd maxim

um mo deled air parameter v alues specific to the l ocation

(see Se ction 4. 3). I f this in itial ev aluation sugg ests tha

t the rec eptors a

re protected, then no additional assessment is n ecessary. I f, on the other hand,this evaluation estim ates levels of risk which are of c oncern, a refine d eval uation m ay be needed. The refi

ned exp osure sc enario would evaluate the

specific exposure pathwa ys appropriate to the special population.
Take, for exam

ple, a children’s school o r day care center loc ated in an area receiv ing deposition of facility emissions. You could ev aluate potential exposure of children at this location using the Resident Child scenario at the location of the school or day care center. I

n most cases, evaluating this s cenario at the school location will ov er-estimate exposure. This is because the Resident Child scen ario includes an exposure pathway

(ingestion of hom

egrown produce) which is most likely not occu rring at that location. Also, the residential scenario assumes that a child breaths the air 24 h ours/day, ing ests 100 mg

of soil/day ; and is

expose d for 6 years - when the child is p robably only at day

care 5 days/w

eek an d up to 10 hours/day. If this ge

nerates risk estim

ates of concern, y

ou could conduct a m

ore refined evaluation that adjusts the exposure assum ptions to be mo

re representative of the site.
We don't routinely

recommend assessing wo rkers at a facility that burns hazardous waste in the risk assessment, becau se we assume that those workers are protected by reg ulation and guidanc e of the U.S. Occupa tional S afety and He alth Ad ministration (OSHA

). There are, ho wever , som

e instan ces whe re workers impacted by exposure to facility emissions ar e not covered by the appropri ate OSHA regulations. For example, work ers located at a nearby

but separate facility or commercial area, whose duties are inde pendent of combustor ope rations, are not necessarily covered by the ap propriate OSHA regula tions. Also, on a sit

e with m ultiple on-s ite activ

ities (e. g., m

anufact uring,hazar

dous w aste combustion, and

military opera

tions) the OSHA reg

ulations would address the worker at the
manufacturin

g ope rations with res

pect to those o

peration s and not the e

missi ons from

the sep arate hazardous waste combustion operations . Considering such instances in the risk assessment m

ay be appropriate.
We no longer refer to our recomm ended farmer and

fisher exposure scenarios a s “subsistence” scenarios. The asso ciated d

aily c onsum

ption am ounts (s ee Table 4-2, as well as App endix C ) are m

ore com parable to reasonable (versus subsistence) amoun ts.

### Human Health Risk Assessment Protocol Chapter 4: Exposure Scenario Identification May 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 4-13 

### As mentioned above, an exposure scen ario is defined as a combination of exposure pathways to which a receptor is subjected at a particular location. Table 4-1 presents the exposure pathways we recommend evaluating for each of the exposure scenarios. Food-related ingestion pathways could represent significant potential exposure to COPCs rel eased from combustion sources (U.S. EPA 1994l; 1994g; 1998c; NC DEHNR 1997), due primarily to the potential for COPCs to bioaccumulate up the food chain.

TABLE 4-1 RECOMMENDED EXPOSURE SCENARIOS FOR A HUMAN HEALTH RISK ASSESSMENT

Exposure Pathways Recommended Exposure Scenarios aFarmerFarmer ChildResidentResident ChildFisherFisher ChildAcute Receptorb

Inhalation of Vapors and Particulates • • • • • • • Incidental Ingestion of Soil • • • • • • -- Ingestion of Drinking Water from Surface Water Sources • • • • • • -- Ingestion of Homegrown Produce • • • • • • -- Ingestion of Homegrown Beef • • -- -- -- -- -- Ingestion of Milk from Homegrown Cows • • -- -- -- -- -- Ingestion of Homegrown Chicken • • d d d d -- Ingestion of Eggs from Homegrown Chickens • • d d d d -- Ingestion of Homegrown Pork • • -- -- -- -- -- Ingestion of Fish d d d d • • -- Ingestion of Breast Milk c -- c -- c -- -- Notes: • Pathway is included in exposure scenario. -- Pathway is not included in exposure scenario.

a Exposure scenarios are defined as a combination of exposur e pathways evaluated for a receptor at a specific location.

b The acute receptor scenario evaluates short-term 1-hour maximum COPC air c oncentrations (see Chapter 3) at any land use area that would support the other recommended expos ure scenarios, as well as commercial and industrial land use areas (excluding workers at the facility be ing directly evaluated in the risk assessment).

c Infant exposure to PCDDs, PCDFs, and di oxin-like PCBs via the ingestion of thei r mother’s breast milk is evaluated as an additional exposure pathway, separately from the r ecommended exposure scenarios id entified in this table (see Chapter 2).

d Site-specific exposure setting characteristics (e.g., presence of ponds on farm s, or presence of ponds or small livestock within semi-rural residential areas) may warrant the permitting authority consider adding this exposure pathway to the scenario (see Section 4.2).

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-14 

### As indicated in Table 4- 1, some expo sure setting characteristics m ay warrant y

ou consider including additional exposure pathways when ev aluating a particular exp osure scenario. For example, the
recommen

ded Farmer exp osure scenario doesn’t ty pically include the fish ingestion exposure p athway. However, in s ome areas of the country it’s com mon for farms to have stock ponds that are fished o

n a regular basis for the fa

rm family ’s consumption. Since the ingestion rates we recom

mend for those food pathways already

considered in the ev

aluation are not significa

nt enough to pre clude the Farmer also ingest ing the fish c aught

from the loc al pond , the fi sh ing estion exposure pathwa y may als o be rel evant

in such lo cations . You

could u se the s ame r

ationale for resi dential scenario s where residen ts are lo cated in semi-rural areas which allow sm all livestock (e.g ., free range po ultry for egg s), and/or residents located by sm all ponds suitab le for fi shing , or we tlands t hat sup port cra wfish harvest

.
We also r ecom mend evalu ating infant exposure

to PCD Ds and PCDFs

via the inge stion of

their m other’s breast milk a s an additional exposure pathway at all recom mended adult ex

posure scenario locations. Chapte r 2 and Ap pendi x C furt her des cribe the inge stion of brea st milk exp osure pathwa y.
In addition, although som e risk assessm

ents conducted by

U.S. EPA (1 996b) have discou nted the direct inhalati on risk

s to all receptors except the ad ult Res ident (n

onfarm er) and Residen

t Child (nonfa rmer) , we generally recommen

d evaluating the direct inhalation exposure pathway for all receptors.

We don’t typic ally re comm

end evaluating

the fol lowing

exposu re pathways as

part of an exp osure scenario : Ingestion of Ground

Water - U.S. EPA (1998c) found that ground water is an insignificant exposu re pat hway for combusti on emiss ions; in addi tion, U.S. EPA (1 994k) not ed that uptake from groun

d water into food crops

and livestock

is minim al because of the hy

drophobic nature of dioxin-like compounds. We anticipate potential exposure to COPCs throug h ingestion of drinking wate

r from surface water bodies to be m uch more sig

nificant. Ingestion of ground w ater is further discussed in Section 6.2.4.2. Inhalation of Resuspended Dust - U.S. EPA (19 90e) found that risk estimates from

inhalation of resuspended dust was insignificant. We anticipa te exposure through

direct inhalation of vapor and particle phase COP Cs and incidental ing estion of soil to be m uch more sig

nificant. Inhalation of res

uspended dust is further d iscussed in Section 6.2. 3.3. Dermal Ex

posure to Sur face Wat er, Soi l, or A ir - Available data indicate that the co ntribution of dermal exposu

re to soils to overall risk is typically small (U.S. EPA 1996g ; 1995h). For example, the risk

assessment cond

ucted for the Waste Technologies Industries, I nc., hazardous waste in cinerator in East Live

rpool, Ohio, indicate d that—f or an ad ult farm er in a s ubarea with high exposures—the risk resulting from

soil ingestion and dermal contact wa s 50-fold less than

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-15 

### the risk from

any other expos

ure pathway and

300-fold less than the total estimated risk (U.S. EPA 1996g; 1995h). Also, the re are significant uncertain ties associated with estim ating potential COPC exposure v

ia the dermal exp osure pathway. The most sign ificant of these uncertainties are associated with determ ining the im

pact of soil characteristics and the extent of exposure (e. g., the am ount of soil on the sk in and t he leng th of ex posure)on esti

matin g com pound- specific absorption fractions (ABS). We don’t generally

recommend evaluating

the dermal expo sure to soil pathway as part of the recommen

ded exposure scenarios. However, if either a facility or a permitting auth ority feel that site-specific con

ditions indicate derma

l exposure to soil m

ay contribute sig

nificantly to total soil-related exposu

res, we recomm

end following the relevant metho ds described in U.S. EPA NCEA docum

ent, Methodology for Assessing H ealth Risks Associated with Multiple Pathways of Exposure to Combu

stor Emissions(U.S. EPA 1 998c). Derm al expo sure is further discuss ed in Section 6.2.3.2 of this guidance. Inhalation of COPCs

and In gestion of Water

by Ani mals - We don’t re commend these animal exposu re pathways in

calcula ting a nimal tissue concent

ration b ecause we exp ect thei r contributions to total risk to be negligible compared to the contributions of the recommended animal exposure p athways. Ho wever, yo u might n eed to evaluate these

exposure pathway s on a case-by- case basis considering site-specific exposu re setting characteristics.
Our recomm

ended exposure scenarios are further discussed in the following subsections.

4.2.1 Farmer
The Farmer exposure scenario is made up of the exposure pa thways throug

h which an adult m

ember of a farming or ra

nching fam

ily could be expo sed. We recomm end including this s cenario when farm ing or ranching takes place, or may reasonably take place some time in the futur e, in the study area. As indicated in Table 4- 1, we recom mend assum

ing the Farm

er is exposed to CO PCs emitted from the facility through the following expos ure pathways:

• Direct inhalation of vapors and particles

• Inci dental i

ngesti on of so il

• Ingestion of drinking w ater from surface water sources

• Ingestion of homegro wn produce (i.e. fruits and vegetables )

• Ingestion of homegro wn beef

• Ingestion of milk from homegrown cows

• Ingestion of homegro wn chicken

• Ingestion of eggs from homegrow

n chickens

• Ing estion o f homegrow n pork

• Ingestion of breast milk (evaluated separately , for an infant of the Farmer; see Cha pter 2)

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-16 

### While on the farm property, the Farm er inhales air containing

COPC- impacted va

pors and suspended particles. Through daily

activities, the Farm

er ingests incidental am

ounts of soil. I f site characterization sugg ests tha

t imp acted su

rface w aterbod

ies are used as d

irect dr inking water s ources (see Se ction 4. 1.2), the farm fam

ily receives its water from a surface waterbody. The farm family raises and consumes beef and milk cattle, pigs, and free-range chickens (including eggs). Cattle ingest soil wh ile foraging on

a grazing fi eld, as

well as being fed sila ge and grain grow n on th e farm . Pig s are contained within a yar d or small field, w

here they are assum

ed not to forage, but ingest soil w hile being fed a combination of silage and gra

in grown on the farm. Free- range chickens

are contained within a yard or field, where they ingest soil wh ile bein g fed grain grown

on the farm. The Far

mer g rows en ough fruits an

d veg etables to supply the fam

ily with produce.

The scenario assumes that a portion of the Farm er’s diet comes from

each homeg

rown food type listed above (see Table 6- 1 and Appendix C for consumption

rates). All of these p ortions are impacted by emissions from

the facility being

assessed. The recom

mended consum

ption rates don’t represent the Farme r’s enti re in take of ea ch fo od typ e, bu t rat her o nly t he ho megro wn po rti on of the F armer ’s di et. It is therefore reasonable to assu me that 100% of this subset of each food type (i.e. the homegrown portion) is conta minat ed. Al so, bec ause the

portion s repres ent only

the hom egrow n portion of the

Farmer diet, assuming in

gestion of all m

eat groups by

the Farmer do es not grossly overestimate the total amount o f meat a farm

er or rancher could reason ably consum

e. Breaking

out consumption by food ty pe is an important step in e stimating the relative contributions to C OPC-specific risk from ingestion of each food type.
Previous Ag ency guidan

ce (for example, U.S. EPA 19 93f and U.S. E PA 1994f) didn’t includ

e the ingest ion of c hicken a nd eggs exp osure pathwa ys. NC DEHNR (1 997) co nside rs chi cken and egg ingest ion path ways only f

or expo sure to dioxins

and fur ans, be cause b iotransf

er factors were

only available for dioxins a

nd furans when that g

uidance was published. U.S. EPA (1998c) includes ing estion of both poultry an

d eggs. C urrently, biotransfer factors can be derived from literature data for other organi c compoun ds and met als. T heref ore, we general ly recommen d inclu ding the chicken and egg ingestion exposure p athways for all C OPCs with available biotransfer factors. Fu rther discussion of these exposure pathways, including num eric equations, param

eters values, and C OPC-specific inputs, can be found in Chapter 5 and Appendices A , B, and C.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-17 

### When evaluating the in gestion of drinking water fr om surface water for th e Farmer scenario, we generally recom

mend also cons idering the potential for ingestion of cistern water at farm or ranch locations, in addition to s urface water sources. If site-specific inform ation (e.g. interv

iews with local health departments) s

uggests that ciste

rn water is likely

used, or could be used for a drinking water source, you c ould ev

aluate i ngesti on of ci stern w ater in a manner sim

ilar to t hat used to ev aluate ingestion of water from a surface wa ter body (see Chapter 5 and Appendix B). Site- specific information (e.g. do cist

erns in the stud

y area tend to be cov ered or uncovered?) c an educ ate deci sion m akers as to appropriate equations and p arameter values to use in assessing

the ingestion of d

rinking water from cisterns.
We don’t usually recom

mend the ingestion of fish exposure pa thway for the Fa

rmer exposure scen

ario. However, as indicated in the notes to Table 4-1, we do recomm end that you con sider evaluating the fish ingestion pathway

if regional or site- specific exposure setting characteristics (e.g., p resence of ponds on farms or ranches that support fish for hum an consumption) are identified that warrant con sideration. You
can use the app licable estimating media concen tration equations for i

ngesti on of fi sh as pr

esented in Chapter 5 and App endix B. Also, evaluating the Fisher and Fisher Child exposure scenarios (see Sections 4.2.5 and 4.2.6) at farm or ranch locations m ay be appropriate w

here on-site po

nds are used as sources of fish for hum

an consumption.

We recommend evaluating the exposure of an infant to PCDDs, P CDFs, and dioxin-like PC Bs via the ingestion of breast m

ilk as an additional exposure pathway , separately from this exposure scenario (see Chapte r 2).

If si te-sp ecific informa

tion is a vailab le indic ating that far mers in the s tudy a

rea don ’t raise a type

of livest ock, nor is r

aising that ty pe of li vestoc k lik ely to occur i n the fu ture, then you could

reasonably consi der el iminati ng the re lated exposu re pat hway (or pathwa ys, in the case of chicken and egg ingestion). However, if one m eat source is not used, its place in the diet is often taken by one or more of the remaining

exposure pathway s. Take care, therefore, to consider the intak e rates of the rem

aining exposu re pathways, to ensu

re that t he total amou nt consumed

(sum med f raction from each fo od gro up) is representative. See Chapter 6 (Quantify ing Exposure) for further discussion of the im plications of modifying

our recomm

ended exposure pathways.

### Human Health Risk Assessment Protocol

Chapter 4: Ex

posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-18 

### 4.2.2 Farmer C hild

The Farmer Child exposure scenario is m ade up of the exposu

re pathways throug

h which a child m

ember of a farming

or ranching fam

ily may reasonably be ex

pected to be exposed. Agency policy recom

mends consistently and exp licitly evaluating environme

ntal health risks to infa

nts and children in all risk
assessm ents (U .S. EPA 1995

j). As in dicated in Table 4-1 , the sc enario a ssume s the Fa rmer C hild is exposed to COPC s emitted from the facility throug

h the same exp osure pathways as the Farmer. The prima ry dif ference s betwe en the F armer and Fa rmer C hild are in expo sure du

ration ( 6 years for the child vs . 40 y ears for the adult), and c onsumption rates (e .g. 1.4 hom egrown produce servings per week for child v s. 2.8 home grown

produc e servings p er week for adu lt, see Table 6- 1).

4.2.3 Resident
The Resident exposure scena rio is made up of the exposure pathwa ys through which an adult receptor may be exposed in an urban or nonfarm rural s etting. We recom mend including

the adult Resident scenario , becau se poten

tial exp osure to

COPC s throug

h inge sting home grown

produc e has be en show

n to be pote ntially signi ficant. This ex

posure scenario

equate s with t

he “Ho me G ardener

” scena rio
recom mend ed by U.S. EPA (1 994g)and NC DEHN R (199 7). As

indicat ed in Tab le 4- 1, the scenario assumes the adult Resident is exposed to COPCs from the emission sou

rce through the follow

ing exposure pathway s:

• Direct inhalation of vapors and particles

• Inci dental i

ngesti on of so il

• Ingestion of drinking w ater from surface water sources

• Ingestion of homegro wn produce

• Ingestion of breast milk (evaluated separately , for an infant of the Resident; see Chapter 2) While on their property, the Resident inhales air containing COPC -impacted vapors and susp ended particle s. Throu

gh da ily activitie s, the R

esident ingests incid

ental am ounts o f soil. If s ite characterization suggests that imp acted surface waterbodies are used as direct drink

ing water sources (see Section 4.1. 2), the resident family receives its water f rom a surface waterbod y. The Resident grows fruits an d veg etables for hom

e consu mption (NC D EHNR 1997). Break ing ou t consu mption by exposure pathway is an im

portant step in estim

ating the relative contributions to COPC -specific risk from

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-19 

### ingestion of each fo od type. Fu rther discussion of these exp osure pathways, including equations, parameter valu

es, and COPC- specific inputs, can be fo und in Chapter 5 an

d Appendices A, B, and C.
We don’t usually recom

mend eva luating the ing estion of fish exposure pa thway for the R

esident exposure scenario. H owever, as indica ted in the notes to Table 4- 1, we do recom mend that y

ou consider evaluating the fish

ingestion pat

hway if expo sure set

ting character

istics (e .g., presence of ponds wit hin semi-rural residential areas that support fish for human cons umption) are identified

that warrant consideration. I

t may be appropriate to evaluate the Fisher and Fisher C hild exposure scenarios (see Sections 4.2.5 and 4.2.6) at residential locations where ponds or su

rface water bodies are used as a potential source of fish for h uman consum

ption.

We recommend evaluating exposure of an infant to PCDDs, PC DFs, and dioxin- like PCBs v ia the ingestion of breast m

ilk as an additional exposure pathway , separately from this exposure scenario (see Chapte r 2).

4.2.4 Reside nt Chil d

The Resi dent Ch

ild expo sure sce

nario is made up of t he expo sure pa

thway s throug

h which a child receptor may

be exposed in an u

rban or nonfarm rural setting. This expo sure scenario equates with the “Child of the Hom

e Gardener” scenario recom mended by

U.S. EPA (1 994g) and NC DEHNR (1997 ). Agency po licy re comm

ends consisten

tly and explic itly ev

aluating envir onme ntal hea lth risk s to inf ants and children in all risk

assessments (U. S. EPA 1995j). A s indicated in Table 4- 1, the scenario assum es the Resident Child is ex

posed to COPCs emitted from the facility throug

h the same exp osure pathways as the Res ident ad

ult. The primary di fference s betwe en the R esident and Re sident C

hild are in expo sure duration (6 years fo r the child vs . 30 years for the adult), and consumptio n rates (e.g. 1.2 homegrown produce serving s per week for the child vs. 2. 3 homeg rown produce serv

ings per week

for the adult, see Table 6- 1).

4.2.5 Fisher
The Fisher exposure scenario is made up of the exposure pathways through which an adult receptor m ay be exposed in an urb an or nonfarm rural setting where fish is the main so

urce of protein in the receptor diet. We recomm

end including the Fisher scenario, because food-related ingestion routes may represent

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-20 

### signif icant potent ial ex posur e to COPCs relea sed fr om combusti on sour ces (U. S. EPA 199 4l; 199 4g; 1998c; NC DEHNR 1 997). The pote ntial ex posure is due primar

ily tothe pot

ential fo r COPC s to bioaccu mulat e up the food ch ain. B reakin

g out consum

ption by exp osure p athway is an im portant step in estimating the relat ive contributio ns to COPC-specific risk from ingesti on of each food type. As indicate d in Tabl e 4- 1, the scenario assum es the F isher is

expose d to CO PCs em

itted from the

facility through the followin

g exposure pathways:

• Direct inhalation of vapors and particles

• Inci dental i

ngesti on of so il

• Ingestion of drinking w ater from surface water sources

• Ingestion of homegro wn produce

• Ingestion of fish

• Ingestion of breast milk (evaluated separately , for an infant of the Fisher; see Chapter 2)

While on their property

(i.e. w here the y resi de), the Fishe

r inhale s air containin

g CO PC- impacted va

pors and sus pended particle s. Throu

gh da ily activitie s, the F isher in gests inciden

tal am ounts o f soil. If s ite characterization suggests that imp acted surface waterbodies are used as direct drink

ing water sources (see Section 4.1. 2), the fisher fa mily receives its water fr om a surface waterbody. The Fis her grows fruits and vege

tables for home c onsumption (NC DEHNR 1997 ). The Fisher harvests enough fish from waterbodies in the study

area impacted by

facility emission s to supply the fa mily with a significant portion of their protein. Further discussion of these exposure pathway s, including num eric equations, parameters values, and COPC spe cific inputs , can be found in Chapter 5 and Appendices A, B, and C.

We recommend evaluating the exposure of an infant to PCDDs, P CDFs, and dioxin-like PC Bs via the ingestion of breast m

ilk as an additional exposure pathway , separately from this exposure scenario (see Chapte r 2).

4.2.6 Fisher C hild
The Fisher Child exposure scenario is made up of the exposure pa thways throug

h which a child recepto

r may be exposed in an urban or nonfarm rural s etting where fish is the main source of protein in the receptor diet. Eva

luating this exposure scenario is the sam e as the adult/child pairing s recomm ended for the Farm er and R esident scenari os. I

n additi on, Agency p olicy recom mend s consistently

and ex plicitly

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-21 

### evaluating env

ironmental health risk

s to infants and children in all risk assessm ents (U.S. EPA 1995j). As indicated in Table 4- 1, the scenario assum es the Fisher Child is exposed to COPCs emitted from

the facility through the same exposure pathways as the

Fisher. The prim

ary differences between

the Fisher and Fisher Child are in

exposure duration (6 y

ears for child vs. 30 years for the a dult), and consum

ption rates (e.g. 1.2 homegrown p roduce servings per week f or the c hild vs. 2.3 homegro wn produ ce ser vings per wee k for the adu

lt, see Table 6- 1).

4.2.7 Acute R

eceptor Scenar io
In addition to long-term chronic effe cts evaluated in th e other recommended exposur e scenarios, we generally recom

mend eva luating the acute exp osure scenario. The acute re ceptor scenario accounts for short-term

effects of exposure to m aximum 1-hour conce

ntrations of COPCs in emissions from the facility (see Chapter 3) through direct inhalation of vapors and particles (see Table 4-1 and Chapter 7). A receptor could be ex

posed in an urban or rural setting where h uman activity

or land use supports any of the recomm

ended exposure scenarios. The receptor could also b e exposed in com mercial and industrial land use areas (excluding workers from

the facility) not ty

pically covered by the other recom mended exposure scenarios. A s mentioned in Section 4.2 above, we assume that workers from the facility being assessed in the risk assessment are protected by OSHA programs, and therefore aren’t g enerally included in hazardous waste

combustion risk

assessments.

We discuss further this recom mended exposu

re scenario and associated e xposure pathway,including numeric equations, parameters values, and COPC -specific inputs, in Chapter 7 and A ppendices A, B, and C.

4.3 SELECTING EXPOSURE SCENARIO LOCATIONS
Exposure scenario locations are the physical place s within the study area selected for eva

luating one or
more of the r

ecom mend ed expo sure sce

narios. We ge

nerally recom mend choosi ng ex posure scenario location s based

on CO PC air concent

rations and dep osition rates from I SCST3 ( see Cha pter 3) specific to land use area s define d durin g exp osure se

tting characte

rizatio n (see S ection 4 .1). L ocation -spe cific air concent rations and dep osition rates ar e then u sed as i

nputs to the equ ations w hich est imate medi a concentrations.

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-22 

### We would like to emphasize that the method an d resulting selection of exposure scenario locations is one of the m ost criti cal step s of the

risk a ssessm

ent proc ess, wi

th hug e imp acts on standar dizati on acro ss all facilitie s eval

uated, and reproducib ility o f results . This is , at lea st partly, becau se IS CST3-mode led air parameter v alues (a

nd the r esulting medi a conce

ntration estimates) ca

n vary signi ficantly , eve

n withi n individual land use areas.
To ensure consistent and reprod ucible risk assessm

ents, we recom

mend using

the following pro cedures to select your expo sure scenario locations. These procedures also reduce the chances that the location(s) you s elect to

evalu ate a lan d use ar ea ove rlook location s within

that sa me la nd use area tha

t would result in hig her risk estimates. Th

is can b e imp ortant g

iven t he com plexity of mu ltiple m odeled air para

meters and pha ses per location , possi bly m ultiple facility

emis sion sources, each wi th mu ltiple so urce- specific COPCs. This approa

ch also provides a more com plete risk evalua

tion of areas surrounding the facility. This information often be comes releva nt later in the perm

itting process and in risk comm unication to the surrounding public.
As detailed in Chapter 3, ISCS T3 estimates COPC concentrations in the air ab ove, and depo sition rates onto , spe cif

ic lo cat ions (i.e . rec ept or gr id no des) arou nd a c ent ral poin t (e. g. comb ust or fa cil ity s tac k). If all the locations mo deled by I SCST3 are viewed as a group, they form a g rid of horizontal and vertical lines on a map,with each location a n ode, or intersection betwe en vertical and horizontal lines; hence the name “grid nodes” for mod eled locations. Also, Section 4.1 of this ch apter explained the steps an d issues involv ed in characterizing

the v arious uses of t

he land in the study a

rea. F igure 4-1 is a gr

aphic representation of these two sets of information, and demonstrates some of the relation ship between them

. For exa mple, a single land use area can hav e mul tiple g rid nod es assoc iated with it, e ach nod e with i ts own air concentration and deposition levels. Choosing exp osure scenario location(s) for a land use area is a matter of cho osing which g rid node(s) will prov

ide the data used to generate media conc entrations used in the exposure sc enario. We recom mend the follow

ing steps:

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posure Scenario Ide ntification September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-23 

### FIGURE4-1 ISCST3 GRID NODES AND LAND USE DESIGNATIONS

Step 1: Define

Land U se Area s To Ev aluate - To avoid confusion and misidentification, land use areas, water bodies, and watersheds identified during the exposu re setting characteriz ation step, are best defined an

d mapped usin

g UTM coordinates in a

format consistent w

ith that used to define locati ons of f

acility emis sion sources an

d the I SCST3 r

eceptor grid n odes. F ormat s include NAD27 or NAD83 UTM. Step 2: Identify Receptor Grid Node(s) Within E ach Defined Land Use Area
- For each defined land us e area, identif

y the receptor grid

nodes within or on the bound ary of that are a (defined in Step 1)that rep

resent t he loca tion of highe st yearly average concen tration for each

ISC ST3 air parameter output (i. e., air concentration, d ry deposition, wet deposition) for each pha se (i.e., vapor, p article, particle-boun d). We recomm

end choosing con

centrations specific to each facility emis sion source (e. g., stacks, fugit ives), as well

as all e missi on sour

ces at the facilit

y comb ined. This resu

lts in se lecting

one or more receptor grid nodes (and the

refore t he expo sure scenario locations for that land use area), with the fo llowing attributes:

C 

### Highest vapo

r phase air concentration

C 

### Highe st vap or phas e dry deposit ion rate

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Chapter 4: Ex

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-24 

### C 

### Highe st vap or phas e wet d epositio n rate

C 

### Highest particle phase air concentration

C 

### Highe st partic le phase wet de position rate

C 

### Highe st partic le phase dry d epositio n rate

C 

### Highest particle-

bound phase air concen

tration

C 

### Highe st partic le-b ound ph ase wet deposi tion rate

C 

### Highe st partic le-b ound ph ase dry deposi tion rate With the exception of water bodies and watersheds (discussed in Step 4 be low), we recom mend using only air parameters for a single receptor g rid node as inputs into the media equation s for each exposure scenario loc ation. We also recom mend using

actual parameter v

alues, without averaging or other statistical ma

nipulation. Howev

er, based generally

on the numb er and location of facil ity em

ission s ources, you m

ight s elect m

ultiple exposu

re scena rio loca tions for a specific land use area. U.S. EPA R

egion 6 applied these criteria to actual sites, using actual modeled air parameters, and found that only 1 to 3 receptor grid nodes were typically selected per land use are a. This was beca use, in mos t cas es, t he hi ghes t air conc ent rat ion a nd de posi tio n rat e occ urr ed at the s ame receptor grid node. Please note: while these criteria tend to minimiz e the chances of ov erlooking m

aximum risk w ithin a land us e area, they do not preclud e you from selectin g add itional exposu

re scenario locations within that same land use area based on site- specific risk conside rations (see Ste

p 3 belo w). Step 3: Identify Receptor Grid Nodes For Acute Risk and Site-Specific Risk Consid erations - In addition to the receptor grid nod es selected in Steps 1 an

d 2 above, y

ou might consider additional receptor grid nodes to evaluate a cute risk or site- specific risk considerations (e.g., special populations). To eval uate a l and use area (i nclud ing commerc ial an d indus trial land us e areas ) for ac ute ri sk, choose location(s) from

receptor grid nodes

with the highest modeled hourly vapor phase

air concent ration a nd hig hest hourly

particle phase air concentration (see Chapter 3) specific to each emission source, as well as all em ission sources com

bined. For site- specific risk considerations, we recomm

end considering the receptor grid node c losest to the exposure po int being eva luated (e.g. school, h

ospital). However, in some ca ses, a more p rotective approach m

ight select the closest receptor grid no de or nodes with the highest mod eled air parameter v

alues. Step 4: Identify Receptor Grid Nodes For Water Bodies and Waters heds
- For recomm

ended exposure scenar ios that inclu de evaluating water bodi es and their asso ciated waters heds, we recommen

d considering the re ceptor grid nodes w ithin their area extent or "effectiv e" areas (defined and m apped i n Step 1). For water bodies, you c ould se lect the receptor grid

node w ith the hig hest m odeled air para

meter value s. You

could a lso average the air p arame ter va lues for all receptor grid nodes within the area of the water body. Fo r watersheds, you

could averag e the modeled air param

eter values of all receptor grid nodes w ithin the drainage bas in (excluding the area of the water body

). Media concentration equ ations for water bodies an d watersheds need the s ame air p aram

eter val ues a s fou

nd in Step 2 ab ove ; ye arly

ave rag es for each I SCS T3

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 4-25 

### modeled air param

eter (e.g., air con

centration, dry depo sition, wet deposition) for each phase (e.g., va por, particle, particle-

bound); specific to each em ission source (e.g. , stacks, fug itives) as well as all emission

sources at the facility combined.

For e valu ati ng pot ent ial expo sur e rou tes othe r tha n inge sti on of fish , we co nsi der i t rea sona ble to as sume that the Fisher and Fishe

r Child reside at the sam

e exposure scenario location s as the Resident scenario

. You can s imilar ly assume t hat the Fisher and Fis her Chi ld expo sure sc enari os are e xposed through ingestion of fish from

the water body with the highest m odeled combined

deposition, that can or does support fish po pulations. As

a resul t of som e site sp ecific c onditions, it m ay be appropr

iate to e valua te the Fisher and Fisher C

hild assuming

exposure through

ingestion of fish ca

lculated using CO PC water concentrations from one water body,and exposure from ingestion of drink

ing water calculated using COPC wate r conce ntrat ions fr om a diffe rent wa ter bod y.
To reiterate, we recom

mend initially evaluating curren t and reasonable potential fu ture land use areas defined during the exposure setting chara cterization, using

the most represen

tative recomm

ended exposure scenario(s), at actu al receptor grid node s selected using the four-step process explained above.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-1



### 5.1 Calculating COPC Concentrations in Air for Direct Inhalation 5.2 Calculating COPC Concentrations in Soil 5.3 Calculating COPC Concentrations in Produce 5.4 Calculating COPC Concentrati ons in Beef and Dairy Products 5.5 Calculating COPC Concentrations in Pork 5.6 Calculating COPC Concentrations in Chicken and Eggs 5.7 Calculating COPC Concentrations in Drinking Water and Fish 

## 5.8 Using Site-Specific vs. Default Parameter Values 

# Chapter 5 Estimating Media Concentrations What’s Covered in Chapter 5:

PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak in this chapter is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. The purpose of this chapter is to describe the equa tions (and associated parameters) for estimating media concentration that we recommend using to evaluate the exposure scenarios presented in Chapter 4. In most cases, we include the origin and development of each of these equations, and describe the associated parameters. We also present the equations in A ppendix B in a more condensed form (i.e. without derivation), and organize them according to exposur e pathway. Discussions of ISCST3-modeled unitized air parameters are presented in Chapter 3. A ppendix B also includes equations for modeling phase allocation and speciation of mercury concentrati ons. Appendix A-2 lists compound-specific parameters the equations need to estimate media concentrati ons, as well as our recommended hierarchies of sources. The HHRAP companion database provides recomme nded values for compound-specific parameters.

Section 5.1 describes the equations that estimate air concentrations for evaluating direct inhalation of COPCs. Section 5.2 describes equations for estima ting COPC concentrations in soils. Section 5.3

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-2 

### Figure 5-1 - COPC Concentration in Air for Direct Inhalation describes equations for estimating COPC concentrati ons in produce. Sections 5.4 through 5.6 describe equations for estimating COPC concentrations in an imal products (such as milk, beef, pork, poultry, and eggs) resulting from animals ingesting contaminated f eed and soil. Section 5.7 describes equations for estimating COPC concentrations in fish th rough bioaccumulation (or, for some compounds, bioconcentration) from the water column, dissolved water concentration, or bed sediment—depending on the COPC. Please Note : references made throughout Chapter 5 to particle phase are generic and made without distinction between particle and particle-bound.

5.1 CALCULATING COPC CONCENTRATIONS IN AIR FOR DIRECT INHALATION
We recommend calculating COPC concentrations in air by summing the vapor phase and particle phase air concentrations of COPCs. To eval uate long-term or chronic exposure via direct inhalation, we generally recommend using unitized yearly air parameter values to calculate air concentrations, as specified in Appendix B, Table B-5- 1. To evaluate short-term or acute exposure via direct inhalation, we recommend using unitized hourly air parameter values to calculate air concentrations, as specified in Appendix B, Table B-6-1.

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-3 COPC Emissions

Vapor Phase Air Concentration

Vapor Phase

Deposition

to Soil

Leaching, Erosion, and Runoff COPC Soil Losses Degradation (Biotic + Abiotic) and Volatilization

COPC Concentration in Soil Particle Phase Air Concentration

Particle Phase

Deposition

to Soil 

### FIGURE 5-2 - COPC CONCENTRATION IN SOIL 5.2 CALCULATING COPC CONCENTRATIONS IN SOIL
We recommend estimating COPC concentrations in soil by summing the vapor phase and particle phase deposition of COPCs to the soil. We generally recommend considering wet and dry deposition of particles and vapors. Calculate dry deposition of vapors from the vapor air concentration and the dry deposition velocity. We consider it appropriate for soil concentration calculations to account for loss of COPCs by several mechanisms, including leaching, erosion, runoff, degradation (biotic and abiotic), and volatilization. These loss mechanisms all lower the soil concentration associated with the deposition rate. We present our recommended equations for calculating soil concentration and soil losses of COPCs in Appendi x B, Tables B-1 for land use areas, and Tables B-4 for watersheds (see Section 5.7).

Soil concentrations might require many years to reach steady state. As a result, the equations we suggest to calculate the average soil concentration over the period of deposition were de rived by integrating the

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Chapter 5: Es ti mating Media Concent rati ons September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of S olid Waste Center for Combustion Science and Engineering 5-4 

### Equ ation 5-1 in st an tane ous so ilco nc en tr at io n e quati on ove r t he pe ri od of

de pos it io n. For

ca rc in oge ni c CO PCs , we
reco mm end usin g tw o va riation s of th e equ ation (ave rage soil co nce ntratio n ov er ex pos ure d uratio n):
1. one vari ati on if the expos ure dur ati on ( T2 ) is grea ter tha n or equ al to the ope rat ing lif eti me of the emiss ion sour ce or t ime per iod of combusti on, and
2. the other form if the exposure du ration is less than t he opera ting lif

eti me of the emiss ion source or t ime per iod of combusti on. Fo r non carcin oge nic C OP Cs, w e reco mm end usin g the seco nd fo rm o f the ca rcino gen ic equ ation . This equa tion calcu lates the high est annu al averag e CO PC soil conc entration o ccurring during the exp osure durat ion. We descri be thes e equat ions i n more det ail in Sect ion 5. 2.1.

Soil c onditi ons—such as pH, s truc ture , organic matter content , and moi stur e conte nt—affect the dist ribution and mobil ity of COPCs. Modeling t he los s of COPCs from soi l use s rat es spe cif ic t o the physica l and c hemical chara cter ist ics of t he soi l. We descri be thes e vari ables and the ir us e in t he following sub sections, along with the recomm ended eq uations.

5.2.1 Calculat ing Cumulative Soil Concent rati on ( Cs )

U.S . EP A (1 990 e) reco mm end ed u sing Eq uatio n 5-1

— ada pted from Trav is, et al. (19 83)

— to calc ulate cumulat ive s oil concentrat ion:

wh ere Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) 100 = Un its conve rsion facto r (mg-m 2 

### /kg-cm 2 

### ) Dydp = Un itized y early dry dep ositio n fro m p article p hase (s/m 2 

### -yr) Dywv = Un itized y early we t dep ositio n fro m v apo r pha se (s/m 2 

### -yr) ks = COPC soil los s con st antdue t o al l pr oces ses (yr G 1 

### ) tD = Time peri od over whic h deposi tion occurs (ti me peri od of combust ion)

(yr) Z s 

### = Soi l mi xi ng z one dep th (c m) BD = Soil bulk densit y (g soil/ cm 3 

### soil)

U.S . EP A (1 993 f) stated that E qua tion 5 -1 ev alua ted d epo sition of pa rticle p hase CO PC s, bu t failed to consider vapor phase deposi tion or di ffusion. To account for vapor phase di ffusion, U.S. EPA (1998c) recommended usi ng the f ollowi ng equati on:

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of S olid Waste Center for Combustion Science and Engineering 5-5 

### Equati on 5-1A

Equati on 5-1B wh ere Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) 100 = Un its conve rsion facto r (mg-m 2 

### /kg-cm 2 

### ) Dydp = Un itized y early dry dep ositio n fro m p article p hase (s/m 2 

### -yr) Dywv = Un itized y early we t dep ositio n fro m v apo r pha se (s/m 2 

### -yr) L dif 

### = Dry vap or ph ase d iffusio n loa d to so il (g/m 2 

### -yr) ks = COPC soil los s con st antdue t o al l pr oces ses (yr G 1 

### ) tD = Time peri od over whic h deposi tion occurs (ti me peri od of combust ion)

(yr)
Z s 

### = Soi l mi xi ng z one dep th (c m) BD = Soil bulk densit y (g soil/ cm 3 

### soil)
Other gui dance ( U.S. EPA 1994g) re commended the or igina l Equat ion 5-1, but onl y for ca lcul ati ng Cs for 2,3,7 ,8-T CD D. U .S. E PA (199 4g) also re com me nde d settin g the CO PC soil los s con stant ( ks ) equalto 0 for a ll other

COPCs. For COPCs other t han 2,3, 7,8-TCDD, U.S. EPA (1994g) recommended Equat ion 5- 1B

— wh ich elim inates the C OP C so il loss co nstan t:

wh ere Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) 100 = Un its conve rsion facto r (mg-m 2 

### /kg-cm 2 

### ) Dyd = Ye arly d ry d epo sition rate of pollu tant (g /m 2 

### -yr) Dyw = Ye arly w et dep ositio n rate of po llutan t (g/m 2 

### -yr) tD = Time peri od over whic h deposi tion occurs (ti me peri od of combust ion)

(yr) Z s 

### = Soi l mi xi ng z one dep th (c m) BD = Soil bulk densit y (g soil/ cm 3 

### soil)

Mor e r ec en t gui da nc e d oc ume nt s—U. S. EPA ( 199 4r ) and NC DEHNR (1 997 )—r ec omme nde d u si ng tw o differ ent equati ons (Equations 5-1C and 5-1D) with carci nogenic COPC s. Equati on 5-1C was

recom men ded fo r T 2 

### # tD and E quation 5-1D was rec om men ded fo r T1 

### < tD < T 2 

### . For n onc arcin oge nic COPC s, Equat ion 5-1E was recommended.

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### Equati on 5-1C

Equati on 5-1D

Equati on 5-1E We recomm end using Equations 5-1C, 5-1D, and 5-1E to cal culate Cs . App endix B, Ta ble B-1 -1 discusses further how to use these eq uations.

Recomm ended Equations f or Calcul ating: Cumulati ve Soi l Conce ntrat ion ( Cs ) Carcinog ens 

### : For T 2 

### # tD

For T

1 

### < tD < T

2

Nonca rcinogens:



### wh ere Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) Ds = Dep osition term (mg C OP C/kg soil/yr) ks = COPC soil los s con st antdue t o al l pr oces ses (yr G 1 

### ) tD = Tim e period over w hich d eposition occurs (tim e period of com bustion ) (yr) T1 

### = Tim e period at the beg inning of com bustion (yr) Cs tD 

### = Soil concentr ation at time tD (mg/kg) T 2 

### = Len gth of ex posu re duration (yr)
We discuss the deposit ion term furt her in thi s Section, as well as Section 5.2. 3. Secti on 5.2.2 discuss es the C OP C-s pec ific soil lo ss co nstan t ( ks ). Chapter 2 disc usses how the per iod of time a t the beginni ng of combusti on ( T1 

### ) rel ates t o character izing si te condit ions immediatel y preceding the st udy period. Chapter 2 also addresses the time period during which bu rning - and therefore depo sition - occurs ( tD ), as it

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### relates to setting em ission rates. C hapter 3 address es air dispersio n m odeling aspects o f tD . Chap ter 6 further discusses how the duration of exposure ( T 2 

### ) rel ates t o character izing exposure.
As in U.S. EPA (1994r) and NC DEH NR (1997 ), we recommend using Equation 5-1C when y ou model an exposu re duration that is less th an or eq ua l to the ope rat ing l ife time of the e missi on source or hazard ous w aste com bustor ( T 2 

### # tD ). We recommend using Equ ation 5-1D when you m odel an exposure durat ion great er t han the ope rating lifetime o f the haza rdou s waste c om bustor ( T1 

### < tD < T 2 

### ). For nonc ar ci noge nic COPCs, we r eco mmend Eq uat ion 5-1 E.
We generall y recommend usi ng the COPC soil concentrat ion aver aged over the e xposure dur ati on (r epre sent ed by Cs ) for car cinogenic compounds. Carcinogenic r isk is averaged over the l ifet ime of an indiv idua l. Bec ause the h azard quo tient as socia ted w ith no nca rcino gen ic CO PC s is bas ed o n a th resh old dos e rath er tha n a lifetim e exp osu re, w e reco mm end usin g the high est an nua l aver age CO PC soil concentrat ion ( Cs tD 

### ) occ urrin g du ring the ex pos ure d uratio n pe riod for n onc arcin oge nic C OP Cs. Cs tD 

### typic all y occurs at t

he end of t

he opera ting lif

e of t he emiss ion sour ce or t he ti me peri od of combust ion.

As in U.S. EPA (1994r) and NC DEHNR (1997), we recommend usi ng the hi ghest1-year annual avera ge soil concent

rati on, determined usi ng Equation 5-1E, to evaluat e risk f rom noncarcinogenic COPC s (see Cha pter 7).

5.2.2 Ca lculating the C OP C S oil Lo ss Co nstan t ( ks )
Organic and inorganic COPCs can be l ost f rom the s oil by sever al pr ocess es that may or may not occur simu ltaneo usly . The rate at w hich a CO PC is lost fro m th e soil is k now n as th e soil lo ss co nstan t ( ks ). We recommend determining ks by usin g the soil’s p hy sical, ch em ical, an d bio logic al cha racteris tics, to

es ti mat e the C OPC- sp ec if ic lo ss re su lt in g f

ro m: (1) leach ing, (2) runo ff, (3) erosi on, (4) bioti c and abi otic degrada tion, and (5) volat ili zati on.

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### Equ ation 5-2

Equati on 5-2A U.S. EPA (1990e) recomm ended Equation 5-2 to calc ulate ks :

wh ere ks = COPC soil los s con st antdue t o al l pr oces ses (yr G 1 

### ) ksl = COPC loss cons tan t due to l each ing ( yr G 1 

### ) ksg = COPC loss cons tan t due to bi oti c and abi oti c degr adat ion ( yr G 1 

### ) ksv = COPC loss cons tan t due to vo lat il iza ti on (yr G 1 

### )

We recomm end using Equation 5-2A to calcul ate ks

. We de sc ri be t hi s e qua ti on f

ur th erin Appe ndi x B, Table B-1- 2. Us ing Equ ati on 5-2 A is c onsi st entwit h U.S. EPA (1994g) , U. S. EPA ( 1994r) , U. S. EPA (199 8c) and NC DE HN R (19 97).

Recomm ended Equation f or Calcul ating: CO PC Soil L oss C onsta nt ( ks )

wh ere ks = COPC soil los s con st antdue t o al l pr oces ses (yr G 1 

### ) ksg = COPC loss cons tan t due to bi oti c and abi oti c degr adat ion ( yr G 1 

### ) kse = COPC loss cons tan t due to s oil ero si on (yr G 1 

### ) ksr = COPC loss cons tan t due to s urf ace runof

f ( yr G 1 

### ) ksl = COPC loss cons tan t due to l each ing ( yr G 1 

### ) ksv = COPC loss cons tan t due to vo lat il iza ti on (yr G 1 

### )

Secti on 5.2. 2.1 di scuss es l oss due t o biot ic and abiot ic degr adati on ( ksg ). Section 5.2.2.2 discusses loss due to e rosi on ( kse ). Section 5 .2.2.3 discu sses loss du e to surface runoff ( ksr ). Sect ion 5.2.2. 4 discusses Loss due t o leac hing ( ksl ). Secti on 5.2. 2.5 di scuss es l oss due t o volat ili zati on ( ksv ).
As highlighted i n Section 5.2. 1, using Equation 5-2A in Equations 5- 1C and 5-1D assumes that you can defi ne COPC loss usi ng fir st- order reac tion kinet ics . Fi rst -order reac tion rat es depend on the concentrat ion of one rea ctant (Bohn et al. 1985). The loss of a COPC by a fir st- order proces s depends only on the concentrat ion of the COPC in the soil , and aconst ant f ract ion of the COPC is r emoved from the s oil over t ime. Those proce sses that appare ntly e xhibit

fir st- order reac tion kinet ics without implyi ng a mechanis tic dependence on a fi rst -order loss rat e are ter

med “appare nt fi rst -order ” los s rat es (Sparks 1989). The assumpt ion that COPC loss f ollows f irs t-or der r eact ion ki neti cs may be an ove rsi mplif icat ion

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### bec ause

— at var ious con cen tration s or u nde r vario us en viro nm enta l con dition s— the lo ss rates from soil systems w ill res emble different kinetic expressions. How ever, at low concentrations, a first- order loss constan t may be ade quate to describe the loss of th e CO PC from so il (U.S. EP A 1 998 c).

CO PC loss in soil can also follow zero or sec ond -order reac tion kine tics. Zero-ord er reaction k inetics are inde pen den t of rea ctan t con cen tration s (Bo hn e t al. 19 85) . Zero -ord er loss rates d escrib e pro cesse s in which the reac tant s are prese nt at very hi gh concentrat ions. Under zer o-order kinet ics , a c onsta nt amount of a COPC is l ost f

rom the s oil over t ime, i ndependent of i ts c oncentr ati on. Proc esse s tha t fol low second- order reac tion kinet ics depend on the concent rat ions of

two rea ctant s or t

he concent

rat ion of one reactant squared (Bohn et al. 1985). The loss const ant of a COPC following a second-order proces s can be contingent on it s own concentration, or on both its concentrat ion and the concentr ation of anot her reacta nt, suc h as a n en zym e or ca talys t.

Be cau se C OP C lo ss from soil de pen ds o n m any com plex facto rs, it ma y b e diffic ult to m ode l the o vera ll rat e of l oss. In addi tion, because the phys icalphenomena tha t caus e COPC loss can oc cur simult aneousl y, usi ng Equati on 5-2A might a lso ove rest imate loss rat es for each pr ocess (Valentine 198 6). W e reco mm end , wh en p ossib le, takin g into acco unt th e com mo n oc curre nce of all lo ss pro cesse s. It’s possible t o derive combined rate s of soilloss by these processes e xperimentall y. U.S. EPA (1986c) presents values for some C OPC s.

5.2.2 .1 COP C Loss Constant Due to Bi otic and Abiotic Degradation (ksg)

Soil l osses resul ting from bi otic and abi otic degrada tion ( ksg ) are d eterm ined em pirica lly fro m fie ld studies and should b e available in the lit erature (U.S. EPA 1998c). Ac cording to Ly man et al. (1982), it’s

reason able to assu me th at degrad ation rates follo w first ord er kinetics in a h om ogen ous m edia. Yo u’re there fore a ble to relate th e half -life of a com pou nd to the d egra datio n rate con stant. Id eally , ksg is t he sum of al l bi otic and abi otic rat e const ants in the soi l media . Ther efore , i f the half -li fe of a compound (f

or all of the m echan isms of tran sform ation) is kn ow n, you can calcu late the deg radation rate. How ever, lit erature sources don’t pr ovide suffi cient dat a for al l such mechanisms, es peciall y for soil . Earli er Agency guidance (U.S. EPA 1994g) recommended se tti ng ksg fo r a llCOPCs othe r t ha n 2 , 3, 7, 8- TCDD equ al to ze ro . The HHRAP co mpan io n da tabas e pr es ent s o ur re comme nde d va lu es fo r t hi s COP Cspecifi c variabl e.

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### Recom mend ed Values for: COP C Loss Constant Due to Bi otic and Abiotic Degradation ( ksg) CO PC -Sp ecific (See the HHRA P companion database)

The rat e of bi ologic al degr adati on in soi ls de pends on the concent rat ion and a cti vity l evels of t he microbi al popul ati ons in t he soi l, the s oil condit ions, and the COPC concentrat ion (J ury and Vale ntine 198 6). Fir st-ord er loss rates o ften fa il to acc oun t for the high varia bility of the se fea tures in a sing le soil syste m. H ow eve r, usin g sim ple ra te exp ressio ns m ay b e app rop riate at lo w c hem ical co nce ntratio ns (e.g ., nanogram per kilogram soil ). A fi rst- order dependence on chemical concentr ation may be reasonable at low chemica l conce ntra tions . The r ate of biol ogicaldegrada tion is COPC-speci fic , and de pends on the complexity of the COPC and the usefulness of the COPC to the micr oorganisms. Some substances, rather than being used by the organi sms as a nutri ent or energy source , are s imply degraded with other s imilar COPC s, whi ch can be f urthe r uti liz ed. Envi ronmental - and COPC-speci fic fact ors t hat can li mit t

he biodegradati on of COP Cs in the soi l environment (Valent ine and Schnoor 1986) include:

• ava il abi li ty of

th e COPC ;

• nutrient limitati ons;

• toxic ity of

the COPC; and

• in ac ti vat io n or

non exi st enc e of

enz ymes ca pab le of

deg ra di ng t

he C OPC.
Chemical degrada tion of orga nic compounds c an be a si gnifi cant mec hanis m for re moving COPCs from soil ( U.S. EPA 199 8c). Hydrolysis and oxidation-r eduction reac tions ar e the pri mary chemical transformation pr ocess es occur ring i n the uppe r layers of soil s (Val enti ne 1986). General rat e expre ssi ons describing the transformation of som e CO PCs by all non-biological processes are available. These exp ressio ns are help ful w hen divis ion in to co mp one nt rea ction s isn’t p ossib le.
Hydrolysi s in a queous sys tems i s char acte riz ed by thr ee proc esse s: a cid- cata lyzed, base- cata lyzed, and neutral reacti ons. The overall rate of hydrolysis i s the sum of the f irst -order rates of t

hese processes (Valent ine 1986) . I n soilsyst ems, s orpti on of t he COPC can incre ase, decre ase, or notaff ect t he rat e of hydrolysi s, a s numerous s tudie s ci ted i n Valent ine ( 1986) have s hown. We recommend predi cti ng the

ove rall (i.e. tota l) rate o f hy dro lysis in soil by add ing th e rates in the soil an d w ater p hase s. W e recommend assuming that these r ates ar e fir st-order reacti ons at a fi xed pH (Valentine 1986). Lyman et al. (1982) describes method s for estimating these hydrolysis constants.

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### Equ ation 5-3 Org anic and inorg anic com pou nds also u nde rgo oxid ation -redu ction (redo x) rea ction s in the soil (Valent ine 1986) . Organi c redox r eact ions i nvolve t he rea cti ng molecul es exchanging oxygen and hyd rogen atom s. Inorgan ic redox reactions m ay inv olve the reactants ex chan ging a toms o r electrons. In soil s ystems where the ident iti es of oxidant and reductant spec ies ar en’t known, you can acquire a fir st- order rat e const ant f or desc ribi ng loss by redox r eact ions ( Valent ine 1986) . Redox r eact ions invo lving me tals m ay p rom ote lo sses fro m su rface s oils b y m akin g m etals m ore m obile (e.g., lea chin g to subsu rface soils).

5.2.2 .2 COPC L oss Constant Due to So il Erosi on ( kse )
U.S. EPA (1998c) recommended usi ng Equati on 5-3 t o calc ulat e the const ant f or soi l l oss r esul ting from erosi on ( kse ).

wh ere kse = COPC soilloss const ant due to soi l er osion 0.1 = Units conversi on factor ( 1,000 g-kg/10,000 cm 2 

### -m 2 

### ) X e 

### = Un it soil los s (kg /m 2 

### -yr) SD = Sedimen t delivery ratio (unitl ess) ER = Soil enrichment ratio (unitless) BD = Soil bulk densit y (g soil/ cm 3 

### soil) Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = So il/wa ter pa rtition c oeffic ient (m l wa ter/g so il) 2 sw 

### = Soil volumetri c water content (ml water/ cm 3 

### soil) = 0.2 ml/cm 3



### W e recomm end using the U niversal Soil Loss Equ ation (USL E) to calculate unit soil l oss ( X e 

### )(See Sect ion 5 .7. 2). We descr ibe soi l bul k dens ity ( BD ) in Se ction 5.2.4 .2. W e des cribe Soil m ixing dep th ( Z s 

### ) in Se ction 5.2.4 .1. W e des cribe soil vo lum etric w ater co nten t ( 2 sw 

### ) in Section 5.2.4.4. We discuss site-sp ecific v ariab les asso ciated with Eq uatio n 5-3 furth er in A ppe ndix B.

U.S . EP A (1 994 g an d 19 94r ) reco mm end ed se tting a ll kse values eq ual to zero . U.S. E PA (1994 r) recommended se tti ng kse equal to zer o because contaminated s oil er odes both onto and off of t he site

.

As in U.S. EPA (1994g and 1994r), we recommend set ting kse equ al to ze ro.

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### Equ ation 5-4 Recom mend ed Value for: COPC L oss Constant Due to Er osi on ( kse ) 0

For addi tiona l i nformat ion on addr essi ng kse , we recomm end consu lting U.S. EPA (1998c). W e also furt her des cri be usi ng kse values in Appendix B, Table B-1-3.

5.2.2 .3 CO PC Loss Co nstan t Du e to R uno ff ( ksr )

Ear lier U .S. E PA guid anc e (19 94g ) reco mm end ed se tting a ll ksr valu es eq ual to zero .

As in U .S. E PA (199 4r; 19 98c ) and NC DE HN R (1 997 ), we reco mm end usin g E qua tion 5 -4 to c alcu late ksr . We furt

her di scuss using Equat ion 5-4 in Appendix B, Table B-1- 4.

Recomm ended Equation f or Calcul ating: CO PC Loss Co nstan t Du e to R uno ff ( ksr )

wh ere ksr = COPC loss cons tan t due to r unoff (yr G 1 

### ) RO = Av erage an nual su rface run off from pervio us areas (cm /yr) 2 sw 

### = Soil volumetri c water content (ml water/ cm 3 

### soil) = 0.2 ml/cm 3 

### Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = So il/wa ter pa rtition c oeffic ient (m l wa ter/g so il) BD = Soil bulk densit y (g soil/ cm 3 

### soil) = 1.5 g/cm 3



### The average annual surf ace runoff f

rom pervious surfac es (RO) is a s ite- specifi c water loss term discuss ed in Se ction 5.2.4 .3. Se ction 5.2.4 .4 de scribe s soil v olum etric w ater co nten t ( 2 sw 

### ). Sect ion 5.2.4. 1 discusses the dept h of soi l mixi ng ( Z s 

### ). Ap pen dix A -2 ex plain s ho w w e reco mm end calcu lating the C OP C-s pec ific soil/w ater p artition coef ficien t ( Kds 

### ). Sect ion 5 .2. 4.2 d esc ri bes s oil bulkdens ity ( BD ).

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### Equ ation 5-5 5.2.2 .4 COP C Loss Constant Due to Leac hing ( ksl )

Losses of soi l COPCs due to l eachi ng ( ksl ) dep end on th e am oun t of w ater av ailable to ge nera te leac hate and soil properties such as bulk den sity, soil moisture, s oil porosity, and soil sorption properties.
U.S. EPA (1990e) recomm ended using Equation 5-5 to cal culate ksl

.

wh ere ksl = COPC loss cons tan t due to l each ing ( yr G 1 

### ) P = Av erage an nual p recipitation (cm /yr) I = Av erage an nual irrigation (cm/y r) E v 

### = Av erage an nual ev apotran spiration (cm /yr) 2 sw 

### = Soil volumetri c water content (ml water/ cm 3 

### soil) = 0.2 ml/cm 3 

### Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = So il/wa ter pa rtition c oeffic ient (m l wa ter/g so il) BD = Soil bulk densit y (g soil/ cm 3 

### soil)
U.S. EPA (1993f

) de ter mined tha t Equa ti on 5-5 does not p rope rl y acc ount for sur fac e ru noff

. U. S. EPA (19 94g ) reco mm end ed se tting a ll ksl values to ze ro.

More recent

guidance (U.S. EPA 1994r; 1998c; NC DE HNR 1997) have r ecommended usi ng Equati on 5- 5A to calculat e ksl

. As wi th U. S. EPA ( 199 4r ), U. S. EPA ( 199 8c ), an d NC D EHNR ( 199 7) , we recommend usi ng Equati on 5-5A to ac count f or runof f whil e cal culat ing ksl . We further discuss the use of thi s equat ion i n Appendix B, Tabl e B-1-5.

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### Equati on 5-5A

Equ ation 5-6 Recomm ended Equation f or Calcul ating: COP C Loss Constant Due to Leac hing ( ksl )

wh ere ksl = COPC loss cons tan t due to l each ing ( yr G 1 

### ) P = Av erage an nual p recipitation (cm /yr) I = Av erage an nual irrigation (cm/y r) RO = Av erage an nual su rface run off from pervio us areas (cm /yr) E v 

### = Av erage an nual ev apotran spiration (cm /yr) 2 sw 

### = Soil volumetri c water content (ml water/ cm 3 

### soil) = 0.2 ml/cm 3 

### Z s 

### = Soi l mi xi ng z one dep th (c m) BD = Soil bulk densit y (g soil/ cm 3 

### soil) = 1.5 g/cm 3 

### Kds 

### = Soil/water parti tion coeff

icient (cm 3 

### wa ter/g so il)

Ap pen dix B desc ribes h ow we sug gest a cqu iring site-sp ecific v ariab les asso ciated with Eq uatio n 5-5 A. Th e ave rage ann ual v olum e of w ater av ailable to ge nera te leac hate is the m ass b alan ce of all wa ter inp uts and output s fr om the ar ea under consi derat ion (P + I - RO - E v 

### ). Th ese v ariab les are desc ribed in Sec tion 5 .2.4.3 . Sectio n 5.2 .4.4 d escrib es so il volu me tric w ater co nten t ( 2 sw 

### ). Sect ion 5.2.4. 1 describes the s oil mixing dept

h ( Z s 

### ). Sect ion 5 .2. 4.2 s oil bulkdens ity ( BD ). App en di x A- 2 d es cr ib es ho w we
reco mm end calcu lating the C OP C-s pec ific soil/w ater p artition coef ficien t ( Kds 

### ).

5.2.2 .5 COP C Loss Constant Due to Vol atil izat ion ( ksv )

Semi-volati le and volat ile COPCs emitted in hi gh concentrati ons may becom e adsorbed to soi l part icles and exhibi t vol ati liz ati on loss es fr om soil . The l oss of a COPC from the soi l by volatil izat ion depends on the ra te of m ove me nt of th e CO PC to the soil su rface, th e che mic al vap or co nce ntratio n at th e soil surface, an d the rate at w hich v apor is carried away by the atmo sphere (Jury 1 986 ).
U.S. EPA (1990e; 1993f; 1998c) recommend ed using Equation 5-6 to cal culate ksv

.

wh ere ksv = COPC loss cons tan t due to vo lat il iza ti on (yr G 1 

### ) Ke = Equ ilibrium co efficient (s/cm -yr) Kt = Gas ph ase mass transfer coefficient (cm/s)

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### Equati on 5-6A U.S. EPA (1990e; 1993f; 1998c) don’t identif y a refere nce for Equation 5-6. U.S. EPA (1993f) stated that Equati on 5-6 had been independently verif ied as accur ately r epresenti ng volatil izati on loss, but that the equ ation for Kt(Equation 5-8) appear ed to fit to data empir icall y. U.S. EPA (1993f) also st ated that ksv is mo dele d as a me ans o f limitin g so il con cen tration . Bec ause this m ass flu x ne ver e xpe rienc es rain out, o r wa sho ut an d su bseq uen t re-de pos it, soil C OP C co nce ntratio ns are und erestim ated for so luble vola tile CO PC s. U.S . EP A (1 993 f) furth er reco mm end ed th at add itiona l resea rch b e con duc ted to determine the magnitude of the uncert ainty int roduced for volat ile COPCs. U.S. EPA (1998c)

rec ommended not

cons ide ri ng th e vol ati li zed r esi dues of s emi- vola ti le COPCs (su ch as diox in) . U. S. EP A (1 994 g) rec om me nde d settin g all ksv values to ze ro.
U.S. EPA guidance (1994r) and NC DEH NR (1997 ) recommended using Equation 5-6A to calculat e ksv

. Equati on 5-6A appear s to i ncorporate equations that U.S. EPA (1990e) recommended f or cal culat ing Ke (equi librium coef

fic ient ) and Kt (gas ph ase m ass transfer co efficient).

wh ere ksv = COPC loss cons tan t due to vo lat il iza ti on (yr G 1 

### ) 3.1536 × 10 7 

### = Un its conve rsion facto r (s/yr) H = Hen ry’s L aw co nstant (atm -m 3 

### /mo l) Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = Soil/water parti tion coeff

icient (cm 3 

### wa ter/g so il) R = Un iversal gas c onstan t (atm-m 3 

### /m ol -K) T a 

### = Ambient ai r te mperatur e (K) = 298. 1 K BD = Soil bulk densit y (g soil/ cm 3 

### soil) 0.482 = Em pirical con stant (unitless) U nits conv ersion facto r [(3600 s/hr) 0.78 

### (10 0 cm /m )/(3 60 0 s/h r)] A (empir icalconst ant 0.0292) W = Averag e annual w ind speed (m /s) 0.78 = Em pirical constant (unitles s) : a 

### = Viscosity of air (g/cm-s) D a 

### = Density of air (g/cm 3 

### ) D a 

### = Diffusivi ty of COPC in air (cm 2 

### /s) -0.67 = Em pirical constant (unitles s) A = Surfac e area of co ntam inated area (m 2 

### ) -0.11 = Em pirical constant (unitles s)

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### Equ ation 5-7

Equ ation 5-8

Equati on 5-10 Equ ation 5-9 U.S. EPA (1990e) recomm ended using Equation 5-7 to cal culate Ke and Equation 5-8 to calc ulate Kt

.

wh ere Ke = Equ ilibrium co efficient (s/cm -yr) 3.1536 × 10 7 

### = Un its conve rsion facto r (s/yr) H = He nry ’s La w c ons tant (a tm-L /mo l) 10 3 

### = Un its con vers ion fa ctor (L /m 3 

### ) Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = Soil/water parti tion coeff

icient (cm 3 

### wa ter/g so il) R = Un iversal gas c onstan t (atm-m 3 

### /m ol -K) T a 

### = Ambient ai r te mperatur e (K) = 298. 1 K BD = Soil bulk densit y (g soil/ cm 3 

### soil) Kt = Gas ph ase mass transfer coefficient (cm/s) 0.482 = Un its conve rsion facto r [(3600 s/hr) 0.78 

### (10 0 cm /m )/(3 60 0 s/h r)] A (empir icalconst ant 0. 0292) W = Averag e annual w ind speed (m /s) Sc a 

### = Schm idt numbe r for gas phase (unitless) d e 

### = Eff ec ti ve d ia met erof

con ta min at ed m edi a ( m)
U.S. EP A (199 0e) also recomm ended using Equation 5 -9 to calculate the Schmidt num ber for gas phase ( Sc a 

### ), and Equation 5-10 t o calculat e the eff ective di ameter of contaminated media ( d e 

### ).

wh ere Sc a 

### = Schm idt numbe r for gas phase (unitless) : a 

### = Viscosity of air (g/cm-s) D a 

### = Density of air (g/cm 3 

### ) D a 

### = Diffusivi ty of COPC in air (cm 2 

### /s) d e 

### = Eff

ec ti ve d ia met erof

con ta min at ed m edi a ( m) A = Surfac e area of co ntam inated area (m 2 

### )

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### Equati on 5-7A As in U.S. EPA (1998c), we recomm end using Equation 5-7A to calcul ate ksv , i n cases where hi gh

con cen tration s of v olatile o rgan ic com pou nds are ex pec ted to be p resen t in the soil.

Recomm ended Equation f or Calcul ating: COPC L oss Constant Due to Vol ati li zat ion ( ksv )

wh ere ksv = COPC loss cons tan t due to vo lat il iza ti on (yr G 1 

### ) 3.1536 × 10 7 

### = Un its conve rsion facto r (s/yr) H = Hen ry’s L aw co nstant (atm -m 3 

### /mo l) Z s 

### = Soi l mi xi ng z one dep th (c m) Kds 

### = Soil/ water parti tion coeff

ici ent ( ml/g) R = Un iversal gas c onstan t (atm-m 3 

### /m ol -K) T a 

### = Ambient ai r te mperatur e (K) = 298. 1 K BD = Soil bulk densit y (g soil/ cm 3 

### soil) = 1.5 g/cm 3 

### D a 

### = Diffusivi ty of COPC in air (cm 2 

### /s) D soil 

### = Solids part icle dens ity (g/ cm 3 

### ) = 2.7 g/cm 3 

### 2 sw 

### = Soil volumetri c water content (ml/cm 3 

### soil) = 0.2 ml/cm 3



### Hen ry ’s La w co ns tant s a re co mpo und -s pe ci fi c, an d we su pply r ec omme nde d v al ue s i n the HHRAP companion dat abase. We descri be the soil mixing dept h ( Z s 

### ) i n. App en di x A- 2 d es cr ib es ho w we
reco mm end calcu lating the C OP C-s pec ific soil/w ater p artition coef ficien t ( Kds 

### ). The Universal gas constant ( R) and ambient air t emperature ( T a 

### ) are d iscus sed fu rther in Ap pen dix B , Tab le B- 1-6 . Soil bulk densi ty (BD ) is descr ibed bel ow, as wel l as in Sect ion 5. 2.4. 2. Appendix A-2 disc usses the diffusivity o f a CO PC in air ( D a 

### ). Soli ds pa rt icl e dens ity ( D soil 

### ) is disc usse d in th is Sec tion, b elow . Soil volu me tric w ater co nten t ( 2 sw 

### ) is furt her des cri bed below, as wellas i n Secti on 5.2. 4.4.
Equation 5-7A is based on gas equil ibrium coeffi cients and gas phase mass tr ansfer, and combines Equations 5-7, 5-7B, and 5-7C. You can derive ksv by adapti ng the Hwang and Fal co (1986) equati on for soil vapor phas e dif

fusi on, t o obtai n Equati on 5-6, as pre viousl y report ed by U.S. EPA (1990e) . Base d on gen eral so il prop erties, y ou c an als o w rite the gas-p hase ma ss tran sfer co efficien t, K t 

### , as f ollows (Hill el 198 0; M iller and G ardiner 1 998 ):

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### Equati on 5-7B

Equati on 5-7C wh ere K t 

### = Gas ph ase mass transfer coefficient (cm/s) Z s 

### = Soi l mi xi ng z one dep th (c m) D a 

### = Diffusivi ty of COPC in air (cm 2 

### /s) 2 v 

### = Soil void fr action ( cm 3 

### /cm 3 

### )

We describe Soil mixing dept h ( Z s 

### ) in Secti on 5.2. 4.1. The soi l voi d fra cti on ( 2 v 

### ) is the v olum etric fraction of a soil that does not con tain solids or water, and can be expressed as:

wh ere 2 v 

### = Soil void fr action ( cm 3 

### /cm 3 

### ) BD = Soil bulk densit y (g/cm 3 

### ) = 1.5 g/cm 3 

### D soil 

### = Solids part icle dens ity (g/ cm 3 

### ) = 2.7 g/cm 3 

### 2 sw 

### = Soil volumetri c water content (ml water /cm 3 

### soil) = 0.2 ml/cm 3


### The exp res si on cont ain ing b ulk d ensi ty (BD ) di vide d by sol ids par ti cle dens ity ( D soil 

### ) give s the volume of soil o ccu pied by pore spac e or v oids (M iller an d G ardin er 19 98) . Soil b ulk d ensity is affec ted b y th e soil str uctur e, s uch as l oosenes s or c ompactnes s of t he soi l, and depends on the wat er and c lay cont ent of the soil ( Hillel 1980). A range for bulk densi ty of 0.83 to 1. 84 was originall y cited i n Hoffman and B aes (19 79) . Blak e and Ha rtge (1 996 ) and Hille l (198 0) bo th su gge st that th e m ean den sity o f solid partic les is about 2.7 g/cm 3 

### . We recommend a default soil bul k density of 1. 5 g/cm 3 

### , based on a mean value for loam soil from Carsel et al. (19 88).

Th e soil w ater co nten t ( 2 sw 

### ) dep end s on both the av ailable wa ter an d the soil stru cture of a p articu lar soil. Valu es for 2 sw 

### range from 0.03 to 0. 40 ml/cm 3 

### depending on soiltype ( Hoffman and Baes 1979). The lower values ar e typi cal of sandy soi ls, which can’ t re tai n much water; the hi gher values ar e typi cal of

so il s s uc h a s c lay or

l oa m so il s wh ic h c an re ta in wat er . If si te -s pe ci fi c i nf

or mat io n i sn ’t

av ai la bl e, we recommend a m id-point def ault val ue of 0.2 ml water/ cm 3 

### soil. Howev er, s ince 2 sw 

### is uniq ue fo r each soil typ e, w e hig hly reco mm end usin g site-s pec ific info rma tion.

W e discuss ksv furt

her i n Appendix B, Tabl e B-1-6.

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### Equati on 5-11 5.2.3 Calculating the Deposition Term ( Ds )

We re comme nd u si ng Equat io n 5- 11 t o ca lc ul at e the d epo si ti on t er m (Ds) . This equat ion is f urther described i n Appendix B , Table B-1-1. Using Equation 5-11 to calcul ate Ds is cons is ten t wi th U. S. EPA (1994r) and NC D EHN R (1997), which both incorporat e Ds in to Equa ti on 5 -1 C.

Recomm ended Equation f or Calcul ating: De po si ti on Te rm (

Ds )

wh ere Ds = Dep osition term (mg C OP C/kg soil/yr) 100 = Un its conve rsion facto r (mg-m 2 

### /kg-cm 2 

### ) Q = CO PC em ission rate (g/s) Z s 

### = Soi l mi xi ng z one dep th (c m) BD = Soil bulk densit y (g soil/ cm 3 

### soil) = 1.5 g/cm 3 

### F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Dydv = Un itized y early aver age dry dep ositio n fro m v apo r pha se (s/m 2 

### -yr) Dywv = Un itized y early aver age we t dep ositio n fro m v apo r pha se (s/m 2 

### -yr) Dydp = Un itized y early aver age dry dep ositio n fro m p article p hase (s/m 2 

### -yr) Dywp = Un itized y early aver age we t dep ositio n fro m p article p hase (s/m 2 

### -yr)

Chapters 2 and 3 explain how we suggest quantif ying the COPC emission rat e ( Q ). Chapter 3 describes generating mo deled air parameters Cyv , Dydv , Dy wv , Dydp , and Dywp . We descr ibe t he soi l mixi ng depth ( Z

s 

### ) i n Sect ion 5 .2. 4.1. Soi l bul k dens ity ( BD ) is des cribe d in S ection s 5.2 .2.5 a nd 5 .2.4.2 , as w ell as Ap pend ix B. A ppen dix A -2 describ es how we su ggest d etermin ing the C OP C-sp ecific param eter Fv

.
5.2.4 Site -Speci fic Parameters f or Calcul ating Cumulati ve SoilConcentrati on

Calcul ati ng Cs requires the following site-specific parameters:

• Soil mi xing zone depth ( Z s 

### )

• Soil bulkdens ity ( BD )

• Av ailable w ater ( P + I - RO - E v 

### )

• So il volu me tric w ater co nten t ( 2 sw 

### )
We di sc us s t

hes e para met er s f

ur th erin th e f

ol lo win g s ubs ec ti ons , and i n App end ix B.

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### 5.2.4 .1 SoilMixing Zo ne Dept h ( Z s 

### )
When modeling exposur es t o COPCs in soil s, t he depth of cont aminat ed soi ls i s import ant i n calc ulat ing the appropria te soilconcentrat ion. Til ling might mix deposit ed COP Cs deeper into t he soil, whether manually in a garden or mechanical ly in a l arge fi eld. I ncreasing t he volume of soil t

hrough which CO PC s are mix ed w ill tend to dec rease (i.e. dilute) con centration s. The v alue of Z s 

### you choose may affect the ou tcom e of the risk a ssessm ent, becau se soil con centration s that are base d on soil depth are used to calc ulate e xpo sure via se vera l path wa ys:

• inge stion of pla nts co ntam inated by root u ptak e;

• dire ct i ngest ion of soil by humans, cattl e, s wine, or chicke ns; a nd

• surface runoff into water bodies.
For example , i n calc ulat ions of exposure s res ulti ng from upt ake thr ough plant roots , the aver age
con cen tration of C OP Cs o ver th e dep th of th e plan t root d eterm ines p lant u ptak e.
In gener al, U.S. EPA (1992d, 1998c) es timat ed that if the ar ea under

consi derat ion i s li kely t o be ti lle d, soil d epth is abo ut 10 to 20 centim eters, d epe ndin g on local c ond itions and the eq uipm ent u sed. If s oil is not moved, COP Cs were assumed to be retai ned in the shal lower, upper soi l layer . In t his case, earli er Ag ency guida nce (U .S. EP A 1 990 e; U.S. E PA 199 8c) typ ically recom men ded a v alue of 1 centim eter.
U.S. EPA (1998c) recommended se lect ing Z s 

### as follows:

Soil Depth (

Z s ) Exposure Description 1 cm Direct inge stion of s oil Human exposure: in gardens, lawns, landscaped areas, parks, and recreational areas. Animal expo sure: in p astures, la wns, and p arks (untilled soils). 1 cm Surface wa ter runoff in nonagricul

tural areas These areas are typically assumed to be untilled.

20 cm Plant uptak e for agric

ultural soils The root dep th is assu med to equ

al the tillin

g depth of 20 centime

ters. In untilled soils, the root zone does not directly reflect tilling depth, although it is assumed that tilling depth is an adequate substitute for root zone depth. 20 cm Surface wa ter runoff in agricultura

l areas These areas are typically assumed to be tilled.



### W e recom men d the follo wing values fo r Z s 

### :

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### Recom mend ed Values for: SoilMixing Zo ne Dept h ( Z s 

### ) 2 cm - untill ed 20 cm - till ed

W e reco mm end a defa ult Z s 

### of 2 cm for

est imati ng surf

ace soi l conce ntra tions in unt ill ed soi ls, based on a stud y th at pro filed d ioxin me asur em ents w ithin s oil (B rzuz y et a l. 199 5). W e reco mm end a defa ult Z s 

### of 20 c m fo r estim ating surfa ce so il con cen tration s in tilled soils, as in U .S. E PA (199 8c).

5.2.4 .2 Soil Dry Bulk Dens ity ( BD )

BD is t he rati o of the mass of s oil t o its t otal volume. This variabl e is af fected by the s oil st

ructure, type, and mo isture c onte nt (H illel 19 80)

.

U.S . EP A (1 994 r) reco mm end ed d erivin g w et soil b ulk d ensity by we ighin g a th in-w alled, tu be so il

sam ple (e .g., a S helb y tu be) o f kno wn volu me and sub tractin g the tube we ight (A ST M M etho d D 293 7). M oistu re co nten t can th en b e calc ulated (AS TM M etho d 22 16) to co nve rt we t soil bu lk de nsity to dry soil bulk densi ty.

As in U.S. EPA (1994g; 1998c) and pres ented i n Hoffman and Baes (1979), we recommend the foll owing value fo r BD :

Recom mend ed Value for: Soil Dry Bulk Dens ity ( BD ) 1.50 g/cm 3



### 5.2.4 .3 Available Water ( P + I - RO - E v 

### )
The average annual volume of water avai lable ( P + I - RO - E v 

### ) for generating leachate is the mass balanc e of al l wate r input s and out puts f rom the a rea unde r consi derat ion. A wide range of val ues for these site-specifi c parameters could app ly in the various Age ncy regions.

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### The average annual precipitation ( P ), irrigation ( I ), runoff ( RO ), and evapotranspiration ( E v 

### ) rates and other climatological data are available from either data recorded on site or from the Station Climatic Summary for a nearby airport.
Meteorological variables—such as the evapotranspiration rate ( E v 

### ) and the runoff rate ( RO )—might also be found in resources such as Geraghty et al. (1973). You could also estimate surface runoff by using the Curve Number Equation developed by the U.S. Soil Conservation Service (NC DEHNR 1997). U.S. EPA (1985b) cited isopleths of mean annual cropl and runoff corresponding to various curve numbers developed by Stewart et al. (1975). Curve numbers were assigned to an area on the basis of soil type, land use or cover, and the hydrologic conditions of the soil (NC DEHNR 1997).
The wide range of available values, however, dem onstrates the uncertainties and limitations in our ability to estimate these parameters. For example, Geraghty et al. (1973) presented isopleths for annual surface water contributions that include interflow and ground water recharge. U.S. EPA (1994g) recommended reducing these values by 50 percent, to represent surface runoff only.
5.2.4.4 Soil Volumetric Water Content ( 2 sw 

### )

The soil volumetric water content ( 2 sw 

### ) depends on the available water and the soil structure. A wide range of values for these variables may apply in th e various Agency regions. As in earlier guidance documents, (U.S. EPA 1993i; U.S. EPA 1994g; NC DE HNR 1997), we recommend using a default value of 0.2 ml/cm 3 

### for 2 sw 

### .

Recommended Value for: Soil Volumetric Water Content ( 2 sw 

### ) 0.2 ml/cm 3



### 5.3 CALCULATING COPC CONCENTRATIONS IN PRODUCE
Indirect exposure resulting from ingestion of produce depends on the total concentration of COPCs in the leafy, fruit, and tuber portions of the plant. Because of general differences in

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-23 

## Deposition of Particles (Section 5.3.1) 

## Vapor Transfer (Section 5.3.2) 

## Root Uptake from Soil (Section 5.3.3)



## COPC Concentration in Aboveground Produce FIGURE 5-3 COPC CONCENTRATION IN PRODUCE contamination mechanisms, we recommend separating produce into two broad categories—aboveground produce and belowground produce. In addition, aboveground produce can be further subdivided into exposed and protected aboveground produce.
Aboveground Produce
Aboveground exposed produce is typically assumed to be contaminated by three possible mechanisms:

• Direct deposition of particles— wet and dry deposition of particle phase COPCs on the leaves and fruits of plants (Section 5.3.1).

• Vapor transfer— uptake of vapor phase COPCs by plants through their foliage (Section 5.3.2).

• Root uptake—root uptake of COPCs available from the soil and their transfer to the aboveground portions of the plant (Section 5.3.3).

As in U.S.EPA (1998c), we recommend calculati ng the total COPC concentration in aboveground exposed produce as a sum of contamination occurring th rough all three of these mechanisms. However, edible portions of aboveground protected produce, such as peas, corn, and melons, are covered by a protective covering. They are therefore protected from contamination from deposition and vapor transfer. Root uptake of COPCs is the primary mechanis m through which aboveground protected produce becomes

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### Equati on 5-13 contami nated ( Secti on 5.3. 3). Appendix B furt her des cri bes the equat ions a nd paramet ers we r ecommend to calcul ate COPC concentrations in exposed and prot ected aboveground produce.
Belowground Produce

For bel owground produce, we recommend ass uming contaminati on occurs only thr ough one mechan ism— root uptake of C OPC s available from soil (Section 5.3.3). The HH RA P doesn’t add ress
co nt ami na ti on of

be lo wgr oun d p ro duc e v ia di re ct de pos it io n o f p arti cl es an d v ap ort ra ns fe r b ec au se we assume t hat t he root or tuber i s prot ecte d from cont act wi th cont aminant s in t he vapor pha se. Appendix B furth er de scribe s the e qua tions and para me ters w e reco mm end to calc ulate C OP C co nce ntratio ns in belowground produce.

Gener all y, we do n’tcons ide r r is ks as soci ate d with expos ure to VOCs vi a fo od-c hai n pathways signi fic ant. This i s pri maril y because VOCs are typi call y low-molec ular -weight COPCs that do not persist in the envi ronment and do not bioaccumulate (U.S. EPA 1994r; U.S. EPA 1996g ). However, as discusse d in C hapter 2 , we reco mm end ev aluating a ll CO PC s, including VO Cs, for eac h exp osure pat hway.

5.3.1 Aboveground Produce Concent rati on Due to Dire ct Dep osi ti on (Pd )

Some earl ier

guidance documents ( U.S. EPA 1990e; 1998c ) re commended using Equat ion 5- 13 to ca lculate CO PC conce ntrations in abov egrou nd v egetation resulting fro m w et and d ry depositi on onto plant surf aces of l eafy plants and exposed produce ( Pd ):

wh ere Pd i 

### = Concentr ati on of pol lutant due t o dire ct depos iti on in the i th pl ant gr oup (μg C OP C/g p lant tissue D W )) 1,000 = Units c onversi on fact or (kg/ 10 3 

### g and 10 6 

### μg /g po llutan t) Dyd = Ye arly d ry d epo sition from partic le ph ase (g /m 2 

### -yr) Fw = Fraction of CO PC w et deposition that adheres to plant surfaces (unitless) Dyw v = Ye arly w et dep ositio n fro m v apo r pha se (g/m 2 

### -yr) Rp i 

### = Inte rcept ion fr acti on of t he edibl e port ion of plant ti ssue f or the i th pl ant group (un itless) kp = Plan t s urf ace los s coe ff

ici ent(yr G 1 

### )

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### Equati on 5-14 Tp i 

### = Length of plant ’s expos ure t o deposi tion per har vestof t he edibl e port ion of the i th plant g roup (yr) Yp i 

### = Yield or st anding crop biomass of edibl e portion of t he i th pl ant gr oup (kg DW /m 2 

### )
U.S. EPA (1994r) modifi ed Equati on 5-13 t o incl ude st ack emis sions adjus ted t o remove the fr acti on of air concent

rati on in vapor phase [ Q (1 - F v 

### )] (Eq uatio n 5-1 4).

We recomm end using Equation 5-14 to cal culate Pd . W e furth er disc uss th e use of this equ ation in Appendix B, Tabl e B-2-7.

Recomm ended Equation f or Calcul ating: Aboveground Produce Concent rati on Due to Dire ct Dep osi ti on (Pd )

wh ere Pd = Plan t ( above groundprodu ce) conce ntr ati on due t o dir ect (wet and dr y) de pos it io n ( mg COP C/ kg DW) 1,000 = Units c onversi on fact or (mg/ g) Q = CO PC em ission rate (g/s) F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Dydp = Un itized y early aver age dry dep ositio n fro m p article p hase (s/m 2 

### -yr) Fw = 0.2 for anions, 0.6 for cations & m ost organics (unitless) Dywp = Un itized y early we t dep ositio n fro m p article p hase (s/m 2 

### -yr) Rp = Interception fraction of the edible portion of plant (unitless) kp = Plan t s urf ace los s coe ff

ici ent(yr G 1 

### ) Tp = Length of plant exposure to depos iti on per har vestof t he edibl e port ion of the i th plant g roup (yr) Yp = Yiel d or s tan ding crop bioma ss o f the edible port ion o f the pl ant(pr oduct ivi ty)

(kg DW /m 2 

### )

Chapters 2 and 3 explain how we recommend q uantifyi ng the COPC emission rat e ( Q ). App endix A-2 describe s how we rec om men d determ ining the CO PC -specific para meter Fv . Chapt er 3 des cri bes how the

mo deled air p arame ters Dydp and Dywp are ge nerat ed. Appendi x B explai ns our r ecommendati ons for Fw

. Rp , kp , Tp , and Yp are ne ithe r si te- nor COPC-speci fic , and a re des cri bed in Sec tions 5.3. 1.1 through 5.3. 1.4.

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### 5.3.1 .1 Interce ption Fra ction o f the E dible P ortion of Plan t ( Rp )

U.S . EPA (1998 c) stated that N RC mo dels assum ed a co nstant of 0 .2 for Rp for dr y and wet depos iti on of partic les (B oon e et al. 1 981 ). Ho we ver, S hor et al. (19 82) sug geste d tha t dive rsity o f plan t grow th necessit ated vegetat ion-speci fic Rp values.

As summarize d in Baes et a l. (1984), experi mental studi es of pasture gr asse s ide ntif ied a corre lat ion betw een initial Rp values and prod uctivity (standing crop biom ass [ Yp ]) (Cham berlain 1 970 ):

Rp = 1 - e - ( Yp 

### Equati on 5-14A wh ere Rp = Interception fraction of the edible portion of plant (unitless) ( = Empiric al cons tant (Chamberl ain [ 1970] gi ves the range as 2. 3 to 3. 3 for pasture g rasses; Ba es et al. [1984 ] used the m idpoin t, 2.88, for pa sture gras ses.) Yp = Stan ding crop bio ma ss (pro duc tivity ) (kg DW /m 2 

### for silag e; kg W W /m 2



### for exposed produce)

Baes et al. (1984) a lso de veloped met hods for est imati ng Rp values for l eafy vege tabl es, sil age, and exposed pr oduce. However, t hese vege tat ion cl ass- speci fic calc ulat ions pr oduced Rp values th at were independent of producti vity measurements. This independence led t o potential ly unreasonable es timates of surface plant concentr ations. Therefore, Baes et al . (1984) proposed usi ng the same empirical relat ionship developed by Chamberlain (1970) for other vegetat ion class es. Baes et al. (1984) developed class-s pec ific estim ates o f the em pirica l con stant ( ( ) by for cing an exponenti al r egres sion e quati on throug h seve ral points. Po ints includ ed ave rage an d theo retical max imum estimates o f Rp and Yp . The following class-specific empirical constants ( ( ) were de veloped:

• Exposed produce = 0.0324

• Leafy vegetables = 0.0846

• Sila ge = 0.769
U.S. EPA (1994r) and U.S. EPA (1995e) proposed a defaul t aboveground produce Rp value of 0.05, based on a weighted average of cl ass-speci fic Rp values. Specific ally, class- specifi c Rp values w ere calculated using the equation dev eloped by Cham berlain (1970) and the follow ing emp irical constants:

• Leafy vegetables were a ssigned the s ame empirical const ant (0.0846) devel oped by Baes et al. (1984 ).

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### • Fruit s, f

ruit ing veget ables , and l egumes were a ssi gned the empiri cal c onsta nt (0. 0324) orig inally dev elop ed b y B aes et a l. (198 4) fo r “ex pos ed p rod uce .” Vegetables and fruits i ncluded in each class are as follows:

• Fruit s—apple, apric ot, berry, cher ry, c ranber

ry, gr ape, peach, pear, plum/pr une, a nd strawb erry

• Fru iting V ege tables

— aspa ragu s, cuc um ber, eg gpla nt, sw eet pe ppe r, and tom ato

• Legumes—snap beans

• Leafy Vegetables—broccoli, bruss el sprout s, caul ifl ower, celer y, lettuce, and s pinach

The class-s pecifi c Rp valu es w ere th en w eigh ted b y rela tive in gestio n (by hum ans) of eac h clas s, to determine a weighted aver age Rp value of 0.05. However, t he produce clas ses and rel ati ve inges tion values used by U.S. EPA (1994r) and U. S. EPA (1995e) t o calc ulat e and weight the Rp values are not
cu rr en t wi th t he U. S. EPA 1997 Exposure Factors Handb ook (U.S . EP A 1 997 b). In a dditio n, the ove rall Rp valu e pre sente d in U .S. E PA (199 4r; 19 95e ) wa s bas ed o n lim ited in form ation ; sub sequ ent re visio n to U.S . EP A (1 994 r; 199 5e) re sulted in an ove rall Rp valu e of 0 .2 (R TI 1 997 ).

For purpos es of consi ste ncy, we combine d the pr oduce cl asse s int o two groups—exposed f ruit and exp osed veg etab les. W e use d the exp osed prod uce em pirica l con stant ( ( ) to cal culate Rp . Si nce the exposed vege tabl e cat egory i ncludes leaf y and frui ting vegeta

bles , we cal culat ed Rp for l eafy and frui ting vegetables. We then calculated t he exposed vegetable Rp by a w eigh ted av erag e bas ed o n pro duc tivity ( Yp ) of le afy and fruit ing vegetables , res pectivel y. The relat ive ingest ion rate s used to det ermine an

avera ge weight ed Rp value we derive d from the int ake of homegr own produce di scuss ion pre sent ed in t he 1997 Exposure Fact

ors Handbook

(U.S. EPA 1997b ). We recommend using the weighted average Rp valu e of 0 .39 a s a de fault Rp value, because itrepr esent s the most cur rent paramet ers, incl uding st anding crop biom ass and relative ingestion rates.

Recom mend ed Value for: Interce ption Fra ction o f the E dible P ortion of Plan t ( Rp ) 0.39

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### Equati on 5-15 Unweighted Rp and ingestion rates used for the weigh ting are as follows:

Aboveground Produce Class Rp Ingestio n Rate (g DW/kg-da y) Exposed fr

uits 0.053 0.19 Exposed vegetables 0.982 0.11



### One of the primar

y uncert aint ies assoc iat ed with t his va ria ble i s whether

the a lgori thm devel oped by Chamberlai n (1970) and the e mpiri cal c onsta nts de veloped by Bae s et al. (1984) f

or use in this a lgori thm

accur atel y repre sentaboveground pr oduce. Specif ical ly, Chamber lai n (1970) ba sed hi s al gorit hm on stud ies of p asture grass rathe r than abo veg rou nd p rod uce . Bae s et al. (1 984 ) note d tha t their ap pro ach to developing clas s-speci fic Rp valu es is “a t best ad hoc ,” but st ated t hat t his approach was just ifi ed, because the c onsequence s of us ing Rp estim ates th at are in dep end ent o f pro duc tivity are “se riou s.”

5.3.1 .2 Plan t Surfa ce Lo ss Co efficient ( kp )

U.S . EP A (1 998 c) ide ntified seve ral pro cesse s— inclu ding win d rem ova l, wate r rem ova l, and grow th di lu ti on—th at

re duc e the amoun t o f c ont ami nan t t hat has dep os it ed o n pl ant su rf ac es . The te rm kp is a

measur e of

the amountof c onta minant tha t i s l ostto t

hese physi cal proc ess es ov er t ime. U.S. EPA (1998c) cit ed Mille r and Hoff man (1983) f

or the foll owing equat ion:

wh ere kp = Plan t s urf ace los s coe ff

ici ent(yr G 1 

### ) t 1/2 

### = Half-life (days) 365 = Un its conve rsion facto r (days/y r)

Miller and Hoffman ( 1983) re porte d half -li fe values ranging fr om 2.8 to 34 days for a vari ety of contami nants on herbac eous veget ati on. These half -li fe values conver

ted t o kp valu es of 7 .44 to 90.3 6 (yr -1 

### ). U.S. EPA (1994r; 1998c) recommended a kp value o f 18, base d on a gene ric 14-da y half-life

corre sponding t o physica l proc esse s only. The 14-day hal f-l ife is a pproximat ely the midpoint of t he range (2 .8 to 34 days) e stimated by M iller and H offma n (198 3).

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### Lacking expe riment al dat a support ing chemi cal- and/or sit e-spe cif

ic values, we recommend usi ng a defa ult kp value of 18. This kp valu e is the mid poin t of M iller an d H offm an’s (198 3) ran ge o f valu es. Based on this r ange (7. 44 to 90. 36), pl ant conc entr ati ons coul d range f rom about 1. 8 ti mes higher to about 48 times lower than the plant c oncentrati ons, based on a kp valu e of 1 8. If ch em ical- o r site-sp ecific d ata is avai lable, you could also calc ulate s ite- and chemical-speci fic kp values usi ng the equation i n Miller and Ho ffma n (19 83)

.

Recom mend ed Value for: Plan t Surfa ce Lo ss Co efficient ( kp )

18 yr -1



### The primar

y uncert aint

y associ ated wi th kp rel ates to i ts pos iti on as the sol e surf ace l oss t erm in Equat ion 5-1 4. A s defin ed b y M iller an d H offm an (1 983 ) and U.S . EP A (1 998 c), kp only represent s potenti al losse s from the p hy sical p roce sses liste d ab ove , not all pote ntial lo sses (e .g. ch em ical de grad ation ). Ho we ver, in form ation rega rdin g ch em ical de grad ation of co ntam inan ts on plan t surfa ces is lim ited. Including chemical degradation proce sses would decrease half-l ife val ues and thereby incr ease kp valu es. Note that effective plant concentration decreases as kp increas es. Theref ore, usi ng a kp value that does not consider chemica l degradati on processes i s protect ive.

In additi on, there are uncert ainti es associ ated with t he half-l ife val ues reporte d by M ill er and Hoffman (1983) wit

h regar d to how accur atel y these values repr esent the be havior

of ri sk ass essment

COPCs on aboveground pr oduce. However, t he rel ati ve impact

of t his s econd uncer

tai nty is les s tha n the omis sion of chemical degrad ation processes.

5.3.1 .3 Len gth o f Plan t Exp osur e to D epos ition pe r Ha rvest of E dible P ortion of Plan t ( Tp )
U.S. EPA (1990e; 1993f; 1994r; 1998c ), and NC DE HNR (1997) r ecommended tr eati ng Tp as a co nstan t, base d on the av erag e per iod b etw een succ essiv e hay harv ests. B elch er an d T ravis ( 198 9) estim ated this perio d at 6 0 da ys (0 .164 yea rs), w hich repre sents the len gth o f time that ab ove gro und veg etation (in this case, hay) i s exposed to contaminant depositi on before being harvest ed. Calcula te Tp as follows:

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### Equati on 5-16

Equati on 5-17 wh ere Tp = Length of plant exposure to depos iti on per har vestof t he edibl e port ion of plan t (yr) 60 = Averag e period between successive hay harve sts (days) 365 = Un its conve rsion facto r (days/y r) As in previous guidance, we recommend using a Tp valu e of 0 .164 yea r.

Recom mend ed Value for: Len gth o f Plan t Exp osur e to D epos ition pe r Ha rvest of E dible P ortion of Plan t ( Tp ) 0.164 years
The primary uncertai nty associat ed with using thi s value is that i t is based on the growing season for hay rather than abovegr ound produce. The avera ge peri od between s uccess ive hay harvest s (60 da ys) may not refl ect t he lengt h of t he growing s eason or the pe riod be tween suc cess ive har vest s for aboveground produce a t spe cif

ic s ite s. To t

he exte nt that i nformat ion document ing the growing s eason or peri od betw een succ essiv e har vests for ab ove gro und prod uce is ava ilable, th is info rma tion c ould be ap pro priate to esti mate a sit e-specif ic Tp value. The great er the di fference between site -specif ic Tp and our

recomm ended va lue, the greater the effect on plant concen tration esti mates.

5.3.1 .4 Stan ding Cro p B iom ass (Pr odu ctivity) ( Yp )

U.S . EPA (1998 c) recom men ded th at the best estim ate of Yp is pr oducti vity, which Baes e t al . (1984) and Shor et al. (1982) define as follows:

wh ere Yh i 

### = Harvest yiel d of the i th cr op (k g DW) Ah i 

### = area plant ed to the i th crop (m 2 

### )
U.S. EPA (1994r) and NC DEH NR (1997 ) recommended using this equat ion and calculated a Yp value of 1.6 for aboveground produce, based on weighted aver age Yh and Ah values for four aboveground produce

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### classe s (fr

uits, fruit ing vegetables , legumes, and leafy vegetabl es). Vegetables and fr uits i ncluded in each class were as follows:

• Fruit s—apple, apric ot, berry, cher ry, c ranber

ry, gr ape, peach, pear, plum/pr une, a nd strawb erry

• Fru iting V ege tables

— aspa ragu s, cuc um ber, eg gpla nt, sw eet pe ppe r, and tom ato

• Legumes—snap beans

• Leafy Veget ables —broccoli, bruss el s prouts , caulif lower, cele ry, l ett

uce, and spi nach.
Class-speci fic Yp values were est imated using U.S. aver age Yh and Ah values for avari ety of frui ts a nd veg etab les for 199 3 (U SD A 1 994 a; U SD A 1 994 b). Yh values were conver ted t o dry weight

using average clas s-speci fic convers ion fact ors (Baes et al. 1984). U.S. EPA (1994r and 1995e) calculated class- specifi c Yp values and then used r elati ve ingesti on rates of each group to calc ulate t he weighted average Yp val ue of

1.6. However , t

he pr oduce cl ass es a nd re lat ive inge st ion v alu es us ed by U. S. EPA (1994r and1995e) to calcul ate and weight the Yp values are not curr ent wit

h the U.S. EPA 1997 Exposu re Factors Handbook . In ad dition , ove rall Yp value present ed in U.S. EPA (1994r and U.S. EPA 1995e) was based on limited i nformation; s ubsequent revis ion to U.S. EPA (1994r and 1995e) has result ed in an

ove rall Yp valu e of 1 .7 (R TI 1 997 ).

For consiste ncy, we combined the produce classes into two groups— exposed fruit and exposed vegetables. We derived the exposed vegetable Yp summing Yh values for leafy and fr

uiti ng vegetables and d ividing by the sum of Ah values for l eafy and frui ting vegeta bles . We deri ved the rel ati ve inges tion rat es use d to ca lcul ate an overal l aver age weight ed Yp value from t he homegrown produce disc ussi ons prese nted i n the 1997 Exposure Fact ors Handbook

(U.S. EPA 1997b). We recommend usi ng the weighted average Yp valu e of 2 .24 a s a de fault Yp valu e, bec ause this va lue re pres ents th e m ost co mp lete and thorough information avai lable.

Recom mend ed Value for: Stan ding Cro p B iom ass (Pr odu ctivity) ( Yp )

2.24

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### Unweighted Yp and ingestion rates used for the weighting are as follows:

Aboveground Produce Class Yp Ingestion Rate (g DW/kg-day) Exposed fruits 0.25 0.19 Exposed vegetables 5.66 0.11


### The primary uncertainty associated with this variable is that the harvest yield ( Yh ) and area planted ( Ah ) may not reflect site-specific conditions. To the extent to which site-specific information is available, you can estimate the magnitude of the un certainty introduced by the default Yp value.
5.3.2 Aboveground Produce Concentration Due to Air-to-Plant Transfer ( Pv )
The method we recommend for estimating COPC concentrations in exposed and aboveground produce due to air-to-plant transfer ( Pv ) was developed with cons ideration of items which might limit the transfer of COPC concentrations from plant surfaces to the inner portions of the plant. These limitations result from mechanisms responsible for • inhibiting the transfer of lipophilic COPCs (e.g., the shape of the produce); and • removing COPCs from the edible portion of the produce (e.g., washing, peeling, and cooking). We recommend using Equation 5-18 to calculate Pv . We further discuss the use of this equation in Appendix B, Table B-2-8.

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### Equati on 5-18 Recomm ended Equation f or Calcul ating: Abovegro und Prod uce Concentration Due to A ir-t o-Plant Transfer (Pv )

wh ere Pv = Con centration of CO PC in the plan t resulting from air-to-plant trans fer ( : g CO PC / g DW) Q = CO PC em ission rate (g/s) F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Cyv = Unitized yearl y average air concentrat ion from vapor phase ( : g-s/g-m 3 

### ) Bv ag 

### = CO PC air-to-p lant b iotran sfer fac tor ([m g C OP C/g DW plan t]/[mg CO PC /g

air]) ( unitless) VG ag 

### = Em pirical correcti on factor for aboveg round pro duce (unitless) D a 

### = De nsity of air (g /m 3 

### )

Chapters 2 and 3 explain how we recommend q uantifyi ng the COPC emission rat e ( Q ). App endix A-2 describes how we recom mend determining the C OPC -specific parameters Fv and Bv ag 

### . Chap ter 3 describes generati ng the modeled air par ameter Cyv . As di scuss ed below i n Secti on 5.3. 2.1, the param eter VG ag 

### de pe nds on t he l ip oph il ic it y of t he COPC. App en di x B f ur th er de sc ribe s h ow we recommend usi ng Equati on 5-18, incl uding cal culat ing D a 

### .

5.3.2 .1 Em pirical Correction Factor for Abovegroun d Produce ( VG ag 

### )

The param eter VG ag 

### was incor porat ed int o Equati on 5-18 t o addres s the potent ial to over est imate the transfer of l ipophil ic COPCs to the inner porti ons of bul ky produce, such as apples . Because of the prote cti ve outer

skin, siz e, a nd shape of bulky produc e, t

ransf er of li pophili c COPCs (log K ow 

### greater than 4) to the ce nter

of t he produce is not

as l ikel y as for

non-lipophili c COPCs. As a re sult , the inner porti ons will be le ss af

fect ed.

To a ddress th is issue, U.S . EPA (1994 m) reco mm ende d an em pirical correctio n factor ( VG ag 

### ) of 0. 01 for lipophil ic COPCs to reduce estimate d vegetable concentrati ons. The fact or of 0.01 is based on a simil ar correction factor ( VG rootveg 

### ) for b elow gro und prod uce . VG rootveg 

### was estimate d for unspecif ied vegetabl es as follows:

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### Equati on 5-19

wh ere VG rootveg 

### = Correct ion fa ctor for be lowground produc e (g/ g) M skin 

### = Mass of a t hin (s kin) l ayer of

belowground ve getabl e (g) M vegetable 

### = Mass of the enti re vege tabl e (g)

As sum ing th at the d ensity of the skin and the w hole veg etab le are th e sam e, this eq uatio n be com es a ratio of the volu me of the skin to tha t of the wh ole v ege table. U .S. E PA (199 4m ) assu me d tha t the v ege table skin is 0.03 centim eters, w hich is the lea f thick ness of a b road -leaf tree , as w as us ed in exp erim ents conducte d by Rieder er ( 1990). Using thi s ass umption, U.S. EPA (1994m) ca lcul ated VG rootveg 

### values of 0.09 and 0. 03 for

car rot s andpota toe s, res pect ive ly.

Based on the work by Wipf etal. (1982), U.S. EPA (1994m) i denti fie d other proces ses—such as peeli ng,
coo ki ng, andcl ea ni ng—th at fu rt her re duc e the v ege tabl e c onc ent ra ti on. U. S. EPA ( 199 4m) recommended a VG rootveg 

### value of 0.01 for l ipophil ic COPCs. These are l ess t han the est imate s of 0. 09 and 0.03 for the c arrot s and pot atoes mentione d earl ier , but great er t han the est imate would be i f the

corre ction facto r wa s adju sted fo r clean ing, w ashin g, an d pe eling , as de scribe d by W ipf et al. (1 982 ). Fol lo win g t hi s l in e of

re as oni ng, U.S . E PA ( 199 4m) re comme nde d a li pop hi li c COPC VG ag 

### value of 0.01 for a ll aboveground pr oduce exce pt l eafy vege tabl es. As with VG rootveg 

### , U.S. EPA (1994m) noted that assi gnment of t

his va lue i s base d on the c onside rat ion that i t “s hould be l ess t han est imate d just

based on surfa ce vo lum e to w hole fruit vo lum e ratio s.”

U.S . E PA ( 199 4m) re comme nde d a li pop hi li c COPC VG ag 

### of 1.0 for pasture gra ss because of a direct analogy to exposed azalea and grass l eaves (for

which data were avail able). Pasture gr ass is described as “lea fy veget ati on.” However, the l eafy vege tabl e group, as def ined i n Secti on 5.3. 1.1, is c omposed of bulkie r produc e such a s brocc oli, bruss el s prouts , caulif lower, cele ry, l ett

uce, and spi nach. In addi tion, the out er l eaves of

most of the pr oduce in this cate gory are removed duri ng prepar ati on. Ther efore , the VG ag 

### valu e of 1 .0 for leafy veg etab les is ina ppr opr iate an d m ay o vere stima te CO PC con cen tration s. A def aul t l ip oph il ic COPC VG ag 

### value of 0.01 for leafy vegetables is mo re appropriate for leafy vegetables, bec ause the lea fy v ege table c ateg ory repre sents bulk ier, m ore p rotec ted p lants a s com pare d to sin gle

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### leaves of grass blades. U.S. EPA (1994r) and NC DEHNR (1997) recommended a lipophilic COPC VG ag 

### value of 0.01, for all classes of aboveground produce.
For COPCs with a log K ow 

### greater than 4, we recommend using a lipophilic VG ag 

### value of 0.01 for all aboveground exposed produce. For COPCs with a log K ow 

### less than 4, we recommend using a VG ag 

### value of 1.0, because we assume these COPCs pass more easily through the skin of produce.

Recommended Values for: Empirical Correction Factor for Aboveground Produce ( VGag 

### ) 0.01 for COPCs with a log K ow 

### greater than 4 1.0 for COPCs with a log K ow 

### less than 4
Uncertainty may be introduced by assuming VG ag 

### values for leafy vegetables (such as lettuce) and for legumes (such as snap beans). Assuming a VG ag 

### value of 0.01 for legumes and leafy vegetables may underestimate concentrations because these species ofte n have a higher ratio of surface area to mass than other bulkier fruits and fruiting vegetables, such as tomatoes.
5.3.3 Produce Concentration Due to Root Uptake (Pr )
Root uptake of contaminants from soil may contribute to COPC concentrations in aboveground exposed produce, aboveground prot ected produce, and belowground produce. As in previous guidance (U.S. EPA 1994m ; U.S. EPA 1994r; and U.S. EPA 1995e), we recommend using Equations 5-20A and 5-20B to calculate Pr . We discuss the use of these equations further in Appendix B.

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### Equati on 5-20A

Equati on 5-20B Recomm ended Equation f or Calcul ating: Produce C oncentration Due to Root Up take ( Pr ) Exposed an d protected aboveground p roduce:

Belowgroun d produce:

wh ere Pr = Concentr ati on of COPC in produce due to r oot upt ake (mg/ kg) Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) Br = Plant-soil bioconcentration factor for produce (unitless) RCF = Root con centration factor (unitless ) VG rootveg 

### = Em pirical correcti on factor for belowg round pro duce (unitless) Kds 

### = Soil/ water parti tion coeff

ici ent ( L/kg)

Appendix B and Sect ion 5. 2 explai n how we recommend calc ulat ing Cs . Appendix A-2 descr ibes how

we recom mend calculating the COP C-specific parameters Br , RCF , and Kds 

### . Si milar to VG ag 

### and as discu ssed in Se ction 5.3.2 .1, VG rootveg 

### is base d on the lip oph ilicity o f the C OP C.
Equati on 5-20A is based on t he soi l-t o-abovegr ound plant transfer approac h develope d by Travis and Arms (1988). This approach is appropriat e for eval uating exposed and protect ed aboveground produce; however, it might not

be appropriat e for soi l-t o-belowground plant transfers. For belowground produce, U.S. EPA (1994m) and U. S. EPA (1995e) r ecommended Equati on 5-20B, whic h incl udes a r oot
con cen tration facto r (RC F) d eve lope d by Brig gs et a l. (198 2). R CF is the ra tio of C OP C co nce ntratio n in the ed ible ro ot to th e CO PC con cen tration in the soil w ater. S ince Brig gs et a l. (198 2) co ndu cted their exp erim ents in a gro wth solu tion, in orde r to us e this e qua tion y ou m ust d ivide the C OP C so il concentrat ion ( Cs ) by the C OP C-s pec ific soil/w ater p artition coef ficien t ( Kds 

### ) (U.S . EP A 1 994 m).
As in U.S. EPA (1994m ), we recommend using a VG rootveg 

### value of 0.01 for l ipophil ic COPCs (l og K ow 

### great er than 4) bas ed on root vegeta bles li ke carrots and pota toes . A val ue of 0. 01 appear s to r epres ent the most complet e and thorough inf ormati on avail able. For COPCs with a l og K ow 

### l es s t ha n 4 , we recommend a VG rootveg



### value of 1.0.

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### Recommended Values for: Empirical Correction Factor for Belowground Produce ( VGrootveg 

### ) 0.01 for COPCs with a log K ow 

### greater than 4 1.0 for COPCs with a log K ow 

### less than 4

5.4 CALCULATING COPC CONCENTRATIONS IN BEEF AND DAIRY PRODUCTS
We generally recommend that you estimate COPC concentrations in beef tissue and milk products on the basis of the amount of COPCs that cattle are assumed to consume through their diet. The HHRAP assumes the cattle's diet consists of: • forage (primarily pasture grass and hay), • silage (forage that has been stored and fermented), and • grain. Additional contamination may occur through the cattle ingesting soil. The HHRAP calculates the total COPC concentration in the feed items (e.g., forage, silage, and grain) as a sum of contamination occurring through the following mechanisms:

• Direct deposition of particles —wet and dry deposition of particle phase COPCs onto forage and silage (Section 5.4.1).

• Vapor transfer —uptake of vapor phase COPCs by forage and silage through foliage (Section 5.4.2).

• Root uptake —root uptake of COPCs available from the soil and their transfer to the aboveground portions of forage, sila ge, and grain (Section 5.4.3).
Feed items consumed by animals can be classifiedas exposed or protected, depending on whether they have a protective outer covering. Because the outer covering on protected feed acts as a barrier, we assume that there is negligible contamination of protected feed through depos ition of particles and vapor transfer. In the HHRAP, grain is classified as prot ected feed. As a result, we recommend that you assume grain contamination occurs only through root uptake. We also recommend assuming that contamination of exposed feed items, including forage and silage, occurs through all three mechanisms.

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Wet and Dry Deposition of Particles (Section 5.4.1) Root Uptake from Soil (Section 5.4.3) Forage and

Silage Concentration

Grain Concentration

COPC Concentration in Beef & Dairy Products Soil Concentration 

### FIGURE 5-4 COPC CONCENTRATION IN BEEF AND DAIRY PRODUCTS The HHRAP assumes that the amount of grain, silage, forage, and soil consumed varies between dairy and beef cattle. Sections 5.4.4 (beef) and 5.4.5 (dairy) describe the methods we recommend to estimate consumption rates and subsequent COPC concentrations in cattle. As in previous guidance (U.S. EPA 1990e and 1994a; NC DEHNR 1997), we recommend assuming that 100 percent of the plant materials eaten by cattle were grown on soil contaminated by emission sources. Therefore, we recommend assuming that 100 percent of the feed items are contaminated.
Appendix B, Tables B-3-1 through B-3-11, describe how we recommend calculating (1) the COPC concentrations in soil and feed ite ms (forage, silage, and grain) cons umed by beef and dairy cattle, and (2) the resulting COPC concentrations in beef and milk.
5.4.1 Forage and Silage Concentrations Due to Direct Deposition ( Pd)

COPC concentrations in fora ge and silage result from we t and dry deposition onto exposed plant surfaces; similar to aboveground produce (Section 5.3.1). Therefore, we recommend also using Equation 5-14 to calculate Pd for forage and silage. We discuss calculating Pd for Forage and silage furthe r in Appendix B. Appendix A- 2 explains how we recommend calculating COPC-specific Fv values for forage and silage (i.e. exactly as they are calculated for aboveground produce). Sections 5.4.1.1 through 5.4.1.4 describe how we recommend calculating Rp , kp , Tp , and Yp for use in calculating forage and silage concentrations.

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### 5.4.1.1 Interception Fraction of the Edible Portion of Plant ( Rp )
As discussed in Section 5.3.1.1, Chamberlain (1970) found a correlation between Rp and productivity, Yp (standing crop biomass). This correlati on is expressed in Equation 5-14A.
Based on U.S. EPA (1994r and 1995b) and NC DE HNR (1997), we recommend using Equation 5-14 to calculate Rp values for forage and silage.
Substituting the Baes et al. (1984) empirical constant ( ( 

### ) value of 2.88 for pasture grass, and the standing crop biomass value of 0.24 kg DW/m 2 

### (these variables are discussed in Section 5.3.1.1) into Equation 5- 14, the forage-specific Rp is 0.5. Substituting the Baes et al. (1984) empirical constant ( ( 

### ) value of 0.769 for silage, and the standing crop biomass value of 0.8 kg DW/m 2 

### into Equation 5-14, the silage-specific Rp value is 0.46.

Recommended Value for: Interception Fraction of the Edible Portion of Plant ( Rp ) Forage = 0.5 Silage = 0.46

Several uncertainties are associated with the Rp variable: • The empirical relationship developed by Chamberlain (1970) is based on a study of pasture grass, and therefore may not accurately represent site-specific silage types. • The empirical constant for silage developed by Baes et al. (1984) used in Chamberlain’s empirical relationship may also fail to accurate ly represent site-specific silage types. • The range of empirical constants recommended by Baes et al. (1984) for pasture grass does not result in a significant range of estimated Rp values for forage (the calculated Rp range is 0.42 to 0.54). Therefore, using the empirical constant midpoint (2.88 for pasture grass) does not significantly affect the Rp value and the resulting estimate of plant COPC concentration.
5.4.1.2 Plant Surface Loss Coefficient (kp )
We recommend using Equation 5-15 (Section 5.3.1.2) to calculate the plant surface loss coefficient kp for aboveground produce. The kp factor is derived in the same manne r for cattle forage and silage. The uncertainties of kp for cattle forage and silage are simila r to the uncertainties for aboveground produce.

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### Equati on 5-21 5.4.1 .3 Len gth o f Plan t Exp osur e to D epos ition pe r Ha rvest of th e Ed ible Po rtion o f Plan t ( Tp )

As discussed in S ection 5.3.1.3, the HHR AP treats Tp as a constant, based on t he average peri od between

succ essiv e hay harv ests. T his p eriod , wh ich B elch er an d T ravis ( 198 9) estim ated at 60 day s, repre sents the l ength of

ti me that

aboveground ve getat ion (i n thi s cas e, ha y) would be expos ed to pa rti cle de posit ion before being ha rvest ed. We used E quation 5-16 (Sect ion 5.3.1. 3), t o calculat e a Tp of 0.1 6 y ear fo r cattle sila ge.

For ca ttle forage, w e mo dified E quation 5-16 to consid er the ave rage of :
1. the ave rage pe riod be tween suc cess ive hay harvest s, and
2. the av erag e per iod b etw een succ essiv e gra zing

.

Based on Belcher and T ravis (1989), the we assum ed the average period b etween hay harvests is 60 days, and the avera ge peri od between s uccess ive gr azing i s 30 days. We theref ore ca lcul ated Tp as follo ws :

Recom mend ed Value for: Plan t Exp osur e Len gth to Dep osition p er H arve st of the E dible P ortion of Plan t ( Tp ) Forag e = 0. 12 yr Sil age = 0 .16 yr
The primar

y uncert aint ies assoc iat ed with Tp are si milar t o those for aboveground produce, as discussed in Sect ion 5. 3.1. 3.

5.4.1 .4 Stan ding Cro p B iom ass (Pr odu ctivity) ( Yp )

As d iscussed in Section 5.3.1.4, U .S. EP A (1 998 c) stated that the best estima te of Yp is producti vity, as defi ned in Equat ion 5-17. Consequent ly, unde r thi s approa ch, you would c onside r dry har vestyiel d ( Yh ) and are a harve ste d (Ah ).

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### We calculated forage Yp as a weighted average of the calculated pasture grass and hay Yp values. We assumed weightings of 0.75 for forage and 0.25 for hay. The weightings are based on the fraction of a year that cattle are assumed to be pastured and eati ng grass (9 months per year) or not pastured and fed hay (3 months per year). We assumed an unweighted pasture grass Yp of 0.15 kg DW/m 2 

### (U.S. EPA 1994r; U.S. EPA 1994m). We then calculated an unweighted hay Yp of 0.5 kg DW/m 2 

### using Equation 5-17 and the following Yh and Ah values: Yh = 1.22×10 11 

### kg DW, calculated from the 1993 U.S. average wet weight Yh of 1.35×10 11 

### kg (USDA 1994b) and a conversion factor of 0.9 (Fries 1994). Ah = 2.45×10 11 

### m 2 

### , the 1993 U.S. average for hay (USDA 1994b). The unweighted pasture grass and hay Yp values were multiplied by their weighting factors (0.75 and 0.25, respectively), and summed to calculate the recommended weighted forage Yp of 0.24 kg DW/m 2



### . We recommend assuming a production-weighted U.S. average Yp of 0.8 kg DW/m 2 

### for silage (Shor, et al. 1982).

Recommended Values for: Standing Crop Biomass (Productivity) ( Yp ) Forage = 0.24 kg DW/m 2



### Silage = 0.8 kg DW/m 2


### The primary uncertainty associated with this variable is that the harvest yield ( Yh ) and area planted ( Ah ) may not reflect site-specific conditions. To the extent that site-specific information is available, it’s feasible to estimate the magnitude of th e uncertainty introduced by the default Yp value. In addition, the weightings assumed in this discussion for the amount of time that cattle are pastured (and foraging) or stabled (and being fed silage) coul d be adjusted to reflect site-specific conditions, as appropriate.
5.4.2 Forage and Silage Concentrations Due to Air-to-Plant Transfer ( Pv )
We recommend using Equation 5-18 (Section 5.3.2) to calculate the COPC concentration in aboveground produce resulting from air-to-plant transfer ( Pv ). Pv is calculated for cattle fora ge and silage similarly to the way that it’s calculated for aboveground pr oduce. We provide a detailed discussion of Pv in Section 5.3.2. We present differences in VG ag 

### values for forage and silage, as compared to the values for aboveground produce described in Section 5.3.2.1, in Section 5.4.2.1. We discuss calculating Pv further

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### in Appendix B. Appendix A-2 explains how we recommend calculating COPC-specific Bv values for forage and silage (i.e. the same as th ey are calculated for aboveground produce).
5.4.2.1 Empirical Correction Factor for Forage and Silage ( VGag 

### )
Please Section 5.3.2.1 for a detailed, general introduction to VG ag 

### . Using such a factor while estimating COPC concentrations specifically for forage and sila ge assumes that there is insignificant translocation of COPCs deposited on the surface of bulky silage to the inner parts of the vegetation. Applying a silage VG ag 

### would be relevant if the silage can’t be characteri zed as leafy (e.g., if grain is used as silage). As a point of clarification, forage and silage are consid ered vegetative plant parts, and grains are considered reproductive plant parts.
U.S. EPA (1994m) didn’t recommend a VG ag 

### value for silage. NC DEHNR (1997) recommended a VG ag 

### factor of 0.5 for bulky silage but didn’t present a specific rationale for this value. U.S. EPA (1995b) noted that a volume ratio of outer whole surface area to volume of vegetation could be used to assign a silage VG ag 

### value, if one knew the proportions of each type of vegetation of which sila ge consisted. In the absence of specific data concerning the quantities of di fferent silage material (e.g., hay and grain), U.S. EPA (1995b) recommended assuming a VG ag 

### of 0.5 for silage without rigorous justification.
We recommend using VG ag 

### values of 1.0 for forage and 0.5 for silage. As discussed, the primary uncertainty associated with this variable is the lack of specific information on the proportions of each vegetation type of which sila ge may consist, leading to the default assumption of 0.5.

Recommended Values for: Empirical Correction Factor for Forage and Silage ( VGag 

### ) Forage = 1 Silage = 0.5
5.4.3 Forage, Silage, and Grain Concentrations Due to Root Uptake (Pr )
We recommend using Equations 5-20A and 5-20B (Section 5.3.3) to calculate the COPC concentration in aboveground and belowgr ound produce resulting from root uptake. Pr is calculated for cattle forage, silage, and grai n in the same way that it is calculated for aboveground produce, except that we recommend using forage/silage- and grain-specific

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### Equati on 5-22 bioconcen tration factors ( Br forage 

### and Brgrain 

### respe cti vely). Appendix A-2 expl ains how we recommend calculat ing COPC -specif ic Br values for f

orage a nd sil age (i .e. exact ly as it’ s cal culat ed for aboveground produce) . We provide a det ail ed dis cussi on on how we recommend calc ulat ing Pr in Se ction 5.3.3 . W e further disc uss the ca lculation o f Pr in Appe ndi x B.

5.4.4 Beef

Concent rati on Resul ti ng fr om Plant and Soi l I ngest ion ( A beef 

### )

As in U.S. EPA (1995h), we r ecommend using Equat ion 5-22 to cal culat e COPC concentra tion in beef t issue (

A beef 

### ). The eq uat ion was modif iedfr om an equ ati on pre sent ed i n U.S. EPA (1990c), U.S. E PA (19 94r), U.S. EPA (1995b), and N C D EH NR (1996) by introducing a me tabolism fact or (MF). Equati on 5-22 cal culat es the daily amount of aCOPC that is consumed by cat tle through the ingestion of contamina ted feed items (plant) and soil. The equation includes biotransfer and m etabolism fact ors t o transform the dai ly ani mal int ake of a COPC (mg/day) int o an ani mal COPC tiss ue
con cen tration (mg CO PC /kg tis sue) . W e furth er disc uss u sing this eq uatio n in A ppe ndix B, T able 3-10

.

Recomm ended Equation f or Calcul ating: Co ncen tration of CO PC in Bee f ( A beef 

### )

wh ere A beef 

### = Concentration of COPC in beef (mg COP C/kg FW tis sue) F i 

### = Fraction of plant type i grown on contaminated soil and i ngested by the animal

(cattle) (unitless) Qp i 

### = Quantity of plant type i eat en by t

he ani mal ( cattl e) p er d ay (k g DW plant /da y) P i 

### = Concentr ati on of COPC in each pl ant t ype i eaten by the ani mal (catt le) ( mg / kg DW) Qs = Quanti ty of soi l e ate n by th e ani mal ( cattl e) e ach day (kg/ day) Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) Bs = Soil bioavailability factor (unitl ess) Ba beef 

### = COP C biotransfer factor for beef ( day/kg FW tis sue) MF = M etabolism factor (unitless)
Sections 5.4.4.1 through 5.4.4.7 describe the parameters F i 

### , Qp i 

### , P i 

### , Qs , Cs , Bs, and MF , respe ctively

. Ap pend ix A-2 explain s how we rec om men d calcula ting the C OP C-sp ecific param eter Ba beef 

### .

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### 5.4.4 .1 Fraction of Plant Type i Gro wn on C onta min ated S oil and Eate n by the A nim al (Ca ttle)( F i 

### )

As in U.S. EPA (1990e and 1994r) , and NC DEHN R (1997), we recommend ass uming that 100 perce nt of the plant

mater ial s eat en by cattle were grown on soi l cont aminat ed by the e missi on source s bei ng evalua ted. This as sum ption tran slates to a defau lt value of 1 .0 for F i 

### .

Recom mend ed Value for: Fraction of Plant Type i Gro wn on C onta min ated S oil and Eate n by the A nim al (Ca ttle) ( F i 

### ) 1

5.4.4 .2 Quantity of Pl ant Type i Eaten by the Animal ( Cattle ) Each Day ( Qp i 

### )

Th e daily qua ntity of pla nts ea ten b y ca ttle can be es tima ted (k g D W /day ) for ea ch ca tego ry o f plan t feed

. U.S . EP A (1 994 r and 199 8c) a nd N C D EH NR (199 7) rec om me nde d inc ludin g for age , silage , and grain feed s in this estim ate.

NC DE HNR (1997) r ecommended plant inges tion rat es for

the c att le of

eit her subs ist ence bee f fa rmers or typical beef far

mers. Subsist ence beef far mers rely on a higher

percentage of forage and si lage to f eed catt le, whereas typic al bee f fa rmers rel y on great er amount s of gr ain t o feed c att le. U.S. EPA (1990e) and U.S . EP A (1 994 r) iden tified p lant in gestio n rate s on ly fo r sub sisten ce farm ers. T he fo llow ing d aily quant it ies of f

orag e, grai n, a nd si lag e ea ten by cat tl e were rec ommended by NC DEHNR (1997) , U. S. EPA (1994 r and 1 990 e), and B oon e et al. (1981 ):

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Source Forage

(kg DW/da

y) Grain (kg DW/da

y) Silage (kg DW/da

y) References
NC DEHNR (1997) Subsisten ce Farmer Beef Cattle 8.8 0.47 2.5 Boone et al. (1981) NAS (1987)
NC DEHNR (1997) Typical Farm

er Beef Cattle 3.8 3.8 1.0 Rice (1994)

U.S. EPA ( 1994r) Subsisten ce Farmer Beef Cattle 8.8 Not report ed Not report

ed Boone et al. (1981) NAS (1987)
U.S. EPA ( 1990e) Subsisten ce Farmer Beef Cattle 8.8 0.47 2.5 Boone et al. (1981) McKone and

Ryan (1989) Boone et al. (1981) 8.87 1.9 2.5 Boone et al. (1981)



### W ith the exception of a higher grain ingestion rate, Boon e et al. ( 1981) rates are consistent with those recommended by U.S. EPA (1990e and 19 94r), and NC DEH NR (1997 ). For t ypical far

mer beef catt le, NC D EHN R (1997) cites Ric e (1994) as a r eference f or the Qp i 

### vari ables and note s tha t the value s inc lude grain supplemented duri ng the growing phase for beef cattl e.
U.S. EPA (1990e) noted t hat McKone and Ryan (1989) reported an avera ge tot al i ngest ion ra te of 12 kg DW/day f

or t he t hree pla nt f

eeds , whi ch i s con si st entwit h the tot al rec ommended by U. S. EPA (199 0e) and NC DE HN R (19 97) (fora ge, grain, an d silage total o f 11.8 k g D W /day). U .S. EP A (1 994 r) and NC DEH NR (1997) als o noted t hat NAS (1987) r eport ed a dai ly dry matter int ake that i s 2 per cent of

an aver age beef

catt le body wei ght of 590 kil ograms. This r esul ts i n a dai ly tot al i ntake r ate of 11.8 kg DW/day. NAS (1987) r eport ed that a nonla ctat ing cow eat s dry mat ter equival ent t o 2 perce nt of its bo dy we ight.

We recomm end using the fol lowing beef catt le ingest ion rate s of forage, sil age, and grai n. These values

are base d on t he t ota l da il y int ake r ate of about 12 kg DW/day.

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### Equati on 5-23 Recom mend ed Values for: Quantity of Pl ant Type i Eaten by the Animal ( Cattle ) Each Day ( Qp i 

### ) Forage = 8.8 kg DW /day Silage = 2.5 kg DW/day Grain = 0.47 kg DW /day

The princ ipal uncert aint y associ ated wi th Qp i 

### is t he vari abil ity be tween for age, sil age, and grai n inges tion rates fo r cattle.

5.4.4 .3 Concentration of CO PC in Plant Typ e i Eate n by the A nim al (Ca ttle) ( P i 

### )

We gen erall y recommend using Eq uation 5-23 to ca lculat e the tot al COPC con centrat ion in fora ge, si lage, and g rain. W e recom men d deriv ing va lues for Pd , Pv , and Pr for e ach type of fe ed by usi ng Equati ons 5-14, 5-18, and 5- 20, r espe cti vel y.

Recomm ended Equation f or Calcul ating: Concentration of CO PC in Plant Typ e i Eate n by the A nim al (Ca ttle) ( P i 

### )

wh ere P i 

### = Concentration of COPC in each plant t ype i ea te n by th e a ni mal (mg CO PC / kg DW) Pd = Pl an t co nc en tr at io n d ue t o d ir ec t de pos it io n ( mg COP C/ kg DW) Pv = Pl an t co nc en tr at io n d ue t o a ir -t o- pl an t tr an sf er (m g COP C/ kg DW) Pr = Pl an t co nc en tr at io n d ue t o r oot up take (m g COP C/ kg DW)

Thi s e qua ti on i s f

ur th erdes cr ib ed i n App end ix B.

5.4.4 .4 Quantity of

Soil Eaten by the Animal ( Cattle ) Per Day ( Qs )

Ad dition al cattle c onta min ation occu rs thro ugh inge stion of so il.

NC DE HN R (1 997 ) and U.S . EP A (1 994 r) reco mm end ed a s oil ing estion rate fo r sub sisten ce be ef cattle of 0.5 kg/day. This rate i s based on Fries (1994). U.S. EPA (1994r) and NC D EHN R (1997) noted that

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### Fries (1994) reported soil ingestion to be 4 percent of the total dry matter intake. NAS (1987) was also referenced. NAS (1987) cited an average beef cattle weight of 590 kg, and a daily dry matter intake rate (nonlactating cows) of 2 percent of body weight. This results in a daily dry matter intake rate of 11.8 kg DW/day and a daily soil ingestion rate of about 0. 5 kg/day. U.S. EPA (1990e) reported a soil ingestion rate that is 3 percent of the forage intake rate of 8.8 kg DW/day, resulting in a daily soil ingestion rate of approximately 0.3 kg/day. Simmonds and Linsley (1981) and Thornton and Abrams (1983) were cited as the references for this assumption.
We recommend using 0.5 kg/day for the quantity of soil ingested by the animal (cattle).

Recommended Value for: Quantity of Soil Ingested by the Animal (Cattle) Per Day ( Qs ) 0.5 kg/day
5.4.4.5 Average Soil Concentration Over Exposure Duration ( Cs )
We recommend using Equations 5-1C, 5-1D, and 5-1E to calculate the COPC concentration in soil as discussed in Section 5.2.1. Also, Appendix B fu rther describes how we recommend calculating the soil concentration.
Please Note: You might need to generate soil concentration estimates for grain separate from those for forage and silage. Currently , the HHRAP assumes that forage and silage are grown on untilled land, and grain is gr own on tilled land. We highly recommend that your C s 

### calculations include the appropriate Z s 

### (1 for untilled land, 20 for tilled land).
5.4.4.6 Soil Bioavailability Factor (Bs )
The efficiency of transfer from soil may differ from the efficiency of transfer from plant material for some COPCs. If the transfer efficiency is lower for soils, th en the ratio would be less than 1.0. If it is equal to or greater than that of vegetation, the Bs value would be equal to or greater than 1.0.
Until more COPC-specific data becomes available for this parameter, we recommend a default value of 1 for Bs

.

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### Recommended Values for: Soil Bioavailability Factor (Bs ) 1.0

5.4.4.7 Metabolism Factor ( MF )
The metabolism factor (MF ) estimates the amount of COPC that remains in fat and muscle. Based on a study by Ikeda et al. (1980), U.S. EPA (1995h) used a COPC-specific MF to account for metabolism in animals and humans. Evidence indicates BEHP is mo re readily metabolized and excreted by mammalian species than other contaminants (ATSDR 1987). As in U.S. EPA (1995h), we recommend a MF of 0.01 for bis(2-ethylhexyl)phthalate (BEHP). Lacking data to support derivation of other chemical-specific MF s, we recommend using a MF of 1.0 for all chemicals other than BEHP. Using the recommended values for this variable, MF has no quantitative effect on A beef 

### (with the exception of BEHP).

Recommended Values for: Metabolism Factor (MF ) bis(2-ethylhexyl)phthalate (BEHP) = 0.01 All other COPCs = 1.0

The MF presented above for BEHP applies only to mamma lian species, including beef cattle, dairy cattle, and pigs. It does not relate to metabolism in produ ce, chicken, or fish. In addition, since exposures evaluated in this guidance are intake driven, using an MF applies only to estimating COPC concentrations in food sources used in evaluating indirect human e xposure, including ingestion of beef, milk, and pork. In summary, an MF is not applicable for direct exposures to air, soil, or water, or to ingestion of produce, chicken, or fish.
5.4.5 COPC Concentration In Milk Due to Plant and Soil Ingestion ( A milk 

### )
We recommend modifying Equation 5-22 (Section 5.4. 4) to calculate COPC milk concentrations ( A milk 

### ), as follows:

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### Equati on 5-24 Recomm ended Equation f or Calcul ating: Concent rati on of COPC in Mil k ( A milk 

### )

wh ere A milk 

### = Concentr ati on of COPC in milk ( mg COP C/kg milk) F i 

### = Fraction of plant type i grown on contaminated soil and i ngested by the animal

(dairy cattle) ( unitless) Qp i 

### = Quantity of plant type i ea te n b y t he an im al (d ai ry ca tt le ) e ac h d ay (k g DW pla nt/ day) P i 

### = Concentration of COPC in plant type i eaten by the ani mal (dairy cat tle) ( mg / kg DW) Qs = Quanti ty of soi l e ate n by th e ani mal ( dai ry ca tt le) eac h day ( kg soi l/ day) Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) Bs = Soil bioavailability factor (unitl ess) Ba milk 

### = COP C biotransfer factor for milk ( day/kg W W tissue) MF = M etabolism factor (unitless)

Ap pend ix A-2 explain s how we rec om men d calcula ting the C OP C-sp ecific param eter Ba milk 

### . The discussion in Section 5.4.4 of the variables F i 

### , Qp i 

### , P i 

### , Qs , Cs , and MFfor b eef ca ttle gen erally app lies to the cor respondi ng vari ables for da iry c att le. However, t here a re some di ffer ences i n assumpt ions made for dairy cattle; t

hese differences are summ arized in the following subsections.

We recomm end using Equation 5-24 to est imate A milk 

### . Usin g E qua tion 5 -24 is desc ribed furth er in Appendix B, Tabl e B-3-11.

5.4.5 .1 Fraction of Plant Type i Grow n on Co ntaminated Soil and Eaten by the Animal (Dairy Ca ttle) ( F i 

### )

The calculation of F i 

### for dairy c attle is identical to that for b eef cattle (Sectio n 5.4.4 .1).

5.4.5 .2 Quan tity of

Plant Type i Eaten by the Animal ( Dairy Cattl e) Per Day ( Qp i 

### )

As discu ssed in Se ction 5.4.4 .2, the daily qua ntity of fo rage , silage , and grain feed con sum ed b y ca ttle is esti mated for each cat egory of feed materi al. How ever, dai ly ingesti on rates f or dairy cat

tle ar e esti mated

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### differently than for beef cattle. We generally r ecommend estimating the daily quantity of feed consumed by cattle on a dry weight basis for each category of plant feed.
NC DEHNR (1997) recommended using plant ingestion rates for either subsistence dairy farmer or typical dairy farmer cattle. In addition, subsisten ce dairy farmers rely on a higher percentage of forage and silage to feed cattle, whereas typical dairy farm ers rely on greater amounts of grain to feed cattle. U.S. EPA (1990e and 1994r) identified plant ing estion rates only for subsistence farmers.
The following daily quantities of forage, grain, and s ilage eaten by dairy cattle were recommended by NC DEHNR (1997), U.S. EPA (1994r), U.S. EPA (1990e), and Boone et al. (1981):

Source Forage (kg/day DW) Grain (kg/day DW) Silage (kg/day DW) References

NC DEHNR (1997) Subsistence Dairy Farmer Cattle 13.2 3.0 4.1 Boone et al. (1981) NAS (1987)

NC DEHNR (1997) Typical Dairy Farmer Cattle 6.2 12.2 1.9 Rice (1994)

U.S. EPA (1994r) Subsistence Dairy Farmer Cattle 13.2 Not reported Not reported Boone et al. (1981) NAS (1987)

U.S. EPA (1990e) Subsistence Dairy Farmer Cattle 11.0 2.6 3.3 Boone et al. (1981) McKone and Ryan (1989) Boone et al. (1981) 11.0 2.6 3.3 Boone et al. (1981)


### U.S. EPA (1990e) noted that McKone and Ryan ( 1989) reports an average total ingestion rate of 17 kg/day DW for the three plant feeds, which is cons istent with the total ingestion rate recommended by U.S. EPA (1990e). U.S. EPA (1994r) and NC DEHNR (1997) noted that NAS (1987) reports a daily dry matter intake that is 3.2 percent of an average dairy cattle body weight of 630 kilograms. This results in a daily total intake rate of appr oximately 20 kg/day DW, which is c onsistent with the average total ingestion rates for the three plant feeds recommended by U.S. EPA (1994r) and NC DEHNR (1997) . NAS (1987) reported that dairy cows eat dry matter e quivalent to 3.2 percent of their body weight; the

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### 630-kilogram average dairy cow body weight was not confirmed. U.S. EPA (1995b) also cited a feed ingestion rate of 20 kg/day DW, citing U.S. EPA (1993c).
Based on more recent references (NAS 1987; U.S. EPA1993c) which recommend a feed ingestion rate of 20 kg/day DW, we recommend a default total inges tion rate of 20 kg DW/day for dairy cattle.

Recommended Values for: Quantity of Plant Type i Eaten by the Animal (Dairy Cattle) Per Day ( Qp i 

### ) Forage = 13.2 kg DW/day

Silage = 4.1 kg DW/day Grain = 3.0 kg DW/day
Uncertainties associated with estimating Qp i 

### include estimating forage, grai n, and silage ingestion rates, which will vary from site to site. Assuming uniform contamination of plant materials consumed by cattle also introduces uncertainty.
5.4.5.3 Concentration of COPC in Plant Type i Eaten by the Animal (Dairy Cattle) (Pi 

### )

The estimation of P i 

### for dairy cattle is identical to that for beef cattle (Section 5.4.4.3).
5.4.5.4 Quantity of Soil Eaten by the Animal (Dairy Cattle) Per Day ( Qs )
As discussed in Section 5.4.4.4, contamination of dairy cattle also results from the ingestion of soil. We generally recommend the following soil ingestion rate for dairy cattle:

Recommended Values for: Quantity of Soil Eaten by the Animal (Dairy Cattle) Per Day ( Qs ) 0.4 kg/day

U.S. EPA (1994r) and NC DEHNR (1997) recommended a soil ingestion rate of 0.4 kg/day for dairy cattle, based on Fries (1994). U.S. EPA (1994r) and NC DEHNR (1997) noted that Fries (1994) reported soil ingestion rates as 2 percent of the total dry ma tter intake. NAS (1987) was also referenced, which

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### reported an average dairy cattle weight of 630 kilogr ams and a daily dry matter intake rate (nonlactating cows) of 3.2 percent of body weight. This resulted in a daily dry matter intake rate of 20 kg/day DW, and a daily soil ingestion rate of approximately 0.4 kg/day. NC DEHNR (1997) recommended a soil ingestion rate of 0.2 kg/day for the cattle of typical dairy farmers, citing Rice (1994). U.S. EPA (1990e) reported soil ingestion rates as 3 percent of the fora ge intake rate. U.S. EPA (1990e) assumed that the more protective forage intake rate of 13.2 kg/day DW results in a daily soil ingestion rate of about 0.4 kg/day. Simmonds and Linsley (1981) and Thornton and Abrams ( 1983) were cited as the references for this assumption.

Uncertainties associated with Qs include the lack of current empirical data to support soil ingestion rates for dairy cattle. Assuming uniform contamination of soil ingested by cattle also adds uncertainty. 5.4.5.5 Average Soil Concentration Over Exposure Duration ( Cs )

The calculation of Cs for dairy cattle is the same as for beef cattle (Section 5.4.4.5).

Please Note: You might need to generate soil concentration estimates for grain separate from those for forage and silage. Currently , the HHRAP assumes that forage and silage are grown on untilled land, and grain is grown on tilled land. We highly recommend making sure that your C s 

### calculations include the appropriate Z s 

### (2 for untilled land, 20 for tilled land).
5.4.5.6 Soil Bioavailability Factor (Bs )

The calculation of Bs for dairy cattle is the same as for beef cattle (Section 5.4.4.6).
5.4.5.7 Metabolism Factor ( MF )

The recommended values for MF are identical to those we recommend for beef cattle (Section 5.4.4.7).

5.5 CALCULATING COPC CONCENTRATIONS IN PORK
Under the approach recommended in this guidan ce, COPC concentrations in pork tissue are estimated on the basis of the amount of COPCs that swine consume through a diet consisting of silage and grain. Additi onal COPC contamination of pork tissue may occur through their ingestion of soil.

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### FIG UR E 5-5 COPC CONCENTR ATION I N PORK

Equati on 5-25 Equati on 5-22 (Se cti on 5.4. 4) desc ribe s how

we rec ommend cal cul ati ng COPC concentrat ion in beef cattl e (A beef 

### ). We sugg est modif ying Equ ati on 5-2 2 to c alc ula te COPC concentrat ions in swine ( A pork 

### ), as foll ows:

Recomm ended Equation f or Calcul ating: Concent rati on of COPC in Por k ( A pork 

### )

wh ere A pork 

### = Concentration of COPC in pork (mg CO PC/kg FW tis sue) F i 

### = Fract ion of plant type i grown on contaminated soil and i ngested by the animal (swine)(unitless) Qp i 

### = Quantity of plant type i ea te n b y t he an im al (s wi ne ) e ac h d ay (k g DW pla nt/ day) P i 

### = Concentration of COPC in plant type i eaten by the ani mal (swine)

( mg / kg DW) Qs = Quanti ty of soi l e ate n by th e ani mal ( swine ) ( kg/day) Cs = Av erag e soil c onc entra tion o ver e xpo sure dura tion (m g C OP C/k g so il) Bs = Soil bioavailability factor (unitl ess) Ba pork 

### = COP C biotransfer factor for pork (day/kg FW tissue) MF = M etabolism factor (unitless)

Ap pend ix A-2 explain s how we rec om men d calcula ting the C OP C-sp ecific param eter Ba pork 

### . The discussions in Section 5.4.5 of the variables F i 

### , Qp i 

### , P i 

### , Qs , Cs and MF for b eef ca ttle gen erally app ly to the corresponding variables for pork. How ever, some different assump tions are made for pork. Th ese differences are summa rized in the following subsections.

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### We generally recommend using Equation 5-25 to calculate COPC pork concentrations ( Apork 

### ). This equation is further described in Appendix B, Table B-3-12.
5.5.1 Fraction of Plant Type i Grown on Contaminated Soil and Eaten by the Animal (Swine) ( F i 

### )
The calculation of F i 

### for pork is identical to that for beef cattle (Section 5.4.4.1).
5.5.2 Quantity of Plant Type i Eaten by the Animal (Swine) Each Day ( Qp i 

### )
Section 5.4.4.2 discusses estimating the daily quantity of forage, silage, and grain feed consumed by beef cattle for each feed category. However, daily inges tion rates for pork are estimated differently than for beef cattle. U.S. EPA (1994r and 1998c), and NC DEHNR (1997) recommended only including silage and grain feeds to estimate daily plant quantity eaten by swine. Because swine are not grazing animals, they are assumed not to eat forage (U.S. EPA 1998c). We therefore generally recommend estimating the daily quantity of plant feeds (kilograms of DW) cons umed by swine for each category of plant feed.
U.S. EPA (1990e) and NC DEHNR (1997) recommended grai n and silage ingestion rates for swine of 3.0 and 1.3 kg DW/day, respectively. NC DEHNR (1997) references U.S. EPA (1990e) as the source of these ingestion rates. U.S. EPA (1990e) reported tota l dry matter ingestion rates for hogs and lactating sows as 3.4 and 5.2 kg DW/day, respectively. U.S. EPA (1990e) cites Boone et al. (1981) as the source of the ingestion rate for hogs, and NAS (1987) as the source of the ingestion rate for a lactating sow. Boone et al. (1981) reported a grain ingestion rate of 3.4 kg DW/day for a hog. NAS (1987) reported an average ingestion rate of 5.2 kg DW/day for a lact ating sow. U.S. EPA (1990e) recommended using the average of these two rates (4.3 kg DW/day).
U.S. EPA (1990e) assumed that 70 percent of the swine diet is grain and 30 percent silage to obtain the grain ingestion rate of 3.0 kg DW/day and the silage ingestion rate of 1.3 kg DW/day. U.S. EPA (1990e) cited U.S. EPA (1982b) as the source of the grain and silage dietary fractions. U.S. EPA (1995b) recommended an ingestion rate of 4.7 kg DW/day for a swine, referencing NAS (1987). NAS (1987) reported an average daily intake of 4.36 kg DW/day for a gilt (young sow) and a average daily intake of 5.17 kg DW/day for a sow, which averages out to 4.7 kg/DW/day. Assuming the 70 percent grain to 30 percent silage diet noted above, estimated i ngestion rates of 3.3 kg DW/day (grain) and 1.4 kg DW/day (silage) are derived.

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### Recommended Values for: Quantity of Plant Type i Eaten by the Animal (Swine) Each Day ( Qp i 

### ) Grain = 3.3 kg DW/day Silage = 1.4 kg DW/day

Uncertainties associated with this vari able include the variability of actua l grain and silage ingestion rates from site to site. You could use site-specific data to mitigate this uncertainty. In addition, assuming uniform contamination of the plant materials consumed by swine produces some uncertainty.
5.5.3 Concentration of COPC in Plant Type i Eaten by the Animal (Swine) (Pi 

### )
The suggested calculation of P i 

### for pork is identical to that for beef cattle (Section 5.4.4.3).
5.5.4 Quantity of Soil Eaten by the Animal (Swine) Each Day ( Q s 

### )
As discussed in Section 5.4.4.4, additional contamina tion of swine results from ingestion of soil. The following Q s 

### values were recommended by earlier guidance:

Guidance Quantity of Soil Ea ten by Swine Each Day ( Q s ) U.S. EPA (1990e) Stated that sufficient data are not available to estimate swine soil ingestion rates. NC DEHNR (1997) 0.37 kg/day Estimated by assuming a soil intake that is 8% of the plant ingestion rate of 4.3 kg DW/day). U.S. EPA (1993f) was cited as the reference for the soil ingestion rate of 8 percent of dry matter intake. U.S. EPA (1998c) Cites a companion “Param eters Guidance Document” for detailed recommendations on Q. The “Par ameters” document has not been published.


### As in NC DEHNR (1997), we recommend the following soil ingestion rate for swine:

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### Recommended Value for: Quantity of Soil Eaten by the Animal (Swine) Each Day ( Q s 

### ) 0.37 kg DW/day

Uncertainties associated with this variable include the lack of current empirical data to support soil ingestion rates for swine, and assuming uniform contamination of the soil ingested by swine.
5.5.5 Average Soil Concentrat ion Over Exposure Duration ( Cs )
Our suggested calculation of Cs for pork is the same as for beef cattle (Section 5.4.4.5).

Please Note: You might need to generate soil concentration estimates for grain separate from those for silage. We recommend assuming that silage is grown on untilled land, and grain is grown on tilled land. We highly r ecommend that you make sure that your C s 

### calculations include the appropriate Z s 

### (2 for untilled land, 20 for tilled land).
5.5.6 Soil Bioavailability Factor (Bs )
Our suggested calculation of Bs for pork is the same as for beef cattle (Section 5.4.4.6)
5.5.7 Metabolism Factor ( MF )

Our recommended values for MF are identical to tho se we recommended for beef cattle (Section 5.4.4.7).

5.6 CALCULATING COPC CONCENTRATIONS IN CHICKEN AND EGGS
Under the approach outlined in this guidance document, estimates of the COPC concentrations in chicken and eggs are based on the amount of COPCs that chickens consume through ingestion of grain and soil. We recommend assuming that the uptake of COPCs via inhalation and via ingestion of water ar e insignificant relative to other pathways. The HHRAP assumes that chickens are housed in a typical manner that allows contact with soil. Because of this, chickens are assumed to consume 10 percent of th eir diet as soil. Assuming 10 percent is consistent with the study from which the biotransfer factors were obtained (Stephens et al. 1995). We recommend assuming that the remainder of the diet (90 percent) consists of grain grown at the exposure scenario

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Grain Concentration

COPC Concentration in Chicken and Egg 

### FIGURE 5-6 COPC CONCENTRATION IN CHICKEN & EGGS location. Therefore, it’s appropriate to assume 100 pe rcent of the grain consumed is contaminated. The equations don’t account for the uptake of COPCs vi a ingestion of contaminated insects and other organisms (e.g., worms, etc.), which may also contribute to the ingestion of COPCs. This may be a limitation, depending on the site-specific conditi ons under which the chickens are raised.
We generally recommend using the algorithm for aboveground produce described in Section 5.3 to estimate the COPC concentration in grain. Grain is considered to be protected from direct deposition of particles, and vapor transfer. This approach considers only contamination due to root uptake of COPCs in calculating COPC concentrations in grain. Our recommended equations for calculating concentrations in chicken and eggs are presented in Appendix B. The method we used to derive biotransfer factors, and the COPC-specific values for chicken and eggs are presented in Appendix A-2.
As in NC DEHNR (1997), we recommend using Equation 5-26 to calculate COPC concentrations in chicken and eggs (Stephens et al. 1995). We generally recommend cal culating COPC concentrations in chicken and eggs separately. Pa rameters and variables in Equation 5-26 are further described in Appendix B, Tables B-3-13 and B-3-14.

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### Equation 5-26 Recommended Equation for Calculating: Concentration of COPC in Chicken and Eggs ( A chicken 

### or A egg 

### )

where A chicken 

### = Concentration of COPC in chicken (mg COPC/kg FW tissue) A egg 

### = Concentration of COPC in eggs (mg COPC/kg FW tissue) F

i 

### = Fraction of plant type i (grain) grown on contaminated soil and ingested by the animal (chicken)(unitless) Qp i 

### = Quantity of plant type i (grain) eaten by the animal (chicken) each day (kg DW plant/day) P i 

### = Concentration of COPC in plant type i (grain) eaten by the animal (chicken) (mg/kg DW) Qs = Quantity of soil eaten by the animal (chicken) (kg/day) Cs = Average soil concentration over exposure duration (mg COPC/kg soil) Bs = Soil bioavailability factor (unitless) Ba chicken 

### = COPC biotransfer factor for chicken (day/kg FW tissue) Ba egg 

### = COPC biotransfer factor for eggs (day/kg FW tissue)
Appendix A-2 explains how we recommend de termining the COPC-specific parameters Ba chicken 

### and Ba egg 

### . The remaining parameters are discussed in Appendix B and in the following subsections.
5.6.1 Fraction of Plant Type i Grown on Contaminated Soil and Eaten by the Animal (Chicken)( F i 

### )
The calculation of F i 

### for chicken is identical to that for beef cattle (Section 5.4.4.1).
5.6.2 Quantity of Plant Type i Eaten by the Animal (Chicken) Each Day ( Qp i 

### )
Section 5.4.4.2 discusses estimating the daily quantity of forage, silage, and grain feed consumed by beef cattle for each feed category. However, daily ingesti on rates for chicken are estimated differently than for beef cattle. NC DEHNR (1997) recommended that only grain feeds be included in this estimate. Because chickens are not grazing animals, they are assumed not to eat forage (U.S. EPA 1998c). Chickens are similarly assumed not to consume any silage. We recommend only estimating the daily quantity of plant feeds (kilograms of DW) consumed by chicken ( Qp ) for grain feed.

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### Equati on 5-27 As in Ensminge r (1980) , Fri es (1982) , and NAS (1987), we recommend usi ng the f ollowi ng inges tion rate:

Recom mend ed Value for:

Quan tity of

Plant Type i Eaten by the Animal ( Chicken) Each Day ( Qp i 

### )

Grai n = 0. 2 kg DW/day

Un certain ties asso ciated with this va riable inclu de th e var iability of actu al gra in ing estion rates fro m site to sit e. In addi tion, a ssuming uniform contaminati on of plant mater ials consumed by chicken produces

some unc ert ain ty.

5.6.3 Concentration of CO PC in Plant Typ e i Eate n by the A nim al (Ch icken ) ( P i 

### )

The tot al COPC concentr ati on is t he COPC concentra tion in gra in. We recommend using Equat ion 5-27 to calcul ate P i 

### . Thi s e qua ti on i s f ur th erdes cr ib ed i n App end ix B.

Recomm ended Equation f or Calcul ating: Concentration of CO PC in Plant Typ e i Eate n by the A nim al (Ch icken ) ( P i 

### )

wh ere P i 

### = Concentration of COPC in each plant t ype i ea te n by th e a ni mal (mg CO PC / kg DW) Pr = Pl an t co nc en tr at io n d ue t o r oot up take (m g COP C/ kg DW)

We gen erall y recommend calculating plant concentrat ion due to root upt ake ( Pr ) using Equation 5-20, as disc ussed i n Secti on 5.3. 3.

5.6.4 Quantity of

Soil Eaten by the Animal ( Chicken) Each Day ( Qs )

COPC c onc en tr at io n i n c hi ck en s a ls o r es ul ts fr om i nt ak e o f s oi l. As di sc us se d e ar li er , The HHRAP

assu me s that c hick ens c ons um e 10 perc ent o f their to tal diet a s soil, a p ercen tage that is co nsiste nt w ith the s tudy fr om Stephens e t al . (1995) . We recommend the foll owing soilinges tion rat e for chic ken:

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### Recommended Value for: Quantity of Soil Eaten by the Animal (Chicken) Each Day ( Qs ) 0.022 kg DW/day

Uncertainties associated with this variable include the lack of current empirical data to support soil ingestion rates for chicken, and assuming uniform contamination of soil ingested by chicken.
5.6.5 Average Soil Concentrat ion Over Exposure Duration ( Cs )

The calculation of Cs for chicken is the same as for beef cattle (Section 5.4.4.5).

Please Note: We recommend assuming that forage and silage are grown on untilled land, and grain is grown on tilled land. We highly recommend making sure that your C s 

### calculations include the appropriate Z s 

### (20 for tilled land).
5.6.6 Soil Bioavailability Factor (Bs )

The calculation of Bs for chicken is the same as for beef cattle (Section 5.4.4.6)

5.7 CALCULATING COPC CONCENTRATIONS IN DRINKING WATER AND FISH
We generally recommend calculating COPC c oncentrations in surface water for all water bodies you selected to evaluate in the risk assessment. Specifically, those waterbodies selected as potential sources for the drinking water and/or fish ingestion exposure pathways. Mechanisms we suggest considering in determin ing COPC loading of the water column include: • Direct deposition, • Runoff from impervious surfaces within the watershed, • Runoff from pervious surfaces within the watershed, • Soil erosion over the total watershed, • Direct diffusion of vapor phase COPCs into the surface water, and • Internal transformation of compounds chemically or biologically.

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Bed Sediment Benthic Burial Water Body Soil Erosion (Sediments) Runoff to

Direct Deposition (Section 5.7.1.1) Runoff from Impervious Surfaces (Section 5.7.1.3) Runoff from Pervious Surfaces (Section 5.7.1.4) Soil Erosion (Section 5.7.1.5) Vapor Transfer (Section 5.7.1.2)

Toal W ater Body Concentration Volatilization (Section 5.7.4.3) Benthic Burial (Section 5.7.4.7) 

### FIGURE 5-7 COPC LOADING TO THE WATER BODY Considering other potential mechanisms may be appr opriate, due to site-specific conditions (e.g., tidal influences). Typically, though, we assume that contributions from other potential mechanisms are negligible compared to those evaluated in the HHRAP.

The total concentration of each COPC partitions between the sediment and the water column. Partitioning between water and sediment varies with the COPC. The HHRAP uses the Universal Soil Loss Equation (USLE) and a sediment delivery ratio to estimate the rate of soil erosion from the watershed. The equations we recommend for estima ting surface water concentrations include a sediment mass balance, in which the amount of sediment assu med to be buried and lost from the water body is equal to the difference between the amount of soil introduced to the water body by erosion and the amount of suspended solids lost in downstream flow. As a result, we typically assume that sediments do not accumulate in the water body over time, and an equ ilibrium is maintained between the surficial layer of sediments and the water column. The total water column COPC concentration is the sum of the COPC concentration dissolved in water and the COPC concentration associated with suspended solids. Appendix B-4 presents the equations we recommend using to estimate surface water concentrations.

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### To evaluate the COPC loading to a water body fro m its associated watershed, we generally recommend calculating watershed soil-specific COPC concentrati ons. The equation in Section 5.2 for estimating COPC concentration in soil includes a loss term that considers the loss of contaminants from the soil after deposition. These loss mechanisms all lower the soil concentration associated with a specific deposition rate. Appendix B (Tables B-4-1 through B-4-28) pr ovides the equations we recommend for calculating COPC concentrations in waters hed soils and in the water body.
The equations presented in Appendix B for modeling COPC loading to a water body represent a simple steady-state model to solve for a water column in equilibrium with the upper sediment layer. These equations (Appendix B) predict the steady-state mass of contaminants in the water column and underlying sediments, and don’t address the dynamic exchange of contaminants between the water body and the sediments following changes in external loadings. While appropriate for calculating risk under long-term average conditions, evaluating complex water bodies or shorter term loading scenarios might be improved by using a dynamic modeling framework [e.g., Expos ure Analysis Modeling System (EXAMS), or Water Quality Analysis Simulation Program (WASP), both of which can be downloaded from the EPA Center for Exposure Assessment Modeling]. Although typically more resource intensive, such analysis may be able to refine modeling of contaminant loading to a water body. Also, the computations may better represent the exposure scenario you are evaluating.
For example, EXAMS allows performing computations for each defined segment or compartment of a water body or stream. These compartments are c onsidered physically homogeneous and are connected via advective and dispersive fluxes. Compartments can be defined as littoral, epilimnion, hypolimnion, or benthic. Such resolution also makes it possible to assign receptor locations specific to certain portions of a water body where evaluating exposure is of greatest interest.
The following are some considerations regarding th e selection and use of a dynamic modeling framework or simulation model to evaluate water bodies: • Will a complex surface water modeling effort provide enhanced results over the use of the more simplistic steady-state equations presented in Appendix B? • Are the resources needed to conduct, as well as review, a more complex modeling effort justified compared to the more refined results? • Has the model been used previously for re gulatory purposes, and therefore, already has available documentation to support such uses?

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### Equati on 5-28 • Can the model conduct ste ady-st ate and dynamic analysis? and

• Do es the mo del re quir e calib ration with field d ata, an d if so , are the re suf ficien t qua ntity and quali ty of s ite -spec ifi c data avail able t o support

calibrat ion?

As m entioned previou sly in Chapter 2 (Section 2 .3.5.3 - “Mercury”), the SE RA FM mod el offers a dyn amic m odeling framew ork for m ercury that enab les the user to mo del spec ific water bo dy m ercury transformation processes in lieu of applying d efault speciation assumptions.

5.7.1 Total COPC Load to the Water Body ( L T 

### )

As in U.S. EPA (1994r) and NC DEHNR (1997), we recommend usi ng Equati on 5-28 t o calc ulat e the tot al COPC load t o a wat er b ody ( L T 

### ). Thi s equat ion i s desc ribe d in det ail in Appendix B, Table B-4-7.

Recomm ended Equation f or Calcul ating: Total COPC Load to the Water Body ( L T 

### )

wh ere L T 

### = Total COPC load to the water body (inc luding deposi tion, runoff , and e rosi on) (g/yr) L DEP 

### = Total (wet a nd dry) par tic le phas e and vapor

phase COPC direc t depos iti on load to w ater bod y (g/y r) L dif 

### = Vap or pha se CO PC diffusion load to w ater bod y (g/y r) L RI 

### = Run off load fro m im pervio us surfac es (g/yr) L R 

### = Run off load fro m p erviou s surfaces (g /yr) L E 

### = Soil eros ion load (g/yr) L I 

### = Internal trans fer (g/yr)

Du e to th e lim ited d ata an d un certain ty ass ocia ted w ith the chem ical or biolo gica l intern al tran sfer, L I 

### , of

com pou nds into d egra datio n pro duc ts, we gen erally reco mm end a defa ult va lue fo r this v ariab le of ze ro. How ever, i f a permitting authori ty determines that si te-speci fic condit ions indicate cal culati ng internal tr ansf er ma y need to be cons ide red, we re commend f oll owing t

he methods de scr ibe d in U. S. EPA (1998c). The rem aining variables ( L DEP 

### , L dif 

### , L RI 

### , L R 

### , and L E 

### ) are discussed in the following subsections.

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### Equati on 5-29 5.7.1 .1 Tota l (W et and Dry ) Particle P hase and Va por P hase CO PC Direc t Dep osition L oad to Water Body ( L DEP 

### ) As in U.S. EPA (1994r) and NC DEH NR (1997 ), with the incl usion of the di rect deposi tion of t otal vapor, we recommend using Equation 5-29 to calculate the l oad to the water body from the direct depos it ion o f wet

and dr y par ti cle s andvapor s ont o the sur fac e of the wate r body (

L DEP 

### ). Th e equ ation is descr ibed i n detai l i n Appendix B, Tabl e B-4-8.

Recomm ended Equation f or Calcul ating: Total Parti cle Phase a nd Vapor Phas e Dir ect Deposi ti on Load to Water Body ( L DEP 

### )

wh ere L DEP 

### = Total (wet a nd dry) par tic le phas e and vapor

phase COPC direc t depos iti on load to w ater bod y (g/y r) Q = CO PC em ission rate (g/s) F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Dyt wv = Unit ize d year ly ( wate r body o r wat ers hed) aver age t ota l ( wet a nd dry)

dep ositio n fro m v apo r pha se (s/m 2 

### -yr) Dyt wp = Unit ize d year ly ( wate r body o r wat ers hed) aver age t ota l ( wet a nd dry)

dep ositio n fro m p article p hase (s/m 2 

### -yr) A W 

### = W ater bod y surfac e area (m 2 

### )

Ap pend ix A-2 describe s how we rec om men d determ ining the CO PC -specific para meter F v 

### . Chap ter 3 desc ribes g ene rating the m ode led air para me ters, Dyt wv and Dyt

wp . Methods for deter mining the water bod y su rface a rea, A w 

### , are des cr ib ed i n Chapt er4 a nd Ap pen di x B.

5.7.1 .2 Vapor Phase COPC Diffus ion Load to Water Body (L dif 

### )
As in U.S. EPA (1994r) and NC DEH NR (1997 ), we recommend using Equation 5-30 to calc ulate L dif 

### . The equati on is de scribed in de tai l i n Appendix B, Tabl e B-4-12.

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### Equati on 5-30 Recomm ended Equation f or Calcul ating: Vapor Phase COPC Diffus ion Load to Water Body (L Dif 

### )

wh ere L dif 

### = Vap or pha se CO PC diffusion load to w ater bod y (g/y r) K v 

### = Ov erall CO PC transfer rate coe fficient (m/y r) Q = CO PC em ission rate (g/s) F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Cywv = Uniti zed year ly (wat er body or waters hed) ave rage a ir c oncentr ati on from

vapo r phase (μ g-s/g-m 3 

### ) A W 

### = W ater bod y surfac e area (m 2 

### ) 10 -6 

### = Units c onversi on fact or (g/ μg) H = Hen ry’s L aw co nstant (atm -m 3 

### /mo l) R = Un iversal gas c onstan t (atm-m 3 

### /m ol -K) T wk 

### = Wat er

bo dy t emp er at

ur e ( K)

Ca lculatin g the ove rall C OP C tra nsfe r rate co efficien t ( K v 

### ) is des cribe d in S ection 5.7.4 .4, as w ell as in Appendi x B, Ta ble B-4- 19. Chapt ers 2 and 3 expl ain how we re commend qua nti fyi ng th e COPC emission rat e ( Q ). Ap pen dix A -2 de scribe s ho w w e reco mm end deter min ing th e CO PC -spe cific parameters F v 

### , H , and R . Ch apte r 3 de scribe s gen eratin g the mo dele d air p aram eter, Cywv . Methods f or dete rmin ing th e w ater b ody surfa ce are a, A w 

### , are de scribe d in C hap ter 4 an d A ppe ndix B. C ons istent w ith U.S . EPA (1994 r) and U .S. EP A (1 998 c), we reco mm end a d efault w ater bod y tem perature ( T wk 

### ) of 298 K (or 25° C).

5.7.1 .3 Runo ff Load from Im pervious Surfaces ( L RI 

### )

In so me wa tershe d so ils, a po rtion of the total (w et and dry ) dep ositio n in th e w atersh ed w ill be to imper vious sur fac es. This depos it ion ma y acc umulat e and be was hed of f dur ing r ain event s. As in U.S. EPA (1994r) and NC DEHNR (1997), with t he inclusion of

tot al ( wet and dry) vapor pha se depos iti on,
we rec ommend usi ng Equat ion 5 -31 t o cal cul ate imper vious runof

f l oad t o a wat er b ody ( L RI 

### ). The equati on is a lso pr esent ed in Appendi x B, Table B-4-9.

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Chapter 5: Es ti mating Media Concent rati ons September 2005

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### Equati on 5-31 Recomm ended Equation f or Calcul ating: Runo ff Load from Im pervious Surfaces ( L RI 

### )

wh ere L RI 

### = Run off load fro m im pervio us surfac es (g/yr) Q = CO PC em ission rate (g/s) F v 

### = Fraction of CO PC air concen tration in vapor phase (unitless) Dyt wv = Unit ize d year ly ( wate r body o r wat ers hed) aver age t ota l ( wet a nd dry)

dep ositio n fro m v apo r pha se (s/m 2 

### -yr) Dyt wp = Unit ize d year ly ( wate r body o r wat ers hed) aver age t ota l ( wet a nd dry)

dep ositio n fro m p article p hase (s/m 2 

### -yr) A I 

### = Imp erviou s watersh ed area rec eiving C OP C de position (m 2 

### )

Chapters 2 and 3 explain how we recommend q uantifyi ng the COPC emission rat e ( Q ). App endix A-2 describe s how we rec om men d determ ining the CO PC -specific para meter F v 

### . Chapter 3 describes a

me thod for g ene rating the m ode led air para me ters, Dyt wv and Dyt

wp . Impervious water shed area

rece iving COPC deposi tion ( A I 

### ) is the p ortio n of th e total e ffectiv e w atersh ed ar ea tha t is imp ervio us to rai nfal l (s uch as r oofs, drive ways, st reet s, and parki ng lot s) and drai ns to t he water body. Our recommended method for de termining A I 

### is des cr ib ed i n Chapt er4 a nd Ap pen di x B.

5.7.1 .4 Runo ff Load from Pervious Surfaces ( L R 

### )

As in U.S. EPA (1994r) and NC DEHNR (1997), we recommend usi ng Equati on 5-32 t o calc ulat e the runoff diss olved COPC load t o the wat er body fr om pervious soilsurf aces i n the wat ershe d ( L R 

### ). The equati on is a lso pr esent ed in Appendi x B, Table B-4-10.

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### Equati on 5-32 Recomm ended Equation f or Calcul ating: Runo ff Load from Pervious Surfaces ( L R 

### )

wh ere L R 

### = Run off load fro m p erviou s surfaces (g /yr) RO = Av erage an nual su rface run off from pervio us areas (cm /yr) A L 

### = Total w atershed area receiv ing C OP C de position (m 2 

### ) A I 

### = Imp erviou s watersh ed area rec eiving C OP C de position (m 2 

### ) Cs = Aver age so ilcon ce nt ra ti on o ver exp os ur e du ra ti on ( in wat er sh ed s oi ls ) ( mg CO PC /kg s oil) BD = Soil bulk densit y (g soil/ cm 3 

### soil) = 1.5 g/cm 3 

### 2 sw 

### = Soil volumetri c water content (ml water/ cm 3 

### soil) = 0.2 ml/cm 3 

### Kds 

### = Soil-water parti tion coeff

icient (cm 3 

### wa ter/g so il) 0.01 = Units conversi on factor ( kg-cm 2 

### /mg-m 2 

### )

Ap pend ix B d escribes h ow we rec om men d determ ining the site-specific param eters RO , A L 

### , A I 

### , BD , and 2 sw 

### . We al so ad dres s so il bulkdens ity ( BD ) in Se ction 5.2.4 .2. W e also add ress so il wa ter co nten t ( 2 sw 

### ) in Sec tion 5 .2.4.4 . Ou r reco mm end ed m etho d for calcu lating the C OP C co nce ntratio n in w atersh ed so ils ( Cs ) i s d is cu ss ed i n Se ct io n 5

. 2. 1 a nd App en di x B, Ta bl e B- 4- 1. App en di x A- 2 d es cr ib es ho w we
reco mm end calcu lating the C OP C-s pec ific soil/w ater p artition coef ficien t ( Kds 

### ).

5.7.1 .5 Soil Eros ion Load ( L E 

### )

As in U .S. E PA (199 4r) an d N C D EH NR (199 7), w e reco mm end usin g E qua tion 5 -33 to calc ulate s oil erosi on load (

L E 

### ). The equati on is a lso pr esent ed in Appendi x B, Table B-4-11.

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### Equation 5-33 Recommended Equation for Calculating: Soil Erosion Load (L E 

### )

where L E 

### = Soil erosion load (g/yr) X e 

### = Unit soil loss (kg/m 2 

### -yr) A L 

### = Total watershed area (evaluated) receiving COPC deposition (m 2 

### ) A I 

### = Impervious watershed area receiving COPC deposition (m 2 

### ) SD = Sediment delivery ratio (watershed) (unitless) ER = Soil enrichment ratio (unitless) Cs = Average soil concentration over expos ure duration (in watershed soils) (mg COPC/kg soil) BD = Soil bulk density (g soil/cm 3 

### soil) = 1.5 g/cm 3 

### 2

sw 

### = Soil volumetric water content (ml water/cm 3 

### soil) = 0.2 ml/cm 3 

### Kd s 

### = Soil-water partition coefficient (ml water/g soil) 0.001 = Units conversion factor (k-cm 2

### /mg-m 2 

### )

Section 5.7.2 describes unit soil loss ( X

e 

### ). Chapter 4 and Appendix B describe how we recommend determining the site-specific parameters A L 

### and A I 

### . We generally recommend calculating the watershed sediment delivery ratio ( SD ) as described in Section 5.7.3 and in Appendix B, Table B-4-14. COPC concentration in soils ( Cs ) is described in Section 5.2.1, and A ppendix B, Table B-4-1. Soil bulk density ( BD ) is described in Section 5.2.4.2. Soil water content ( 2 sw 

### ) is described in Section 5.2.4.4. Appendix B, Table B-4-11 describes how we recommend determining the COPC-specific soil enrichment ration ( ER ).
5.7.2 Universal Soil Loss Equation - USLE
As in U.S. EPA (1994g and 1994r), we generally recommend using the universal soil loss equation (USLE), Equation 5-33A, to calculate the unit soil loss (X e 

### ) specific to each watershed. This equation is further described in Appendix B, Table B-4-13. A ppendix B also describes how we suggest determining the site- and watershed-specific values for each of the variables associated with Equation 5-33A.

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Chapter 5: Es ti mating Media Concent rati ons September 2005

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### Equati on 5-33A

Equati on 5-34 Recomm ended Equation f or Calcul ating: Unit So il Loss (

X e 

### )

wh ere X

e 

### = Un it soil los s (kg /m 2 

### -yr) RF = USLE rai nfal l ( or e ros ivi ty) fac tor (yr G 1 

### ) K = USL E erodibili ty fact or (ton/ acre) LS = USL E length-slope factor (unitless) C = USL E cover m anagem ent factor (unitless) PF = USL E supp orting practice factor (unitl ess) 907.18 = Units c onversi on fact or (kg/ ton) 4047 = Un its conve rsion facto r (m 2 

### /acre)

The USLE RFvaria ble, w hich repre sents the in fluen ce of prec ipitatio n on erosio n, is de rived from data on the f requenc y and int ensi ty of s torms. This va lue i s typi call y deri ved on a st orm-by-s torm bas is, but

avera ge annual values have been c ompiled ( U.S. Department of Agricul ture 1982). Infor mation on deter mining s ite -spec ifi c value s for vari ables used i n calc ulat ing X e 

### is pr ovided i n U.S. Depar tment of Ag ricultu re (U .S. D epa rtme nt of A gricu lture 1 997 ) and U.S . EP A g uida nce (U.S . EP A 1 985 b). Ref erto Appen dix B, Ta

ble B-4- 13 f

or a ddi ti onaldi scu ss ion of t he USLE.

5.7.3 Sediment Delivery Ratio ( SD )
We recommend using Equat ion 5-34 to cal culat e the sedi ment del iver y rat io ( SD ). Th e use of this equati on is f

urthe r desc ribe d in Appendix B, Table B-4-14.

Recomm ended Equation f or Calcul ating: Sediment Delivery Ratio (SD )

wh ere SD = Sedimen t delivery ratio (watershed) (unitless) a = Em pirical inter cept coefficient (unitles s) b = Em pirical sl ope coefficient (unitless) A L 

### = Total w atershed area (eva luated) rece iving C OP C de position (m 2 

### )

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### The sedi ment del iver

y rat io ( SD ) for

a la rge l and are a (i .e. a water shed or part of a wat ershe d) can be calcu lated, o n the basis of the area o f the w atersh ed, b y u sing an ap pro ach prop osed by Va non i (197 5). Accordingly, U.S. EPA (1998c) recommended using Equ ation 5-34 t o calculat e the SD

.
According t o Vanoni (1975) , se diment de live ry rat ios va ry approxi matel y with the -0. 125 power of t he drai nage ar ea. Theref

ore, the e mpiri cal s lope coe ffi cient is a ssumed t o be equal to 0. 125. An ins pecti on of the data prese nted by Vanoni (1975) i ndicat es that t he empir icalint erce pt coef fic ient vari es wit

h the size o f the w atersh ed, as illustrate d in A ppe ndix B, T able B-4 -14

.

A L 

### is t he tot al wat ershe d surf ace ar ea evaluated t

hat i s aff ecte d by deposi tion and drai ns to t he body of wat er (s ee Chapt er

4)

. In as si gni ng va lu es t o the wat er sh ed su rf ac e a re a a ff

ec te d b y de pos it io n, we gen erally con sider th e follo win g rele van t:

• the d istanc e from the em ission sou rce,

• the locat ion of the ar ea affec ted by depositi on fallout with respect

to the point

at which drinkin g w ater is extracted o r fishing o ccurs

• the w atersh ed h yd rolo gy .

5.7.4 Total Water Body COPC Concentrati on ( C wtot

### )
We recommend using Equat ion 5-35 to cal culat e the tota l wate r body COPC concentra tion ( C wtot 

### ). C wtot 

### in cl ude s b ot h t he wate r c ol umn a nd t he b ed s edi ment

. The equ at io n i s a ls o pr es ent ed i n App end ix B, Table B-4- 15.

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### Equati on 5-35 Recomm ended Equation f or Calcul ating: Total Water Body COPC Concentr ati on ( C wtot

### )

wh ere C wtot 

### = Total water body COPC concentrat ion (incl uding water column and bed sedim ent) (g CO PC /m 3 

### wate r body) L T 

### = Total COPC load to the water body (inc luding deposi tion, runoff , and e rosi on) (g/yr) Vf x 

### = Av erage v olum etric flow rate th roug h w ater bod y (m 3 

### /yr) f wc 

### = Fr ac ti on o f t ot al wat erbod y COPC c onc ent ra ti on i n t he wate r c ol umn (unitless) k wt 

### = Overa ll tot al wate r body COPC di ssi pat ion r ate cons tan t ( yr G 1 

### ) A W 

### = W ater bod y surfac e area (m 2 

### ) d wc 

### = Dept

h of wat ercolumn ( m) d bs 

### = Dept

h of upp erben th ic se di ment layer (m)

The t ota l COPC loa d to t he wat er b ody ( L T



### )— inclu ding dep ositio n, run off, an d ero sion

— is des cribe d in Sect ion 5 .7. 1 and Appe ndix B, Tabl e B-4- 7. Ave rage volu metr ic fl ow rat e t hrough the wate r body ( Vf x 

### ) and water body surface ar ea ( A w 

### ) ar e dis cusse d in Appendix B. Sect ion 5. 7.4. 1 disc usses the f ract ion of tota l COPC concentr ati on in the water column (

f wc 

### ). Sec tion 5 .7.4.2 discu sses th e CO PC dissip ation rate
con stant ( k wt 

### ). Chapter 4 discusses the water body-speci fic d wc 

### . W e disc uss th e dep th of th e up per b enth ic sedim ent layer ( d bs 

### ) b el ow.

The depth of the up per ben thic layer ( d bs 

### ), whi ch repr esent s the porti on of t he bed that i s in e quilibrium with the water c olumn, cannot be preci sely speci fied; however, U.S. EPA (1998c) recomm ended values ranging from 0.01 to 0. 05. As in U.S. EPA (1994r), we recommend a default value of 0.03, which represent s the midpoint of the speci fied range. Iss ues rela ted to t he remaining parameter s are summarized in the following subsections.

Recom mend ed Default Value for: Depth of Upp er Benthic Sediment Layer ( d bs 

### )

0.03 m

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Chapter 5: Es ti mating Media Concent rati ons September 2005

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### Equati on 5-36B Equati on 5-36A 5.7.4 .1 Fr ac ti on of

Tot al Wat er Bod y CO PC Co nc en tr at i on i n t he Wat er Col umn ( f wc 

### ) an d B enth ic Sedi ment (

f bs 

### )

We gener all y rec ommend usi ng Equat ion 5 -36A t o cal cul ate the fr act ion o f t ota l wat er b ody COPC concentrat ion i n the wat er column ( f wc 

### ), and Equati on 5-36B to c alcul ate t he tot al wat er body cont aminant

con cen tration in be nthic sedim ent ( f bs 

### ). The equati ons are als o prese nted i n Appendix B, Tabl e B-4-16.

Recomm ended Equation f or Calcul ating: Fract ion of

TotalWater Body COPC Concentr ati on in the Wate r Column (

f wc 

### ) and Ben thi c Sedi ment ( f bs 

### )

wh ere f

wc 

### = Fr ac ti on o f t ot al wat erbod y COPC c onc ent ra ti on i n t he wate r c ol umn (unitless) f bs 

### = Fract ion of tota l wate r body COPC concentra tion in bent hic s ediment (unitless) Kdsw 

### = Suspended s ediment s/s urfac e water part iti on coeff

ici ent ( L water/

kg susp end ed se dim ent) TSS = Tot al sus pend ed s oli ds c once ntr at ion (mg/L) 1 x 10 -6 

### = Units c onversi on fact or (kg/ mg) d z 

### = Tot al wat erbod y de pt h ( m) 2 bs 

### = Bed sedim ent po rosity (L water 

### /L sediment 

### ) Kd bs 

### = Bed sedi ment/s ediment pore wat er par

tition coef

fic ient (L water

/kg bot tom sedim ent) C BS 

### = Bed sediment concentrat ion (g/cm 3 

### [eq uiv alen t to k g/L ]) d wc 

### = Dept

h of wat ercolumn ( m) d bs 

### = Dept

h of upp erben th ic se di ment layer (m)

Th e CO PC -spe cific p artition coef ficien t ( Kdsw 

### ) descri bes the part iti oning of a contaminant bet ween sorb ing m aterial, su ch as soil, su rface w ater, su spen ded solid s, and bed sedim ents (s ee A ppe ndix A-2 ). Total suspende d soli ds (TSS), tot al wat er body dept h ( d z 

### ), bed s edi ment p oros ity ( 2 bs 

### ) and bed s ediment concentrat ion ( C BS 

### ) ar e addre ssed be low. Bed s ediment and sedi ment pore water part iti on coeff ici ent

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### Equati on 5-36C ( Kd bs 

### ) is disc ussed i n Appendix A-2. Depth of wat er column ( d wc 

### ) and d epth o f uppe r benth ic layer ( d bs 

### ) are di scuss ed in Sec tion 5.7. 4.

U.S . EP A (1 998 c) an d N C D EH NR (199 7) rec om me nde d us ing E qua tions 5-36 A a nd 5 -36 B to calcu late f wc 

### and f

bs 

### . NC DEHN R (1997) al so rec ommended adding the depth of the water column to t he depth of the up per ben thic layer ( d wc 

### + d bs 

### ) to calc ulat e the tota l wate r body depth ( d z 

### ).

NC DEH NR (1997) recom mend ed a default total suspended solids ( TSS ) concentrat ion of 10 mg/L, which

wa s ada pted from U.S . EP A (1 993 e). H ow eve r, due to va riability in w ater b ody spec ific va lues fo r this vari able, we recommend usi ng water body-speci fic measure d TSS values rep resentative o f long-term averag e annu al values. A verage annu al values fo r TSS are ge nera lly ex pec ted to be in the ran ge o f 2 to 300 mg/L. Addit ional infor mation on antic ipat ed TSS values is av ailable in U .S. EP A (1 998 c).

If measured dat a are not avai lable, or of unacceptabl e qualit y, it’ s possibl e to cal culate a TSS value for

non -f lo win g wat erbod ie s u si ng Equat io n 5- 36C.

wh ere TSS = Tot al sus pend ed s oli ds c once ntr at ion (mg/L) X e 

### = Un it soil los s (kg /m 2 

### -yr) A L 

### = Total w atershed area (eva luated) rece iving C OP C de position (m 2 

### ) A I 

### = Imp erviou s watersh ed area rec eiving C OP C de position (m 2 

### ) SD = Sedimen t delivery ratio (watershed) (unitless) Vf x 

### = Average vol umetri c fl ow rate through wat er body (va lue s hould be 0 f or quiesce nt lakes o r pond s) (m 3 

### /yr) D ss 

### = Suspended s olids deposi tion rat e (a de faul t val ue of 1, 825 for qui escent

lakes or p ond s) (m/yr) A W 

### = W ater bod y surfac e area (m 2 

### )

The default va lue of 1,8 25 m /yr prov ided fo r D ss 

### is chara cteri stic of Stoke’s set tli ng velocity for

an interm edia te (fine to m ediu m) s ilt.

Als o, it’s p ossib le to ev alua te the a ppr opr iatene ss of w atersh ed-s pec ific va lues u sed in calcu lating the u nit soil loss (

X e 

### ), as de scribe d in S ection 5.7.2 and Ap pen dix B , by c om parin g the wa ter-bo dy spec ific measured TSS value to the est imate d TSS value obtai ned usi ng Equati on 5-36C. I f the measure d and

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### Equati on 5-37 calc ulat ed TSS valu es diff er sign ifican tly, w e reco mm end re-ev alua ting th e par am eter v alue s use d to calculat e X

e 

### . You might also re- evaluate TSS and X e 

### if the ca lcul ated TSS value is outside of t he normal range expected for

average annual measured val ues, as di scussed above.
One appr oach t o cal cul ati ng bed s edi ment p oros ity ( 2 bs 

### ) fr om the bed s ediment concentrat ion i s by usi ng the follow ing eq uation (U .S. EP A 1 998 c):

wh ere 2 bs 

### = Bed sedim ent po rosity (L water 

### /L sediment 

### ) D s 

### = Bed s edi ment dens it y (k g/L ) C BS 

### = Bed s edi ment conc ent ra ti on ( kg/ L)

We recommendthe fol lowi ng def aul t va lue for

bed s edi ment p oros ity ( 2 bs 

### ), ad ap te d f ro m NC DEH NR (199 7):

Recom mend ed Value for: Bed Sediment Porosi ty ( 2 bs 

### ) 2 bs 

### = 0.6 L water 

### /L sediment assuming D s = 2.65 k g/L [bed sedimen t density]

and C BS = 1.0 kg /L [bed sed iment con centration])


### U.S. EPA (1994r) and NC DEH NR (1997) rec ommended a benthi c sol ids c oncentr ati on ( C BS 

### ) ra nging from 0.5 to 1.5 k g/L , wh ich w as ad apte d fro m U .S. E PA (199 3e). W e reco mm end the fo llow ing d efau lt value f or bed s ediment

concentrat ion ( C BS 

### ):

Recom mend ed Default Value for: Bed Sedi ment Conce ntrat ion ( C BS 

### ) 1.0 k g/L

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### Equati on 5-38 5.7.4 .2 Ov erall To tal W ater B ody CO PC Dissipa tion R ate C onsta nt ( k wt

### )

As in U.S. EPA (1994r) and NC DEHNR (1997), we recommend usi ng Equati on 5-38 t o calc ulat e the overal l di ssi pati on rat e of COPCs in sur face water, resul ting from vol ati liz ati on and benthic bur ial . The equati on is a lso pr esent ed in Appendi x B, Table B-4-17.

Recomm ended Equation f or Calcul ating: Ov erall To tal W ater B ody CO PC Dissipa tion R ate C onsta nt ( k wt

### )

wh ere k wt 

### = Overa ll tot al wate r body d is si pat ion r ate cons tan t ( yr G 1 

### ) f wc 

### = Fr ac ti on o f t ot al wat erbod y COPC c onc ent ra ti on i n t he wate r c ol umn (unitless) k v 

### = Watercol umn vola ti li zat ion r ate cons tan t ( yr G 1 

### ) f bs 

### = Fract ion of tota l wate r body COPC concentra tion in bent hic s ediment (unitless) k b 

### = Benth ic buri al rat e cons tan t ( yr G 1 

### )

The variables f wc 

### and f

bs 

### are di scuss ed in Sec tion 5.7. 4.1. The water column volatil izat ion ra te cons tant ( k v 

### ) is disc usse d in S ection 5.7.4 .3. Th e ben thic b urial ra te con stant ( k b 

### )is disc usse d in S ection 5.7.4 .7.

5.7.4 .3 W ater C olum n V olatilization Ra te Co nstan t ( k v 

### )
As in U.S. EPA (1994r) and NC DEH NR (1997 ), we recommend using Equation 5-39 to calc ulate k v 

### . The equati on is a lso pr esent ed in Appendi x B, Table B-4-18.

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### Equati on 5-39 Recomm ended Equation f or Calcul ating: W ater C olum n V olatilization Ra te Co nstan t ( k v 

### )

wh ere k v 

### = Watercol umn vola ti li zat ion r ate cons tan t ( yr G 1 

### ) K v 

### = Ov erall CO PC transfer rate coe fficient (m/y r) d z 

### = Tot al wat erbod y de pt h ( m) Kdsw 

### = Suspended s ediment s/s urfac e water part iti on coeff

ici ent ( L water/

kg suspended sediments) TSS = Tot al sus pend ed s oli ds c once ntr at ion (mg/L) 1 x 10 -6 

### = Units c onversi on fact or (kg/ mg)

Th e ov erall tran sfer rate coef ficien t ( K v 

### ) is disc ussed i n Secti on 5.7. 4.4. Total water body depth ( d z 

### ), susp end ed se dim ent an d su rface w ater p artition coe fficien t ( Kdsw 

### ), and tot al s uspended s olids concentrat ion ( TSS ), are d escrib ed in Sec tion 5 .7.4.1

. Kdsw 

### is also d iscus sed in Ap pen dix A -2.

5.7.4 .4 Ov erall C OP C T rans fer Ra te Co efficient ( K v 

### )

Vo latile org anic chem icals ca n m ove betw een the w ater co lum n an d the ove rlyin g air. T he o vera ll transf er rat e K v 

### , orco ndu ct iv it y, i s d et ermi ne d b y a t wo- laye r r es is tanc e mo de l th at as su mes t ha t tw o “stagnant f

ilms” are bounded on either si de by well-mixed compartments. Concentra tion dif ferences

serv e as th e driv ing fo rce fo r the w ater lay er diffu sion . Press ure d ifferen ces d rive th e diffu sion for the air layer. From balance considerat ions, t he same mass must pass thr ough both films; t he two resist ances thereby combine in ser ies, so that t he conductivit

y is the r eciprocal of the t otal r esist ance.

As in U .S. E PA (199 3f; 19 93e ; 199 8c), an d N C D EH NR (199 7), w e reco mm end usin g E qua tion 5 -40 to calculat e K v 

### . The equa tion is a lso pr esent ed in Appendi x B, Table B-4-19.

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### Equati on 5-40 Recomm ended Equation f or Calcul ating: Ov erall C OP C T rans fer Ra te Co efficient ( Kv 

### )

wh ere K v 

### = Ov erall CO PC transfer rate coe fficient (m/y r) K L 

### = Liqu id pha se transfer co efficient (m/y r) K G 

### = Gas p hase tran sfer coefficien t (m/yr) H = Hen ry’s L aw co nstant (atm -m 3 

### /mo l) R = Un iversal gas c onstan t (atm-m 3 

### /m ol -K) T w k 

### = Wat er

bo dy t emp er at

ur e ( K) 2 = Tem perature correction factor (unitless)

Th e liqu id an d ga s ph ase tra nsfe r coe fficien ts, K L 

### and K G 

### , respe ctively , vary with the ty pe o f wa ter bo dy

. W e disc uss th e liqu id ph ase tra nsfe r coe fficien t ( K L 

### ) in Secti on 5.7.4.5, and the gas phase t ransfer

coe fficien t ( K G 

### ) in Secti on 5.7. 4.6.

He nry ’s La w c ons tants g ene rally in creas e w ith inc reasin g va por press ure o f a CO PC and gen erally decrease wit

h increasi ng solubili ty of a COPC. Henry’s Law constants are COPC-specific and we offer

reco mm end ed d efau lt valu es in th e H HR AP com pan ion d atab ase. T he u nive rsal ide al gas con stant, R , is 8.205 × 10 -5 

### atm-m 3 

### /mol-K , at 20°C . The tem perature c orrection factor ( 2 ), whi ch is equal to 1. 026, adjusts for the actual water temperature. Equation 5-40 assu mes that volatilizati on occurs m uch less readily in lakes and reservoirs than in mov ing water bod ies.

The value of

the conduc ti vit

y K v 

### depends on t

he int ensi ty of t

urbule nce in the wat er body and t he

over lyi ng atmospher e. As Henry’ s Law con st antinc rea ses , t he con duct ivi ty t ends to be inc rea si ngly influenced by the int ensi ty of t urbule nce in water. Conversel y, as Henry’s Law const ant dec reas es, the valu e of th e con duc tivity tend s to be incre asing ly inf luen ced by the in tensity of atm osp heric turbu lenc e.

5.7.4 .5 Liqui d Phase Tr ansf er Coef fi cie nt ( K

L 

### )

W e gen erally reco mm end usin g E qua tions 5-41 A a nd 5 -41 B to calcu late liqu id ph ase tra nsfe r coe fficien t. ( K L 

### ). Th e use of the se eq uatio ns is fu rther d escrib ed in Ap pen dix B , Tab le B- 4-2 0.

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### Equati on 5-41A

Equati on 5-41B Recomm ended Equation f or Calcul ating: Liqui d Phase Tr ansf

er Coef fi cie nt ( K

L 

### )

For flow ing stream s or rivers:

For qu iescent lakes or pon ds:

wh ere K

L 

### = Liqu id pha se transfer co efficient (m/y r) D w 

### = Diffusivi ty of COPC in water ( cm 2 

### /s) u = Current velocity (m/s) 1 × 10 -4 

### = Un its conve rsion facto r (m 2 

### /cm 2 

### ) d z 

### = Tot al wat erbod y de pt h ( m) C d 

### = Drag coefficient (unitless) W = Averag e annual w ind speed (m /s) D a 

### = Density of air (g/cm 3 

### ) D w 

### = Density of water ( g/cm 3 

### ) k = von K arman’s con stant (unitless) 8 z 

### = Dimen sionless viscous sublayer thickness (unitless) : w 

### = Viscosity of water correspon ding to water temp erature (g/cm-s) 3.1536 x 10 7


### = Un its conve rsion facto r (s/yr)

As in U .S. EPA (1994r) and N C D EH NR (1997), we recom mend using the following d efault values:

• a dif

fusi vity of

chemica l i n water rangi ng ( D w 

### ) fr om 1.0 × 10 G 5 

### to 8. 5 × 10 -2 

### cm 2 

### /s,

• a dra g co efficien t ( C d 

### ) of 0.00 11 w hich w as adap ted from U.S. E PA (1998 c),

• a dens ity of air ( D a 

### ) of 0.0012 g/cm 3 

### at st an da rdco ndi ti ons (t emp er at ur e = 20 °C or29 3 K, pressure = 1 atm or 760 millimeters o f mercu ry) (W east 198 6),

• a dens ity of w ater ( D w 

### ) of 1 g/cm 3 

### (W east 198 6),

• a vo n K arm an’s con stant ( k ) of 0. 4,

• a dimensionless viscous su blayer thickness ( 8 z 

### ) of 4,

• a viscosity of wa ter ( : w 

### ) of a 0.01 69 g /cm-s co rrespon ding to water tem perature (W east 198 6).

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### Equati on 5-42A

Equati on 5-42B The values a

bove a re f

urther dis cuss ed i n Appendi x A-2. Chapt er 4 dis cuss es t he cur rent vel oci ty ( u ). Chapter 3 descr ibes methods f

or det ermini ng the a verage annual wind speed ( W ). Sec tion 5 .7.4.1 disc usses the t otal water body depth ( d z 

### ) for liq uid p hase transf er co efficien ts.

For a f lowing st

ream or r iver , the tr ansfe r coef fic ient s are contr olle d by flow-i nduced tur bulence . For thes e syst ems, we r ecommend calc ulat ing K L 

### using Equat ion 5-41A, which is the O’Connor and Dobbins (19 58) form ula, as prese nted in U .S. E PA (199 8c).
For a stagnant s ystem (quiescent lake or pond), the tr ansfer coef fici ent is controll ed by wind-induced turbul ence. For quie scent lakes or ponds, we recommend cal culat ing K L 

### using Equat ion 5-41B (O’C onn or 198 3; U.S . EPA 199 8c).

5.7.4 .6 Gas Phase Transf er Coef fi cie nt ( K G 

### )
We generall y recommend usi ng Equati ons 5-42A and 5- 42B to cal culat e gas pha se transf er coe ffi cient ( K G 

### ). The equati on is a lso di scuss ed in Appendi x B, Table B-4-21.

Recomm ended Equation f or Calcul ating: Gas Phase Transf

er Coef fi cie nt ( K G 

### )

For flow ing stream s or rivers:

For qu iescent lakes or pon ds:

wh ere K G 

### = Gas p hase tran sfer coefficien t (m/yr) C d 

### = Drag coefficient (unitless) W = Averag e annual w ind speed (m /s) k = von K arman’s con stant (unitless) 8 z 

### = Dimen sionless viscous sublayer thickness (unitless) : a 

### = Viscosity of air corresponding to air temp erature (g/cm-s) D a 

### = Density of air corresponding to water temperature (g/cm 3 

### ) D a 

### = Diffusivi ty of COPC in air (cm 2 

### /s) 3.1536x 10 7 

### = Un its conve rsion facto r (s/yr)

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Chapter 5: Es ti mating Media Concent rati ons September 2005

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### Equati on 5-43 The fo ll owi ng pa ra met er s, i nc lu di ng de faul t va lu es , ar e d is cu ss ed i n Se ct io n 5

. 7. 4. 5, an d i n Ap pe ndi x A2: C d 

### , k , 8 z 

### , and D a 

### . Chapt er 3 des cri bes methods for de termining t he aver age annualwind speed ( W ). As in U.S. EPA (1994r) and NC DEHNR (1997), we recommend usi ng a val ue of 1. 81 x 10 -4 

### g/cm-s for the viscos ity of ai r corres ponding to air t emperature ( : a 

### ). Ap pen dix A -2 dis cuss es the CO PC -spe cific param eter D a 

### . U.S. EPA (1998c) indi cate d that the r ate of

transfer of a COPC from the gas phas e for a fl owing str eam or river is assum ed to be constan t, in accorda nce w ith O’C onn or and Do bbins (1 958 ) (Equ ation 5-4 2A ).
For a stagnant s ystem (quiescent lake or pond), the tr ansfer coef fici ents are controll ed by wind-induced turbul ence. For quie scent lakes or ponds, we recommend cal culat ing the gas pha se transf er coe ffi cient using t he equat ion pre sent ed in O’Connor (198 3) (Eq uation 5 -42B ).

5.7.4 .7 Ben thic B urial R ate C onsta nt ( k b 

### )
We gen erall y recommend using Eq uation 5-43 to ca lculat e benthic buri al rat e ( k b 

### ). The equation is also discu ssed in A ppe ndix B, T able B-4 -22

.

Recomm ended Equation f or Calcul ating: Ben thic B urial R ate C onsta nt ( k b 

### )

wh ere k b 

### = Benth ic buri al rat e cons tan t ( yr G 1 

### ) X e 

### = Un it soil los s (kg /m 2 

### -yr) A L 

### = Total w atershed area (eva luated) rece iving d eposition (m 2 

### ) SD = Sedimen t delivery ratio (watershed) (unitless) Vf x 

### = Av erage v olum etric flow rate th roug h w ater bod y (m 3 

### /yr) TSS = Tot al sus pend ed s oli ds c once ntr at ion (mg/L) A W 

### = W ater bod y surfac e area (m 2 

### ) C BS 

### = Bed sediment concentrat ion (g/cm 3 

### ) d bs 

### = Dept

h of upp erben th ic se di ment layer (m) 1 x 10 G 6 

### = Units c onversi on fact or (kg/ mg) 1 x 10 3 

### = Units c onversi on fact or (g/ kg)

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### Equati on 5-44 Section 5.7.2 discusses the unit soil loss ( X e 

### ). Secti on 5.7. 3 disc usses waters hed are a eval uated r ecei ving COPC deposi tion ( A L 

### ) and s ediment deli very ra tio ( SD ). Average volumetri c flow rate through the water body ( Vf

x 

### ) and water body surface area ( A w 

### ) are d iscus sed in Ap pen dix B

. A w 

### is also d iscus sed in Appendix A-2. Secti on 5.7. 4.1 di scuss es t otal suspende d soli ds concent rat ion ( TSS ) and bed s ediment concentrat ion ( C BS 

### ). Section 5 .7.4 discu sses the de pth of th e upp er benth ic sedim ent layer ( d bs 

### ).
It’s po ssible to ex pres s the b enth ic bu rial rate c ons tant ( k b 

### ), whi ch i s c al cul at ed i n Equ at io n 5- 43, in te rms of the rate of

buria l ( Wb ):

wh ere Wb = Ra te of burial (m /yr) k b 

### = Benth ic buri al rat e cons tan t ( yr G 1 

### ) d bs 

### = Dept h of upp erben th ic se di ment layer (m) According t o U.S. EPA (1994r) and NC DEH NR (1997), COPC loss from t he water column re sult ing from buri al i n benthi c sedi ment can be calc ulat ed usi ng Equati on 5-43.

W e exp ect k b 

### va lu es t o r an ge fr om 0 t o 1

. 0: Low k b 

### values for wat er bodi es wit h li mited or

no sedi mentat ion (r iver s and f astflowi ng str eams), and k b 

### valu es clo ser to 1 .0 for wa ter bo dies c hara cteristic of higher sedi mentation (l akes). This range of val ues is base d on the relation between the benthi c burial rate an d rate of bu rial ex pres sed in Eq uatio n 5-4 4; w ith the dep th of u ppe r ben thic se dim ent lay er he ld constant. If you calcul ate a negat ive k b 

### value (water bodies with hi gh avera ge annual volumetr ic f low rates in comparison to water shed area eval uated), we recommend using a k b 

### value of 0 i n calc ulat ing the tota l wate r body COPC concentra tion ( C wtot 

### ) in Equati on 5-35. If t he cal culat ed k b 

### va lu e e xc ee ds 1. 0, we recommend re- evalua ting the par ameter values used i n calc ulat ing X e 

### . Our expe rie nce has shown that the value ca lculated fo r X e 

### is the m ost lik ely re ason for estim ating a large and pote ntially unre alistic b enth ic buria l ra te. Infor

mation a bout det ermini ng sit e-spe cif ic values and va ria

bles for c alcul ati ng Xe are i n the refere nce s cited in Se ction 5.7.2

.

5.7.4 .8 Total COPC C oncent rati on in Wate r Column ( C wctot

### )

As in U .S. E PA (199 4r) an d N C D EH NR (199 7), w e gen erally reco mm end usin g E qua tion 5 -45 to calc ulat e tot al COPC concentr ati on in wate r col umn ( C wctot 

### ). Th e equ ation is also d iscus sed in Ap pen dix B, Table B-4-23.

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of S olid Waste Center for Combustion Science and Engineering 5-82 

### Equati on 5-45

Equati on 5-46 Recomm ended Equation f or Calcul ating: Total COPC C oncent rati on in Wate r Column ( C wctot

### )

wh ere C wctot 

### = Total COPC concentrat ion i n water column (mg COPC/L water c olumn) f wc 

### = Fr ac ti on o f t ot al wat erbod y COPC c onc ent ra ti on i n t he wate r c ol umn (unitless) C wtot 

### = Total water body COPC concentrat ion, including water column and bed

sedi ment ( mg COPC/L wate r body) d wc 

### = Dept

h of wat ercolumn ( m) d bs 

### = Dept

h of upp erben th ic se di ment layer (m)

We discuss ed the frac tion of tot al wat er body COPC concentr ati on in the water column (

f wc 

### ) in Secti on 5.7. 4.1. We discuss ed the tota l COPC Concentrat ion i n the wat er column ( C wctot 

### ), a s well as dept h of t he water c olumn ( d wc 

### ) and b enthic sed imen t layer ( d bs 

### ) in Secti on 5.7. 4.

5.7.4 .9 Diss olve d Phase Wate r Concent rati on ( C dw 

### )

We recomm end using Equation 5-46 to cal culate t he concentrat ion of COPC dissolved i n the water column ( C dw 

### ). The equati on is di scuss ed in de tai l in Appendi x B, Table B-4-24.

Recomm ended Equation f or Calcul ating: Diss olve d Phase Wate r Concent rati on ( C dw 

### )

wh ere C dw 

### = Disso lved p hase w ater conc entration (m g CO PC /L w ater) C wctot 

### = Total COPC concentrat ion i n water column (mg COPC/L water c olumn) Kdsw 

### = Suspended s ediment s/s urfac e water part iti on coeff

ici ent ( L water/

kg susp end ed se dim ent) TSS = Tot al sus pend ed s oli ds c once ntr at ion (mg/L) 1 x 10 -6 

### = Units c onversi on fact or (kg/ mg)

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-83 

### Equation 5-47 We discussed C wctot 

### in Section 5.7.4.8. We discussed Kd sw 

### and TSS in Section 5.7.4.1.
Using Equation 5-46 to calculate the concentration of COPC dissolved in the water column is consistent with recommendations in U.S. EPA (1994r) and NC DEHNR (1997).
5.7.4.10 COPC Concentration Sorbed to Bed Sediment ( C sb 

### )
We recommend using Equation 5-47 to calculate CO PC concentration sorbed to bed sediment ( C sb 

### ). The equation is also presented in Appendix B, Table B-4-25.

Recommended Equation for Calculating: COPC Concentration Sorbed to Bed Sediment ( C sb 

### )

where C sb 

### = COPC concentration sorbed to bed sediment (mg COPC/kg sediment) f

bs 

### = Fraction of total water body COPC concentration in benthic sediment (unitless) C

wtot 

### = Total water body COPC concentration, including water column and bed sediment (mg COPC/L water body) Kd bs 

### = Bed sediment/sediment pore water partition coefficient (L COPC/kg water body) 2

bs 

### = Bed sediment porosity (L pore water 

### /L sediment 

### ) C

BS 

### = Bed sediment concentration (g/cm 3 

### ) d

wc 

### = Depth of water column (m) d

bs 

### = Depth of upper benthic sediment layer (m)

We discussed f bs 

### , 2 bs 

### , and C BS



### in Section 5.7.4.1. We discussed C wtot 

### , d wc 

### , and d bs 

### in Section 5.7.4. We discuss Kd bs 

### in Appendix A-2.
As in U.S. EPA (1994r) and NC DEHNR (1997), we continue to recommend using Equation 5-47 to calculate the COPC concentration sorbed to bed sediment.

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-84 Soil Concentration Direct Deposition Vapor Transfer

Total Water Body

Concentration Benthic Burial

Dissolved-Phase Water Concentration Total Water Column Concentration Bed Sediment Concentration Volatilization 

### FIGURE 5-8 COPC CONCENTRATION IN FISH 5.7.5 Concentration of COPC in Fish ( C fish 

### ) We generally recommend calculating the COPC concentration in fish using either a COPC-specific bioconcentration factor ( BCF ), a COPC-specific bioaccumulation factor ( BAF ), or a COPC-specific biota-sediment accumulation factor ( BSAF ). Under this approach you would
use BCFs for COPCs with a log K ow 

### less than 4.0. We assume that COPCs with a log K ow 

### greater than 4.0 (except for extremely hydrophobic compounds such as dioxins, furans, and PCBs), have a high tendency to bioaccumulate. As a result, BAF s are used. While we assume that extremely hydrophobic COPCs like dioxins, furans, and PCBs also have a hi gh tendency to bioaccumulate, they are expected to be sorbed to the bed sediments mo re than associated with the wate r phase. Therefore, we recommend using BSAF s to calculate concentrations of dioxins, fura ns, and PCBs in fish. Appendix A-2 provides a detailed discussion on the sources of the COPC-specific BCF , BAF , and BSAF values, and the method we used to derive them.

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### Equati on 5-48 BCF and BAF values are generally based on dissolved water conce ntrations. Therefore, when yo u use BCF or BAFvalues, it’s appropriat e to cal culate t he COP C concentrati on in fish usi ng dissolved water

con cen tration s. BSAF

values are ba sed on bent hic s ediment

concentrat ions. Theref ore, when using BSAF valu es, w e reco mm end calcu lating CO PC con cen tration s in fish usin g be nthic sedim ent co nce ntratio ns. We describe our re commended equati ons for calc ulat ing fi sh concent rat ions i n the s ubsequent subsections.

5.7.5 .1 Fish Concentr ation ( C fish 

### ) from Bioconcentration Factors Using Dissolved Phase W ater Concentrati on As in U .S. EPA (1994r) and N C D EH NR (1997), we recom mend using Equ ation 5-48 to calculate fish

con ce nt ra ti on f

ro m BCF s using diss olved phase water concentr ation. Using this equat ion is f urther descr ibed i n Appendix B, Tabl e B-4-26.

Recomm ended Equation f or Calcul ating: Fish Concent rati on ( C fish 

### ) from B ioconcentra tion Factors ( BCF fish 

### ) Using Diss olve d Phase Wate r Concent rati on

wh ere C

fish 

### = Concentration of COPC in fish (mg COPC /kg FW tis sue) C dw 

### = Dis sol ved p has e wat erconc ent ra ti on ( mg COPC/L) BCF fish 

### = Bioconcent rat ion fa ctor

for COPC in fi sh (L/kg)

We discuss ed C dw 

### in Se ction 5.7.4 .9. CO PC -spe cific BCF fish 

### va lu es ar e p re se nt ed i n the HHRAP

com pan ion d atab ase.

5.7.5 .2 Fish Concent rati on ( C fish 

### ) from Bioaccum ulation Factors Using Dissolved Phase W ater Concentrati on
We re comme nd u si ng Equat io n 5- 49 t o ca lc ul at e f is h co nce nt ra ti on f

ro m BAF s using dissolved pha se water c oncentr ati on. The equa tion is a lso pr esent ed in Appendi x B, Table B-4-27.

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### Equati on 5-49

Equati on 5-50 Recomm ended Equation f or Calcul ating: Fish Concent rati on (C fish 

### ) from Bioaccum ulation Factors ( BAF fish 

### ) Using Diss olved Phase Water Concent rati on

wh ere C

fish 

### = Concentration of COPC in fish (mg COPC /kg FW tis sue) C dw 

### = Dis sol ved p has e wat erconc ent ra ti on ( mg COPC/L) BAF fish 

### = Bioaccumulation fact or for COPC in fish (L/kg FW tissue)

We discuss ed C dw 

### in Sect ion 5. 7.4. 9. COPC-speci fic bioacc umulati on fact or (BAF fish 

### ) values are presented in the HH RA P co mp anio n da taba se.

5.7.5 .3 Fish Concent rati on ( C fish 

### ) f rom Bi ota -To- Sedi ment Ac cumul ati on Fac tor s Us ing COPC Sorbed t o Bed Sedi ment

As in U .S. EPA (1994r) and N C D EH NR (1997), we recom mend using Equ ation 5-50 to calculate fish

con ce nt ra ti on f

ro m BSAF s usi ng COPC concentrat ions s orbed t o bed sedi ment. We recommend using BSAFs for very hyd rophob ic compo unds such as dioxins, furans, and PCB s. The equation is also prese nted i n Appendix B, Tabl e B-4-28.

Recomm ended Equation f or Calcul ating: Fish Concent rati on ( C fish 

### ) from B iota-To-Sed iment A ccum ulation Fa ctors (BS AF) Using COPC Sorbed to Bed Sedi ment

wh ere C

fish 

### = Concentration of COPC in fish (mg COPC /kg FW tis sue) C sb 

### = Co nce ntratio n of C OP C so rbed to be d sed ime nt (m g C OP C/k g be d sed ime nt) f lipid 

### = Fish lipid content (unitless) BSAF = Biota-to-sediment accum ulation factor (unitless) OC sed 

### = Fraction of organic carbon in bottom sedim ent (unitless)

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-87 

### We discussed C sb 

### in Section 5.7.4.10. We discuss f lipid 

### and OC sed



### below. Our recommended default values for f lipid 

### and OC sed



### are given in Appendix B, Table B-4-28. We offer biota-to-sediment accumulation factors ( BSAF ), which are applied only to dioxins, furans, and PCBs, in the HHRAP companion database.

Values recommended by U.S. EPA (1998c) range from 0.03 to 0.05 for OCSED 

### . These values are based on an assumption of a surface soil organic carbon (OC) content of 0.01. U.S. EPA (1998c) states that the organic carbon content in bottom sediments is higher than the organic carbon content in soils because (1) erosion favors lighter-textured soils with higher or ganic carbon contents, and (2) bottom sediments are partially comprised of detritus materials.
The fish lipid content ( f

lipid 

### ) value is site-specific and dependent on the type of fish consumed. As stated in Appendix B, Table B-4-28, we recommend a defau lt range of 0.03 to 0.07 specific to warm or cold water fish species. U.S. EPA (2000c) provides info rmation supporting a value of 0.03 (3 percent lipid content of the edible portion). U.S. EPA (1993e) recommended a default value of 0.04 for OCSED 

### , which is the midpoint of the specified range. U.S. EPA (1993f; 1993e) recommended using 0.07, which was originally cited in Cook et al. (1991).

5.8 USING SITE-SPECIFIC vs. DEFAULT PARAMETER VALUES
As initially discussed in Chapter 1, many of the parameter values we recommend in the HHRAP are not site-specific. After completing a risk assessment using HHRAP default values, you might choose to investigate using site-specific parameter values. More site-specific values might provide a more representative estimate of site-specific risk. If you u se parameter values other than those specified in the HHRAP, we recommend that you clearly described them in the risk assessment report. We also recommend that you discuss them with the permitting au thority prior to using them. We recommend that requests to change default parameter values in clude the following information, as appropriate: 1. An explanation of why using a more site-sp ecific parameter value is warranted (e.g., the default parameter is based on data or studies at sites in the northwestern U.S., but the facility is located in the southeast); 2. The technical basis of the site-specific para meter value, including readable copies of any relevant technical literature or studies;

### Human Health Risk Assessment Protocol Chapter 5: Estimating Media Concentrations September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 5-88



## C Identification of site-specific or alternate de fault media equations and/or inputs; including justification and full referencing C 

### Media concentration calculations RECOMMENDED INFORMATION FOR RISK ASSESSMENT REPORT 3. A comparison of the weight-of-evidence between the competing studies (e.g., the site-specific parameter value is based on a study that is more representative of site conditions, a specific exposure setting being ev aluated, or a more scientifically valid study than the default parameter, the site-sp ecific parameter is based on the analysis of 15 samples as opposed to 5 for the default paramete r, or the site-specific study used more stringent quality control/quality assurance procedures than the study upon which the default parameter is based); 4. A description of other risk assessments or proj ects that used the site-specific parameter value, and how such risk assessments or projects are similar to the current risk assessment.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 6-1 

# Chapter 6 Quantifying Exposure What’s Covered in Chapter 6: 6.1 Inhalation Exposure Pathways 6.2 Ingestion Exposure Pathways 6.3 Dermal Exposure Pathways 6.4 Exposure Frequency 6.5 Exposure Duration 6.6 Averaging Time

PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. This chapter describes the factors to evaluate in quantifying the exposure received under each of the recommended exposure scenarios described in Chapter 4. Calculating COPC-specific exposure rates for each exposure pathway involves some or all of the following, depending upon the medium being assessed: • the estimated COPC media concentrations calculated in Chapter 5, • consumption rates of the medium, • receptor body weight, and • the frequency and dura tion of exposure. We recommend repeating the appropriate calculati on for each COPC and for each exposure pathway included in an exposure scenario, to generate multip le exposure concentration estimate s , as recommended in the EPA information quality guidelines (see Ch apter 1, page 1-11). We present recommended exposure pathway-specific equations in Appendix C. The following sections describe a general exposure rate calculation and the exposure pathway-specific vari ables that may affect this calculation. Acute exposure resulting from direct inhalation is discussedas a separate issue in Chapter 7, Section 7.4.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-2 

### 6.1 INHALATION E XPOSURE PATHWAY S

We recommend using CO PC air concentrations calcu lated using the equ

ation in Table B-5 -1 to represent air concentrations for estim ating exposure v

ia inhalation by all exposure scenarios in the risk assessment (see Tabl e 4- 1).

Direct inhalation of vapors and particulate em issions from com

bustion sources is a poten tial pathway of exposure. Chapter 2

presented various v

ariables and conditions that affect the rate, type, and quantity of combustor emissions. Chapte r 3 presented the air dispersio n and deposition modeli ng techniques we
recommen

d using to estim

ate airborne concentrations of vapors and particulates in the assessment area.

As a res ult of normal

respira tion, re ceptors

in the a ssessm

ent area could b e expos ed to C OPCs i n vap or, particle , and p article-

bound p hases. Exam

ples of factors that aff

ect exp osure fr

om vapor and partic

ulate inhalation include vap or and particulate COPC concentrations, particle size, and length o f exposure.
Exposu re can o ccur ov

er a per iod of t ime. To calcu

late an average expos

ure per unit of time (Exposu re Concen tration, or EC

), we r ecom mend divid ing the total exposure

by the time

period. We ge

nerally
recommen

d using total CO PC air concentrations ( C a 

### , estimated using

the equation in Table B- 5-1) when estimat ing EC

values. Estimati ng ECs doesn’t involve or require adjustment fo r respiration rates, as those are inherent to inhalation toxicity factors. S ections 6.4 throug h 6.6 discuss exposu

re time-re lated paramet ers, an d Append ix C Tab les C-2-1 and C-2-2 furthe r disc uss est imating EC

.
We consi der it ap

propria te to es timate

noncar cinog enic ha

zards and car

cinog enic risks ass ociated with direc t inhal ation exposu re by combi ning ECs with inhalation toxicity factors (reference concentrations [RfCs] or unit risk factors [URFs]). These tox icity factors are developed for all hum an populations, including sensitive subpopulations (including children) who m

ight be exposed to continuous concent rations over a

lifetim e. I nhalatio n risk param eters an d inhala tion pharmac okinetics are large ly chem ical- specific

and a " one size fits al l" appro ach to c onver t the sta ndard R fC or U RF para meters into scenario -spe cific tox

icity v alues m ay no t be app

ropriate . We th erefore gener ally re comm

end tha t a single (lifetime) inh

alation risk be predicted

for each receptor identified in Chapter 4, Table 4- 1.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-3 

### Inhalation expo sure concentrations for v apors and particles (arising from outdoor s ources) can be influenced by the re lative amoun t of time that a re ceptor spends indoors. Although v apors entering buildings and residen

ces as a result of air exchange are likely to remain airborne

and, therefore m

ay be inhaled, particulates entering these same bu

ildings are m

ore likely to s ettle out and not be inhaled. However, for the purpose of the risk assessment, we recomm

end assuming

that both vapor and particulates are inhaled throug hout the day, b oth indoors and outdoo rs.

6.1.1 Soil Inhalation Resu lting from Dust Resuspension
We don’t typically recommen d evaluating the soil inhalation of resuspen ded dust exposure pathw

ay. However, site- specific exposure setting characteristics migh t support evaluating

it (e.g. arid, w

indy climates). This section therefore discusses exposure to soil resulting from dust resuspension.

Inha lation o f soil re sulting

from dust re suspens ion cou

ld be an issue f or site- specific

exposu re scena rio location s at wh

ich ther e is littl e veg etativ e cove

r. Wind erosion could r esuspen d pollu tants in contaminated soil as

particles in the air. A s dust is resuspended, receptors could inhale the p ollutant particles (direct inhalation of particula te matter is addressed

in Section 6.1). The amount resuspen ded depends on the:

• moisture content of the soil,

• fraction of vege

tation cover,

• wind velocity ,

• soil particle size,

• pollutant concentration in the soil, and

• size of the contam inated area. Study of estim

ated exposures to deposited combustor em

issions via dust resusp ension indicates that dust resuspension by w

ind erosion is usually

not a significant pa

thway (U.S. EPA 1998c). Metho ds have also been developed to

assess the exposure to pollutants resuspended by wind erosion for landfills and Superfu nd sites (U.S. EPA 1 985a; 1 988b; 1 994q). We recommend con sulting these r eferenc e docum

ents

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-4 

### Equa tio n 6-1 if you ’ll be ev

aluating this ex posure pathwa

y. Also, it may

be usef ul to review the methods describ ed in U.S. E PA (19 98c).

6.2 INGES TION E XPOSURE PATHWAY S
Exposure can occur over a period of time. To calc ulate an average exposur e per unit of time, we
recommen

d dividing the total exposure by the time period. Express an average exposure in terms of body weigh t. I ngesti on expo sures qu

antified per the HHRA P are

• unitized for tim

e and body weight,

• presented in units of m illigrams per k

ilogram of b ody weigh

t per day, and

• termed “intake s.” Equation 6- 1 is a g eneric e quation for calc ulating ingestion che

mical intak e (U.S . EPA 1989e):

where I = Intake—the amount of CO PC at the exchang e boundary (m g/kg/day ); for evaluating exposu

re to noncarcinogeni c COPC s, the i ntake is refer red to as average d

aily dose (

ADD ); for ev

aluating exposu re to ca rcinog enic compounds, the intake is referred to as lifetime avera ge daily dos e ( LADD ) C gen 

### = Generic

COPC concen tration in me dium of conc ern (e. g., m g/kg for soi l or mg/L for surface water; see Cha pter 5) CR = Consumption rate —the amount of c ontaminated m edium consum

ed per unit of time o

r even t (e.g ., kg /day f or soil or L/da

y for water) EF = Exposu

re frequ ency ( days/y

ear) ED = Exposure duration (y ears) BW = Average bo dy weight o f the re cepto r over th e expos ure per iod (kg) AT = Averaging time—the period ov

er which exposure is a

veraged (days); for car cin ogens , the avera ging t ime is 25,5 50 da ys, ba sed o n a li fet ime exposure of 70 years; for noncarcinogen s, averaging time equals ED (years ) mul

tiplied by 36 5 day s per y

ear.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-5 

### We recom

mend varia tions of Equati on 6- 1 to cal culate p athway- and recep tor-s pecific exposu

res to COPCs. We presen

t the equations recom

mended for each

exposure pathway

in Appendix C. The variation of input variables is also de scribed in Appendi x C.
The expo sures ca

lculated using the HH RAP ar e intend ed to re present reasonable m

aximu m exp osure (RME) conditions, as furthe r described in U.S. EPA (1989e). S tudies of the com pounding of conservatism in probabilistic risk assessments show that setting as few as two factors at RME lev

els or high end (e.g ., near the 90th perc entile), while setting the remaining variables at less protectiv e typical, or “central tendency” v

alues (e.g., nea

r the 50th percentile) results in output insignificantly

different from output gener

ated usi ng all input v ariables at an R ME lev el (e.g ., 99th

percen tile va lue) (Cu llen 199 4).
As described in Chapter 2 (Section 2.2.1), the estimated air c oncentrations and deposition rates are based on RME emiss ions from tria l or risk burns. We recommend sett ing the follow

ing variables

set at R ME levels:

• the hig

hest I SCST3 m

odeled air conc entrations and deposit ion rate s at cho sen exp osure scenario locations,

• the exposure frequency , and

• the exposure duration. We generally recommend setting other exposure parameters (e.g . body weig ht) at average levels.

6.2.1 Body Weight
The choice of body weight to use in the risk characteriza tion equations presented in Appendix C depends on the d efinition of the

receptor at risk

—which,in turn , depen

ds on exposure

and su sceptib ility t

o adverse effects. U .S. EPA (1990 e) defines the body weight of the re ceptor as either adult weig ht (70 ki logram

s) or ch ild weig ht (1 to 7 yea rs; 17 k ilogra ms) on the ba sis of d

ata pres ented in

Nelson et al. (1969) . However, as in ot her Agenc y guidanc e (U.S. EP A 1991b; 1994r; 1994g), we recommend u sing a weight of 15 k

ilograms for the child (exposure duration of 6 years) in the risk assessm ent.
The daily intake fo

r an exposure pathway

is expressed as the do se per body weight. Because children have l ower bo dy we ights than ad ults. Ty pical in gestion expos

ures pe r body weig ht, such as for

soil,

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-6 

### milk, and f

ruits & veg etables,can be substan tially highe

r for ch ildren. This is the prim

ary re ason to evaluate the child resid

ent scenario (U.S. E

PA 1996g). However, u sing these two b ody weigh ts may not account for significant differences between weig hts of infants and toddlers or weights of teena gers and adults. Please rem

ember that, for the purposes of the risk assessment, the child scenario is defined by the average body

weight, rather tha

n the chronological age. Obv iously, the weig

ht of a child chang es significantly ov

er the first several y

ears. We assume

15 kilogram

s is a realistic averag e estimate for an exposure duration of 6 years. 15 k ilograms ov

erestimates the weig

ht of the child for the ea

rly years, an

d then un derestim ates it f or the l ater years (U .S. EPA 1996 g).

6.2.2 Food (Ingestion) Ex posure Pathways

Plants and anima

ls impacted by

emission sources may tak e up emitted C OPCs in the air or deposited COPCs in soil. Humans could then be exposed to C OPCs via the food chain when they consume these plants and animals as food. We ge nerally recomm

end determining

human intak

e of COPCs based

on the:

• types of foods consumed,

• amount of food

consumed per day,

• concentration of COPC s in the food, and

• percentage of the d iet contaminated by

COPCs. Chapte r 6 describes pr

ocedure s for determin

ing the conce

ntration of COP Cs in fo od. I

t also c onsiders the variations in expo sure resulting from food preparation m

ethods and type of food item (e. g., aboveground

versus belowg

round - i.e. root - v

egetables). Other variables, described b elow, may also significantly affect ex

posure estimates.

6.2.2.1 Types of Foods Consumed
The types of foods co

nsumed will affect exposure, because different plant and animal tissues take up differen t COPC s, and take t

hem u p at dif ferent r ates. The COPC

concen trations a receptor is ex

posed t o will then vary

with the types o f food in the diet. Therefore , it is important to determine CO PC

### Human Health Risk Assessment Protocol

Chapter 6: Quantifying E xposure September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-7 

### concent rations in food

accord ing to the ty pe of fo od. The

types of food consum ed mi ght al so var

y with the age of the rece

ptor, geograp

hical region, and socio-cultural factors.

6.2.2.2 Food Co nsumpti on Rat e Consumption rate

is the amount of contaminated m edium (soil, food

) consumed per unit of time or ev ent. The soil at an exposure location are inherent to the locatio n. Food consum

ed at an exposure location, however, m

ay or may not have originated there. The HHR AP assumes th

at only food prod

uced at the exposure location is contam inated by em

issions from the fac ility being assess ed. Food not pro duced at the point of exposure is not assumed to be contaminated, and is irrelevant to the assessment. Therefore, the con sump tion rates we re comm end in t he HHR AP (see Table 6- 1 and A

ppendix C) are for food

that is both produced and co

nsumed at the e

xposure location (i.e. at home).
Please Note : these rates do not represe nt the entire dietary inta

ke of the indiv

idual, but only that portion of the diet produc ed at home. For example, the beef consum ption rate represents only the amount of

beef co nsumed ea ch day whi ch was ra ised on the far m propert y.

TABLE 6-1 MEAN CONSUMPTION RATES a 

### FOR RECOMMENDEDEXPOSURE SCE NARIOS (number of servings per week)

Contaminated food Expo sure Sc enario
Farmer b Farmer

Child

b Resident Resident

Child Fisher Fisher Child Produce (8 oz servings) 2.8 1.4 2.3 1.2 2.3 1.2 Beef (1/4 lb servings) 5.3 0.7 N/A N/A N/A N/A Milk (8 oz servings) 29.5 10.5 N/A N/A N/A N/A Chicken (1/4 lb servings) 2.8 0.4 N/A N/A N/A N/A Eggs (number c ) 4.3 0.7 N/A N/A N/A N/A Pork (1/4 lb servings) 2.4 0.4 N/A N/A N/A N/A Fish (1/4 lb servings) N/A N/A N/A N/A 5.4 0.8 Notes:

a Values deriv

ed from the U.S. EPA

Exposure Fa

ctors Handbook

(1997). b Values based on consumpt ion rates of

a 154 lb adult a

nd a 33 lb child.

c Values based on an assumed egg weight of 3.0 ounces.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-8 

### As desc ribed in Section 6.2, exposure s calcul ated usi ng HH RAP m ethods are inte

nded to represe nt RME conditi ons. Accordin

gly, the HH

RAP re comm

ends de fault values for expos ure para meters that w

ill result in RME estim

ates. Howeve

r, there are likely

to be differences between recommended default, and regional and site- specific exposure param eter values. This m

ay be especially

true for the consum

ption rates (a general term

for intake rates and

inhalation rates). I

n addition to estim

ates using the
recommen

ded default parame

ter values, y

ou can refine the y

our risk assessm

ent by including supplem ental ca lculations usin

g regional-

or site- specific

param eter v alues. We recommend doi ng thi s only i f you docum

ent the region

al- or site- specific

param eter v alues in

the risk assessm ent repo rt. We
recommen

d providing these supplemental calculations in addition to, and not instead of estim ates based
on recomm

ended default exposure p arameter values . This will help standardize risk assessm ent methods, thereby aiding the ability to com pare outputs from different risk assessm ents. The following subsections describe exposure pathwa y-specific c onsiderations regarding consumption rate

. This section gives some of the pe rtinent history of consu

mption rates. I

t also describes the series of steps we followed to deriv

e the recomm

ended consumption rates found in Table 6- 1. Site-spe cific conditions might exist s

uch that you nee d to derive an altern ative, or additional c onsumption rate. For example, you may need a consum

ption ra te for an additional exp osure sc enario (e.g. consum ption o f deer m

eat for a hunter scenario). I f you need to c alculate your own consumption rate(s), we recomm end using the process described below. For transparency and clarity, we recommen d identifying a

ll consumption rates used in the risk assessm ent. We also re comm

end cle arly id

entify ing an d discu ssing alteratio

ns to
recommen

ded default rates, and ad

ditional consumption

rates, with the perm

itting authority prio

r to use.

The amount of

daily food co nsum ption v aries with ag e, sex, body

weig ht, and geog raphic r egion , and i

t also varies within the se categories. U .S. EPA (1998 c) recomm ended using v

alues from the 19 97 Exposure Factors Ha ndbook (EFH) (U.S. E

PA 1997b) to com

plete the risk assessm

ent process. The EFH used the 198 7-1988 US DA Food Consu mption Survey to represent cons umption rates for u

rban and suburban areas. However, if site- specific information ind icates that the population is in a more rural o r agricultural area, U. S. EPA (1990e) recommen ded using the 19 66-67 US DA Food Consu mption Survey to represent the consum

ption rates of a m

ore agrarian population

.

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-9 

### The 1997 Exposure Factors Ha ndbook (EFH) (U.S. E

PA 1997b) perform

ed an analysis of the 1987-198 8 USDA National F ood Consum ption Survey

(NFCS). The NF CS collects inform ation over a 7- day period on the socioeconom

ic and demog

raphic characteristics of househo lds, and the type s, values, and sources of food s consu

med. The foll owing

inform ation was tak

en from the sur vey:

• whethe r or not the foo d produ ct was us ed in th e house that we ek;

• whethe

r or not the foo d produ

ct used that we ek was home produ ced;

• the quantity (m

ass, such as pounds or kilograms) of food consum ed (home produ

ced or not) i n the ho use tha t week;

• the number, age, and body weight of indiv iduals in the household; and

• the number of weekly m eals consumed b

y each fam

ily mem ber. All households were s

urveyed abo

ut the same food

types, and con sumption rates were averaged over the entire survey p opulation - to calculate what are kn own in the EFH as the “Per Capita” rates. In addition , EPA calculated consum

ption rates for “consum

ers only:” a rate for only those househ olds which consumed a pa

rticular food stuff during the week the survey was taken. I n addition to total consum ption (i.e. for the entire popula tion of consumers ), rates were brok en out according to various criteria, such as age of consum er, ge ographic region, an d leve l of urb anizat

ion. S urvey

particip ants we

re also asked

if they operated a farm

or ranch, raised anim

als, or had a hom

e garden, and consumption rates were also broken out for thes e sub-g roups. We recom

mend using

food consumption rate information (ingestion rates) from the EF H; specifically, the s ection regarding home produced food items.
Chapte r 13 of the EFH

(Int ake R ates for Various Home

Produc ed Food

Item s) lists consum

er only
cons umpti on ra tes of ho me pro duce d foo d. For examp le, T abl e 13-6 5 (Co nsume r Onl y Intake of Ho me grown Root Vegetables (g/kg -day)) lists a mean consum ption rate of 1.16 g

/kg- day for all househo lds that c onsumed r oot veget ables they pro duced t hemselve s. From the se hous ehold s, the EF H also br eaks out c onsu mpti on ra tes spec ifi c to h ouse hold s who farm ( e.g. a mean o f 2.6 3 g/kg-da y). T hese farmspecific rates represent the am ount of food that farm

families produced themselves that was consum ed during the we ek the

surve y was taken . We rec omm

end usi ng the se cons

umpti on rates

to estim ate exposures to the Farm

er and Farmer C

hild scenarios.

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Chapter 6: Quantifying E xposure September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-10 

### The recom

mend ed farm -spe cific consum

ption ra tes, as listed in

the EF H, are averaged acro ss all fa mily members, regardless of ag e or body weig ht. They also do not consider losses during preparation and cooking of the food. Additional work is needed, therefore, to acquire scena rio-appropriate actua

l consumption rates:

As mentioned above, the EF H provides consu mption rates for the

entire population of cons umers - the
consum er only rate. D ependin

g on d ata availabili

ty, the consu

mer only ra

te is als o brok

en out i nto various age- specific demog raphics, covering

0-1 y ear, 1-2 y ears, 3-5 y

ears, 6-11 y

ears, 12-19 years, 20-3 9 years, and 40-6 9 years. We sugg est com bining the con sumer

only rate, age-ap

propria te demo graph

ic rates , and t

he sub- populat ion rate (e.g. for a fa

rm fam ily) to deriv e a scenario- specific consumption rate (e.g. for an adu lt Farmer) using

equation 6-2 :
Equa tio n 6-2

where: CR scen 

### = Consu mption rate fo

r scenar io CR subpop 

### = Consumption rate of subpopulation TWA gen 

### = Time-weighted average of age- appropriate subset of consu mer only population CR gen 

### = Consumption rate for consumer only population Sufficient age- specific data were not always available. For example, there was insufficient data for the EFH to provide a consumer only poultr y consumption rate for the 12-19 age group. In this event we sugg est ag ain usin

g Equ ation 6-2, to c ombin

e the to tal cons

umer only p opulati on rate, the ag e-sp ecific Per Cap ita rate, and the

total P er Capi

ta rate ( for pou

ltry, Per Cap ita va

lues are found in EFH

Table 11-11), to generate an ag e-specific consum er only rate.
See the example

derivation below for a demonstration of how we recom mend generating scenariospecific consum ption ra tes. To derive

consum ption ra tes for t he Farm er and F armer

Child e xposure scenarios, we recom

mend using

the home pro duced, consum ers only consum

ption rates of households who farm, for home produced beef, pork, chick en, milk, eggs, v

egetables, and fruits.

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-11



### TABLE 6-2 COOKING-RELATE D WEIGHT LOSSE S FOR VARIOUS HOM E-PRODUCED FOO DS Percent Weigh t Losse s from

Prepar ation of Various Meats (SOURCE: EFH Table 13-5) Meat Type Mea n Net Coo king Lo s s ( %) Mea n Net Post Coo king Lo s s ( %) Beef 27 24 Pork 28 36 Chicken 32 31 M ilk N/A N/A Eggs N/A N/A Fish 30 11 

### Percent Weight Losses from Preparation o f Various Produce

(SOURCE: EFH Tables 13- 6 and 13- 7) Produce Type Mean Parin g or Prep aration Loss (% ) Moi s t ur e C on t en t ( %)

Pro tected Fruits 29 87 Protected Vegetables 23 82 Exp osed Fruit 21 85 Exposed Vegetables 16 90 

### Consumption rate s of households who farm are not ne cessarily the m ost appropriate rates for hous eholds who don’t farm . For certain food ty pes, the EFH also breaks out consum ption rates of hom

e-produced foods specific to those ho useholds who g arden. This comb ination of subpopulation (i. e. gardeners) and food source (i.e. hom

e produced) is the closest option available in the EFH to the residen tial and fishing scenarios we recom

mend in the H

HRAP. Con sumption rates for this subpopulation are av ailable for the food types included

in the produce-

related exposure pathways we recomm end (i.e. protected prod

uce, exposed produce, and

belowground v

egetables). We recom

mend using

these rates to gene

rate producerelated consumption rates for the Resident, R esident Child, Fisher, and Fisher Child expo sure scenarios.
The EFH provides information to accou nt for cooking

and post-co oking losses for food products which are hom e produ ced. The se data are sum

marized in Tab le 6- 2. See the exa mple deriva

tion bel ow for a demonstration of h

ow to use cook

ing loss data in d

eriving consum

ption rates.

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### Example Consu mption Rate Derivation: Homegrown Poultry consumption for the Farmer

The Farmer scenario in

cludes an averag e consumption ra te during a 70-

year lifetime, from age 7to 70. Table 13-55 of the EFH lists the follow ing Farmer-

related mean consu

mption rates of home produced poultry (g/k g- day): Total population 1.57 broken out by

age group : ages 6- 11 ND (5 years) ages 12- 19 ND (8 years) ages 20- 39 1.17 (20 years) ages 40- 69 1.51 (30 years) households wh

o farm 1.54 Please note that thoug

h the EFH dem

ographic subset includ

es years 6- 11, the Farme

r scenario begins at age 7, so only 5 years of that con sumption rate are used. In addition, Table 11-11 (Mean Meat Intakes Per Indiv idual in a Day, by Sex and Age (g/day as
consum ed) for 1987- 1988) l ists the following P er Capi

ta consu mption rates of poul

try (am ong o thers):
All ind ividua ls 26 broken out by

age group : ages 6- 11 27 ages 12- 19 27 Using the 12- 19 ag e grou

p as an exam

ple, eq uation 6 -2 is

used to calcula te age -spe cific consumer only rates as follows:
CR ages 12-19 

### = 1.57 * 27/26 = 1.63 g/k g-day A time weig

hted average for an adult Farm er =

And, using E quation 6-2:

CR Farmer 

### = 1.54 * 1.43/1 .57 = 1.40 g /kg- day Table 13-5 of the

EFH lists cook

ing and post- cooking losse s for poultry of 31 % and 32%, respectively

.

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### Therefore: 1.40 * (1- 0.31)*(1-0.3 2) = 0.66

Poultry consum

ption rate for the Farm

er = 0.66 g/k

g-day
Additional con sump tion rate inform ation is presen ted in A ppendix C as fo llows: Table C- 1-2 (produc e); Table C- 1-3 (beef, milk, pork, chick en, and egg s); and Table C- 1-4 (fish).

6.2.2.3 Percentage of Contaminated Food
The percentage of food consumed by an individual w

hich is home- grown will affect ex posure, because the HHRAP as sumes

that on ly the portion of an in dividu al’s dietary in

take w hich is home -g

rown is impacted by

facility emission s.

We recommend assuming that all food produced at the exposure location - i.e. the farm for the farming scenario s, and the hom

e gard en for t he resid ential a nd fishi ng sce narios - is im pacted by fac ility emiss ions. O

nly that porti on of the diet produced at hom e (and t herefore expose d to fac ility e

missi ons) is of consequence in the risk assessment. As detai led in Section 6.2.2 .2, the consumption rat es we
recommen

d represent only the

home- produced portion of the diet. Therefore, by usin g consum ption rates specific to home produced foods, we consider it reasonable to assu me that 100% of those home pro duced foods are contamin

ated.

6.2.3 Soil (Ingestion) Ex posure Pathway
Soil ingestion, dermal expo sure to soil, an d inhala tion of resuspe

nded du st are p otential

soil ex posure pathwa ys. F or the p

urpose of RCR

A com bustion perm itting decisions, we

recom mend consid ering soil ingestion. However, we currently only recom

mend eva luating derma

l exposure to soil (see S ection 6.3) and inhalation of resuspend ed dust (see Section 6. 1.1) if site-specific exposure setting chara cteristics support evaluating

these exposure pathwa

ys. Based on air dispersion m odeling and depo sition of COPCs , emi ssion co

ncentra tions in soil wi ll vary

with d istance from the sou

rce. I t’s poss ible to determ ine pote ntial routes of exposu

re by evaluating the way

in whi ch the s oils in t

he area are used . Soil

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-14 

### used for farming

or recreation will be inv

olved in pathways of human ex posure that differ from

those of soil on roadways or in urban areas.

Children and adults are exposed to COPC s in soil when they consume conta

minated soil that ha s adhered to their hands. Factors that influence exposure by soil ingestion include

soil concentration, the rate of soil ingestion during

the time of exp osure, and the leng th of time spent in the vicinity of contaminated soil. S oil ing estion r

ates in children

are bas ed on s tudies t

hat measured

the qua ntities o f non- absorba

ble tracer minerals in the feces of young children. I

ngestion rates for adu

lts are based on assum

ptions about exposed surface area an d frequency o f hand-

to-m outh activity . In

door du st and o

utdoor soil m

ay bo th contribute to the total daily ingestion. Ex

posure levels are also influenced by the a mount of tim

e that the individual spends in the vicinity of soil exposed to deposition of emitted pollutants.
In addition, some young children—ref erred to as “pica ” children—may intent ionally eat soil. As discussed in U.S. EPA (1989f), the ty pical medical and scientific use of the term “pica” refers to the ingest ion of n on-f ood item s, such as soil , chalk

, and crayon s. Such behav ior is co nsidere d a tem

porary behavior and a n

ormal part of child developmen t. For risk asses sment purposes, pica is typically defined as “an abnormally

high soil ing estion rate” and is believed to be uncom mon in the general population (U.S. EPA 19 89f). A

gency risk a ssessm

ent doc umen ts don’t identif y a de fault “p ica” soi l inge stion ra te (U.S. EPA 19 89e; 1989f ; 1991b). Pica behavior is not generally included as part of risk

assessments.

If available information indicates that there are children exhibiting pica behavior in the assessment area, and you determ

ine that these children represen t a special subpopulation potentially receiving significant exposu re (see C hapter 4 ), it m

ay be prudent

to incl ude the se child

ren in t he risk assessm ent. We
recommen

d making this evaluation on a case-by-case basis base d on site-specific exposure setting characterization.

6.2.4 Water (Ingestion) Ex posure Pathways
Evaluating H

HRAP water expo sure pathways inv olves estimating

COPC concentration s in drinking water from surf

ace wat er bodi es or co llect ed prec ipita tion ( e.g., cis terns ). Conta minants moving thro ugh the wat er pathways al so influ

ence CO PC concentrati ons in f ish. Var ious m odels ar e avai lable to

estimate

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### daily exposures of individuals using these water sources for various purposes, such as fishing and drinki ng wa ter.

We recom

mend using site- specific

inform ation to determ ine whi ch wate

r expos ure path ways to eva

luate in the risk assessm

ent. Whether it’s collected pre cipitation, or from a surface water body such as a lake, farm pond, or city reservoir, the way in wh ich water is used will su

ggest possible exposure pathway s. For example, using a surface water body as a d rinking water source will introduce water ingestion as a possible exposure pathwa y. Com mercial and/or recreation al fishing, with su

bsequent use of fish and shell fish a s a food source , make the fo od chai n an impor tant r oute of exposu re for communiti es havin g a surface water b ody in

the vicinity

of a combus tor.
U.S. EPA (1998c) recommended varying the water in put variables to det ermine a range of exposures . An indivi dual th at fis hes and obtain s drinki ng water from the s ame water source could r epres ent an a verage expo sur e sce nari o. A wo rst -case poss ibi lit y might invol ve a pe rso n who (1) u ses drin king wa ter from a cistern that collects precipitation, a nd (2) fishes in a sm

all farm pond.
Because ground- level concentrations of COPCs gene rally decrease with d

istance from the so

urce, important factors in d

etermining the water concentration include:

• the location of the precipitation-collection apparatu s,

• surface water body onto which em itted COPCs are dep osited, and

• the COPC soil con centration (which affects runo ff and leachate concentrations).
In a ddition , the lo cation a

nd siz e of the

watershed wil l affect the concentrati on of C OPCs s uspend ed in runoff.

6.2.4.1 Ingestion of Drinking Water from Surface Water Sources
For evaluating a surface water body as a drinking

water source, exposu

re is affected by the COPC concentration in the water, the daily am ount of water ing ested, and the leng th of time that the receptor spends in the area serv

iced by that water supply system . The equations we recommend for estimating the COPC concentration in a surface water body are discussed in Chapter 5 and Appendix B. These

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### equations also consider con tributions of COPC lo ading from the surrounding watershed. We recom mend using the water consumpti on rates specif ied in U.S. EPA (1997b) and des cribed in Appendi x C.
As in previous A

gency g uidance (U.S. EPA 1998c), we recommend typically assum ing that treatment processes for drinking

water do not alter disso lved COPC concentrations.

6.2.4.2 Ingestion of Drinking Water from Ground Water Sou rces
For the purpose of R

CRA comb

ustion permitting

decisions, we don’t typically recom mend eva luating exposure from g

round water sources use d as drinking water. Study

of this pathway for combustor emissions indicat es that this isn ’t a significant exposure pathway (U.S. EPA 1998c ). However, COPCs may - because of special site- specific characteristics - infiltrate into ground water, resulting in CO PC exposu re via ingestion when gro

und wa ter is us ed as dr

inking water. This could be b ecause of extre mely shallow aquifers being

tapped for drinking

water, or a k

arst environment in which the local surface water significantly affects the quality of g round water used as a

drinking water source. The m ethod developed to calculate risks from

the ground water pathway was originally intend

ed for use in eva

luating impacts of the land disposal of v

arious wastes (U.S. EPA 1998c; 1994q ; 2003). We recom mend consulting

these refer ence do cuments if you int end to e valuat e this exposu re pat hway.

6.2.4.3 Ingestion of Fish
You may find the fish ingestion ra tes specifie d in U.S. EPA (1997b) and furt her described i n HHRAP Appendix C useful fo

r evaluating the

fish ingestion pathway. Factors that affect human exp osure by ingestion of fish from

a surface water body

affected by com

bustion unit emissions include:

• COPC concentrations in the sediment an d water column ,

• the types of fish an d shellfish consumed,

• the ingestion rates for the various fish and shellfish groups, a

nd

• the percent of dietary fish caught in the surface water body affected by the com bustor.

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### The types of fish consu

med will affect ex

posure, because different ty pes of fish and shellfish tak e up COPCs at different rates. For example , fatty fish tend to accumulate org anic COPCs m ore readily than lean fish. The amo

unt of fish consum

ed also affects exposure, because people who eat large amo unts of fish wil l tend t

o hav e higher expo sures. Fish co nsum ption ra tes va ry g reatly , depen

ding o n geo graph

ic region and so cial or c

ultural factors. For ex ample , popu lations such as

Ind ian trib es, Am

erican & Pacific Islanders, and

some im migrant g roups are known

to have hig

h local fish consum

ption rates. Because 1 00 percent of a receptor’s dietary fish may not originate from the surface water body

near the comb

ustion facility, the percentage of locally caug ht fish is also a va

riable for exposure.

6.3 DERMA

L EXPOS URE PA THWAYS

6.3.1 Dermal E xposu re to So il
For the purpose of R

CRA comb

ustion permitting

decisions, We don’t ty

pically recomm

end evaluating dermal exposure to

COPCs throug

h contact with soil. However, site- specific exposure setting characteristics may

support evaluating

this exposure pathway . Therefore, this section discusses dermal soil exposure.

Available data indicate that the contribution to ov erall risk from dermal exposure to soils impacted from hazardous waste combustion facilities is ty pically small re lative to contributions res ulting from exposures via the food c

hain (U .S. EPA 1995 h; 1996 g). F or exam ple, the risk

assessm ent conducted for the Waste Technologies I

ndustries, Inc. , hazardous wa ste incinerator in East Liv erpool, Ohio, indicated

that—for an adult subsistence farm

er in a subarea with hig

h exposures—the risk resulting from soil ingestion and dermal contact wa s 50-fold less than the risk from any other expos

ure pathway and

300-fold less than the total es timate d risk

(U.S. EPA 1 995h; 1 996g)

.

Huma ns can b e expos ed to C OPCs by abso rption t hroug h the sk in when it com es into contact

with contam inated s oil. Fa

ctors that affect derm

al expo sure inc lude:

• exposed skin surface area;

• contact

time;

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### • contact

amou nt;

• amount of tim

e spent near the com

bustion source; and

• fraction of COPCs ab sorbed through the skin. In general, an increased dose o f COPCs can potentially be absorbed through the sk in as the surface area of the skin is increas ed. Surface area is affected by age and body weig ht; for example, children have less total surface area than adults. The amount of surface area available for exposure to soil is also affected by the am ount of clothing w

orn. An adult working in the garden in long sleeves and pants will have a small er expo sed surf

ace than an adu lt work ing in shorts and a sh

ort-s leeved

shirt. For de

rmal exposure from soil, the ex

posed surface area affects the amount of soil that can adhere to expose d skin.

Contact time refer s to the duration of time each day that skin is in cont act with contaminat ed soil. As duration increases, so doe s the amount o f COPCs that can be absorbed. Derm al exposure is also affected by the am ount of time each

day spent in the

vicinity of the

combustion sou

rce, where the soil m

ay contain pollutants em

itted from the com

bustion facility. I

ndoor dust and outdo or soil may both increase the dail y con tact. C onsider

seasonal expo sure m

ight a lso be a ppropri ate, be cause re giona l climate will influence contact time.

The amount of CO PCs that can be abso rbed through the skin depends on the chemical prope rties of the COPC, properties o f the soil matrix, and dermal pharm acokinetics. I f a COPC can’t b e readily absorbed throu gh the skin , the da ily int ake of th e COPC may be smal l even if other e xposur e chara cteri stics (e.g. contact time)encour

age ab sorption. However , if site -spe cific condition s suggest that dermal expo sure to soil may co

ntribute significantly to total soil-related e xposures, we recom

mend considering

the
assessm ent methods describ ed in U .S. EPA (2004 d).

6.3.2 Dermal Exposure to Water
We don’t typically recommen d evaluating the dermal water exposure pathway when assessing risk from hazardous waste combustor em issions. However, if the surface water b ody affected by combustor emissions is used frequently for recreational purposes such as swim ming and boating, derm

al absorption

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-19 

### of contaminated water becomes another possible route for hum an exposure. Derm

al exposure is affected by:

• the surface area of exposed skin,

• the COPC concen tration in the water,

• the permeability

of the skin to the COPC, and

• the leng

th of tim e that the indiv

idual is in cont act with the wa ter.
6.4 EXPOSURE FREQUENCY

The HHRAP assum

es that the receptors in each recommended exposure scenario are exposed to all of the scenario -spe cific ex

posure pathwa

ys 35 0 day s per y

ear (U. S. EPA

1989e; 1991b; 1991d) . This assumption is base d on the protective estimate that all receptors spend a max

imum o f 2 weeks away from the exposure scenario location selected in Section 4. 3.

6.5 EXPOSUR

E DUR ATION
Exposure duration is the length of tim e that a receptor is expose d via a specific exp osure pathway. A receptor is no longe

r exposed to COPC s via the direct inhala tion exposure pathway

after an emission source ceases operation. However, a receptor could be exposed via the indirect exp osure pathways fo r as long as they rema in in the assessment area. W e recom mend using default RME values to

estimate exposure duration for spec ified receptors.

As in U.S. EPA (199 8c), we recommend a ssuming th at rec eptor s are ex posed t o the lo ng-term avera ge COPC soil or water c oncentr ations ( and the

subseq uent CO PC plan

t or ani mal c oncentr

ations) present

in the environm

ent or media follow

ing a period of tim

e during which there were continuous ha zardous wast e comb ust or emi ssi ons. For ex ist ing f aci lit ies , U.S. EPA (1 990e ) ass umed t hat this peri od of time can be r epresen ted by default time periods

of 30, 60, or

100 years. U .S. EPA (1998 c) sim plified this to assume that the p eriod could be 

## $ 30 years. These values are based on the assumption s that the hazard ous was te com bustion unit or the em ission s ource: 1. is already in place,

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### 2. will continue to be used for the rest of its useful life (estimated to be 30 years), and 3. may be replaced when it reaches the end of its useful life (p ossibly as long as 60 or 100 years), because it is an integral part of the facility operations.
We consider these assum ptions reasonable for a haz ardous waste em

ission source, such as an industrial boiler burning a co

ntinuous stream of facility hazardous waste.

Alth ough a combu sto r may re main i n the same l ocat ion f or 10 0 year s—a nd a p ers on may h ave a l ife time of exposure to em

issions from that combustor— data on population mobility (U.S. Bureau o f the Census, 1986) indicate that many Americans do not remain in the same area for their 70-year lifet ime. An estimate of the num

ber of y ears tha t a pers on is lik

ely to spend in one a

rea, su ch as the vici

nity o f a combustion facility , can be derived from inform

ation about mob ility rate and m edian time in a residence. In addition to the number of years at a particular loc ation or residence, the am ount of time spe

nt at that location each day directly affects exposure. For example , children that attend day care or adults that work in a different location for part of the day may be exposed to higher or lower COPC levels.
The exposure duration values we recomm end are presented in Table 6- 3.

TABLE 6-3 EXPOSURE DURATION VALUES
Recomm ended Exposure Scenario Receptor Value Source Child Reside

nt 6 year s U.S. EPA 1990f ; 1994r Adult Res ident 30 year s U.S. EPA 1990f ; 1994r Fisher 30 year s U.S. EPA 1990f ; 1994r Fisher Child 6 year s Assum

ed to be the s ame a

s the Child Resident Farmer 40 year s U.S. EPA 1994l; 1994r Farmer Child 6 year s Assum

ed to be the s ame a

s the Child Resident

### Human Health Risk Assessment Protocol

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U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 6-21 

### 6.6 AVER

AGING TIME
For noncarcinogenic

COPCs, we generally recom mend using

a value of expo sure duration (years- as specified for each receptor in Section 6.4) x 365 days/year as the averaging time (U.S. EPA 1989e; 1991d). Howev

er, for carcinogenic COPCs—the effects of w hich may have long latency periods—the age of the receptor (i.e., child, adult, o r elderly) influences the COPC exposure p athway, because the exposure durat ion and, therefo re, the quantit y of exposure, will vary. For carci nogenic COPCs, we
recommen

d using an av

eraging tim

e of 70 years.

We recommend evaluating carcinogenic expos

ures for different receptor ag es separately, becaus e the daily activi

ties of t hese rec eptors ( and bod

y wei ghts, as described in Section 6.6) v ary, i ncludin g:

• the am

ounts o f food a

nd wate r consu med;

• the types of food consumed; and

• the amount of e

xposed skin surface. Health-based c

riteria, such as health adv isories for drinking

water, are also different fo r children and adults. As a result, for some exposu re pathways, suc

h as soil ingestion, children may have a g reater quantif iable ex posure and be at gre ater risk than ad ults. S ome b ehavi ors, su ch as m outhing of dirty objects or direct ingestion of soil, which could also contribute to exposure, are also much m

ore prevalent in children than adults.
Because quantifying

carcinogenic CO PC exposure depends on the duration of ex posure, the age of the receptor is important. For risk assessm ent purposes, the av

erage huma

n lifespan is generally

considered to be 70 years. Childhood represents only about 10 pe rcent of the lifespan (6 y

ears) (U.S. EPA 1998c). In actual expo sure scenarios, individ uals may be exposed only during childhood o r adulthood. I

n other cases, exposure m

ay overlap these periods, such as a child who grow s into adulthood and re mains in the same geog

raphical area. Based o

n the age of the receptor and inform ation on the duration of exposure, U.S. E PA (19 90e) rec omm

ended c onsider

ing ri sk to three di fferent receptors: 1. a child who gro

ws to an adult and is exposed for his or her entire 70-y ear lifetime,

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### C Identification of site- specific or alternate default m edia equations and/or inpu ts; including justification and full referencing

C 

### Exposure calculations RECOMMENDED INFORMATI ON FOR THE RISK ASSESSMENT REP ORT 2. a child who gro

ws to an adult and is exposed for only a part of his or her a

dulthood—a total of 30 years, and 3. an adult exposed for 16 years. Because the effects of certain carcinogenic CO PCs may have long

latency periods—in some instances approaching the hu

man lifespan—it m

ay be appropriate to

estimate daily

intake by using the adult v alue for body weig

ht and a longer averaging time. I n cases where effects hav e a shorter latency p eriod, U.S. E PA (19 90e) rec omm

ended a n aver aging time period o f less than 10 y ears. H owev er, whe

re children are known

to be at special risk, it may be more approp riate to use this averag

ing time w

ith a body weight value for toddler s, infants, or young childr en. For COPCs classifi ed as carcinogens, we
recommen

d using a longer averaging time and the a

dult body weig

ht to calculate the risk resulting from air or water exposure.
It is sign ificant that childhood is define d differently in the d ifferent references. U.S. EPA (1990e) defines childhood as being from 1 to 7 years old. As in this and other Agency guidan ce (U.S. EPA 1991b; 1994r; 1998c), we define childhood as having an exposure duration of 6

years. Please

note that some of the da

ta used for input into the various exposure sce nario equations in Appe

ndix C was not availa ble for children , or was avai lable for mor e restrictive a

ge g roups, such as

2-y ear- olds or 4- to 6-year- olds. In such cases, and as n oted in Appendix C

where such va

lues are presented, 1. the available data we re eva luated t o ensur e that the presen

ted defa ult va lues are sufficient for conducting a risk assessm ent, and 2. in cases in which the available data were n ot sufficient, reasonable interpo lations of the available data were p ossible.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 7-1 

### PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak in this chapter is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. 

# Chapter 7 Characterizing Risk and Hazard What’s Covered in Chapter 7: 7.1 Quantitatively Estimating Cancer Risk 7.2 Quantitatively Estimating Noncancer Hazard 7.3 Target Levels 7.4 Estimating Acute Exposure from Direct Inhalation



## It is important that risk characterization exhibit the core values of transparency, clarity, consistency, and reasonableness (please see the related EPA Information Quality Guidelines recommendations as discussed in Chapter 1, page 1-11 ). The final step of a risk assessment is risk charact erization. This involves combining the exposure quantities generated in Chapter 6, and the toxicity benchmarks available in the HHRAP companion database, to calculate the excess lifetime cancer ri sks (risk) and noncancer hazards (hazard) for each of the pathways and receptors identified in Chapte r 4. Risks (and hazards) are then summed for each receptor, across all applicable exposure pathways, to obtain an estimate of total individual risk and hazard. Risk characterization also involves docum enting the uncertainties and limitations associated with the rick assessment, as d escribed in Chapter 8.

Risk from exposure to combustor emissions is the probability that a human receptor will develop cancer , based on a unique set of exposure, model, and toxi city assumptions. We recommend using the slope or unit risk factor in risk assessments to estimate th e probability of an individual developing cancer as a

### Human Health Risk Assessment Protocol Chapter 7: Characterizing Risk and Hazard September 2005

1 

### Currently 2,3,7,8-TCDD TEQ and dioxin-like PCBs are the only COPCs with biotransfer factors for the breastmilk pathway. However, appropriate biotransfer factors for other chemicals may become available and thus provide the information needed to include them in this pathway evaluation. We suggest consulting Chapter 9 (Breastmilk Pathway) of U.S. EPA (1998c). U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 7-2 

### result of exposure to a particular level of a COPC. For example, a risk of 1 x 10 -5 

### is interpreted to mean that an individual has up to a one in 100,000 chance of developing cancer during their lifetime from the exposure being evaluated. In contrast, hazard is the potential for developing noncancerhealth effects as a result of exposure to COPCs. A hazard is not a probability but, rather, a comparison (calculated as a ratio) of a receptor’s potential exposure re lative to a standard exposure level ( RfD or RfC). The standard exposure level is calculated over a similar exposure period and is estimated to pose no appreciable likelihood of adverse health effects to potentia l receptors, including special populations (U.S. EPA 1989e).
Risks and hazards here are typically characterized for single scenarios, and are referred to as individual risks and hazards (U.S. EPA 1989e; 1994g; NC DEHNR 1997). Individual risk and hazard descriptors are intended to convey information about the poten tial risks to individuals potentially impacted by emissions from a facility burning hazardous waste. A risk assessment developed following the procedures described in Chapters 2 thr ough 8 and Appendixes B and C will provide • quantitative and qualitative estimates of risk and hazard associated with exposure to COPCs; • estimates of blood levels associated with exposure to lead; • evaluation of infant exposure via breast m ilk to COPCs with appropriate biotransfer factors 1 

### , and • evaluation of acute risk and hazard resulting from direct inhalation. If a permitting authority feels that you need to consider calculating population risks, we recommend following the applicable methods describ ed in the U.S. EPA NCEA document, Methodology for Assessing Health Risks Associated with Multiple Pathways of Exposure to Combustor Emissions (U.S. EPA 1998c).
Standard rules for rounding apply which will commonly lead to an answer of one significant figure in both risk and hazard estimates. For presentation purposes, hazard quotients (and hazard indices) and

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### C 

### Indicate the scope of the risk assessment (mat ch the level of effort to the scope) C 

### Summarize the major risk conclusions. C 

### Identify key issues (a key issue is critical to pr operly evaluate the conclusions). For example, was surrogate or measured emissions data used. C 

### Describe clearly the methods used to determine risk (provide qualitative narration of the quantitative results). C 

### Summarize the overall strengths and major uncertainties. INFORMATION RECOMMENDED FOR RISK ASSESSMENT REPORT cancer risk estimates are usually reported as one significant figure. We recommend rounding only the final reported results, not the intermediate calculations.

7.1 QUANTITATIVELY ESTIMATING CANCER RISK
As described above, risk estimates represent the incr emental probability that an individual will develop cancer over a lifetime as a result of a specific exposure to a carcinogenic chemical (U.S. EPA 1989e). We recommend calculating these risks as follows:
Inhalation Cancer Risk Cancer Risk = EC @ 

### URF Equation 7-1 where EC = Exposure concentration ( : 

### g/m 3 

### ) [see Chapter 6] URF = Unit risk factor ( : 

### g/m 3 

### ) -1


### Ingestion Cancer Risk Cancer Risk = LADD @ 

### CSF Equation 7-2 where LADD = Lifetime average daily dose (mg/kg-day) CSF = Cancer slope factor (mg/kg-day) -1

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### PLEASE NOTE : In the Supplemental Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens (U.S. EPA 2005g), the Agency recommends estimating inhalation and ingestion cancer risk slightly differently for carcinogens the Agency determines to cause cancer by a mutagenic Mode of Action (MOA, as defined in Guidelines for Carcinogen Risk Assessment [U.S. EPA 2005f]). Unfortunately, we haven’t completed our recommendations for how to implement the guidelines set out in U.S. EPA (2005f; g). We recommend periodically ch ecking the EPA hazardous waste combustion web site ( http://www.epa.gov/epawaste/hazard/tsd/td/combust/index.htm ) for updates on our recommendations.


### It’s possible for receptors to be exposed to multip le COPCs within a individual exposure pathway. We recommend estimating the total risk associated withexposure to all COPCs through a single exposure pathway as follows (U.S. EPA 1989e):


## Cancer Risk T 

## = 

# 3 i 

## Cancer Risk i 

### Equation 7-3 where Cancer Risk T 

### = Total cancer risk for a specific exposure pathway Cancer Risk i 

### = Cancer risk for COPC i for a specific exposure pathway Receptors might be exposed through a number of expos ure pathways (see Table 4-1). We consider it appropriate to sum risks from multiple exposure path ways for a given receptor. The cumulative risk posed to a receptor is the sum of total risks from each individual exposure pathway. Express the cumulative risk as follows:


## Cumulative Cancer Risk = 

# 3 Cancer Risk T 

### Equation 7-4 where Cumulative Cancer Risk = Cumulative cancer risk from multiple exposure pathways Cancer Risk T 

### = Cumulative cancer risk for exposure pathway T In addition to multiple pathways, a receptor might be exposed to emissions from multiple sources (See Chapter 2 for additional discussion on emission sources). In addition to emission source-specific risk/hazard estimates (see Chapter 3 regarding source-specific modeling), we recommend summing the risks from all modeled sources for each receptor at each exposure scenario location. For example, if a facility operates an incinerator and a boiler that both burn hazardous waste, sum the risks from both units for each receptor. For fugitive emissions from stor age and handling of hazardous waste, add the risk

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### Some chemicals don’t demonstrate a threshold response. Lead and ozone are two examples of chemicals with noncancer effects that don’t have a threshold below which no adverse effects are observed. U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 7-5 

### associated with fugitive emissions to the risk s from the combustion unit for each receptor at each exposure scenario location.
We present the equations we recommend to estimate dose and risk levels in Appendix C. The HHRAP companion database presents inhalation URF s and oral CSF s for many potential COPCs. However, for each risk assessment, we recommend checking the hierarchy of toxicity benchmark and slope factor resources listed in Appendix A-2, Section A2.6 (H uman Health Benchmarks) for updated values. We suggest using the same hierarchy to acquire toxic ity values for COPCs not identified in Appendix A-2.
In the assessment of carcinogenic risk from COPCs, we recommend U.S. EPA-derived or reviewed health benchmarks ( URFs and CSFs ). However, for numerous compounds, a complete set of inhalation and oral EPA-derived health benchmarks are not available. In such cases, we calculated the health benchmarks presented in the companion database based on av ailable U.S. EPA-derived benchmark values.

If relevant information is not available from th ese sources, we recommend contacting the appropriate permitting authority, which may be able to assist in developing the necessary toxicity values. For example, Minimum Risk Levels published by th e Agency for Toxic Substances and Disease Registry (ATSDR) might be applicable.
7.2 QUANTITATIVELY ESTIMATING NONCANCER HAZARD
Standard risk assessment models assume that, for mo st chemicals with noncan cer effects, the noncancer effects exhibit a threshold response 2 

### ,. That is, there is a level of e xposure below which no adverse effects will be observed (U.S. EPA 1989e). The default approaches used by USEPA to assess the potential for health effects associated with a nonlinear or thres hold relationship with exposure as set out in U.S. EPA (2002; 2005f) involve: 1. Comparing an estimate of ingested exposure (see Chapter 6) to an RfD for oral exposures; and

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# RfC EC HQ or RfD ADD HQ = = Equation 7-5 2. Comparing an estimated chemical-s pecific air concentration to the RfC for direct inhalation exposures. An RfD is a daily oral intake rate that is estimated to pose no appreciable risk of adverse health effects, even to sensitive populations, over a 70-year lifetime. Similarly, an RfC is an estimated daily concentration of a chemical in air, the exposur e to which over a specific exposure duration poses no appreciable risk of adverse health effects, even to sensitive populations (U.S. EPA 2002).
The exposure durations assumed for the exposure pathwa ys identified in Table 4-1 range from subchronic to chronic in relative length. However, we consider it appropriate to use chronic RfDs and RfCs to evaluate all recommended exposure pathways. Th e comparisons of oral and inhalation exposure estimates to RfD and RfC values, described above, are known as hazard quotients ( HQ ), which are calculated as follows:

where HQ = Hazard quotient (unitless) ADD = Average daily dose (mg/kg-day) RfD = Reference dose (mg/kg-day) EC = Exposure air concentration (mg/m 3 

### ) RfC = Reference concentration (mg/m 3 

### ) Please note that each program office within U.S. EPA determines what HQ level poses a concern to exposed individuals. For example, Superfund has determined that an HQ of less than or equal to 1 is considered health-protective (U .S. EPA 1989e). However, because RfDs and RfCs do not have equal accuracy or precision, and are not based on the same severity of effect, the level of concern does not increase linearly as an HQ approaches and exceeds 1 (U.S. EPA 1989e). In addition, noncancer estimates only identify the exposure level below which adverse effects are unlikely; an RfD or RfC does not say anything about incremental risk for higher exposures (U.S. EPA 1998c).
Also note that background exposures may be an important consideration in setting HQ levels of concern. This is because you generally model noncancer eff ects as thresholds, and biologic systems (including human receptors) do not distinguish between exposur es from regulated versus non-regulated sources. In

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### certain cases, a permitting authority may elect to adjust the assessed facility-specific HQ downward, to account for any exposure that individuals may have from non-assessed sources.
As with carcinogenic chemicals, a receptor might be exposed to multiple chemicals associated with noncancer health effects. We recommend calculating the total chronic hazard for each exposure pathway by following the procedures outlined in U.S. EPA (1986e; 1989e; and 2000e). Specifically, the total chronic hazard attributable to exposure to all COPCs through a single exposure pathway is known as a hazard index ( HI ). The HI is calculated as follows:

HI = 

# 3 i 

### HQ i 

### Equation 7-6 where HI = Hazard index for a specific exposure pathway HQ i 

### = Hazard quotient for COPC i
This method assumes that the health effects of th e various COPCs are additive. This method is a simplification of the HI concept because it doesn’t, at this stage, directly consider the portal of entry associated with each exposure pathway (i.e. inhalation, or ingestion). This method also doesn’t consider the often unique toxic endpoints and toxic ity mechanisms of the various COPCs.
As discussed in Section 7.1 for carcinogenic risks, a receptor might be exposed to COPCs associated with noncancer health effects through more than one expos ure pathway, and from multiple emissions sources. We recommend estimating the noncancer hazards from each modeled source (including fugitive emissions) separately, as well as all sources summed fo r each receptor. We consider it reasonable to estimate a receptor’s total hazard as the sum of the HIs for each of the exposure pathways chosen for the receptor. Specifically, a receptor’s cumulative h azard is the sum of hazards from each individual exposure pathway, expressed as follows:


## Cumulative HI = 

# 3 HI Equation 7-4 where Cumulative HI = Cumulative hazard index from all scenario-specific exposure pathways HI = Hazard index for a specific exposure pathway

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### Summing all HIs As stated above, estimating a single HI encompassing all HI s across all exposure pathways is a simplification of the HI concept. However, it may save valuable resources: if the single HI is not above the target hazard level, then no further segregation would be necessary. We recommend this as a first step, and going to the expense of segregating HI s only if the single HI falls above the target hazard level. 

### As in U.S. EPA (1989e), we recommend further evaluating a cumulative HI which exceeds the target hazard level. A cumulative HI can exceed the target hazard level due to either • One or more COPCs with an HQ exceeding the target hazard level, or • The summation of several COPC-specific HQ s that are each less than the target hazard level. In the former case, you can interpret the presence of at least one COPC-specific hazard greater than the target hazard level as indicating the potential for noncancer health effects. In the latter case, you need to perform a detailed analysis to determine whether th e potential for noncancer health effects is accurately estimated by the total HI . This is because the toxicological e ffects associated with exposure to multiple chemicals, often through different exposure pathways, may not be additive. The total HI might therefore overestimate the potential for noncancer health effects.
To address this issue, we recommend summing the COPC-specific hazards according to toxicological similarity (e.g. the same target organs or systems) (U.S. EPA 2000e). This process is referred to as segregating the HI . It is especially important to consider any differences related to exposure route. If any segregated HI exceeds the target hazard level, noncancer health effects cannot be ruled out. However, if all segregated HIs are less than the target hazard level, noncancer health effects are not likely to result from exposure to the COPCs included in the HI

. Technically, segregating the HI based only on target organs or systems is a simplification of HI . Ideally, the HI would also be segregated according to the often unique mechanisms of toxicity of the COPCs. However, segregating the HI based on mechanisms of toxicity is beyond a screening level or initial risk evaluation approach (U.S. EPA 2000e).
The HHRAP companion database includes information on target organs and systems that are affected by each COPC. The database also presents RfDs and RfCs for these same COPCs. If you include COPCs not identified in Appendix A-2 (and therefore not in the companion database) in the risk assessment, we recommend obtaining RfDs and RfCs for these compounds using the hierarchy of toxicity benchmark and

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### slope factor resources listed in Appendix A-2, Secti on A2.6 (Human Health Benchmarks). If relevant information is not available from these sources, we recommend working with the permitting authority to contact the U.S. EPA National Center for Environm ental Assessment (NCEA) office in Cincinnati, Ohio. NCEA personnel may be able to assist in developing the necessary toxicity values.
In the assessment of noncancer risk from COPCs, we recommend U.S. EPA-derived or reviewed RfD s and RfC s. However, for numerous compounds, a complete set of inhalation and oral health benchmarks is not available. If such was the case for COPCs lis ted in Appendix A-2, we calculated the health benchmarks presented based on available U.S. EPA-der ived benchmarks values. For instance, if the oral RfD (mg/kg/day) was available and the RfC (mg/m 3 

### ) was not, we calculated the RfC by multiplying the RfD by an average human inhalation rate of 20 m 3 

### /day and dividing by the average human body weight of 70 kg. This conversion is called a route-to-route extr apolation, which assumes that the toxicity of the given compound is equivalent over all routes of exposure.
Route-to-route extrapolation introduces additional uncer tainty into the risk assessment, and there isn’t Agency consensus regarding the appropriateness of its use. This method assumes that the qualitative data supporting the benchmark value for a certain route also applies to the route in question. For example, if
an RfD is available and you calculate the RfC from that value, you are assuming that the toxicity seen following oral exposure will be equivalent to toxi city following inhalation exposure. This assumption could overestimate or underestimate the toxicity of the given compound following inhalation exposure.
Because of the degree of uncertainty involved in us ing toxicity benchmark values calculated based on route-to-route extrapolation, we recommend using route-to-route extrapolations for organic compounds (but not inorganic), and revisiti ng the appropriateness of applying th is extrapolation for individual chemicals if they are found to be risk drivers. An example might include using route-to-route extrapolations as the first step in a screening ri sk assessment, then expending resources evaluating the appropriateness of only those extrapolations associated with risk drivers. Including this further evaluation (a qualitative assessment of the toxicity information available for the compound and exposure route ) in the Uncertainty section of the risk assessment report w ill enable the risk manager to make an informed decision concerning the validity of values calculated based on route-to-route extrapolation.

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### 7.3 TARGET LEVELS
Target levels are risk management-based and set by the permitting authority. Target values are not a discrete indicator of observed adverse effect. If a ri sk estimate falls below target levels, a regulatory authority may, without further investigation, conclude that a proposed action does not present an unacceptable risk. A risk estimate that exceeds th ese targets, however, would not, in and of itself, necessarily indicate that the proposed action is not safe or that it presents an unacceptable risk. Rather, a risk estimate that exceeds a target value triggers fu rther careful consideration of the underlying scientific basis for the calculation.

7.4 ESTIMATING ACUTE EXPOSURE FROM DIRECT INHALATION
In addition to long-term chronic effects, we reco mmend considering short-term or acute effects from direct inhalation of vapor phase and particle phase CO PCs. Short-term emissions don’t typically have a significant impact through the indirect exposure pathways (as compared to impacts from long-term emissions). Therefore, we recommend evaluating acute effects only through the short-term (maximum 1- hour) inhalation of vapors and partic ulates exposure pathway of the acute risk scenario. We give our recommendations for where and when to evaluate th e acute risk scenario in Sections 4.2 and 4.3. In order to establish acute inhalation exposure crite ria (AIEC), we needed to identify and evaluate 1. Existing guidelines for acute inhalation exposure; and 2. Existing approaches for developing acute inhalation exposure levels. Existing approaches are composed of hierarchical guidelines for acute inhalation exposure, ranked in order of applicability and technical basis, a nd all being protective of the general public.
Please Note : hierarchical approaches are need ed because criteria values are COPCspecific, and no single organization or me thod has developed acute criteria values or benchmarks for all of the potential COPCs. 7.4.1 Existing Hierarchical Approaches for Acute Inhalation Exposure
Existing guidelines or criteria for evaluating acute inha lation exposure have been or are being developed by several organizations in the United States, including:

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### • Agency for Toxic Substances and Disease Registry (ATSDR 1997); • American Conference of Governmental Industrial Hygienists (ACGIH 1996); • American Industrial Hygiene Association (AIHA 1997); • California Environmental Protection Agency (Cal/EPA) (Cal/EPA 1999); • National Advisory committee (NAC 1997); and • National Institute of Occupationa l Safety and Health (NIOSH 1994); • National Research Council Committee on Toxicology (NRC COT 1986; U.S. EPA 1987b); • Occupational Safety and Health Administration (NIOSH 1994); • U.S. Department of Energy, Subcommittee on Consequence Assessment and Protective Actions (SCAPA) (SCAPA 2001a; 2001b). • U.S. EPA (U.S. EPA 1987b); Acute inhalation exposure guidelines and criteria are • Designed to protect a variety of expos ure groups, including occupational workers, military personnel, and the general public, • Based on varying exposure durations up to 24 hours in length, and • Intended to protect against a variety of toxicity endpoints ranging from discomfort or mild adverse health effects to serious, deb ilitating, and potentially life-threatening effects, up to and including death. Hierarchical approaches for establishing acute inhala tion exposure levels protec tive of the general public have been developed by a variety of organizati ons and teams of organizations. These organizations include: C 

### U.S. Department of Defense (DoD 1996); C 

### U.S. Department of Energy (DoE) (SCAPA 1997a; WSRC 1998). C 

### U.S. EPA Region 3 (EPA 1996b); C 

### U.S. EPA Region 10 (U.S. EPA 1996a); and

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### C 

### Federal Emergency Management Agency, De partment of Transportation (DoT), and U.S. EPA (U.S. EPA 1993i). The acute inhalation exposure guidelines develope d by these organizations are generally quite heterogenous, developed to protect different subpopulations against diffe rent effects and apply to various exposure durations. All the hierarchical approach es listed above except the SCAPA approach needed to adjust the existing guidelines using safety factors (u sually multiples of 10) to account for differences in exposure group, exposure duration, a nd toxicity endpoint, to arrive at acute inhalation exposure values applicable to the general public.
In contrast to the hierarchical approaches deve loped using safety factors, the DoE’s Emergency Management Advisory Committee’s SCAPA devel oped temporary emergency exposure limits (TEELs) based on tiered, formula-like statistical analyses be tween existing guidelines for acute inhalation exposure and AIHA emergency response planning guidelines (ERPG) (Craig et al. 1995; WSRC 1998). The methodology is described at http://www.orau.gov/emi/scapa/ files/ Method_for_deriving_TEELs.pdf and available on-line at http://www.atlintl.com/DOE/teels/teel/teel_pdf.html . Like ERPGs, TEELs are multiple-tiered, representing concentrations associatedwith no effects (TEEL-0), mild, transient effects (TEEL-1), irreversible or serious effects (TEEL- 2), and potentially life-threatening (TEEL-3). DOE developed TEELs for situations where no other value is available. TEELs do not undergo peer review. For compounds for which TEEL values could not be deve loped using this approach, SCAPA developed a supplementary approach using available toxicity info rmation, primarily (1) lethal dose and concentration median, and (2) lethal dose and concentration low values (DoE 1997a).
7.4.2 Our Recommended Hierarchical Approach
After reviewing the existing hierarchical approach es, we recommend the following approach. Because of the daily operations of most combustion units and the potential for upset conditions to sometimes occur during operations, we consider acute values that address intermittent exposures more appropriate and more protective than values that are based on the assumption that acute exposures will be one-time only. When available, we recommend using values from all of the sources that are based on one-hour exposures.

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### 1. Cal/EPA Acute RELs – the concentration in air at or below which no adverse health effects are anticipated in the general population, including sensitive individuals, for a specified exposure period (Cal/EPA 1999) (On-Line Address – http://www.oehha.ca.gov/air/pdf/acuterel.pdf ) 2. Acute inhalation exposure guidelines (AEGL-1) – “the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effect s are not disabling and are transient and reversible upon cessation of exposure. ” (NOAA 2001; U.S. EPA 2001a) (On-Line Address – http://www.epa.gov/oppt/aegl/) 3. Level 1 emergency planning guidelines (ERPG-1) – “the maximum concentration in air below which it is believed nearly all indi viduals could be exposed for up to one hour without experiencing other than mild transi ent adverse health effects or perceiving a clearly defined objectionable odor.” (DoE 2001; SCAPA 2001b) (On-Line Address – http://www.bnl.gov/emergencyservices/ ) 4. Temporary emergency exposure limits (TEEL-1) – “the maximum concentration in air below which it is believed nearly all indivi duals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined odor.” (DoE 2001; SCAPA 2001a) (On-Line Address – http://orise.orau.gov/emi/scapa/files/Method_for_deriving_TEELs.pdf ) 5. AEGL-2 values – “the airborne concentration of a substance above which it is predicted that the general population, including su sceptible individuals, could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape.” AEGL-2 values are to be used onl y if lower ERPG-1 or TEEL-1 values are not available. (NOAA 2001; U.S. EPA 2001a) (On-Line Address – http://www.epa.gov/oppt/aegl/ ) The hierarchy is presented in order of preference, from 1 (most preferred) to 5 (least preferred). We generally recommend the Acute Reference Exposur e Levels (Acute RELs) developed by Cal/EPA (Cal/EPA 1999) as the first choice for acute inhalation values. If no acute REL value is available for a given COPC, you can work down the list in order. If no AEGL-1 value is available, but an AEGL-2 value is available, select the AEGL-2 as the AIEC only if it’s a more protective value (lower in concentration) than an ERPG-1, or a TEEL-1 value if either of these values is available. If no acute values are available for a COPC, an acute value can be developed following the toxicity-based approach used by SCAPA (Tier 5) (DoE 1997a; WSRC 1998). The companion database provides a listing of AIECs compiled from values currently available follo wing the hierarchical approach presented above.

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### Please note that the TEEL-1 values (SCAPA 2001a) are calculated assuming a 15-minute exposure period. As discussed in Section 3.10, for the purposes of this protocol, we recommend evaluating risks due to acute exposure based on the highest 1-hour av erage air concentrations. Therefore, the TEEL-1 values were extrapolated from a 15-minute to a 1-hour exposure basis using a modification to Haber’s Rule developed by ten Berge et al (1986) and usedby Cal/EPA to develop acute RELs (Cal/EPA 1999), as shown below. 

## C n 

## @ 

## T = K Equation 7-8 where C = Concentration (mg/m 3 

### ) n = Constant greater than zero (unitless) T = Time of exposure (hour) K = Constant level or severity of response (unitless) Where available, chemical-sp ecific values for the exponent n were used to make the extrapolations (Cal/EPA 1999). For chemicals for which a chemical-specific value of n was not available, extrapolations were made using a value of n = 1, as recommended by OEHHA, because the extrapolations were all based on an initial exposure period (15-mi nutes) of less than 1 hour duration (Cal/EPA 1999).
Using the modified form of Haber’s Rule allows you to consider contributions by both concentration and time to the overall severity of effect. However, we highly recommend taking special care interpreting the extrapolated air concentrations, as they aren’t absolu tes. For example, chemical-specific values of the exponent n are sometimes based on a relatively limited set of dose-response data. Also, the majority of extrapolated TEEL-1 values were calculated using defau lt exponent values and, therefore, are likely to be even less certain than exponent values based on limited data sets.
The EPA IRIS program is currently developing a dditional acute reference values that do not exclude intermittent exposures. When available, we recommend using those values (referred to as Acute Reference Concentrations [Acute RfCs]) as the firs t choice, with the Cal/EPA acute RELs second in the hierarchy.
7.4.3 Characterizing Potential Health Effects from Acute Exposure
We recommend characterizing the potential for a dverse health effects from acute exposure to COPC-specific emissions by comparing the acute air concentration ( C acute 

### ) resulting from maximum

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# A IEC C AHQ acute inh 

# 001

. 0 ⋅ = Equation 7-9 emissions over a 1-hour period to the COPC-specific AIEC (see Appendix C, Table C-4-1). This comparison is known as the acute hazard quotient ( AHQ inh 

### ). Chapter 3 discusses air dispersion modeling related to obtain 1-hour maximum values. Appe ndix B, Table B-6-1 describes how to calculate C acute 

### . We recommend using Equation 7-9 to calculate the AHQ inh 

### :

where AHQ inh 

### = Acute hazard quotient (unitless) C

acute 

### = Acute air concentration ( : 

### g/m 3 

### ) 0.001 = Conversion factor (mg/ : 

### g) AIEC = Acute inhalation exposure criteria (mg/m 3 

### ) We recommend calculating acute hazard quotients at th e selected acute exposure scenario locations (see Sections 4.2 and 4.3) for COPCs specific to emi ssions from each source, and from all facility sources combined. We recommend summing acute hazard quotie nts from individual chemicals (e.g. acid gases), if they have similar effects. Setting target le vels for evaluating acute hazard quotients is a risk management decision made by the permitting authority.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering 8-1 

# Chapter 8 Interpreting Uncertainty for Human Health Risk Assessment What’s Covered in Chapter 8: 8.1 Uncertainty and Limitations of the Risk Assessment Process 8.2 Types of Uncertainty 8.3 Qualitative Estimates of Uncertainty 8.4 Quantitative Estimates of Uncertainty 8.5 Risk Assessment Uncertainty Discussion

PLEASE NOTE : for the purposes of this guidance, “we” refers to the U.S. EPA OSW. The HHRAP is written for the benefit of a varied audience, including risk assessors, regulators, risk managers, and community re lations personnel. However, the “you” to which we speak in this chapter is the performer of a risk assessment: the person (or persons) who will actually put the recommended methods into practice. This section discusses interpreting uncertainties associ ated with the risk assessment. The discussion of uncertainties in Section 8.1 and 8.2 was adopted from the 1996 Risk Assessment Support to the Development of Technical Standards for Emissions from Combustion Units Burning Hazardous Waste

.

8.1 UNCERTAINTY AND LIMITATIONS OF THE RISK ASSESSMENT PROCESS
Uncertainty can be introduced into a health risk assessment at every step of the process outlined in this document. Uncertainty occurs b ecause risk assessment is a complex process, requiring the integration of the following: C 

### Release of pollutants into the environment C 

### Fate and transport of pollutants, in a variet y of different and variable environments, by processes that are often poorly understood or too complex to quantify accurately

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### C 

### Potential for adverse health effects in humans, as extrapolated from animal studies C 

### Probability of adverse effects in a human popul ation that is highly variable genetically, and in age, activity level, and lifestyle
Uncertainty is inherent in the process even when us ing the most accurate data and the most sophisticated models. The method we recommend in the HHRAP relies on a combination of point values—some protective and some typical—yielding a point estimat e of exposure and risk that falls at an unknown percentile of the full distributions of exposure and risk . For this reason, the degree of conservatism in risk estimates cannot be known. Therefore, you need a form al uncertainty analysis to determine the degree of conservatism. Section 8.2 discusses the types of un certainty and the areas in which uncertainty can be introduced into an assessment. The remaining Sections discuss methods for qualitatively and quantitatively addressing uncertainty in risk assessments.
It should also be noted, variability is often used inte rchangeably with the term “uncertainty,” but this is not strictly correct. “Variability” may be tied to variations in physical and biological processes. Variability can’t be reduced with additional resear ch or information, although it may be known with greater certainty (for example, the age distribution of a population may be known and represented by the mean age and its standard deviation). “Uncertainty ” is a description of the imperfect knowledge of the true value of a particular variable, or its real variability in an individual or a group.
In general, uncertainty is reducib le by additional information-gather ing or analysis activities (that is, better data or better models), whereas real variab ility won’t change (although it may be more accurately known) as a result of better or more extens ive measurements (Hattis and Burmaster 1994).

8.2 TYPES OF UNCERTAINTY
Finkel (1990) and U.S. EPA (1999f) classified all uncertainty into four types: 1. variable uncertainty, 2. model uncertainty, 3. decision-rule uncertainty, and 4. variability.

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### Variable uncertainty and model uncertainty are generally recognized by risk assessors as major sources of uncertainty. Variable uncertainty occurs when variables appearing in equations cannot be measured precisely or accurately, because of either (1) equipmen t limitations, or (2) spatial or temporal variances between the quantities being measured. Random, or sample, errors are common sources of variable uncertainty that are especially critical for small sampl e sizes. It is more difficult to recognize nonrandom, or systematic, errors that result from the basis for sampling, experimental design, or choice of assumptions.
Model uncertainty is associated with all models used in all phases of a risk assessment, including: • animal models used as surrogates for testing human carcinogenicity, • the dose-response models u sed in extrapolations, and • the computer models used to predict the fate and transport of chemicals in the environment. Using rodents as surrogates for humans introduces uncer tainty into the risk factor because of the considerable interspecies variability in sensitivity. Computer models are simplifications of reality, requiring exclusion of some variables that influence predictions but cannot be included in models because of (1) increased complexity, or (2) a lack of data for these variables. The importance of excluded variables is generally considered on a case-by-case basis. A specific variable may be important, in terms of its impacts on uncertainty, in some instances and not in others. A similar problem can occur when a model that is applicable under average conditions is used for a case in which conditions differ from the average. Finally, choosing the correct model form is often difficult, because conflicting theories appear to explain a phenomenon equally well.

The models we recommend in the HHRAP were selectedbased on scientific policy. We selected the air dispersion and deposition model, and the indirect e xposure models, because they provide the information you need to conduct indirect assessments, and we consid er them state-of-the-science. ISCST3—the air dispersion model we recommend—has not been widely applied in its present form. Few data are available on atmospheric deposition rates for chemical s other than criteria pollutants, thereby making it difficult to select input variables related to depositi on, or validate modeled deposition rates. Long-range transport of pollutants into and out of the study ar eas wasn’t modeled, resulting in an underestimation of risk attributable to each facility.

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### In addition to air dispersion modeling, using othe r fate and transport models recommended by this guidance can also result in some uncertainty. For example, the models which estimate COPC concentrations in waterbodies may be particular ly protective for waterbodies located in estuarine environments with tidal influence. Because tidal in fluence is not considered in the models presented in Chapter 5, the resulting dilution of COPC concentra tions in water and sediments likely caused by tidal influence won’t be considered in the risk assessmen t. Thus, the risk assessment results will likely be more protective for tidally influenced waterbodi es than for those waterbodies that aren’t tidally influenced. We recommend that permitting decisions based on risk estimates for estuarine environments consider this uncertainty. The delineation of this un certainty may be one area that could be addressed in a more refined site-specific risk assessment, if warranted.
Decision-rule uncertainty is probably of greatest concern to risk managers. This type of uncertainty arises, for example, out of the need to balance diffe rent social concerns when determining an acceptable level of risk. The uncertainty associated with risk analysis influences many policy and risk management decisions. Possibly the most important aspect for the risk estimates is the selection of constituents to be assessed. Constituents that are identified using th e process provided in this document will include compounds that have the potential to pose the greatestrisk to human health through indirect exposure routes. For example, many PICs are highly lipophilic and tend to bioaccumulate in the food chain, thereby presenting a potentially high risk through the consumption of contaminated food.
A second area of decision-rule uncertainty includes th e use of standard Agency default values in the analysis. These include inhalation rates, body wei ght, and lifespan, which are standard default values used in most Agency risk assessments. Inhalation rate is highly correlated to body weight for adults. Using a single point estimate for these variables instead of a joint probability distribution ignores a variability that may influence the results by a factor of up to two or three.
A third area of decision-rule uncertainty is the use of Agency-verified cancer SFs, RfDs , and RfCs . These health benchmarks are used as single-point estimates throughout the analysis, and uncertainty and variability are both associated with them. U.S. EPA has developed, however, a process for setting verified health benchmark values to be used in all Agency risk assessments. This process is used to account for much of the uncertainty and variability asso ciated with the health benchmarks. With the exception of the dioxin toxicity equivalency methodology, health benchmarks which can be found on

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### IRIS, have been verified through Agency work gr oups. Estimating the uncertainty in using Agnecyverified health benchmarks or the dioxin toxicity equivalency methodology is beyond the scope of the HHRAP.
8.3 QUALITATIVE ESTIMATES OF UNCERTAINTY
Often, sources of uncertainty in a risk assessment can be identified but not quantified. For example, this can occur when you know (or suspect) a factor to vary, but have no data (e.g., presence of COPCs without toxicity data, amount of time that people at a speci fic site spend outdoors). In such cases, default data may be available that can be useful in estimating a po ssible range of values. Uncertainty also often arises out of a complete lack of data. A process may be so poorly understood that you can’t quantify the uncertainty with any confidence. In addition, some sources of uncertainty (such as uncertainty in theories used to deduce models) are inherent qualifications reflecting subjective modes of confidence rather than probabilistic arguments. When you can only present th e uncertainty qualitatively, you might consider the possible direction and orders of magnitude of the potential error.
8.4 QUANTITATIVE ESTIMATES OF UNCERTAINTY
It’s also possible to use knowledge of experimental or measurement errors to introduce a degree of quantitative information into a qualitative presentation of uncertainty. For example, standard laboratory procedures or field sampling methods may have a known error level that you can use to quantify uncertainty. In many cases, it’s possible to express th e uncertainty associated with particular variable values or estimated risks quantitatively, and further eval uate them with variations of sensitivity analyses. Finkel (1990) identified a six-step process for producing a quantitative uncertainty estimate: 1. Define the measure of risk (such as deaths, life-years lost, maximum individual risk (MIR), or population above an “unacceptable” le vel of risk). More than one measure of risk may result from a particular risk assessment: however, the uncertainty may be quantified or reached individually. 2. Specify “risk equations” that present mathematical relationships that express the risk measure in terms of its components. This step is used to identify the important variables in the risk estimation process.

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### 3. Generate an uncertainty distribution for each variable or equation component. These uncertainty distributions may be generate d by using analogy, statistical inference techniques, expert opinion, or a combination of these. 4. Combine the individual distributions into a composite uncertainty distribution. 5. Recalibrate the uncertainty distributions. Infe rential analysis could be used to “tighten” or “broaden” particular distributions to account for dependencies among the variables and to truncate the distributions to exclude extreme values. 6. Summarize the output clearly, highlighting the important risk management implications. Address specific critical factors. - Implication of supporting a point estimate produced without considering uncertainty - Balance of the costs of under- or over-estimating risks - Unresolved scientific controversies, and their implications for research When you need a detailed quantitative treatment of uncertainty, statistical methods are generally considered the most appropriate. We describe tw o possible approaches to a statistical treatment of uncertainty with regard to variable values here, though other methods are certainly available. The methods described here were used in this analysis where appropriate.
The first approach is to use an appropriate statistic to express all variables for which uncertainty is a major concern. For example, if a value comes from a sample (such as yearly emissions from a stack), the mean and standard deviation may both be presented. If the sample size is very small, it may be appropriate to • give the range of sample values and use a midpoint as a best estimate in the model, or • use the smallest and largest measured value to obtain two estimates that bound the expected true value. Selecting the appropriate statistic depends on the amount of data ava ilable and the degree of detail you need. It’s possble to propagate uncertainti es by using analytical or numerical methods.
A second approach is to use the probability distributions of major variables to propagate variable value uncertainties through the equations you use in th e risk assessment. You then develop a probability distribution of expected values for each variable value. These probability distributions are typically

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### expressed as either probability density functions ( PDF ) or cumulative probability density functions ( CPF ). The PDF presents the relative probability for discrete variable values, whereas the CPF presents the cumulative probability that a value is less than or equal to a specific value.
A composite uncertainty distribution is created by combining the individual distributions with the equations used to calculate the probability of particular adverse health effects and points. In Monte Carlo simulations, a computer program is used to re peatedly solve the model equations, under different selections of variable values, to calculate a distri bution of exposure (or risk) values. Each time the equations are calculated, values are randomly sampled from the specified distributions for each variable. The end result is a distribution of exposure (or risk). These can again be expressed as PDF s or, more appropriately, as CPF s. The distribution enables you to choose the value corresponding to the appropriate percentile in the overall distribution. Fo r example, you could select an exposure level or risk level that corresponds to the 95th percentile of the ove rall risk distribution rather than a point estimate of risk that is based on the 95th percentile values for each variable. For more information on how to conduct a quantitative uncertainty analysis, we refer you to Risk Assessment Guidance for Superfund, Volume III: Part A (Process for Conducting Probabilistic Risk A ssessment), which is located at the web address www.epa.gov/oswer/riskassessment/rags3a/index.htm

.
8.5 RISK ASSESSMENT UNCERTAINTY DISCUSSION
The science of risk assessment is evolving. Where th e science-base is incomplete and uncertainties exist, science policy assumptions must me made. It is important for risk assessments to fully explain the areas of uncertainty in the assessments and to identify the key assumptions used in conducting the assessments. Toward that end, one option is to add a table at the end of each section (e.g., stack emissions, air modeling, exposure assessment, toxicity evaluation, risk characterization) that lists the key assumptions in that section, the rationale for those assumptions, their effect on estimates of risk (overestimation, underestimation, neutral), and the magnitude of the e ffect (high, medium, low). For example, it could explain that using a particular input variable, su ch as exit gas temperature, will under- or overestimate chronic emissions, and the resulting risks and hazards, by a factor of (x). These tables could be used to evaluate the extent to which you used public hea lth-protective assumptions in the risk assessment. They could also help determine the nature of the uncertain ty analysis to be performed. The assumptions listed

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### in the risk characterization section, which synth esizes the data outputs from the exposure and toxicity analyses, might include the most significant assumptions from each of the previous sections.
Within the HHRAP, we’ve identified uncertainties and limitations within the discussion of specific technical issues (e.g., TOE, estimates of emission rates, COPC selection process, quantifying non-detects) as they are presented in their respective sections. We present the limitations associated with parameter values and inputs to equations in Appendices A, B, and C, respectively.
As an example discussion, the following summarizes some of the uncertainty involved in the air dispersion modeling component of the risk assessment process.
Although dispersion modeling is a valuable tool for estimating concentration and deposition impacts, it has many limitations. The accuracy of the models is limited by • the ability of the model algorithms to depict atmospheric transport and dispersion of contaminants, and • the accuracy and validity of the input data. For example, most refined models require input of representative meteorological data from a single measuring station. In reality, a release will encounter highly variable meteorological conditions that are constantly changing as it moves downwind. U.S. EPA’s Guideline on Air Quality Models—Revised (U.S. EPA 1986b, 1993b; Title 51 CFR Appendix W) describes two types of model uncertainty. Inherent uncertainty involves deviations in concentrations that occur even if all of the model input is accurate. Reducible uncertainty is associated with the model and the uncertain input values that will affect the results. Although it is important to accurately repr esent actual conditions by selecting the right model, and using accurate and representative input data, all model results are subject to uncertainty. Nevertheless, models are generally considered reas onably reliable in estimating the magnitude of highest concentrations resulting from a release, although they may not necessarily be time-and space-specific (Title 51 CFR Appendix W). When applied properly, ai r dispersion models are typically accurate to ± 10 to 40 percent and can be used to yield a “best estim ate” of air concentrations (Title 51 CFR Appendix W).
As mentioned earlier, uncertainties specific to othe r technical components of the risk assessment process (e.g., TOE, quantification of non-detects) are further described in their respective chapters or sections of

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### this guidance. For more information on Agency policy and guidelines regarding uncertainty in risk assessments, please see the U.S. EPA Science Policy Council’s Risk Characterization Handbook (U.S. EPA 2000f, available at http://www.epa.gov/osa/spc/pdfs/rchandbk.pdf ).U.S. EPA Region 6 U.S. EPA

Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 9-1 

# Chapter 9 Completin g the Risk

Assess ment Repo rt and Follow-OnActivities

What’s Covered in C hapter 9: 9.1 Conclusions 9.2 Activities Following Risk Assessm

ent Completion

PLEASE NO TE : for the purposes of this guidance, “we” refers to the U.S. E PA OSW. The HHRAP is written

for the benefit of a v

aried audience, including risk assessors, regula tors, ri sk m

anage rs, and comm unity relation s person

nel. H owev er, the “you” to which we speak

in this chapter is the perfo rmer of a risk

assessment: the p erson (or persons) who will actually put the recomm

ended methods into practice. Our m ain purp ose in d

evelo ping t he HHR AP was to prov ide yo u with the tool s you

need to efficien tly complete quality , consistent, and defen sible risk assessm ents. You can pro duce the risk assessm ent in a relatively short am

ount of time,rather t

han spe nding years determ ining which C OPCs, exposu re pathways, and receptors to include and ev aluate.
It’s imp ortant to note that final risk assessments m

ight include both h

uman health and

ecological evaluations. I

n addition to availab le Agency guidance for condu cting ecological risk assessmen ts (U.S. EPA 1997e) and Volume 63, Nu mber 93, of the Federal Register, we are currently finalizing an ecological risk a ssessment gu idance document titledU.S. EPA O SW Screening L evel Ecological Risk Assessm ent Pro tocol (U.S. EPA 19 99a), prepared as a companion to this guidance.

9.1 CONCLUSIONS

We recommend that each risk assessment include a Conclusions section. This section is included prima rily to interpr et the re sults of

the risk and ha zard character

ization in lig

ht of the uncer

tainty analy sis. We

recom mend that, a t a mi nimum , it pre sent and

interpr et all ri sk and

hazar d result s

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Chapter 9: Completin g the Risk Assessment Report and Follow-On Activities September 2005

U.S. EPA Region 6 U.S. EPA Multimedi a Planning and Per mitting Division Offic e of Solid W aste Center f or Combustion Science and Enginee ring 9-2 

### exceeding targe

t levels. I t might also identify receptors hav ing the greatest risks and haz ards, in addition to COPCs and ex

posure pathways contributing sign ificantly to these risk

s and hazards. Finally, the Conclusions section is a place for you to present and defend y our position on whethe

r actual or potential releases from the facility

you studied po se significant risks and hazards to hu man populations.

9.2 ACTIV

ITIES FOLLOWIN G RISK ASSE SSMEN T COMPLE TION
As stated previously , we developed the HHRAP to

promote a con sistent approach for com pleting risk
assessm ents tha t:

• Encourages the us e of appropriate site- specific information early in and througho

ut the process;

• Provides a tool for completing q uality and defensible risk assessmen ts;

• Minimizes inefficient expenditure of time and resources by suggesting up front a process to determine whic

h COPCs to con sider, which exposure pathways, and receptors the risk assessment report to include and evaluate,and

• Provi des a comprehensive explanation of

the pro cedures

and uncertaint

ies inv olved in the process. However, the risk assessmen t process does not end following the com pletion, submittal, and approval of the risk assessm

ent report.
Facilities burning hazardous waste are also resp onsible for comm unicating the results of the risk
asses sment pr ocess to affe cted membe rs of th e communit y. One reas on for o ur compre hensi ve explanation of the procedu res and uncertainties inv

olved in the proces s was to provide the facilities, risk assessors, and regu

lators with the tools they

need to clearly communicate the procedures, results, an d limitations of the risk

assessment proces s. Comm unication is an ong oing process.

Final ly, comple ting the risk ass essment proces s involve s using

• site-specific env

ironmental data,

• various assum

ptions, and

• an evolving

procedure for estim

ating risk.

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### We expect that facilities will period ically review ea

ch of these factors, and update the process with the latest facility-spe cific operating and em ission information. Updating will help determine wh ether the best data and procedures are used to estimate the risk resulting

from operating

the facility haza

rdous waste combustor. The permitting authority m

ight establish the period

for this review in the operating permit. However, we recom mend review

ing any sig

nificant changes inv

olving new

ly available data

or risk assessmen

t procedures as they

become av

ailable, to gaug e if they sign ificantly affect the outcom e of the risk assessm

ent process.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-1 

# REFERENCES

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### Amdur, M.O., J. Doull, and C.D. Klaassen, Editors. 1991. Casarett and Doull’s Toxicology. The Basic Science of Poisons . Fourth Edition. New York. Pergamon Press. American Chemical Society. 1980. “Guidelines fo r Data Acquisition and Data Quality Evaluation in Environmental Chemistry.” Analytical Chemistry . Volume 52. Number 14. Pages 2242-2249. December. American Conference of Governmental Industrial Hygienists (ACGIH). 1991. Documentation of the Threshold Limit Values and Biological Exposure Indices. Cincinnati, Ohio. Sixth Edition. ACGIH. 1996. “Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.” Cincinnati, Ohio. American Industrial Hygiene Association (AIHA). 1996. Emergency Response Planning Guidelines and Workplace Environmen tal Exposure Level Guides Handbook . Fairfax, VA. AIHA. 1997. “Workplace Environmental Exposure Level Guide.” Facsimile Transmission from AIHA to Eric Monschein, Tetra Tech EM Inc. August 20, 1997. Auer. 1978. “Correlation of Land Use a nd Cover with Meteorological Anomalies.” Journal of Applied Meteorology . Volume 17. Page 636. May. Bacci, E., D. Calamari, C. Gaggi, and M. Vighi. 1989. “Bioconcentration of Organic Chemical Vapors in Plant Leaves: Experimental Measurements and Pr ediction.” University of Siena. Siena, Italy. Bacci E., D. Calamari, C. Gaggi, and M. Vighi. 1990. “Bioconcentration of Organic Chemical Vapors in Plant Leaves: Experimental Measurements and Correlation.” Environmental Science and Technology . Volume 24. Number 6. Pages 885-889. Bacci E., M. Cerejeira, C. Gaggi, G. Chemello, D. Calamari, and M. Vighi. 1992. “Chlorinated Dioxins: Volatilization from Soils and Bioconcentration in Plant Leaves.” Bulletin of Environmental Contamination and Toxicology . Volume 48. Pages 401-408. Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor . 1984. “Review and Analysis of Parameters and Assessing Transport of Environmentally Rel eased Radionuclides Through Agriculture.” Oak Ridge National Laboratory. Oak Ridge, Tennessee. Barron, M.G., I.R. Schultz, and W.L. Hayton. 1989. “Presystemic Branchial Metabolism Limits of Di-2-ethylhexyl Phthalate Accumulation in Fish.” Toxicology and Applied Pharmacology

. Volume 96. Pages 49-57. Beard, Rodney R., and Joseph T. Noe. 1981. "Aro matic Nitro and Amino Compounds". In George D. Clayton and Florence E. Clayton, Editors. Patty’s Industrial Hygiene and Toxicology . Third Revised Edition. Volume 2A. New York. John Wiley & Sons.

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-3 

### Beckvar, N., J. Field, S. Salazar; et al. 1996. Contaminants in Aquatic Habitats at Hazardous Waste Sites: Mercury. NOAA Technical Memorandum NOS ORCA 100. Seattle: Hazardous Materials Response and Assessment Division, National Oceanic and Atmospheric Administration. 74 pages. Belcher, G.D., and C.C. Travis. 1989. “Mode ling Support for the RURA and Municipal Waste Combustion Projects: Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food Chain Model.” Interagency Agreement No. 1824-A020-A1. Office of Risk Analysis, Health and Safety Research Division. Oak Ridge National Laboratory. Oak Ridge, Tennessee. October. Beard, Rodney R. 1982. Inorganic Compounds of Oxyg en, Nitrogen, and Carbon . Patty’s Industrial Hygiene. Volume 2C. Bergmann, Ake, Anders Hagman, Sven Jacobsson, Bo Jansson, and Maria Ahlman. 1984. “Thermal Degradation of Polychlorinated Alkanes”. Chemosphere . Volume 13. Pages 237 to 250. Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology

. Vol. 22(4):361-367. Blake, G.R. and K.H. Hartge. 1996. Particle Density. Methods of Soil Analysis, Part 1: Physical and Mineralogical Methods, 2nd ed. Arnold Klute, Ed. American Society of Agronomy, Inc. Madison, WI. Page 381. Blum, J.D., and R. Bartha. 1980. “Effect s of Salinity on Methylation of Mercury.” Bull Environ Contam Toxicol 25:404-408. Bloom, N.S., C.J. Watras, and J.P. Hurley. 1991. “Impact of Acidification on the Methylmercury Cycle of Remote Seepage Lakes.” Water Air Soil Pollut. Volume 56. Pages 477-491. Bloom, N.S., and S.W. Effler. 1990. “Seasonal Vari ability in the Mercury Speciation of Onondaga Lake (New York).” Water Air Soil Pollut. Volume 53. Pages 251-265. Bohn H., B.L. McNeal, and G.A. O’Connor. 1985. Soil Chemistry . John Wiley and Sons, Inc. New York. Second Edition. Boone, F.W., Y.C. Ng, and J.M. Palm. 1981. “Te rrestrial Pathways of Radionuclide Particulates.” Health Physics . 41:735-747. Briggs, G.G., R.H. Bromilow, and A.A. Evans. 1982. “Relationships Between Lipophilicity and Root Uptake and Translocation of Nonionized Chemicals by Barley.” Pesticide Science . Volume 13. Pages 495-504. Brzusy, L.P., and R.A. Hites. 1995. “Estima ting the Atmospheric Deposition of Polychlorinated Dibenzo-p-dioxins and Dibe nzofurans from Soils.” Environmental Science and Technology

. 29:2090-2098.

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### DeCicco, S. 1995. Incineration Basics Course Manual. Bellevue, Washington. Deichmann, William B., and M. L. Keplinger. 1981. "Phenols and Phenolic Compounds." In George D. Clayton and Florence E. Clayton, Editors. Patty’s Industrial Hygiene and Toxicology . Third Revised Edition. Volume 2A. New York. John Wiley & Sons. Department of Defense. 1996. “Anniston Army Ammunition Plant Chemical Demilitarization Facility Risk Assessment.” October. Department of Energy (DoE). 1997a. “ T oxicity-Based Methodology, Text of Calc. Note, S-CLC-G-0074.” Facsimile Transmission from Douglas Craig, DoE, to Eric Monschein, Tetra Tech EM Inc. September 26, 1997. DoE. 1997b. “Chemical Exposures Working Group Report to SCAPA, April 1997.” Facsimile Transmission from Douglas Craig, Westinghouse Savannah River Co., to Eric Monschein, Tetra Tech EM Inc. September 26, 1997. DoE. 2001. “Definitions for Different TEEL Levels.” On-Line Address: http://tis-hq.eh.doe.gov/web/Chem_Safety/teeldef.html Dinman, B.D. 1978. “The Mode of Entry and Action of Toxic Materials.” Patty’s Industrial Hygiene and Toxicology . Edited by George D. Clayton and Florence E. Clayton. John Wiley & Sons. New York, New York. Volume 1. Third Revised Edition. Pages 135-164. Driscoll, C.T., C. Yan, C.L. Schofield, R. Munson, and J. Holsapple. 1994. “The Mercury Cycle and Fish in the Adirondack Lakes”. Environmental Science and Technology . 28(3):136A- 143A. 

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. Ikeda, G.J., P.P. Sapienza, J.L. Couvillion, T.M. Farber, C.P. Smith, P.B. Inskeep, E.M. Marks, F.E. Cerra, and E.J. van Loon. 1978. “Distribution a nd excretion of two phthalate esters in rats, dogs and miniature Pigs.” Food Cosmet. Toxicol . 16:409-413. Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 1980. “Comparative Distribution, Excretion, and Metabolism of Di(2-ethylhexyl)phthalate in Rats, Dogs, and Pigs.” Food Cosmet. Toxicology. 18:637-642. Iqbal, M. 1983. An Introduction to Solar Radiation. Academic Press. New York, New York. Jackson, T. A. 1986. “Methyl Mercury Levels in a Polluted Prairie River-Lake System: Seasonal and Site-Specific Variations, and the Domina nt Influence of Trophic Conditions.” Can J Fish Aquat Sci . 43:1873-1887. Jindal, M., and D. Heinhold. 1991. “Development of Particulate Scavenging Coefficients to Model Wet Deposition from Industrial Combustion Sources. Paper 91-59.7.” Proceedings of the 1991 Annual Meeting and Exhibition of the Air and Waste Management Association . Vancouver, British Columbia. June 16-21. Johnson, L. D. 1996. “Determination of Total Or ganic Emissions from Hazardous Waste Combustors.” Anal. Chem. 68:156-161. Junge, C.E. 1977. Fate of Pollutants in the Air and Water Environments . John Wiley and Sons. New York. Part I . Pages 7-26. Jury, W.A. 1986. “Volatilization from the Soil.” Vadose Zone Modeling of Organic Pollutants. S.C. Hern and S.M. Melancorn, Editors. Lewi s Publishers, Inc. Chelsea, Michigan. Jury, W.A., and R.L. Valentine. 1986. “Transport Mechanisms and Loss Pathways for Chemicals in Soils.” Vadose Zone Modeling of Organic Pollutants. S.C. Hern and S.M. Melancorn, Editors. Lewis Publishers, Inc. Chelsea, Michigan. Kalama Chemical, Inc. 1996. Report: Analysis of Stack Gas Samples for Polychlorinated Biphenyls - Kalama Chemical Trial Burn Pretest Program - Boiler U-3 . Internal Technology Corporation, Knoxville, Tennessee. Prepared for Catherine Massimino, U.S. EPA Region 10. June 14. Kaleri, C. J. 2000. “Implementation Issues: Merc ury Transport & Fate, Combustion Risk Assessments in Region 6.” Proceeding of the 12 th

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### Lindqvist, O., K. Johansson, M. Aastrup, A. Ander sson, L. Bringmark, G. Hovsenius, L. Hakanson, A. Iverfeldt, M. Meili, and B. Timm. 1991. “Mercury in the Swedish Environment - Recent Research on Causes, Consequences and Corrective Methods.” Water, Air and Poll . 55:(all chapters). Luijk, R., D.M. Akkerman, P. Slot, K. Olie, and F. Kapteijn. 1994. “Mechanism of Formation of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in the Catalyzed Combustion of Carbon.” Environmental Science and Technology. 28:312-321. Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1982. Handbook of Chemical Property Estimation Methods. McGraw-Hill Book Company. New York, New York. Mackay, D., W.Y. Shiu, and K.C. Ma. 1992. Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals. Volume IV—Oxygen, Nitrogen, and Sulfur Containing Compounds . Lewis Publishers. Boca Raton, Florida. Manahan, Stanley E. 1991. Environmental Chemistry . Fifth Edition. Chelsea, Michigan. Lewis Publishers. March, Jerry. 1985. Advanced Organic Chemistry. Reactions, Mechanisms, and Structure . New York. John Wiley & Sons. McCrady, J.K., and S.P. Maggard. 1993. “Uptake and Photodegradation of 2,3,7,8-Tetrachlorodibenzo-p-dioxin Sorbed to Grass Foliage.” Environmental Science and Technology . 27:343-350. McFarland, V.A. and J.U. Clarke. 1989. “Envir onmental occurrence, abundance, and potential toxicity of polychlorinated biphenyl congeners: Consid erations for a congener-specific analysis.” Environmental Health Perspectives . 81:225-239. McKone, T.E. and P.B. Ryan. 1989. Human Exposures to Chemicals Through Food Chains: An Uncertainty Analysis. Livermore, California: Lawrence Livermore National Laboratory Report. UCRL-99290. McLachlan, M.S., H.Thoma, M. Reissinger, and O. Hutzinger. 1990. PCDD/PCDF in an Agricultural Food Chain, Part 1: PCDD/PCDF Mass Balance of a Lactating Cow. Chemosphere. Vol. 20, Nos. 7-9, pp. 1013-1020. McLachlan, M.S., K. Welsch-Pausch, and J. Tolls. 1995. “Field Validation of the Uptake of Gaseous Soc in Lolium Multiflorum (Rye Grass).” Environ. Sci. Tech. 29(8):1998-2004. March, J. 1985. Advanced Organic Chemistry. Reactions, Mechanisms, and Structure. John Wiley & Sons. Third Edition. New York. Melancon, M.J., Jr., and J.J. Lech. 1976. “D istribution and Biliary Excretion Products of Di-2-ethylhexyl Phthalate in Rainbow Trout.” Drug Metabolism and Disposition . Volume 4. Pages 112-118.

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### C-labeled Di-2-ethylhexyl Phthalate by Mullet, Mugil cephalus .” Bulletin of Korean Fish. Soc. Volume 22. Pages 424-428. Parks, J.W., A. Lutz, J.A. Sutton and B.F., Townsend. 1989. “Water Column Methylmercury in the Wabigoon/English River-Lake System: Factors C ontrolling Concentrations, Speciation, and Net Production. Can J Fish Aquat Sci 46: 2181-2202. PEI Associates, Inc., and H.E. Cramer Company, Inc. 1986. Air Quality Modeling Analysis of Municipal Waste Combustors. Prepared for U.S. EPA, Monitoring and Data Analysis Division. Research Triangle Park, North Carolina. Pennington, J.A.T. 1989a. Bowes and Churches’s Food Values of Portions Commonly Used. J.B. Lippincott Company. 15th Edition. Philadelphia. Pennington, J.A.T. 1989b. Food Values of Portions Commonly Used . 15th Edition. Harper and Row. New York, New York. Petersen, G., A. Iverfeldt, and J. Munthe. 1995. “Atmospheric Mercury Species Over Central and Northern Europe. Model Calculations and Co mparison with Observations from the Nordic Air and Precipitation Network for 1987 and 1988.” Atmospheric Environment. 29:47-68. Ramlal, P.S., J.W.M. Rudd, A. Furutari, et al. 1985. “The Effect of pH on Methyl Mercury Production and Decomposition in Lake Sediments.” Can J Fish Aquat Sci 42: 685-692.

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### Scire, J.S., D.G. Strimaitis, and R.J. Yamartino. 1990. Model Formulation And User’s Guide For The CALPUFF Dispersion Model . Sigma Research Corporation. Concord, Massachusetts. Shannon, J.D., and E.C. Voldner. 1994. “Mode ling Atmospheric Concentrations and Deposition of Mercury to the Great Lakes.” Presented at the DOE/FDA/EPA Workshop on Methylmercury and Human Health. Bethesda, MD. March 22-23. Sheih, C.M., M.L. Wesley, and B.B. Hicks. 1979. “Estimated Dry Deposition Velocities of Sulfur Over the Eastern U.S. and Surrounding Regions.” Atmospheric Environment 13:361-368. Shor, R.W., C. Baes III, and R. Sharp. 1982. Agricultural Production in the United States by County: A Compilation of Information from the 1974 Census of Agriculture for Use in Terrestrial Food-Chain Transport and Assessment Models. ORNL-5786. Shriver, R. 1994. “Dioxin Formation and Control in Cement Kilns.” Presented at the U.S. EPA/American Society of Mechanical Engineers Seminar on Products of Incomplete Combustion (PIC) Formation and Control. Research Triangle Park, North Carolina. March. Simmonds, J.R., and G.S. Linsley. 1981. “A Dynamic Modeling System for the Transfer of Radioactivity in Terrestrial Food Chains.” Nuclear Safety . 22(6): 766-777. Smith, D.G., and D. Heinhold. 1995. Deposition Modeling for Dioxins/fu rans: Realistic Alternatives to the 1993 Epa Addendum Approach for Plant Uptake of Vapors and Particulate . 95-TA34.04. 88 th

### Annual Meeting, Air and Waste Management A ssociation. San Antonio, TX. June 18-23. Sparks, D.L. 1989. Kinetics of Soil Chemical Processes . Academic Press, Inc. San Diego, California. Stalling, D.L., J.W. Hogan, and J.L. Johnson. 1973. “Phthalate Ester Residues. Their Metabolism and Analysis in Fish.” Environmental Health Perspectives . Volume 3. Pp. 159-173. Steffan, R.J., F.T. Korthals and M.R. Winfrey. 1988. Effects of acidification on mercury methylation, demethylation, and volatilization in sediments from an acid-susceptible lake. Appl Environ microbial 54: 2003-2009. Stephens, R.D., M.X. Petras, and D.G. Hayword. 1992. Biotransfer and Bioaccumulation of Dioxins and Dibenzofurans from Soil . Hazardous Materials Laboratory, California Department of Health Services. Berkeley, California. Stephens, R.D., M. Petreas, and G.H. Hayward. 1995. “Biotransfer and Bioaccumulation of Dioxins and Furans from Soil: Chickens as a Model for Foraging Animals.” The Science of the Total Environment. 175: 253-273. July 20. Stewart, B.A, D.A. Woolhiser, W.H. Wischmeier, J.H. Caro, and M.H. Frere. 1975. Control of Water Pollution from Croplands. Volume I. EPA/600/2-75/026a. Stieglitz, L., G. Zwick, J. Beck, H. Bautz, and W. Roth. 1989. “Carbonaceous Particles in Fly Ash-A Source for the De-Novo-Synthesis of Organochlorocompounds.” Chemosphere. 19: 283-290.

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-15 

### St. Louis, V.L., J.W.M. Rudd, C.A. Kelley, K.G. Beaty, R.J. Flett, and N.T. Roulet. 1996. “Production and Loss of Methylmercury and Loss of Tota l Mercury from Boreal Forest Catchments Containing Different Types of Wetlands. Environmental Science and Technology . 30(9):2719- 27. Stokinger, H.E. 1981. “The Halogens and the Nonmetals, Boron and Silicon.” Patty’s Industrial Hygiene and Toxicology . Edited by George D. Clayton and Florence E. Clayton. John Wiley & Sons. New York, New York. Volume 2A. Third Revised Edition. Pp. 2937-3044. Subcommittee on Consequence Assessment and Protec tive Actions (SCAPA). 1997a. “Emergency Response Planning Guidelines (ERPG) and TEELS for Chemicals of Concern at the Savannah River Site: Rev. 12.” PEC-CAT-97-0044A. July 9. SCAPA. 2001a. “Revision 17 of ERPGs and TEELs for Chemicals of Concern.” U.S. Department of Energy. January 10. On-Line Address: SCAPA. 2001b. “SCAPA ERPG Working List.” August 13. On-Line Address: http://www.orau.gov/emi/scapa/qa.htm ten Berge, W.F., A. Zwart, and L.M. Appleman . 1986. “Concentration-Time Mortality Response Relationship of Irritant and Systemically Acting Vapours and Gases.” Journal of Hazardous Materials . Volume 13. Pages 301 through 309. Thorton, I. and P. Abrams. 1983. “Soil Ingestion: A Major Pathway of Heavy Metals into Livestock Grazing Contaminated Land.” Science Total Environmental . 28: 287-294. Todres, H., A. Mishulovich, and J. Ahmed. 1992. “Cement Kiln Dust Management: Permeability.” Research and Development Bulletin RD103T. Portla nd Cement Association. Skokie, Illinois. Page 7. Trapp, S., and M. Matthies. 1995. “Generic One- compartment Model for Uptake of Organic Chemicals by Foliar Vegetation.” Environ. Sci. Tech. 29(9):2333-2338. Travis, C.C., and A.D. Arms. 1988. “Bioconcentr ation of Organics in Beef, Milk, and Vegetation.” Environmental Science and Technology. 22:271-274. Travis, C.C., C.F. Baes, and L.W. Barnthouse. 1983. Exposure Assessment Methodology and Reference Environments for Synfuel Risk Analysis. Oak Ridge National Laboratory. ORNL/TM-8672. Prepared for U.S. EPA Office of Research and Development under Interagency Agreement EPA 82-D-X0533 and DOE-40-740-78. Travis, C.C., and H.A. Hattemer-Frey. 1988. “Uptake of Organics by Aerial Plant Parts: A Call for Research.” Chemosphere . 17(2): 277 to 283. Turnbull, D., and J.V. Rodricks. 1985. “Assessment of Possible Carcinogenic Risk to Humans Resulting from Exposure to Di(2-ethylhexyl) Phthalate.” Journal of Am Coll Toxicol . 4:111-146.

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-16 

### Turner, D.B. 1986. FORTRAN Computer Code/User’s Guide for COMPLEX I Version 86064: An Air Quality Dispersion Model in Section 4. Additional Models for Regulatory Use. Source File 31 Contained in UNAMAP (Version 6). National Technical Information System (NTIS) PB86-222361/AS. U.S. Bureau of the Census. 1986. “Geogr aphical Mobility: March 1983 to March 1984.” Current Population Reports . Series P-20. Number 407. U.S. Government Printing Office. Washington, D.C. U.S. Congress. 1989. “Clean Air Act Amendments of 1989.” Senate Report No. 228. 101st Congress. First Session. Pages 153-154. December 20. U.S. Department of Agriculture (USDA). 1982. Average Annual Values for the Rainfall Factor, R . Soil Conservation Service Technical Guide, Section I-C-2. Columbia, Missouri. July. USDA. 1994a. Noncitrus Fruits and Nuts 1993 Summary . National Agricultural Statistics Service, Agricultural Statistics Board. Washington, D.C. Fr Nt 1-3 (94). USDA. 1994b. Vegetables 1993 Summary . National Agricultural Statistics Service, Agricultural Statistics Board. Washington, D.C. Vg 1-2 (94). USDA. 1997. Predicting Soil Erosion by Water: A Guide to Conservation Planning With the Revised Universal Soil Loss Equation (RUSLE) . Agricultural Research Service, Agriculture Handbook Number 703. January. U.S. Department of Health and Human Services (USDHHS). 1993. Hazardous Substances Data Bank (HSDB) . National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993. U.S. Environmental Protection Agency (EPA). 1979. Industrial Source Complex Dispersion Model User’s Guide, Volume I. Prepared by the H.E. Cramer Company. Salt Lake City, Utah. Prepared for the Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. EPA 450/4-79/030. NTIS PB80-133044. U.S. EPA. 1980a. Environmental Assessment of a Waste-to -Energy Process. Braintree Municipal Incinerator. Office of Research and Development (ORD). Washington, D.C. EPA 600/7-80/149. U.S. EPA. 1980b. User’s Guide for Multiple Point Source M odel with Terrain (MPTER): A Multiple Point Gaussian Dispersion Algorithm with Optional Terrain Adjustment . Environmental Sciences Research Laboratory (ESRL). Research Triangle Park, North Carolina. EPA 600/8-80/016. NTIS PB80-197361. U.S. EPA. 1982a. MPTER-DS: The MPTER Model In cluding Deposition and Sedimentation . Prepared by the Atmospheric Turbulence and Diffusion Laboratory. National Oceanic and Atmospheric Administration. Oak Ridge, Tennessee. Preparedfor the ESRL. Research Triangle Park, North Carolina. EPA 600/8-82/024. NTIS PB83-114207.

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-17 

### U.S. EPA. 1982b. Pesticides Assessment Guidelines Subdivision O: Residue Chemistry. Office of Pesticides and Toxic Substances. Washington, D.C. EPA-600-90-003. January. U.S. EPA. 1982c. Air Quality Criteria for Particulate Matter and Sulfur Oxides (1982) (Second Addendum): Assessment of Newly Available Health Effects Information. Final Report. U.S. Environmental Protection Agency, Washi ngton, D.C., EPA/600/8-86/020F (NTIS PB87176574. U.S. EPA. 1985a. Rapid Assessment of Exposure to Particulat e Emissions from Surface Contamination Sites. Prepared by Midwest Research Institute under Contract 68-0303116. Office of Health and Environmental Assessment (OHEA). Washington, D.C. EPA/600/8-85/002. NTIS PB 85-192219. U.S. EPA. 1985b. Water Quality Assessment: A Screeni ng Procedure for Toxic and Conventional Pollutants in Surface and Ground Water—Part I (Revised). ORD. Athens, Georgia. EPA/600/6-85/002a. U.S. EPA. 1986a. Air Quality Modeling Analysis of Municipal Waste Combustors. Prepared by PEI Associates. Cincinnati, Ohio. U.S. EPA. 1986b. Guideline on Air Quality Models (Revised). Office of Air Quality and Planning and Standards. Research Triangle Park, North Carolina. EPA 450/2-78/072R. NTIS PB86-245248. U.S. EPA. 1986c. Superfund Public Health Evaluation Manual. Office of Emergency and Remedial Response (OERR). Washington, D.C. EPA/540/1-86/060. U.S. EPA. 1986d. “Test Methods for Evaluating So lid Waste—Physical/Chemical Methods.” SW-846, Third Edition and Update I (July 1992), U pdate II (September 1994), and Update IIB (January 1995). U.S. EPA. 1986e. “Guidelines for the Health Risk Assessment of Chemical Mixtures.” Federal Register . 51(185):34014-34025. September 24. U.S. EPA. 1987a. Air Dispersion Modeling of a Municipal Waste Combustor in Rutland, Vermont. Prepared by PEI Associates. Cincinnati, Ohio. U.S. EPA. 1987b. On-Site Meteorological Program Guidance for Regulatory Modeling Applications. Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. U.S. EPA. 1987c. “Technical Guidance for Hazar ds Analysis.” EPA-OSWER-88-0001. December. U.S. EPA. 1988a. Drinking Water Criteria Document for Polychlorinated Biphenyls (PCBs). PB89-199256. April. U.S. EPA. 1988b. Superfund Exposure Assessment Manual. Office of Emergency and Remedial Response. Washington, D.C. EPA/540/1-88/001. NTIS PB 89-167985.

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U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-18 

### U.S. EPA. 1988c. Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion . Federal Guidance Report No. 11. EPA-520/1-88-020. September. U.S. EPA. 1989a. Development of Risk Assessment Methodology for Land Application and Distribution and Marketing of Municipal Sludge. ORD. OHEA. Environmental Criteria and Assessment Office. Cincinnati, Ohio. EPA 600/6-89/001. NTIS PB90-135740/AS. U.S. EPA. 1989b. Hazardous Waste Treatment, Storage, and Disposal Facilities: Background Information for Proposed Resource Conserva tion and Recovery Act (RCRA) Air Emission Standards . EPA/450/3-89-023. U.S. EPA. 1989c. Hazardous Waste Treatment, Storage, and Di sposal Facilities: Fugitive Particulate Matter Air Emissions Guidance Document . Office of Air Quality Planning and Standards. EPA/450/3-89-019. U.S. EPA. 1989d. Interim Procedures for Estimating Risks A ssociated with Exposures to Mixtures of Chlorinated Dibenzo-p-Dioxins (CDD) and Dibenzofurans. U.S. EPA. 1989e. Risk Assessment Guidance for Superfund: Vo lume I. Human Health Evaluation Manual (Part A) . OERR. Washington, D.C. OERR 9200 6-303-894. U.S. EPA. 1989f. Handbook: Guidance on Setting Permit Conditi ons and Reporting Trial Burn Results. Volume II of the Hazardous Wa ste Incineration Guidance Series. ORD. EPA/625/6-89/019. January. U.S. EPA. 1989g. Handbook: Hazardous Waste Incineration Measurement Guidance Manual. Volume III of the Hazardous Waste Incineration Guidance Series. Office of Solid Waste and Emergency Response (OSWER). EPA/625/6-89/021. June. U.S. EPA. 1990a. Operations and Research at the U.S. EPA Incineration Research Facility. Annual Report for FY 89. Risk Reduction Engineering Laboratory. ORD. Cincinnati, Ohio. EPA/600/9-90/012. U.S. EPA. 1990b. “Standards for Owners and Operat ors of Hazardous Waste Incinerators and Burning of Hazardous Wastes in Boilers and Industrial Furnaces.” Federal Register . 55:17862-17921. U.S. EPA. 1990c. Technical Support Document for Lead. Final Draft . Environmental Criteria and Assessment Office (ECAO)-CIN-757. Cincinnati, Ohio. U.S. EPA. 1990d. User’s Manual for the PM-10 Open Fug itive Dust Source Computer Model Package. EPA-450/3-90-010. U.S. EPA. 1990e. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environmental Criteria and Assessment Office. ORD. EPA-600-90-003. January.

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-19 

### U.S. EPA. 1990f. Exposure Factors Handbook . OHEA. Exposure Assessment Group. Washington, D.C. March. U.S. EPA. 1990g. “National Oil and Hazardous Substances Pollution Contingency Plan.” Federal Register. 55(46). March 8. U.S. EPA. 1990h. Development of Relative Potency Estimat es for Polycyclic Aromatic Hydrocarbons (PAH) and Hydrocarbon Combustion Product Fractions Compared to Benzo(a)pyrene and Their Use in Carcinogenic Risk Assessments . OHEA. EPA/600/R-92/134. September. U.S. EPA 1990i. Handbook: Quality Assurance/Quality Control (QA/QC) Procedures for Hazardous Waste Incineration . Office of Research and Development. EPA/625/6-89/023. January. U.S. EPA. 1991a. “Burning of Hazardous Waste in Boilers and Industrial Furnaces: Final Rule.” Federal Register . 56:7134-7240. U.S. EPA. 1991b. Memorandum Regarding Human H ealth Evaluation Manual, Supplemental Guidance: “Standard Default Exposure Factors.” From Timothy Fields, Jr., Acting Director, OERR and Bruce Diamond, Director, Office of Waste Programs Enforcement (OWPE). To Various Regional EPA Directors. OSWER Directive 9285.6-03. March 25. U.S. EPA. 1991c. Dose-Response Analysis of Ingested Benz o(a)pyrene (Chemical Abstract Service (CAS) No. 50-32-8). ORD. EPA/600/R-92/045. December. U.S. EPA. 1991d. Risk Assessment Guidance for Superfund: Volume I—Human Health Evaluation Manual (Part B, Development of Risk-Based Preliminary Remediation Goals).” Interim Final. December. U.S. EPA. 1992a. “Implementation of Boiler a nd Industrial Furnace Regulations, New Toxicological Data.” Memorandum from Shiva Garg, OSWER. February 11. U.S. EPA. 1992b. “An Science Advisory Board (S AB) Report: Review of the Uptake Biokinetics Model for Lead.” EPA-SAB-IAQC-92016. March. U.S. EPA. 1992c. Technical Implementation Document for EPA’s Boiler and Industrial Furnace Regulations. OSWER. EPA-530-R-92-011. March. U.S. EPA. 1992d. “Estimating Exposure to Dioxin-Like Compounds. Draft Report.” OHEA. Washington, D.C. EPA/600/6-88/005B. August. U.S. EPA. 1992e. Health Reassessment of Dioxin-Like Compounds, Chapters 1 to 8. Workshop Review Draft. OHEA. Washington, D.C. EPA/600/AP-92/001a through 001h. August. U.S. EPA. 1992f. National Study of Chemical Residues in Fish . Office of Science and Technology. September.

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-20 

### U.S. EPA. 1992g. Guidance for Data Useability in Risk Assessment (Part A): Final . NTIS PB92-963356/XAB. Office of Emergency and Reme dial Response. U.S. EPA. Washington, D.C. April. U.S. EPA. 1993a. Development and Testing of Dry Deposition Algorithms. Office of Air Quality Planning and Standards. Research Triangl e Park, North Carolina. EPA/4504/R-92/017. U.S. EPA. 1993b. Guideline on Air Quality Models (Revised). Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. EPA/450/2-78/072R. U.S. EPA. 1993c. Technical Support Document for Land Application of Sewage Sludge. Volumes I and II. EPA 822/R-93-001a. Office of Water. Washington, D.C. U.S. EPA. 1993d. Provisional Guidance for Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons . EPA/600/R-93/089. July. U.S. EPA. 1993e. “Addendum to the Methodology for Assessing Heath Risks Associated with Indirect Exposure to Combustor Emissions.” Working Group Recommendations. Office of Solid Waste. ORD. Washington D.C. September 24. U.S. EPA. 1993f. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions . OHEA. ORD. EPA/600-AP-93-003. November 10. U.S. EPA. 1993g. “Report to Congress on Cement Kiln Dust.” OSWER. EPA/530-R-94-001. December. U.S. EPA. 1993h. “Report to Congress on Cement Kiln Dust.” Executive Summary. OSWER. EPA/530-S-94-001. December. U.S. EPA. 1993i. “Handbook of Chemical Incinerator Trial Burn Risk Assessment.” Volume 1. Prepared by Roy F. Weston for EPA Region 3. June 21. U.S. EPA. 1993j. External Exposure to Radionuclides in Air, Water, and Soil . Federal Guidance Report No. 12. EPA 402-R-93-081. September. http://www.epa.gov/radiation/ docs/federal/402-r-93-081.pdf U.S. EPA. 1994a. Health Assessment Document for 2,3,7,8-TCDD and Related Compounds. Volume III. Review Draft. ORD. Washington, D.C. EPA/600/BP-92/001c. U.S. EPA. 1994b. Health Effects Assessment Summary Tables. Annual Update. ORD. OHEA-ECAO-CIN-909. Environmental Criteria and Assessment Office. Cincinnati, Ohio. U.S. EPA. 1994c. User's Guide for the Industrial Source Complex Dispersion Models (Revised). Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. Draft. U.S. EPA. 1994d. Air/Superfund National Technical Guidance Study Series. Volume V—Procedures For Air Dispersion Modeling At Superfund Sites . Office of Air Quality Planning and Standards. Research Triangle Park, North Carolina. February.

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-21 

### U.S. EPA. 1994e. Guidance Manual for the Integrated Expos ure Uptake Biokinetics Model for Lead in Children. OERR. Washington, D.C. EPA/540/R-93/081. February. U.S. EPA. 1994f. Draft Exposure Assessment Guidance fo r RCRA Hazardous Waste Combustion Facilities . OSWER. EPA-530-R-94-021. April 22. U.S. EPA. 1994g. Draft Guidance for Performing Screeni ng Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachme nt C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . April 15. U.S. EPA. 1994h. Table 1, “Chemicals Recommended for Identification,” and Table 2, “Chemicals for Potential Identification.” Attachment A, Draft Exposu re Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . April 15. U.S. EPA. 1994i. Draft Revision, Implementation Guidance for Conducting Indirect Exposure Analysis at RCRA Combustion Units. Attachment, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities. April 22. U.S. EPA. 1994j. Draft Guidance on Trial Burns. Attachme nt B, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . May 2. U.S. EPA. 1994k. Estimating Exposure to Dioxin-Like Co mpounds. Volume I: Executive Summary. Review Draft. ORD. Washington, D.C. EPA/600/6-88/005Ca. June. U.S. EPA. 1994l. Estimating Exposure to Dioxin-Like Compounds. Volume II: Properties, Sources, Occurrence, and Background Exposures. Review Draft. ORD. Washington, D.C. EPA/600/6-88/005Cb. June. U.S. EPA. 1994m. Estimating Exposure to Dioxin-Like Compounds. Volume III: Site-Specific Assessment Procedures. Review Draft . ORD. Washington, D.C. EPA/600/6-88/005Cc. June. U.S. EPA. 1994n. Draft Revision of Guidance on Trial Burns. Attachment B, Draft Exposure Assessment Guidance for RCRA Hazar dous Waste Combustion Facilities . OSWER. June 2. U.S. EPA. 1994o. “Memorandum Regarding Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities.” OSWER Directive 9355.4-12. From Elliot P. Laws, Assistant Administrator. To Regional Administrators Regions I - X. July 14. U.S. EPA. 1994p. Errata, Draft Guidance for Performing S creening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Expos ure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . October 4. U.S. EPA. 1994q. Draft Technical Background Docume nt for Soil Screening Guidance. EPA/540/R-94/106. OSWER. Washington, D.C. December. U.S. EPA. 1994r. Revised Draft Guidance for Performing S creening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachme nt C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . OERR. OSW. December 14.

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-22 

### U.S. EPA. 1994s. Estimating Radiogenic Cancer Risks . Office of Radiation and Indoor Air. U.S. EPA. Washington, DC. EPA 402-R-93-076. June. U.S. EPA. 1995a. Compilation of Air Pollutant Emission Facto rs: Volume I, Stationary Point and Area Sources. Research Triangle Park, North Carolina. 5th Edition. AP-42. January. U.S. EPA. 1995b. Further Issues for Modeling the Indirect Exposure Impacts from Combustor Emissions. ORD. Washington, D.C. January 20. U.S. EPA. 1995c. User's Guide to the Building Profile Input Program . EPA-454/R-93-038. Office of Air Quality Planning and Standards, Technical Support Division. Research Triangle Park, North Carolina. February. U.S. EPA. 1995d. “Regulatory Determinati on on Cement Kiln Dust; Final Rule.” Federal Register. February 7. U.S. EPA. 1995e. Review Draft Development of Human He alth-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project . Volumes I and II. Office of Solid Waste. March 3. U.S. EPA. 1995f. User’s Guide For The Industrial Source Co mplex Dispersion Models, Volumes I and II. Office of Air Quality Planning and Standards. Emissions, Monitoring, and Analysis Division. Research Triangle Park, North Carolina. EPA-454/B-95-003a. September. U.S. EPA. 1995g. PCRAMMET User’s Guide. Office of Air Quality Planning and Standards. Emissions, Monitoring, and Analysis Division. Research Triangle Park, North Carolina. October. U.S. EPA. 1995h. “Waste Technologies Industries Screening Human Health Risk Assessment (SHHRA): Evaluation of Potential Risk from Exposure to Routine Operating Emissions.” Volume V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois. U.S. EPA. 1995i. Development of Compliance Levels from Analytical Detection and Quantitation Levels . U.S. EPA, Washington, DC. NTIS PB95-216321. U.S. EPA. 1995j. New Policy on Evaluating Health Risks to Children . Memorandum to Assistant Administrators, General Counsel, Inspector Ge neral, Associate Administrators, regional Administrators. From Carol M. Browner, Administrator, and Fred Hansen, Deputy Administrator. U.S. EPA, Washington, DC. October 20. U.S. EPA. 1995k. Protocol for Equipment Leak Emission Estimates . Office of Air Quality Planning and Standards. Emissions, Monitoring, and Analysis Division. Research Triangle Park, North Carolina. EPA/453/R-95-017. November http://www.epa.gov/ttn/chief/efdocs/lks95_ch.pdf U.S. EPA. 1996b. “Response to Comments Regardi ng the Screening Level Risk Assessment for the Drake Chemical Company Superfund Site Incinerator.”

## Human Health Risk Assessment Protocol References September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering R-23 

### U.S. EPA. 1996c. Review and Comments of EPA’s Peer Review Panel on the Risk Assessment in Support of a Proposed Rule for Technical St andards for Emissions from Combustion Units Burning Hazardous Wastes. U.S. EPA. 1996d. Guidance for Total Organics . Final Report. Radian Corporation. Contract 68-D4-0022, Work Assignment 8. EPA/600/R-96/033. March. U.S. EPA. 1996e. “Proposed Guidelines for Carcinogen Risk Assessment.” Federal Register . 61 Federal Register (FR) 17960. Volume 61. Number 79. April 23. U.S. EPA. 1996f. “Accidental Release Prevention Re quirements: Risk Management Programs Under Clean Air Act Section 112(r)(7).” Federal Register . 61FR31667. Volume 61. Number 120. June 20. U.S. EPA. 1996g. Public Participation Record for Screen ing Risk Assessment for Operation of the Tooele Chemical Demilitarization Facility at th e Tooele Chemical Activity and Resulting Permit Modification. June 20. U.S. EPA. 1996h. “Formation of Dioxin-Like PICs During Incineration of Hazardous Wastes.” Memorandum to the Record. Dorothy Canter. June 21. U.S. EPA. 1996i. “Memorandum regarding Johnston Atoll Chemical Agent Disposal System (JACADS) Risk Assessment Issues.” From Dorothy Canter to Patrick Wilson. July 24. U.S. EPA. 1996j. "Meteorological Processor For Regulatory Models User's Guide." EPA-454/B-96-002. Office of Air Quality Planni ng and Standards, Emissions Monitoring and Analysis Division. Research Triangle Park, North Carolina. August. U.S. EPA. 1996k. Guideline on Air Quality Models . Title 40 Code of Fede ral Regulations Part 51, Appendix W. September. U.S. EPA. 1996m. Internal Memorandum Regarding JACADS Risk-Related Issues. From Timothy Fields, Jr., Deputy Assistant Administrator, OSWER. To Julie Anderson, Director, Waste Management Division. October 2. U.S. EPA. 1996n. Telefax Memorandum Regarding Ev aluation of Acute Inhalation Exposure to Kalama Chemical Company Upset Incinerator Emissions. From Cathy Massimino, U.S. EPA Region 10. To David Weeks, U.S. EPA Region 6. December 5. U.S. EPA. 1996o. “Region 10 Tiered Approach for Developing Acute Inhalation Exposure Values.” Facsimile Transmission from Cathy Massimino, EPA Region 10 to David Weeks, EPA Region 6. December 16, 1996. U.S. EPA. 1996p. “Drake Chemical Incinerator Tria l Burn Risk Assessment, Volume 1.” Prepared by Roy F. Weston for EPA Region 3. June 21.

## Human Health Risk Assessment Protocol References September 2005

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### U.S. EPA. 1996q. "PCBs: Cancer Dose-Response Assessment and Application to Environmental Mixtures." National Center for Environmental Assessment, Office of Research and Development. EPA/600/P-96/001F. September. U.S. EPA. 1996r. Recommendations for the Technical Review Workgroup for Lead for an Interim Approach to Assessing Risks Associated with Adult Exposures to Lead in Soil . Technical Review Workgroup for Lead. December. U.S. EPA. 1996s. Mercury Study Report to Congress, Volume III, SAB Review Draft. Office of Air Quality Planning and Standards a nd ORD. EPA/452/R-96-001c. April. U.S. EPA. 1997a. “Development of a Hazardous Waste Incinerator Target Analyte List of Products of Incomplete Combustion, Draft Final Report”. National Risk Management Research Laboratory, Air Pollution Prevention and Control Division, U.S. EPA. Research Triangle Park, North Carolina. July 25. U.S. EPA. 1997b. Exposure Factors Handbook. Office of Research and Development. EPA/600/P-95/002Fc. August. U.S. EPA. 1997c. Mercury Study Report to Congress, Volumes I through VIII. Office of Air Quality Planning and Standards and ORD. EPA/452/R-97-001. December. U.S. EPA. 1997d. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments. Interim Final. OSWER, U.S. EPA. EPA 540-R-97-006. June. U.S. EPA. 1997e. Notice of Draft Source Category Listing for Section 112(d)(2) Rulemaking Pursuant to Section 112(c)(6) Requirements. Federal Register. 62: 33625. June 20. U.S. EPA. 1997f. Model Parameter Sensitivity Analysis . Prepared by The Air Group - Dallas for U.S. EPA Region 6 Center for Combustion Science and Engineering. U.S. EPA. 1997g. Special Report on Environmental Endocrine Disruption: An Effects Assessment and Analysis . U.S. EPA, Risk Assessment Forum, Washington, DC. USEPA 630/R-96/012. Feb 1997. U.S. EPA. 1998a. The Inventory of Sources of Dioxin in the United States. External Review Draft. Office of Research and Development, National Center for Environmental Assessment, U.S. EPA. EPA/600/P-98/002As. April. U.S. EPA. 1998b. Region 6 Risk Management Addendum - Draft Human Health Risk Assessment Protocol for hazardous Waste Combustion Facilities . U.S. EPA Region 6. EPA-R6-98-002. July. U.S. EPA. 1998c. Methodology for Assessing Health Risks A ssociated with Multiple Pathways of Exposure to Combustor Emissions (MPE) . Update to EPA/600/6-90/003. Office of Research and Development, National Center for Environmental Assessment, U.S. EPA. EPA/600/R-98/137. December.

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### U.S. EPA. 1998d. Supplement to the Second Addendum (1986) to Air Quality Criteria for Particulate Matter and Sulfur Oxides: Assessment of New Findings on Sulfur Dioxide and Acute Exposure Health Effects in Asthmatic Individuals . U.S. Environmental Protection Agency, Washington, DC, EPA 600/AP-93/002, 1986. U.S. EPA. 1999a. Screening Level Ecological Risk Assessmen t Protocol for Hazardous Waste Combustion Facilities . Peer Review Draft. Office of Solid Waste and Emergency Response. Washington, D.C. August. U.S. EPA. 1999b. Guideline on Air Quality Models (GAQM)(Revised 7-1-99). Office of Air Quality and Planning and Standards. Research Triangle Park , North Carolina. As published in 40 CFR Part 51, Appendix W. U.S. EPA. 1999c. Addendum to Meteorological Processo r for Regulatory Models (MPRM)

. EPA-454/B-96-002. June. http://www.epa.gov/scram001/userg/relat/mprmadd.pdf U.S. EPA. 1999d. Cancer Risk Coefficients for Environmental Exposure to Radionuclides . Federal Guidance Report No. 13. EPA 402-R-99-001. September. http://www.epa.gov/radiation/federal/docs/fgr13.pdf U.S. EPA. 1999e. Addendum to Meteorological Processo r for Regulatory Models (MPRM)

. EPA-454/B-96-002. June. http://www.epa.gov/scram001/userg/relat/mprmadd.pdf U.S. EPA. 1999f. OAQPS Economic Analysis Resource Document, Section 8.4 Addressing Uncertainty . April. http://www.epa.gov/ttn/ecas/econdata/Rmanual2/index.html U.S. EPA. 2000a. “RCRA Site-Specific Risk Assessment Policy for Hazardous Waste Combustion Facilities Fact Sheet”. Hazardous Waste Combustion NESHAP Toolkit. July. U.S. EPA. 2000b. Exposure and Human Health Reassessment of 2, 3, 7, 8- Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds . Parts 1, 2, and 3. Draft Report for Science Advisory Board Review. Washington, DC: National Center for Environmental Assessment, Office of Research and Development. EPA/600/P-00/001B(b-e). U.S. EPA. 2000c. Draft Methodology for Deriving Ambient Water Quality Criteria for Protection of Human Health. Technical Support Document Vo lume III: Bioaccumulation Part 1 - Development of National Bioaccumulation Factors. Office of Science and Technology in the Office of Water. U.S. EPA. 2000d. Air Quality Criteria for Carbon Monoxide . U.S. Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment, Washington Office, Washington, DC, EPA 600/P-99/001F, 2000. U.S. EPA 2000e. Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures

. EPA/630/R-00/002. Risk Assessment Forum, Washington DC.

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### U.S. EPA 2000f. Risk Characterization Handbook. Prepared for the U.S. Environmental Protection Agency by members of the Risk Characterization Implementation Core Team, a group of EPA’s Science Policy Council. EPA 100/B-00/002. December. Available at http://www.epa.gov/osa/spc/pdfs/rchandbk.pdf U.S. EPA. 2001a. Email Memorandum Regarding Summary of AEGL Results as of September 13, 2001. From Paul Tobin, U.S. EPA. To Vicki M. Kier, Combustion Technical Assistance Center (CTAC). September 20. U.S. EPA. 2001b. National-Scale Air Toxics Assessment for 1996 . Research Triangle Park, NC 27711. EPA-453/R-01-003. January. U.S. EPA. 2001c. Risk Burn Guidance for Hazar dous Waste Combustion Facilities. Prepared by U.S. EPA Region 4 and the Office of Solid Waste. EPA 530-R-01-001. U.S.EPA. 2002. A Review of the Reference Dose and Reference Concentration Processes

. EPA/630/P-02/002F. Risk Assessment Forum, Washington DC. U.S.EPA. 2002b. Child-Specific Exposure Factors Handbook . EPA-600-P-00-002B. National Center for Environmental Assessment (Washington Office) and U.S. EPA ORD. September. U.S.EPA. 2002c. Guidelines for Ensuring and Maximizing the Quality, Objectivity, Utility, and Integrity, of Information Disseminated by the Environmental Protection Agency . EPA260R-02-008. Office of Environmental Information. October. U.S. EPA. 2004a. The Ozone Report: Me asuring Progress through 2003. Prepared by U.S. EPA Office of Air Quality Planning and Standards Emissions , Monitoring, and Analysis Division. EPA 454/ K-04-001. April 2004. U.S. EPA. 2004b. The Particle Pollution Report: Current Understanding of Air Quality and Emissions through 2003 Prepared by U.S. EPA Office of Air Quality Planning and Standards Emissions, Monitoring, and Analysis Division. EPA 454-R-04-002. December 2004. U.S. EPA. 2004c. Air Quality Criteria for Par ticulate Matter (October 2004). U.S. Environmental Protection Agency, Washington, DC, EPA 600/P-99/002aF-bF, 2004. EPA, 2004d. Risk Assessment Guidance for Superfund Volume I: Human Health Evaluation Manual (Part E, Supplemental Guidance for Dermal Risk Assessment). EPA/540/R/99/005. Office of Superfund Remediation and Tec hnology Innovation, U.S. Environmental Protection Agency Washington, DC. http://www.epa.gov/oswer/riskassessment/ragse/index.htm U.S. EPA. 2005. “Air Quality Trends Reports: Six Pr incipal Pollutants.” Prepared by U.S. EPA Office of Air. World Wide Web Address http://www.epa.gov/airtrends/sixpoll.html . Accessed on August 15, 2005. U.S. EPA. 2005b. Integrated Risk Information System (IRIS): Lead and compounds (inorganic) (CASRN 7439-92-1)

. http://www.epa.gov/iris/ . Accessed August 9, 2005.

## Human Health Risk Assessment Protocol References September 2005

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### U.S. EPA. 2005c. Integrated Risk Information S ystem (IRIS): Nickel Refinery Dust

. http://www.epa.gov/iris/ . Accessed August 9, 2005. U.S. EPA. 2005d. Integrated Risk Information System (IRIS): Nickel carbonyl (CASRN 13463-39-3)

. http://www.epa.gov/iris/ . Accessed August 9, 2005. U.S. EPA. 2005e. Integrated Risk Information System (IRIS): Nickel subsulfide (CASRN 12035-72-2)

. http://www.epa.gov/iris/ . Accessed August 9, 2005. U.S. EPA. 2005f. Guidelines for Carcinogen Risk Assessment . EPA/630/P-03/001F. Risk Assessment Forum, Washington DC. Available at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=116283 U.S. EPA. 2005g. Supplemental Guidance for Assessing Susceptib ility from Early-Life Exposure to Carcinogens . EPA/630/R-03/003F. Risk Assessment Forum, Washington DC. Available at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=116283 U.S. EPA 2005h. Regulatory Impact Analysis of the Clean Air Mercury Rule Final Report . U.S. EPA Office of Air Quality Planning and Standards Emissions, Monitoring, and Analysis Division, Air Quality Strategies and Standards Division. EPA-452/R-05-003. March. U.S. EPA. 2005i. Integrated Risk Information System (IRIS)

. http://www.epa.gov/iris/ . Accessed August 10, 2005. Valentine, R.L. 1986. “Nonbiological Transformation.” Vadose Zone Modeling of Organic Pollutants. S.C. Hern and S.M. Melacon, Editors. Le wis Publishers, Inc. Chelsea, Michigan. Valentine, R.L., and Schnoor. 1986. “Biotransformation.” Vadose Zone Modeling of Organic Pollutants. S.C. Hern and S.M. Melancon, Editors. Lewis Publishers, Inc. Chelsea, Michigan. Van den Berg et al. 1998. “Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for Humans and Wildlife”. Environmental Health Perspectives, Volume 106, Number 12:775-792. Vanoni, V.A. 1975. Sediment Engineering . American Society of Civil Engineers. New York, New York. Pages 460-463. Watras, C.J., and N.S. Bloom. 1992. “Mercury and Methylmercury in Individual Zooplankton: Implications for Bioaccumulation.” Limnol. Oceanogr. Volume 37(6). Pages 1313-1318. Watras, C.J., K.A. Morrison, and J.S. Host. 1995. “Concentration of Mercury Species in Relationship to Other Site-Specific Factors in the Surface Waters of Northern Wisconsin Lakes.” Limnology and Oceanography . 40(3): 556-565. Weast, R.C. 1986. Handbook of Chemistry and Physics . 66th Edition. Cleveland, Ohio. CRC Press. Westinghouse Savannah River Company (WSRC). 1998. “Methodology for Deriving Temporary Emergency Exposure Limits (TEELs) (U).” Prepared for the U.S. Department of Energy. WSRC-TR-98-00080. On-Line Address: http://www.bnl.gov/scapa/teel2.pdf

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### Wikström, Evalena, G. Löfvenius, C. Rappe, and S. Marklund. 1996. “Influence of Level and Form of Chlorine on the Formation of Chlorinated Dioxins, Dibenzofurans, and Benzenes during Combustion of an Artificial Fuel in a Laboratory Reactor.” Environmental Science and Technology . Volume 30. Pages 1637-1644. May. Wipf, H.K., E. Homberger, N. Neuner, U.B. Ranald er, W. Vetter, and J.P. Vuilleumier. 1982. “TCDD Levels in Soil and Plant Samples from the Seveso Area.” In: Chlorinated Dioxins and Related Compounds: Impact on the Environment. Eds. Hutzinger, O. et al. Pergamon, New York. Witby, K.T. 1978. “The Physical Characteristics of Sulfur Aerosols.” Atmospheric Environment. 12:135-159. World Health Organization (WHO). 1998. “Assessment of the Health Risk of Dioxins: Re-evaluation of the Tolerable Daily Intake (TDI).” World Health Organization, European Centre for Environment and Health; International Progra mme on Chemical Safety. WHO Consultation. May 25-29, 1998. Geneva, Switzerland. Wright, D.R. and R.D. Hamilton. 1982. “Release of Methyl Mercury from Sediments: Effects of Mercury Concentration, Low Temperature, and Nutrient Addition. Can J Fish Aquat Sci 39: 1459-1466. Wright, George W. 1978. “The Pulmonary Effects of Inhaled Inorganic Dust.” Patty’s Industrial Hygiene and Toxicology . Edited by George D. Clayton and Florence E. Clayton. John Wiley & Sons. New York. Third Revised Edition. Volume 1. Xun, L., E. R. Campbell and J.W.M. Rudd. 1987. “Measurements of Specific Rates of Net Methyl Mercury Production in the Water Column and Surface Sediments of Acidified and Circumeneutral Lakes. Can J Fish Aquat Sci 44: 750-757.

# APPENDIX A-1 CHEMICALS OF POTENTIAL INTEREST

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### APPENDIX A-1 CHEMICALS OF POTENTIAL INTEREST
Table A-1 presents a comprehensive list of compounds typically found in • hazardous waste; and • hazardous waste combustion stack gas emissions. Table A-1 identifies the Chemical Abstracts Se rvice (CAS) number for each compound, and indicates whether a compound has been identified as a potential COPC by: • U.S. EPA and state risk assessment reference documents; • Emission test results that have identified the compound in the emissions from hazardous waste combustion facilities; or • Other literature that suggests that the risks from the compound may be significant. We provide Table A-1 to help you make sure th at the trial/risk burn considers the full range of compounds potentially emitted from a combustor, and the appropriate analytical method. A risk assessment won’t necessarily evaluate every metal and potential PIC listed in Table A-1. Once the trial/risk burn stack tests are completed, the risk assessment COPCs are selected from the stack test data, rather than Table A-1. This discussion lists reference documents for each of the columns in Table A-1 and briefly describes the quality of data associated with these references. The evaluation of chemical toxicity is also discussed at the end of this section. This informati on is presented for informational purposes only. A1.1 COLUMN 1: CHEMICAL ABSTRACTS SERVICE (CAS) NUMBER The CAS number is a unique number assigned to each compound in the table. A1.2 COLUMN 2: COMPOUND NAME The most common compound name is listed. Wher e appropriate, common synonyms are also listed to help you identify particular compounds. A1.3 COLUMN 3: COMPOUNDS LISTED IN 40 CFR PART 261 APPENDIX VII OR VIII Appendix VII of Title 40 Code of Federal Regulations (40 CFR) Part 261 identifies compounds for which specific hazardous wastes, from specific and nonspecific sources, are listed (U.S. EPA 1995). Appendix VIII of 40 CFR Part 261 identifies acute hazardous wastes and toxic hazardous wastes associated with commercial chemical products, manufacturing chemical intermediates, and off-specification commercial chemical products (U.S. EPA 1995). This column lists hazardous waste codes for the associated compounds. We provide this list for reference pur poses only, because it’s commonly cited by other U.S. EPA combustion risk assessment documents as an original source of the product of incomplete combustion (PIC) lists. An explanation of the reas ons for including a COPC on this list is beyond the scope of the HHRAP.

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### A1.4 COLUMN 4: CHEMICAL-SPECIFIC DATA AVAILABLE This column lists those compounds for which the fo llowing are available (as presented in Appendix A-2): (1) chemical-specific physical and chemical informa tion, and (2) chemical-specific fate-and-transport information. A1.5 COLUMN 5: PICS RECOMMENDED BY U.S. EPA (1994a) FOR ALL HUMAN HEALTH RISK ASSESSMENTS (HHRA) Compounds marked with an “X” in this column are identified by U.S. EPA (1994a) as PICs to be included in all HHRAs. U.S. EPA (1994a) does not d escribe the basis or references for including these PICs in all HHRAs. More information regarding these compounds is presented in Section 2.2 of the HHRAP. A1.6 COLUMN 6: PICS IDENTIFIED IN COMBUSTION UNIT EMISSIONS (U.S. EPA 1993) Compounds marked with an “X” in this column are identified in U.S. EPA (1993) as PICs. The source documents cited by U.S. EPA (1993) are described in the following subsections. These references have been cited by this and other Agency reference documents as “sources” of information regarding PIC emissions from hazardous waste combustors. U.S. EPA (1993) has, in turn, been cited by later guidance documents as a “source” of information regarding PIC emissions from hazardous waste combustors. However, as is indicated by the listing of the re ferences from Dempsey and Oppelt (1993) (which is a summary of existing information), many of the refe rence documents appear to simply cite additional “sources” of information. We’ve not yet identified th e original research and sampling data regarding PIC emissions but, based on a preliminary review of th e information below, the sources of the “original” information cited by all of the most common refe rence documents may be limited and may have been published over 15 years ago. A1.6.1 Demsey and Oppelt (1993) The sections of Demsey and Oppelt (1993) regard ing PICs from hazardous waste combustion facilities (“Combustion Byproduct Emissions” and “Table XVII: Organics that Could Potentially be Emitted from Devices Burning Hazardous Waste”) cite the following references: C 

### U.S. EPA (1989b) didn’t include a list of PICs from combustion sources. U.S. EPA (1989b) discussed ways of ensuring that PIC emissions don’t pose an unacceptable risk to human health and the environment. Stack gas carbon monoxide (CO) concentration is a good indicator of combustion efficiency; therefore, controlling CO is a prudent and reasonable approach for minimizing the potential risk from PICs. The destruction and removal efficiency (DRE) standard of 40 CFR Part 264.242(a) limits stack emissions of principal organic hazardous constituents (POHCs) to 0.01 percent (or 0.0001 percent for dioxin-containing waste) of the quantity of POHC in the waste. This standard, however, does not impose a limit on PICs. Therefore, a limit of 100 parts per million by volume (ppmv) (Tier I) was imposed, below which PIC emissions do not pose unacceptable risks to human health. The proposed rule allows a waiver to the 100-ppmv CO limit, by (1) restricting total hydrocarbon (THC) emissions to 20 ppmv (Tier II), or (2) showing that THC emissions do not pose an un acceptable health risk by using prescribed risk assessment procedures.

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### The above limitations were also provided in th e Federal Register, dated January 23, 1981 (U.S. EPA 1981) and April 27, 1990 (U.S. EPA 1990b) C 

### U.S. EPA (1981) doesn’t contain any informati on regarding PICs not contained in U.S. EPA (1989b). There is no discussion of “risk” in this document. Although the notice deals with permitting standards, there is no risk-based appro ach, and it appears to be an entirely technical discussion. Specifically, it deals with updated material for specific parts of 40 CFR. - 40 CFR Part 122 (Incinerator Facility Permits) - 40 CFR Part 264 (General Standards for Hazardous Waste Incineration) - 40 CFR Part 265 (Interim Status Standards for Hazardous Waste Incineration) Standards are technology-based, not risk-based. C 

### U.S. EPA (1990a) describes amendments to the h azardous waste incinerator regulations for the following purpose: Improve control of toxic metal emissions, HCl emissions, and residual organic emissions; amend the definitions of incinerators a nd industrial furnaces; propose definitions for plasma arc incinerators and infrared incine rators; propose to regulate carbon regeneration units as thermal treatment devices; and make a number of minor revisions to permitting procedures. U.S. EPA (1990a) also states the following: The database on PIC emissions is limited therefore, the risk assessments may under-estimate risk. The assessments consider only the organic compounds that have been actually identified and quantified. Ze ro to 60 percent of total unburned hydrocarbon emissions have been chemically identified at any particular facility. Thus, the bulk of the hydrocarbon emissions have not been considered in those risk assessments. Although many of the unidentified, unquantified organic compounds may be non-toxic, some fraction of the organic emissions is undoubtedly toxic. . . .data on typical PIC emissions from hazardous waste combustion sources were compiled and assessed in recent EPA studies. These studies identified 37 individual compounds in the stack gas of the eight full-scale hazardous waste incinerators test ed, out of which 17 were volatile compounds and 20 semivolatile compounds. Eight volatile compounds (benzene, toluene, chloroform, trichloroethylene, carbon tetrach loride, tetrachloroethylene, chlorobenzene, and methylene chloride), and one semivola tile compound (naphthalene) were identified most frequently in more than 50 percent of the tests. Some of these compounds are carcinogenic. The sources for these statements appear to be Wallace et al. (1986) and Trenholm and Lee (1986). Trenolm and Lee (1986), prepared by Andrew R. Trenholm of Midwest Research Institute and C.C. Lee at the U.S. EPA Hazardous Waste E ngineering Research Laboratory, discussed that emissions from incinerators are only characteri zed for constituents listed in Appendix VIII. However, constituents not listed in Appe ndix VIII are also emitted from the stacks. Data was obtained from HWERL-sponsored tests at eight hazardous waste incinerators, nine boilers that co-fired hazardous wastes, and fi ve mineral processing kilns that fired hazardous wastes as fuel. In addition, SVOC emissions data for two municipal solid waste incinerators and

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### seven coal-fired power plants were also revi ewed. The common PICs are presented in the following table:
Volatile PICs Most Frequent ly Present in Stack Gases VOCs SVOCs Benzene Naphthalene Toluene Phenol Carbon Tetrachloride Bis(2-ethylhexyl)phthalate Chloroform Diethylphthalate Methylene Chloride Butylbenzylphthalate Trichloroethylene Dibutylphathlate Tetrachloroethylene 1,1,1-Trichloroethane Chlorobenzene



### Tests were conducted for three incinerator runs to search for constituents not listed in Appendix VIII . These constituents include:

Non-Appendix VIII Constituents Present in Highest Concentrations in Stack Gases Acetone Ethylbenzaldehyde Ethylbenzene Ethylbenzoic acid Acetophenone Ethylphenol Benzaldehyde Ethylphenyl-ethanone Benzenedicarboxaldehyde Ethynylbenzene Benzoic acid Phenylacetylene Chlorocyclohexanol 1,1'-(1,4-phenylene)bisethanone Cyclohexane Phenylpropenol Cyclohexanol Propenylmethylbenzene Cyclohexene Tetramethyloxirane Dioctyl adipate Trimethylhexane Ethenyl ethylbenzene 

### Emission rates of compounds not in the waste feed were also provided.

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### C 

### U.S. EPA (1985) didn’t include a list of PI Cs from combustion sources. U.S. EPA (1985) discussed views and reviews by the Environmental Effects, Transport, and Fate Committee of the Science Advisory Board of issues related to th e environmental impacts of the incineration of liquid hazardous wastes at sea and on land. Several issues were addressed, including issues concerning the combustion and incineration of h azardous waste. Major findings of the committee were as follows: - Fugitive emissions and spills may release as much or more material to the environment than the direct emissions from waste incineration processes. - Numerous PICs are formed during the combustion processes. However, only a fraction of them are identified or detected. It is possible that the aggregate of all compound emissions that are not categorized as other POHCs or PICs can be more toxic and pose greater risks than those listed. Although 99.99 percent DRE has been claimed, if the unburned or undetected hydrocarbon output is included, the DRE may actually be less than 99.99 percent. Therefore, the concept of destruction efficiency used by EPA was found to be incomplete and not useful for subsequent exposure assessments. All emissions and effluents must be identified and quantified, including their physical form and characteristics. - Local site-specific conditions must be used in characterizing exposure to receptors from waste incinerator emissions. - The evaluation of exposure durations and c oncentrations should be based on a detailed assessment of transport processes and the habits of the exposed organisms. The role of food chains needs particular attention. - At a minimum, the toxicities of representative emissions and effluents from incinerators should be tested on sensitive life stages of representative aquatic and terrestrial vertebrates, invertebrates, and plants of ecological importance. C 

### U.S. EPA (1990b) does not include a list of PICs from combustion sources. It was prepared by the PIC subcommittee of the Science Advisory Board to review the OSW proposal to control emissions of PICs from hazardous waste incinerato rs by instituting process controls that are based on CO and THC emission concentrations. U.S. EPA risk assessments indicate that emissions of PICs at currently measured levels are not likely to produce human effects. However, because the current DRE standard applies only to designated POHCs, 99.99 percent DRE does not preclude the possibility that emission of PICs could presen t significant human health risk. The following summarizes the major findings of the subcommittee review. - The concept of using CO and THC as guida nce for incinerator operational control is reasonable. - At low CO levels, CO correlates well with TH C; therefore, limiting CO in order to ensure high combustion efficiency and low THC levels is reasonable. At high CO concentrations, CO and THC do not correlate well; therefore, relying solely on the controlling of CO may not provide a reasona ble control for THC. Continuous emissions monitoring of THC is preferred. Quantificati on of PICs alone is not practical with the

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### sampling techniques that are available, primarily because PICs are normally emitted in the range of parts per billion (ppb) to parts per trillion (ppt). - A 100-ppmv limit for CO is reasonable. However, supporting documentation does not demonstrate that a CO concentration of 100 ppmv is better than 50 ppmv or 150 ppmv. - Continuous emissions monitoring of THC with a cold system appears to be practical for routine operations. However, a hot transfer line produces better analysis of THC concentrations and detection of a larger fraction of the THCs emitted. - The database characterizing PICs in emissions would not allow a correlation to be established with CO or THC levels for various combustion devices and conditions. Limited data introduces large uncertainties in to U.S. EPA’s risk assessment. Therefore, U.S. EPA’s site-specific risk assessment process is limited in its usefulness in establishing acceptable THC levels. Howe ver, the risk assessment procedures are risk-based. C 

### U.S. EPA (1987) is a report prepared by Andrew R. Trenholm, Acurex Corporation, California, and staff members from the U.S. EPA Hazardous Waste Engineering Research Laboratory in Cincinnati, Ohio. The paper discussed the l ack of information on total emissions from combustion of hazardous wastes, particularly unde r conditions of less than optimal performance. The focus issue was whether additional constituents that are listed in Appendix VIII or not listed in Appendix VIII which were not identified in early tests might be emitted from hazardous waste combustion units. To address this issue and rela ted issues, U.S. EPA initiated this project to qualitatively and quantitatively study the charact eristics of all possible effluents, under steady-state and transient conditions. The following summarizes the major findings: - THC emissions detected as specific compounds ranged from 50 to 67 percent for five runs and were 91 percent for one run. The fraction of THC not detected is most likely explained by uncertainty in the measurements or other analytical problems. - Methane accounted for the largest fraction of THC. - Oxygenated aliphatic com pounds made up the largest class of compounds among the SVOCs, both in total mass and number of compounds. - Transient upsets did not cause significant increases in the concentration of SVOCs or most VOCs. Three VOCs that were increased were methane, methylene chloride, and benzene. - Particulate and HCl emissions did not change between the steady-state and transient test runs. C 

### Duval and Rubey (1976) was prepared by D.S. Duval and W.A. Rubey of the University of Dayton Research Institute, Ohio. The objective of the study was to provide data from which requirements can be assigned for the thermal di sposal of kepone. This report was primarily concerned with the high-temperature destruc tion of kepone, with DDT and Mirex used as comparative Analog. Laboratory tests were conducted to establish destruction temperature

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### characteristics of the vaporized pesticides atpreselected residence times. The following summarizes the major findings. - Kepone was essentially destroyed at a 1-second residence time and a temperature range of 500 o 

### C to 700 o 

### C, depending on the pesticide. - Major decomposition products detected were hexachlorocyclopentadiene and hexachlorobenzene for both kepone and Mirex. These products were formed in different thermal regions. - The study demonstrated that the chemical na ture of the effluent products depends on the temperature and residence time that the basic molecule experiences. C 

### Duval and Rubey (1977) discusses the experimental destruction temperature and residence time relationships for various PCB compounds and mixtures of PCBs. The document states that “upon thermal stressing in air, PCBs decompose to low-molecular-weight products.” However, the document doesn’t identify any of these low-mol ecular-weight products. In fact, the document states directly that the products weren’t identif ied in the study. It further recommends that additional research be conducted on the “degradation products and effluents.” C 

### Dellinger et al. (1984) was prepared by Barry De llinger and others of the University of Dayton, Ohio. This paper presented the gas-phase thermal stability method under controlled laboratory conditions to rank the incinerability of compounds. The objective of this study was to determine the gas-phase thermal decomposition properties of 20 hazardous organic compounds. The compounds were selected on the basis of (1 ) frequency of occurrence in hazardous waste samples, (2) apparent prevalence in stack efflue nts, and (3) representativeness of the spectrum of hazardous waste organic waste materials. The following summarizes the major findings. - Gas-phase thermal stability method is a more effective means of ranking the incinerability of hazardous compounds in a waste. - Numerous PICs were formed during the thermal decomposition of most of the compounds tested. However, PICs were not identified. - Destruction efficiency of 99.99 percent is achieved at 2 seconds mean residence time in flowing air at 600 o 

### C to 950 o 

### C. - No single physical or chemical property describes the ranking scheme for incinerability. C 

### Dellinger et al. (1986) was prepared by Barry Dellinger, B. Douglas, L. Hall, John L. Graham, Sueann L. Mazer, and Wayne A. Rubey of the Un iversity of Dayton Research Institute, Dayton, Ohio, and Myron Malanchuk of U.S. EPA, Ci ncinnati, Ohio. The paper discussed the development of an incineration model basedon laboratory studies conducted by using the nonflame mode of hazardous waste thermal decomposition. The results of these studies were compared to the flame-mode studies and field tests to evaluate the incineration model proposed. The model was based on the premise that incine rators do not operate continuously at optimum conditions. As a result, 1 percent or more of the feed and its flame treatment products must

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### undergo further decomposition in the nonflame region to meet the DRE criterion of greater than 99.99 percent. In the past, several methods were used to rank the incinerability of compounds. Nonflame studies, however, indicated that tests on co mpounds conducted at low oxygen concentrations provided a better correlation with field tests to determine the relative incinerability of compounds. Four experimental studies were conducted to develop and expand the database on POHCs and PICs. Studies were conducted on individual compounds to evaluate degradation compounds and PICs from the original parent compound. The thermal degradation of 2,3',4,4',5-PCB was studied under four reaction atmospheres (at varying levels of oxygen) at a constant gas phase residence time of 2.0 seconds. Tests were conducted at temperatures ranging from 500 o 

### C to 1,000 o 

### C. Tests indicated that the yield of combustion products decreased with increased oxygen levels. Numerous major degradation products were identified from the thermal degradation of 2,3',4,4',5-PCB, including: - Penta-, tetra-, and trichlorodibenzofurans - Tetra- and trichlorobiphenyls - Tri- and dichlorobenzene - Tetra- and trichloronaphthalene - Tri- and dichlorochlorophenylethlyene - Tetrachlorobiphenylenes - C 9 

### H 8 

### OCl - C 10 

### H 3 

### Cl 3 

### Thermal decomposition of chloroform was studied. Numerous decomposition products were identified, including: - CCl 4 

### - C 2 

### H 4 

### Cl 2 

### - C 2 

### HCl 3 

### - C 2 

### HCl 5 

### - C 2 

### Cl 2 

### - C 2 

### Cl 4 

### - C 3 

### Cl 4 

### - C 4 

### Cl 6 

### Thermal decomposition of polychlorinated phenols was studied in nitrogen (N 2 

### ) and oxygen atmospheres because of the potential formation of polychlorinated dibenzodioxins. Pentachlorophenol (PCP) thermal decomposition was studied. Numerous decomposition products of PCP were identified in N 2 

### and/or air atmospheres, including: - Dichlorobutadiyne (in N 2 

### ) - Tetrachloroethylene (in air) - Tetrachloropropyne (in air) - Trichlorofuran (in air) - Tetrachlorofuran (in air) - Trichlorobenzene (in N 2 

### and air) - Tetrachlorobenzene (in N 2 

### and air) - Pentachlorobenzene (in N 2 

### and air) - Hexachlorobenzene (in N 2 

### )

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### - Octachlorostyrene (in N 2 

### ) - Hexachlorodihydronaphthalene (in N 2 

### and air) The paper concluded that PICs in the air atmos phere may have formed directly from the parent material, whereas, in the nitrogen atmosphere, the principal PICs may have evolved from the thermal decomposition of other PICs. C 

### Kramlich et al. (1984) doesn’t include a list of PICs from combustion sources. It was prepared by J.C. Kramlich, W.R. Seeker, and M.P. Heap of Energy and Environmental Research Corporation, California; and C.C. Lee of the Industrial W aste Combustion Group, U.S. EPA. This paper presented a research program to study the flame-mode incineration of hazardous waste liquids in laboratory scale reactors. The objective of this study was to supply the flame-mode data used in evaluating the applicability of various approaches to ranking the ease of incinerability. Five compounds were tested—chloroform, 1,1- dichloroethane, benzene, acrylonitrile, and chlorobenzene—because (1) their range of in cinerabilities is broad, and (2) they are representative of liquid hazardous wastes. The following summarizes the findings. - The flame section of the incinerator destro ys greater than 99.995 percent of the wastes. - The post-flame region destroys the remainder of the wastes. - The destruction efficiency is redu ced because of flame-related failures. - Incinerability ranking depends on actual failure condition. - No incinerability ranking system completely predicts the destruction efficiency of the compounds tested for all failure conditions. C 

### Trenholm and Hathaway (1984) was prepared by Andrew Trenholm and Roger Hathaway of Midwest Research Institute (MRI) in Missouri, and Don Oberacker, U.S. EPA, Cincinnati, Ohio. PICs were defined as any Appendix VIII hazardous organic constituent detected in the stack gas but not present in the waste feed at a concentration of 100 micrograms per gram or higher. Benzene and chloroform were the most commonl y found PICs. PIC emissions were comparable to POHC emissions in concentration and total mass output. This document discussed PIC formation mechanisms and criteria for PIC formations. MRI conducted a series of tests at eight operating hazardous waste incineration facilities and analyzed the collected samples for PICs. The t ests were part of the technical support of U.S. EPA’s preparation of a regulatory impact analysis for hazardous waste incinerators. Each incinerator had a liquid injection burner, and some facilities also included a rotary kiln or hearth. Three incinerators had no air pollution control de vices. The remaining five had wet scrubbers for HCl control, and four of these had other par ticulate control devices. Twenty-nine compounds were classified as PICs from the eight incinerato r tests and are presented in Table A1.6-1. In general, PIC concentrations were slightly hi gher than POHC concentrations, although this ratio varied from site to site. PIC output rate very rarely exceeded 0.01 percent of the POHC input rate. The document stated that the measurement of Appendix VIII compounds at low concentrations in the waste feed, auxiliary fuel, and inflow streams to control systems is often necessary to explain the presence of PICs.

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### TABLE A1.6-1 PICS IDENTIFIED BY TRENHOLM AND HATHAWAY (1984)

PICs Found In Stack Effluents PIC Number of Facilities Low Concentration (ng/L) High Concentration (ng/L) Benzene 6 12 670 Bromochloromethane 1 14 14 Bromodichloromethane 4 3 32 Bromoform 3 0.2 24 Bromomethane 1 1 1 Carbon disulfide 1 32 32 Chlorobenzene 3 1 10 Chloroform 5 1 1,330 Chloromethane 1 3 3 Chlorophenol, o- 1 22 22 Dibromochloromethane 4 1 12 Dichlorobenzene 1 4 4 Diethyl phthalate 1 7 7 Dimethylphenol, 2,4- 1 21 21 Fluoranthene 1 1 1 Hexachlorobenzene 1 7 7 Methyl ethyl ketone 1 3 3 Methylene chloride 2 2 27 Methylene bromide 1 18 18 Naphthalene 3 5 100 Nitrophenol, o- 2 2 50 Pentachlorophenol 1 6 6 Phenol 2 4 22 Pyrene 1 1 1 Tetrachloroethylene 3 0.1 2.5 Toluene 2 2 75 Trichlorobenzene 1 7 7 Trichloroethane, 1,1,1,- 3 0.1 1.5 Trichlorophenol, 2,4,6- 1 110 110
Notes: ng/L = Nanograms per liter PIC = Product of incomplete combustion 

### C 

### Olexsey et al. (1985) was prepared by Robert A. Olexsey and others of the U.S. EPA Hazardous Waste Engineering Research Laboratory in Cincinnati, Ohio. This document discussed PIC generation mechanisms and criteria for PIC forma tions. The paper provided data on emissions of PICs during full-scale tests conducted on incine rators and boilers burning hazardous waste (Trenholm et al. 1984; Castaldini et al. 1984). The documents referenced by this paper

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### summarized a series of full-scale tests conducted on seven incinerators and five boilers conducted by U.S. EPA to support its regulatory developm ent for incinerators and boilers. Commonly found PICs identified in these tests are presented in Tables A1.6-2 and A1.6-3. TABLE A1.6-2 VOLATILE PICS MOST FREQUENTLY IDENTIFIED IN BOILER EMISSIONS (OLEXSY, HUFFMAN, AND EVANS 1985)

PIC Number of Facilities Low Concentr ation (ng/L) High Concentration (ng/L) Benzene 3 9.4 270 Chloroform 5 4.2 1,900 Chloromethane 4 4.6 410 Dichloroethane, 1,2- 3 1.3 1,200 Methylene chloride 4 83 2,000 Tetrachloroethylene 5 0.3 760 Trichloroethane, 1,1,1- 3 5.9 270
Notes: ng/L = Nanograms per liter PIC = Product of incomplete combustion



### TABLE A1.6-3 VOLATILE PICS MOST FREQUENTLY IDENTIFIED IN INCINERATOR EMISSIONS (OLEXSY, HUFFMAN, AND EVANS 1985)

PIC Number of Facilities Low Concentr ation (ng/L) High Concentration (ng/L) Benzene 6 12 670 Chloroform 5 1 1,330 Methylene chloride 2 2 27 Tetrachloroethylene 3 0.1 2.5 Toluene 2 2 75 Trichloroethane, 1,1,1- 3 0.1 1.5
Notes: ng/L = Nanograms per liter PIC = Product of incomplete combustion 

### C 

### For incinerators, ratios of PIC emissions to POHC input ranged from 0.00007 to 0.0028 percent; and ratios of PIC emissions to POHC emissions ranged from 0.01 to 3.89. For boilers, ratios of PIC emissions to POHC input ranged from 0.0032 to 0.3987 percent, and ratios of PIC emissions to POHC emissions ranged from 5.44 to 22.5. These data indicated that PIC emissions were higher for boilers than for incinerators; that is , PIC emissions were reduced with increased POHC

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### DRE which is higher for incinerators. The doc ument proposed seven methods to control PICs and recommended further research on PIC gene ration mechanisms and control technologies. C 

### Trenholm et al. (1992) was prepared by Andrew R. Trenholm and David W. Kapella of MRI in North Carolina and Gary D. Hinshaw of MRI in Missouri. The paper discusses the following issues regarding emissions from incinerators that burn hazardous waste: • emissions of specific constituents presented in Appendix VIII, • emissions of specific compounds or types of compounds, and • data on the size and molecular weight of compounds emitted. The following were among the major issues discussed. - PICs were studied through U.S. EPA-sponsored t ests at eight incinerators, nine industrial boilers, and five mineral processing kilns. The study was limited to compounds presented in Appendix VIII. In all, 52 organic compounds (32 VOCs and 20 SVOCs) were identified. The VOC concentrations were significantly higher than the SVOC concentrations. PICs liste d in this paper included: • benzene, • toluene, • carbon tetrachloride, • trichloromethane, • dichloromethane, • trichloroethene, • tetrachloroethene, • 1,1,1-trichloroethane, • cholorobenzene, • naphthalene, and • phenol. - From the U.S. EPA-sponsored tests, (1) volatile compounds listed in Appendix VIII identified were only a fraction—sometimes about one-half—of the total organic compounds identified, and (2) semivolatile compounds not listed in Appendix VIII identified were three to 30 times the quantity of organic compounds listed in Appendix VIII . Table A1.6-4 lists the compounds identified by the U.S. EPA-sponsored tests.

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### TABLE A1.6-4 MOST FREQUENTLY IDENTIFIED PICS (TRENHOLM, KAPELLA, AND HINSHAW 1992) Appendix VIII Volatile Organic

Compounds Appendix VIII Semivolatile Organic Compounds Compounds Not Listed in Appendix VIII Benzene Bis(2-Ethylhexyl)phthalate (1,4-Phenylene)bisethanone, 1,1'- Carbon tetrachloride Butylbenzylphthalate Acetone Chlorobenzene Dibutylphtahlate Acetophenone Chloroform Diethylphthalate Benzaldehyde Methylene chloride Naphthalene Benzenedicarboxaldehyde Tetrachloroethylene Phenol Benzoic acid Toluene Chlorocyclohexanol Trichloroethane, 1,1,1- Cyclohexane Trichloroethylene Cyclohexanol Ethylbenzene Ethylbenzoic acid Ethylphenol Ethylphenyl-ethanone Ethynylbenzene Phenylpropenol Propenylmethylbenzene Tetramethyloxirane Trimethylhexane 

### - A study of hazardous waste incinerator stack effluent was conducted to characterize the types of compounds emitted. Twenty-nine co mpounds were identified at a concentration range of 0.1 to 980 nanograms per liter. Methane, chloromethane, and chloroform accounted for more than one-half of the total mass of VOCs detected. Other than methane, oxygenated aliphatic hydrocarbons formed the highest fraction of the total emissions. - Based on the incinerator stack effluent study, it was found that as combustion conditions deteriorate, increases in mass emissions are first noted with VOCs. Emissions of these compounds, most notably C1 to C3 compounds, increase proportionately more than larger compounds. For larger compounds, available data indicate that emission increases are more likely to be aromatic compounds. A1.6.3 CARB (1990b) CARB prepared “Technical Support Document of Propo sed Dioxins Control Measures for Medical Waste Incinerators” to meet the requirements of Californi a Health and Safety Code Section 39666 that a needs report be prepared for proposed rules. The report pr esents a proposed airborne toxic control measure for

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### dioxin emissions from medical waste-burning facilities. The report concentrates on dioxin, furan, and cadmium emissions, although other pollutants detected dur ing the tests are listed. Table A1.6-5 lists these pollutants. TABLE A1.6-5 COPCS IDENTIFIED BY CARB (1990b) COPC Ammonia Dibromoethane, 1,2- Nickel Arsenic Dichloroethane Nitrogen oxides Benzene Dichloromethane PM Bromodichloromethane Dichloropropane, 1,2- PAHs Cadmium Ethylbenzene Sulfur dioxide Carbon dioxide Freon Tetrachloroethene Carbon monoxide Hydrocarbon, total Tetratrichloromethylene Carbon tetrachloride Hydrogen chloride Toluene Chlorobenzenes Hydrogen fluoride Tribromomethane Chlorodibromomethane Iron Trichlorethane Chloroform Lead Trichloroethane, 1,1,1- Chlorophenols Manganese Trichloroethylene Chromium, hexavalent Mercury Trichlorotrifluroethane Chromium, total Mesitylene Vinyl chloride Copper Methyl isobutyl ketone Xylenes Cumene Napthalene Zinc Notes: PAH = Polynuclear aromatic hydrocarbons PM = Particulate matter


### A1.6.4 CARB (1991) CARB prepared “Air Pollution Control at R esource Recovery Facilities 1991 Update” to update information presented in its 1984 report, entitled “Air Pollution Control at Resource Recovery Facilities.” Specifically, the document updates available guide lines concerning incinerator technology, emissions control technology, and emission limits for municipal waste, hospital waste, biomass, tire, manure, landfill and digester gas, and sewer sludge incinerato rs. The document states that its guidelines represent levels that have been achieved by existing facilities. In addition, the document summarizes the ultimate anal ysis of waste types undergoing treatment in the facilities described above. An appendix summarizes stack gas analysis data for numerous operating facilities. Pollutants identified in the analyses are summarized in Table A1.6-6.

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### TABLE A1.6-6 STACK GAS ANALYSIS DATA (CARB 1991)

Pollutant Incinerator Type a Municipal

Waste

(5) Hospital Waste

(7) Biomass (4) Manure (1) Tire (1) Landfill Gas (20) Sewage Sludge and Digester Gas (5) Nitrogen oxides 

### U U U UU U U Sulfur oxides 

### U U ND 

### UU U U Particulate matter 

### U U U UU U U Carbon monoxide 

### U U U UU U U Total hydrocarbons 

### U U U UU U U Hydrogen chloride 

### U U NA NA 

### U NA NA Hydrogen fluoride 

### U NA NA NA NA NA NA Amonnia NA NA 

### U NA 

### U NA NA Carbon dioxide 

### U U U UU NA 

### U Oxygen 

### U U U UU NA 

### U Arsenic 

### UU U NA 

### UU U Beryllium 

### U NA NA NA 

### U U b 

### U Cadmium 

### UU U NA ND 

### U b 

### U Chromium (total) 

### UU U NA 

### UU U Chromium (hexavalent) ND 

### U NA NA 

### U NA NA Copper 

### U NA NA NA NA 

### U NA Mercury 

### U U NA NA ND 

### U U Iron NA NA 

### U NA NA NA NA Manganese NA NA 

### U NA NA NA NA Nickel 

### UU U NA ND 

### U U Lead 

### UU U NA ND 

### U U Zinc NA NA NA NA NA 

### U NA Polyaromatic hydrocarbons b 

### U NA 

### U NA 

### U NA NA Polychlorinated biphenyls b 

### U ND 

### U NA 

### U NA NA
CP b 

### U NA 

### U NA 

### U NA NA CB b 

### U NA 

### U NA 

### U NA NA Benzene 

### UU U NA NA NA NA Polychlorinated dibenzo(p) dioxins b 

### UU U NA 

### U NA NA Polychlorinated dibenzofurans b 

### UU U NA 

### U NA NA 2,3,7,8-Tetrachloro dibenzo(p)dioxin equivalents b 

### UU U NA 

### U NA 

### U

Notes: 

### U = Detected in at least one emission test ND = Not detected in any emission test NA = No analysis

a Number in parentheses indicates the number of facilities for which data were tabulated. b Isomers and/or homologues that were not detected were added to total values at one-half the detection limit; pollutant may not have actually been detected.

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### A1.6.5 U.S. EPA (1988) This document, referenced by some docum ents as a 1989 document, was prepared in 1988. U.S. EPA prepared “Hospital Waste Combustion Study: Data Gathering Phase” to assemble available information on hospital waste combustion so that U. S. EPA can evaluate whether airborne pollutant emissions from hospital waste combustion should be regulated. While preparing this document, U.S. EPA reviewed the pertinent literature to determin e which studies would be helpful in completing the database on toxic emissions from medical waste incinerators. The report clearly addresses only those pollutants for which emissions data were found. The da ta reviewed were mostly for larger, controlled air incinerators; and the more commonly used retort incinerators were not evaluated. The study identified several categories of polluta nts that were measured in stack gases; these are discussed in the following paragraphs. Where evaluated, acid gases were detected in stack gases. For example, HCl was detected in 24 of 28 tests; HCl concentration not recorded in the remaining four tests. Particulate matter (PM) was detected in all stack tests for 30 facilities at concentrations ranging from 0.001 grains per dry standard cubic foot (gr/dscf), at a facility with PM add-on control devices, to 0.22 gr/dscf at facilities without such control devices. Trace metals were detected in stack tests for three medical waste incineration facilities. Metals detected include arsenic, cadmium, chromium, iron, manganese, nickel, and lead. The document also states that fine-particle enrichment processes could lead to emissions of molybdenum, tin, selenium, vanadium, and zinc. However, test results for these trace metals are not presented. With respect to organic emissions, dioxins and fura ns were detected in emissions from three facilities, both with and without pollution control devices. Other organic emissions detected in stack tests cited in this report include CO, THC, trichlorotrifluoroeth ane, tetrachloromethane, tetrachloroethene, and trichloroethylene. In a stack testing conducted on three Canadian biom edical waste incinerators, PCBs and PAHs were either not detected (one facility) or not analyzed (two facilities). A1.6.6 CARB (1996) In May 1996, CARB prepared “Proposed Amendments to the Emission Inventory Criteria and Guidelines Report Published in Accordance with the Air Toxi cs ‘Hot Spots’ Information and Assessment Act of 1987.” The purpose of the report is to present the b asis of CARB’s recommended amendments to the Air Toxics Hot Spots Program. The report states thatCalifornia Health and Safety Code (HSC) 44321 requires CARB to compile the list of toxic substances that must be monitored from “designated reference lists of substances.” Therefore, the document is not a primary source of toxics emission information. The primary sources of information are mandated by California HSC 44321, as follows: • California HSC 44321(a): National Toxicology Program, International Agency for Research on Cancer • California HSC 44321(b): Governor’s Listof Carcinogens and Reproductive Toxicants

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### • California HSC 44321(c): CARB • California HSC 44321(d): Hazard Evaluation System and Information Service • California HSC 44321(e): U.S. EPA • California HSC 44321(f): California HSC The lists of toxic substances presented in the documen t are not restricted to incinerator facilities, but apply to any facility discharging airborne pollutant s to the atmosphere. The document also removes numerous substances, primarily medicinal compounds, from lists of toxic chemicals that must always be evaluated, and places them on lists of toxic co mpounds that require evaluation only if a facility manufactures that substance. A1.7 COLUMN 7: U.S. EPA-RECOMMENDED AND POTENTIAL PICS (1994a; 1994b) Compounds marked with an “X” in the appropriate cells are identified in U.S. EPA (1994a and 1994b). Based on information presented in U.S. EPA (1994b) , these tables were developed from available U.S. EPA data and from lists of toxic compounds from various U.S. EPA programs. Because the source lists were not developed as lists of toxic PICs, U.S. EPA deleted compounds that we re not appropriate (U.S. EPA 1994b). U.S. EPA acknowledged the importance of using focused studies to develop a PIC list that is (1) appropriately protective of the environmen t, and (2) not excessively burdensome on the regulated community. Nevertheless, Tables 1 and 2 in U.S. EPA (1994b) were compiled as draft lists for use during the interim period. Tables in U.S. EPA (1994b) were to be revised as additional PIC data were collected. U.S. EPA Permits and State Program Division is currently updating these tables; however, a target completion date is not available. Tables 1 and 2 are based on the following (U.S. EPA 1994b): C 

### Hazardous waste constituent list in 40 CFR Part 261, Appendix VIII C 

### hazardous air pollutants (HAP) list C 

### Office of Research and Development list of organic compounds found in combustion devices developed for U.S. EPA (1993) The following compounds were deleted from this list: C 

### Pesticide compounds not likely to be a PIC C 

### Federal Drug Administration-regulated drugs C 

### Carcinogenic sugar substitutes C 

### Compounds without chemical-specific listings (for example, “coal tar”) C 

### Compounds without U.S. EPA-established sampling and analysis methods C 

### Metallic compounds (because of difficulty in analyzing the specific compounds; metals are still included in elemental totals)

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### C 

### Compounds with low octanol-water partition co efficients and no inhalation toxicity data C 

### Compounds with low toxicity values C 

### Naturally-occurring plant toxins Specific compounds were retained on Tables 1 and 2 on the following basis: C 

### Pesticides with a molecular structure simple enough to be of concern as a PIC C 

### Compounds with very high octanol-water partition coefficients A1.8 COLUMN 8: PICS ACTUALLY DETECTED IN STACK EMISSIONS Compounds marked by an “X” in the appropriate cells are PICs that have actually been detected in stack emissions. U.S. EPA compiled this list by evaluating the studies highlighted in Section A1.6.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-1-21 

# REFERENCES APPENDIX A-1

California Air Resources Board (CARB). 1990a. “Health Risk Assessment Guidelines for Nonhazardous Waste Incinerators.” Prepared by the Stationary Source Division of the CARB and the California Department of Health Services. CARB. 1990b. “Technical Support Document of Proposed Dioxins Control Measures for Medical Waste Incinerators.” May 25. CARB. 1991. “Air Pollution Control at Resource Recovery Facilities. Update.” CARB. 1996. “Proposed Amendments to the Emission Inventory Criteria and Guidelines Report Published in Accordance with the Air Toxics ‘Hot Spots’ Information and Assessment Act of 1987.” May. Castaldini, C., and others. 1984. “Engineering Assessment Report—Hazardous Waste Cofiring in Industrial Boilers.” Report to U.S. Envir onmental Protection Agency under Contract No. 68-02-3188. June. Dellinger, B., D.L. Hall, J.L. Graham, S.L. Mazer, W.A. Rubey, and M. Malanchuk. 1986. PIC Formation Under Pyrolytic and Starved Air Conditions. . Prepared for the U.S. EPA Industrial Environmental Research Laboratory. Prepared by the University of Dayton Research Institute. EPA/600/2-86/006. NTIS PB-86-145422. January. Dellinger, B., J.L. Torres, W.A. Rubey, D.L. Hall, and J.L. Graham. 1984. Determination of the Thermal Decomposition Properties of 20 Sel ected Hazardous Organic Compounds. Prepared for the U.S. EPA Industrial Environmental Research Laboratory. Prepared by the University of Dayton Research Institute. EPA-600/2-84- 138. NTIS PB-84-232487. August. Demsey, C.R., and E.T. Oppelt. 1993. “Incinerati on of Hazardous Waste: A Critical Review Update.” Air and Waste. 43:25-73. Duval, D.S., and W.A. Rubey. 1976. Laboratory Evaluation of High-Temperature Destruction of Kepone and Related Pesticides. EPA-600/2-76-299. NTIS PB-264892/1. December. Duval, D.S., and W.A. Rubey. 1977. Laboratory Evaluation of High-Temperature Destruction of Polychlorinated Biphenyls and Related Compounds . EPA-600/2-77-228. NTIS PB-279139/0. December. Kramlich, J.C., W.R. Seeker, and M.P. Heap. 1984. “Laboratory-Scale Flame Mode Study of Hazardous Waste Incineration.” Proceedings of the Ninth Annual Research Symposium on Incineration and Treatment of Hazardous Waste . Fort Mitchell, Kentucky. May 2 through 4, 1983. EPA-600/9-84/015. NTIS PB-84-234525. Pages 79-94. July. Olexsey, R.A., G.L. Huffman, and G.M. Evans. 1985. “Emission and Control of By-Products from Hazardous Waste Combustion Processes.” Proceedings of the 11th Annual Research Symposium

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### on Incineration and Treatment of Hazardous Waste . Cincinnati, Ohio. April 29 to May 1, 1985. EPA-600/9-85/028. NTIS PB-86-199403. Pages 8-15. September. Trenholm, A., and R. Hathaway. 1984. “Products of Incomplete Combustion from Hazardous Waste Incinerators.” Proceedings of the 10th Annual Research Symposium on Incineration and Treatment of Hazardous Waste. Fort Mitchell, Kentucky. April 3-5. EPA-600/9-84/022. NTIS PB-85-116291. Pages 84-95. September. Trenholm, Andrew R., David W. Kapella, and Gary D. Hinshaw. 1992. “Organic Products of Incomplete Combustion from Hazardous Waste Combustion.” Proceedings of the Air and Waste Management Association 85th Annual Meeting and Exhibition. Kansas City, Missouri. June 21-26. Trenholm, A., and C.C. Lee. 1986. “Analysis of PIC and Total Mass Emissions from an Incinerator.” Proceedings of the Twelfth Annual Research Symposium on Land Dispos al, Remedial Action, Incineration, and Treatment of Hazardous Waste . Cincinnati, Ohio. April 21 to 23, 1986. EPA/60-9-86/022. Pages 376-381. August. Trenholm, A., and others. 1984. “Performance Eval uation of Full-Scale Hazardous Waste Incinerators.” Report to U.S. EPA under Contract No. 68-02-3177. U.S. Environmental Protection Agency (EPA). 1981. “Incinerator Standards for Owners and Operators of Hazardous Waste Management Facilities; In terim Final Rule and Proposed Rule.” Federal Register. 46(15):7666-7690. January 23. U.S. EPA. 1985. Report on the Incineration of Liquid Hazardous Wastes. Science Advisory Board. Environmental Effects, Transport, and Fate Committee. April. U.S. EPA. 1987. Total Mass Emissions from a Hazardous Waste Incinerator. Final Report. Midwest Research Institute. EPA-600/S2-87/064. NTIS PB-87-228508/AS. June 12. U.S. EPA. 1988. “Hospital Waste Combustion Study: Data Gathering Phase.” Office of Air Quality Planning and Standards. Research Triangl e Park, North Carolina. EPA-450/3-88-008. December. U.S. EPA. 1989. Guidance of PIC Controls for Hazardous Waste Incinerators. Volume V of the Hazardous Waste Incineration Guidance Series. EPA/530-SW-90-040. April 3. U.S. EPA. 1990a. “Standards for Owners and Operat ors of Hazardous Waste Incinerators and Burning of Hazardous Wastes in Boilers and Industrial Furnaces; Proposed Rule, Supplemental Proposed Rule, Technical Corrections, and Request for Comments.” Federal Register. 55(82):17862-17921. April 27. U.S. EPA. 1990b. Report of the Products of Incomplete Combustion Subcommittee of the Science Advisory Board; Review of OSW Proposed Cont rols for Hazardous Waste Incineration Products of Incomplete Combustion. EPA-SAB EC-90-004. October 24. U.S. EPA. 1993. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions . OHEA. ORD. EPA-600-AP-93-003. November 10.

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### U.S. EPA. 1994a. Revised Draft Guidance for Performing S creening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes: Attachme nt C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . Office of Emergency and Remedial Response (OERR). OSW. December 14. U.S. EPA. 1994b. “Table 1—Chemicals Recommended for Identification and Table 2—Chemicals for Potential Identification.” Draft Exposure Assessment Guidan ce for Resource Conservation and Recovery Act Hazardous Waste Combustion Facilities : Attachment . April 15. U.S. EPA. 1995. “Basis for Listing Hazardous Waste.: Title 40, Code of Federal Regulations, Part 261, Appendices VII and VIII.

# APPENDIX A-2 CHEMICAL-SPECIFIC PARAMETER VALUES

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### CONTENTS Section Page LIST OF VARIABLES AND COMPOUND-SPECIFIC PARAMETERS . . . . . . . . . . . . . . . . . A-2-ii A2-1 GENERAL ANALYSIS AND METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-1 A2-2 PHYSICAL AND CHEMICAL PROPERTIES A2-2.1 Molecular Weight (MW ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-1 A2-2.2 Melting Point Temperature ( T m 

### ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-2 A2-2.3 Vapor Pressure ( Vp ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-3 A2-2.4 Aqueous Solubility ( S ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-5 A2-2.5 Fraction of Contaminant Air Concentration in the Vapor Phase ( F v 

### ) . . . . . . A-2-6 A2-2.6 Henry’s Law Constant ( H ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-7 A2-2.7 Diffusivity in Air ( D a 

### ) and Water ( D w 

### ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-8 A2-2.8 Octanol/Water Partitioning Coefficient ( K ow 

### ) . . . . . . . . . . . . . . . . . . . . . . . . A-2-9 A2-2.9 Soil Organic Carbon-Water Partition Coefficient ( K oc 

### ) . . . . . . . . . . . . . . . A-2-10 A2-2.9.1 Ionizing Organic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-10 A2-2.9.2 Nonionizing Organic Compounds . . . . . . . . . . . . . . . . . . . . . . . . . A-2-11 A2-2.10 Partitioning Coefficients for Soil-Water ( Kd s 

### ), Suspended Sediment-Surface Water ( Kd sw 

### ), and Bottom Sediment-Sediment Pore Water ( Kd bs 

### ) . . . . . . . A-2-12 A2-2.11 Soil Loss Constant Due to Degradation ( ksg ) . . . . . . . . . . . . . . . . . . . . . . . A-2-14 A2-2.12 Bioconcentration and Biotransfer Factors for Plants . . . . . . . . . . . . . . . . . A-2-15 A2-2.12.1 Root Concentration Factor ( RCF ) . . . . . . . . . . . . . . . . . . . . . . . . . A-2-15 A2-2.12.2 Plant-Soil BCFs in Root Vegetables ( Brrootveg 

### ) . . . . . . . . . . . . . . . . A-2-17 A2-2.12.3 Plant-Soil BCFs for Aboveground Produce ( Br ag 

### ) and Forage ( Br forage 

### ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-17 A2-2.12.4 Air-to-Plant BTFs for Aboveground Produce ( Bv ag 

### ) and Forage ( Bv forage 

### ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-19 A2-2.13 Biotransfer Factors for Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-22 A2-2.13.1 BTFs for Beef ( Ba beef 

### ) and Milk ( Ba milk 

### ) . . . . . . . . . . . . . . . . . . . . A-2-22 A2-2.13.2 BTFs for Pork ( Ba pork 

### ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-26 A2-2.13.3 BTFs for Chicken ( Ba chicken 

### ) and Poultry Eggs ( Ba egg 

### ) . . . . . . . . . . A-2-2 6 A2-2.13.4 Bioconcentration and Bioaccumulation Factors for Fish . . . . . . . . A-2-29 A2-2.13.4.1 Bioconcentration Factors for Fish ( BCF fish 

### ) . . . . . . . . . A-2-29 A2-2.13.4.2 Bioaccumulation Factors for Fish ( BAF fish 

### ) . . . . . . . . . A-2-31 A2-2.13.4.3 Biota-Sediment Accumulation Factor for Fish ( BSAF fish 

### )

A-2-33 A2-3 TOXICITY BENCHMARKS A2-3.1 Prioritization of Data Sources for Chronic Toxicity Benchmarks . . . . . . A-2-3 3 A2-3.2 Explanation of Calculated Toxicity Benchmark Values . . . . . . . . . . . . . A-2-36 A2-3.3 Uncertainties Involved when using T oxicity Benchmarks Calculated based on Route-to-Route Extrapolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-37 A2-3.4 Prioritization of Data Sources for Acute Toxicity Benchmarks . . . . . . . A-2-37 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2-39 COPCs INCLUDED IN THE COMPANION DATABASE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2- 4 9

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### LIST OF VARIABLES AND COMPOUND-SPECIFIC PARAMETERS
D

air 

### = Density of air (g/cm 3 

### ) D

forage 

### = Density of forage (g/cm 3 

### )
Ba beef 

### = Biotransfer factor in beef (mg COPC/kg FW tissue)/(mg COPC/day) OR (day/kg FW tissue) Ba chicken 

### = Biotransfer factor in chicken (mg COPC/kg FW tissue)/(mg COPC/day) OR (day/kg FW tissue) Ba egg 

### = Biotransfer factor in eggs (mg COPC/kg FW tissue)/(mg COPC/day) OR (day/kg FW tissue) Ba milk 

### = Biotransfer factor in milk (mg COPC/kg FW tissue)/(mg COPC/day) OR (day/kg FW tissue) Ba pork 

### = Biotransfer factor in pork (mg COPC/kg FW tissue)/(mg COPC/day) OR (day/kg FW tissue) BAF fish 

### = Bioaccumulation factor in fish (mg COPC/kg FW tissue)/(mg COPC/L total water column) OR (L water/kg FW tissue) BCF fish 

### = Bioconcentration factor in fish (L/kg FW OR unitless) Br ag 

### = Plant-soil bioconcentration factor in aboveground produce ( : 

### g COPC/g DW plant)/( : 

### g COPC/g DW soil)—unitless Br forage/silage 

### = Plant-soil bioconcentration f actor in forage and silage ( : 

### g COPC/g DW plant)/( : 

### g COPC/g DW soil)—unitless Br grain 

### = Plant-soil bioconcentration factor in grain ( : 

### g COPC/g DW grain)/( : 

### g COPC/g DW soil)—unitless Brrootveg 

### = Plant-soil bioconcentration factor for belowground produce ( : 

### g COPC/g DW plant)/( : 

### g COPC/g DW soil)—unitless BSAF fish 

### = Biota-sediment accumulation factor in fish (mg COPC/kg lipid tissue)/(mg COPC/kg sediment)—unitless B vol 

### = Volumetric air-to-leaf biotransfer factor in leaf ( : 

### g COPC/L FW plant)/( : 

### g COPC/L air)—unitless Bv ag 

### = COPC air-to-plant biotransfer factor for aboveground produce ( : 

### g COPC/g DW plant)/( : 

### g COPC/g air)—unitless Bv forage/silage 

### = Air-to-plant biotransfer factor in forage and silage ( : 

### g COPC/g DW plant)/( : 

### g COPC/g air)—unitless

c = Junge constant = 1.7 x 10 -04 

### (atm-cm)
D a 

### = Diffusivity of COPC in air (cm 2 

### /s) D w 

### = Diffusivity of COPC in water (cm 2 

### /s) f

oc,bs 

### = Fraction of organic carbon in bottom sediment (unitless) f

oc,s 

### = Fraction of organic carbon in soil (unitless) f

oc,sw 

### = Fraction of organic carbon in suspended sediment (unitless) f

water 

### = Fraction of COPC in water (unitless) F

v 

### = Fraction of COPC air concentration in vapor phase (unitless) Fw = Fraction of wet deposition that adheres to plant surfaces (unitless)
H = Henry’s law constant

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### Inhalation CSF 

### = Inhalation cancer slope factor (mg/kg-day) -1 

### Inhalation URF 

### = Inhalation unit risk factor ( : 

### g/m 3 

### ) -1


### Kd s 

### = Soil-water partition coefficient (mL water/g soil OR cm 3 

### water/g soil) Kd sw 

### = Suspended sediment-surface water partition coefficient (L water/kg suspended sediment OR cm 3 

### water/g suspended sediment) Kd bs 

### = Bed sediment-sediment pore water partition coefficient (L water/kg bottom sediment OR cm 3 

### water/g bottom sediment) K

ow 

### = Octanol/water partitioning coefficient (mg COPC/L octanol)/(mg COPC/L octanol)—unitless K

oc 

### = Soil organic carbon-water partition coefficient (mL water/g soil) ksg = COPC soil loss constant due to biotic and abiotic degradation (yr -1 

### ) MW = Molecular weight of COPC (g/mole)
p °L 

### = Liquid-phase vapor pressure of COPC (atm) p ° S 

### = Solid-phase vapor pressure of COPC (atm) Oral CSF = Oral cancer slope factor (mg/kg-day) -1


### R = Universal gas constant (atm-m 3 

### /mol-K) RCF = Root concentration factor ( : 

### g COPC/g DW plant)/( : 

### g COPC/mL soil water) RfC = Reference concentration (mg/m 3 

### ) RfD = Reference dose (mg/kg/day) Rp = Interception factor of edible portion of plant (unitless) S = Solubility of COPC in water (mg COPC/L water) ) 

### S f 

### = Entropy of fusion [ ) 

### S f

### /R = 6.79 (unitless)] S T 

### = Whitby’s average surface area of particulates (aerosols) = 3.5 x 10 -06 

### cm 2

### /cm 3 

### air for background plus local sources = 1.1 x 10 -05 

### cm 2

### /cm 3 

### air for urban sources

t 1/2 

### = Half-time of COPC in soil (days) T

a 

### = Ambient air temperature (K) T

m 

### = Melting point temperature (K) TEF = Toxicity equivalency factor (unitless) Vp = Vapor pressure of COPC (atm)

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### APPENDIX A-2 The following sections provide the general methodol ogy and references we used to determine our recommended parameter values. You can find the recommended parameter values themselves in the HHRAP Companion Database (also known as the HHR AP database). In the HHRAP database we provide compound-specific values for 1. physical and chemical properties; 2. fate-and-transport parameters; and 3. Health benchmarks for chronic and acute exposure.

A2-1 GENERAL ANALYSIS AND METHODOLOGY This section describes the general analysis and cr iteria we followed to determine our recommended contaminant-specific parameter values. 1. We compared parameter values among primary and available sources of applicable data, placing priority for selection on sources that are (1) U.S. EPA or State agency peer reviewed, (2) recent, (3) original sources of the values, and (4) generally accessible. 2. We further further researched and evaluate d sources of parameter values, and to the extent possible, included observations a ffecting usability in parameter-specific discussions for each compound. 3. We selected only parameter values from sour ces that could be verified and cited. 4. We generally preferred source-recomme nded parameter values. As necessary, we determined parameter values using correlati ons or equations, us ing input parameter values provided in the HHRAP database. 5. When multiple parameter values were reporte d in a particular source (e.g., CHEMFATE), we selected the source-recommended value in most cases. If more than one parameter value is recommended by the source, then we selected the recommended value that falls closest to the average of the source-recommended values. 6. When reviewing and selecting parameter values from published literature or studies, we preferred using measured values over other types of data.

A2-2 PHYSICAL AND CHEMICAL PROPERTIES A2-2.1 Molecular Weight ( MW ) Molecular weight ( MW ) of a compound is defined as the sum of atomic weights of all atoms in the compound’s molecule. For most compounds (except PCDDs and PCDF s, and methyl mercury), we obtained MW values from one of the following sources, as cited:

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### C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY. C 

### Lide, D.R. 2003. CRC Handbook of Chemistry and Physics, 83rd Edition . CRC Press. Boca Raton, Florida. C 

### O’Neil, M., and A. Smith. 2001. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition. Merck and Company, Inc. Rahway, New Jersey. C 

### Recommended value reported in published litera ture. When multiple parameter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. PCDDs and PCDFs We obtained MW values for PCDDs and PCDFs from U.S. EPA (2000). C 

### U.S. EPA. 2000. Exposure and Human Health Reassessment of 2,3,7,8- Tetrachlorodibenzo-p-Dioxin (TCDD) and Related Compounds . Draft Final Report. Office of Research and Development. Washington, D.C. EPA/600/P-00/001 Bc. September. Mercuric Compounds We obtained MW values for elemental mercury and mercuric chloride from the preferred sources listed above. We obtained the MW value for methyl mercury from U.S. EPA (1997b). C 

### U.S. EPA. 1997b. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. OAQPS and ORD. EPA-452/R-97-005. December. A2-2.2 Melting Point Temperature ( T m 

### ) Melting point temperature ( T m 

### ) is the temperature of the compound (in degrees Kelvin [K]) at which the solid state of the compound undergoes a phase change to a liquid phase. At ambient temperatures and at an atmospheric pressure of 1 atmosphere, compounds are generally in either a solid or liquid state. For most compounds (except PCDDs and PCDFs), we obtained values for T m 

### from one of the following sources, as cited: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY.

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### C 

### Lide, D.R. 2003. CRC Handbook of Chemistry and Physics, 83rd Edition . CRC Press. Boca Raton, Florida. C 

### O’Neil, M., and A. Smith. 2001. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition. Merck and Company, Inc. Rahway, New Jersey. C 

### Recommended value reported in published litera ture. When multiple parameter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. When a recommended range is provided instead of a singe numerical value, we selected the average of the range. PCDDs and PCDFs We obtained T m 

### values for PCDDs and PCDFs from U.S. EPA (2000). U.S. EPA (2000) provides T m 

### values for PCDDs and PCDFs, and states that the values were obtained from various cited literature sources. We selected th e midpoint of the range of values provided in U.S. EPA (2000). Metals We obtained T m 

### values for metals, if available and except for mercury, from the preferred sources listed above. Mercuric Compounds We obtained Tm values for elemental mercury and mercuric chloride from the list of preferred sources noted above. A Tm value for methyl mercury wasn’t available in preferred sources or literature. A2-2.3 Vapor Pressure ( Vp ) The vapor pressure ( Vp ) of a substance is defined as the pressu re in atmospheres exerted by the vapor (gas) of a compound when it is under equilibrium c onditions. It provides a semi-quantitative rate at which it will volatilize from soil and/or water. For most compounds (except PCDDs and PCDFs), we obtained values for Vp from the following preferred sources: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY. C 

### Lide, D.R. 2003. CRC Handbook of Chemistry and Physics, 83rd Edition . CRC Press. Boca Raton, Florida. C 

### O’Neil, M., and A. Smith. 2001. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition. Merck and Company, Inc. Rahway, New Jersey.

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### C 

### Calculated using procedures set forth by: Lyman et al. 1990. Handbook of Chemical Property Estimation Methods

. American Chemical Society. Washington, DC. • Recommended value reported in published literature. When multiple parameter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. If a Vp value wasn’t available in SCDM, then we obtained a vapor pressure value from CHEMFATE, PHYSPROP, CRC Handbook of Chemistry and Physics, or The Merck Index. If more than one value was recommended by the source, then we selected the recommended value that fell closest to the average of the recommended values. If a recommended value w asn’t available, we selected a value measured at 25 / 

### C. If more than one value measured at 25 / 

### C was available, then we sel ected the value falling closest to the average of the available valu es. If no value was available at 25 / 

### C, then we followed the same method using values determined within the range of 20 to 30 / 

### C. If no vapor pressure values were available in any of th e preferred references, then we used the procedures described in Lyman et al. (1990) to calculate vapor pressure. For nonmetallic substances, if vapor pressure wasn’t available, we obtained a normal boiling point from the sources and used it to assign a default vapor pressure. If the boiling point is <25 / 

### C at 1 atmosphere (atm) , we selected a default vapor pressure of 760 Torr, and we assume the substance is a gas at 25 / 

### C. As with SCDM, if no vapor pressure is available fo r a substance and the normal boiling point is equal or greater than 25 / 

### C, we assume the substance is in a particul ate form, rather than a gaseous form, and we assigned a vapor pressure of zero in order to calculate Fv . We made this assumption because the absence of a vapor pressure value often reflects an extremely low and difficult to measure (under standard conditions) value for nongaseous substances (U.S. EPA 2004b). SCDM prefers CHEMFATE-recommended values over estimated or calculated values. If more than one recommended value is in CHEMFATE, SCDM selected the highest of the values. If a recommended value is not available, SCDM uses a value measured at 25 / 

### C. If more than one value measured at 25 / 

### C is available, SCDM uses the highest one. If no value is available at 25 / 

### C, values determined within the range of 20 to 30 / 

### C are used. If more than one value measure d at the same temperature is available and none is recommended, SCDM uses the highest value. If no temperature is specified in CHEMFATE for all vapor pressure measurements for a substance, SCDM uses the highest value. For values not available in CHEMFATE, SCDM followed a similar approach to that outlined above. PCDDs and PCDFs We obtained Vp values for PCDDs and PCDFs from U.S. EPA (2000). Congener group average values were substituted for missing individual congener specific values. Metals Except for mercury compounds, metals that do not have Vp values in the references above we assigned a Vp value of zero since they are assumed to be (1) nonvolatile at ambient temperatures, and (2) insoluble in water, except as certain weak acids. Mercuric Compounds Mercury is a relatively volatile compound. We obtained the Vp value for elemental mercury from a preferred s ource listed above. We obtianed the Vp value for mercuric chloride from U.S. EPA (1997b). The Vp value for methyl mercury was not available in preferred sources or literature.

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### A2-2.4 Aqueous Solubility ( S ) The aqueous solubility ( S ) of a compound is defined as the saturated concentration of the compound in water (mg COPC/L water) at a given temperature a nd pressure, usually at soil/water temperatures and atmospheric pressure (Montgomery and Welkom 1991). For most compounds (except PCDDs and PCDF s and metals), we obtained values for S from the following preferred sources: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY. C 

### Dean, J.A. 2002. Lange’s Handbook of Chemistry. 15th Edition. McGraw-Hill. New York. C 

### Calculated using procedures set forth by: Lyman et al. 1990. Handbook of Chemical Property Estimation Methods

. American Chemical Society. Washington, DC. • Recommended value reported in published literature. When multiple parameter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. If a S value wasn’t available in SCDM, then we obtained solubility values from CHEMFATE, PHYSPROP, or Lange’s Handbook of Chemistry. If more than one value was recommended by the source, then we selected the recommended value fa lling closest to the average of the recommended values. If a recommended value wasn’t ava ilable, we selected a value measured at 25 / 

### C. If more than one value measured at 25 / 

### C is available, then we selected the va lue falling closest to the average of the available values. If no value was available at 25 / 

### C, we used the same method using values determined within the range of 20 to 30 / 

### C. If no solubility values were available in any of the pr eferred references, we used the procedures described in Lyman et al. (1990) to calculate vapor pressure. SCDM prefers CHEMFATE-recommended values over estimated or calculated values. If more than one recommended value is in CHEMFATE, SCDM selected the highest of the values. If a recommended value is not available, SCDM uses a value measured at 25 / 

### C. If more than one value measured at 25 / 

### C is available, SCDM uses the highest one. If no value is available at 25 / 

### C, values determined within the range of 20 to 30 / 

### C are used. If more than one value measure d at the same temperature is available and none is recommended, SCDM uses the highest value. If no temperature is specified in CHEMFATE for all vapor pressure measurements for a substance, SCDM uses the highest value. For values not available in CHEMFATE, SCDM followed a similar approach to that outlined above for determining values reported in Table A-1.

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### Equation A-2-1

Equation A-2-2 PCDDs and PCDFs We obtained S values for PCDDs and PCDFs from U.S. EPA (2000). Congener group average values were substituted for missing individual congener specific values. Metals We obtained S values for metallic compounds, if available and except for mercury, from the preferred sources listed for or ganic and inorganic compounds. Mercuric Compounds Mercury is a relatively volatile compound. We obtained S values for elemental mercury and mercuric chloride from the preferred sour ces listed above. Methyl mercury is stated in the Merck Index as being insoluble in water. Therefore, we assigned an S value of zero for methyl mercury. A2-2.5 Fraction of Contaminant Air Concentration in the Vapor Phase ( F v 

### ) Organics For most compounds (except metals and some mercury compounds), we calculated the fraction of contaminant air concentration in the vapor phase ( F v 

### ) using the following equation:

C 

### Junge, C. E. 1977. Fate of Pollutants in the Air and Water Environments , Part I; Suffet, I. H., Ed.; Wiley; New York. Pages 7-26. If the contaminant is a liquid at ambient temperatures (that is, when p °L 

### is known), we used Equation A-2- 1 to calculate F v 

### using the Vp value recommended for that contamin ant in the HHRAP database. If the contaminant is a solid at ambient temperatures (that is, when p ° S 

### is known), we used the following equation (Bidleman 1988) calculate p °L 

### from p ° S 

### , for use in Equation A-2-1 (using Vp and T m 

### values presented for each contaminant in the HHRAP database):

where c = Junge constant = 1.7 x 10 -04 

### (atm-cm) p °L 

### = Liquid phase vapor pressure of compound (atm) p ° s 

### = Solid phase vapor pressure of compound (atm) R = Universal ideal gas constant (atm-m 3 

### /mole 

### K) ) 

### S f 

### = Entropy of fusion [ ) 

### S f

### /R = 6.79 (unitless)] S T 

### = Whitby’s average surface area of particulates (aerosols) T

a 

### = Ambient air temperature (K)—assumed to be 25 ° 

### C or 298 K

C 

### Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology. Volume 22. Number 4. Pages 361-367.

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### According to Bidleman (1988), Equation A-2-1 assumes that the Junge constant ( c ) is constant for all compounds. However, c can depend on (1) the compound (sorbate) molecular weight, (2) the surface concentration for monolayer coverage, and (3) the difference between the heat of desorption from the particle surface and the heat of vaporization of the liquid-phase sorbate. Metals As in U.S. EPA (1994b), we assumed all metals (except mercury) are present predominately in the particulate phase and not in the vapor phase ( Vp = 0), and therefore, assigned F v 

### values of zero. Mercuric Compounds Elemental mercury and mercuric chloride are relatively volatile and exist in the vapor phase (U.S. EPA 1997b). Therefore, we calculated the Fv value for elemental mercury using Equation A-2-1. Based on discussions in U.S. EPA (1997b), we assigned mercuric chloride an Fv value of 0.85. Also, consistent with information provided in U.S. EPA (1997b), we assumed methyl mercury doesn’t exist in the air phase and, therefore, assigned it an Fv of zero. A2-2.6 Henry’s Law Constant (H) Henry’s Law constant ( H ) is also referred to as the air-water pa rtition coefficient, and is defined as the ratio of the partial pressure of a compound in air to the concentration of the compound in water at a given temperature under equilibrium conditions. Henry’s La w constant values generally can be (1) calculated from the theoretical equation defining the constant , (2) measured, or (3) estimated from the compound structure. For most compounds (excluding PCDDs and PCDFs), we obtained H values from the following preferred sources: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY. C 

### Calculated using procedures set forth by: Lyman et al. 1990. Handbook of Chemical Property Estimation Methods

. American Chemical Society. Washington, DC.

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### Equation A-2-3

Equation A-2-5 Equation A-2-4 where H = Henry’s Law constant (atm-m 3 

### /mole) Vp = Vapor pressure of COPC (atm) S

= Solubility of COPC in water (mg COPC/L water)
H

values calculated with Equation A-2-3 used MW, S, and Vp values found in the HHRAP database. PCDDs and PCDFs We obtained H values for PCDDs and PCDFs from U.S. EPA (2000). We substituted congener group average values for missing individual congener specific values. Metals We obtained H values for metallic compounds, if available and except for mercury, from the preferred sources listed above. Metals that do not have H values in the references above we assigned a value of zero since the subject metals are assumed to be (1) nonvolatile at ambient temperatures, and (2) insoluble in water, except as certain weak acids. Mercuric Compounds We obtained H values for elemental mercury, mercuric chloride, and methyl mercury from U.S. EPA (1997b). A2-2.7 Diffusivity in Air ( D a 

### ) and Water ( D w 

### ) Diffusivity or diffusion coefficients in air ( D a 

### ) and water ( D w 

### ) are used to calculate the liquid or gas phase transfer of a contaminant into a water body. For most compounds (except PCDDs and PCDFs), we obtained diffusion coefficients in air ( D a 

### ) and water ( D w 

### ) values from the following preferred source: C 

### U.S. EPA. 2004c. WATER9—Air Emissions Models Wastewater Treatment

. Version 2.0.0. OAQPS. Research Triangle Park. North Carolina. July 1. If values weren’t available in U.S. EPA (2004c), we calculated values using procedures set forth by: • U.S. EPA. 1997b. Mercury Study Report to Congress. Volume III: Fate and Transport of Mercury in the Environment. OAQPS and ORD. EPA-452/R-97-005. December.

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### Equation A-2-6 D w 

### and D a 

### values calculated with Equations A-2-4 and A-2-5 used MW values recommended in the HHRAP database. PCDDs and PCDFs We obtained Diffusivity values in air and water for 2,3,7,8-TCDD and 2,3,7,8-TCDF from U.S. EPA (2004c). For all other congeners of PCDDs and PCDFs, (1) we recommend a default Dw value of 8 x 10 -06 

### cm 2

### /s, and (2) we estimated Da values from PCDD and PCDF values using the following equation recommended by U.S. EPA (2000) and obtained from Thibodeaux (1979):

where D x,y 

### = Diffusivities in air of compounds x and y (cm 2

### /s) MW x,y 

### = Molecular weights of compounds x and y (g/mol) We calculated Da values for PCDD congeners using the Da value and MW for 2,3,7,8-TCDD. We calculated Da values for PCDF congeners using the Da value and MW for 2,3,7,8-TCDF. This approach is consistent with the methodology specified in U. S. EPA (2000). Values for diffusivity in water range from 1 x 10 -06 

### to 1 x 10 -05 

### cm 2

### /s; therefore, U.S. EPA (1995b) recommended a default value of 8 x 10 -06 

### cm 2

### /s. Diffusivity values calculated using Equations A-2-4 and A-2-5 were within the range specified by U.S. EPA (1995b). Metals We obtained dDiffusivity values for metallic compounds, if available and except for mercury, from the preferred sources listed for organic and i norganic compounds. If values for metals were not available in the preferred sources, we assigned a default value of zero since metals (except mercury and chromium) are generally considered (1) nonvolatile at ambient temperatures, and (2) insoluble in water, except as certain weak acids. Mercuric Compounds We obtained the diffusivity value for elemental mercury from the WATER9 database (U.S. EPA 2004c). We calculated diffusivity values for mercuric chloride and methyl mercury using Equations A-4 and A-5. A2-2.8 Octanol/Water Partitioning Coefficient (K ow 

### ) The n -octanol/water partitioning coefficient ( K ow 

### ) is defined as the ratio of the solute concentration in the water-saturated n -octanol phase to the solute concentration in the n -octanol-saturated water phase (Montgomery and Welkom 1991). For most compounds (except PCDDs and PCDFs, and mercuric chloride), we obtained K ow 

### values from the following preferred sources: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January.

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### C 

### Syracuse Research Corporation (SRC). 2003a. CHEMFATE Database. SRC. Syracuse, NY. C 

### Syracuse Research Corporation (SRC). 2003b. PHYSPROP Database. SRC. Syracuse, NY. C 

### Lide, D.R. 2003. CRC Handbook of Chemistry and Physics, 83rd Edition . CRC Press. Boca Raton, Florida. C 

### Recommended value reported in published litera ture. When multiple parameter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. PCDDs and PCDFs We obtained K ow 

### values for the PCDDs and PCDFs from U.S. EPA (2000). Congener group average values were substituted for missing individual congener specific values. Metals We obtained K ow 

### values for metals, if available and except for mercury, from the preferred sources listed above. K ow 

### values for metals not reported in the above sources we assumed to be zero. This assumption is based on the affinity of most metals to octanol approaches zero. Mercuric Compounds We obtained the K ow 

### value for elemental mercury from the list of preferred sources above. The K ow 

### value for mercuric chloride comes from U.S. EPA (1997b). We couldn’t find a K ow 

### value for methyl mercury. A2-2.9 Soil Organic Carbon-Water Partition Coefficient (K oc 

### ) The soil organic carbon-water partition coefficient ( K oc 

### ) or the organic carbon normalized soil sorption coefficient is defined as the ratio of adsorbed co mpound per unit weight of organic carbon to the aqueous solute concentration (Montgomery and Welkom 1991). The partitioning of ionizing organic compounds can be significantly influenced by soil pH. Because of the soil mechanisms that are inherently involved, we discuss K oc 

### values for the ionizing organics and nonionizing organics separately. A2-2.9.1 Ionizing Organic Compounds Ionizing organic compounds include amines, carboxy lic acids, and phenols. These compounds contain the functional groups that ionize under specific pH conditions, and include the following: C 

### Organic acids (2,4,6-trichlorophenol; pe ntachlorophenol; 2,3,4,5-tetrachlorophenol; 2,3,4,6-tetrachlorophenol; 2,4,5-trichlor ophenol; 2,4-dichlorophenol; 2-chlorophenol; phenol; 2,4-dimethylphenol; 2-methylpheno l; 2,4-dinitrophenol; and benzoic acid) C 

### Organic bases—n-nitroso-di-n-propyla mine; n-nitrosodiphenylamine, and 4-chloroaniline) We obtained K oc 

### values for ionizing organic compounds from the following:

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### Equation A-2-7

Equation A-2-8 C 

### U.S. EPA. 1996. Soil Screening Guidance: Technical Background Document and User’s Guide . Office of Solid Waste and Emergency Response. Washington, DC. EPA/540/R-95/128. May. The K oc 

### values for ionizing organic compounds provided by U.S. EPA (1996) were estimated on the basis of the degree of ionization and the relative proportions of neutral and ionized species. K oc 

### values for ionizing compounds can vary vastly, depending on the pH conditions in the environment. Therefore, for the aforementioned ionizing organic compounds, K oc 

### values in the HHRAP database are based on a pH value of 6.8 to correlate with typical environmental soils.
K

oc 

### values were estimated on the basis of the assumption that the sorption of ionizing organic compounds is similar to hydrophobic organic sorption, because the soil organic carbon is the dominant sorbent. According to U.S. EPA (1996), for low pH conditi ons, these estimated values may overpredict sorption coefficients, because they ignore sorption to components other than organic carbon. A2-2.9.2 Nonionizing Organic Compounds Nonionizing organic compounds include volatile organics, chlorinated pesticides, polynuclear aromatic hydrocarbons (PAHs), and phthalates. We obtained K oc 

### values for nonionizing organic compounds from the following: C 

### U.S. EPA. 1996. Soil Screening Guidance: Technical Background Document and User’s Guide . Office of Solid Waste and Emergency Response. Washington, DC. EPA/540/R-95/128. May. U.S. EPA (1996) calculated the geometric mean valu e from various measured values. For compounds for which K oc 

### values are not directly provided by U.S. EPA (1996), we calculated K oc 

### values using K ow 

### correlation equations provided in U.S. EPA ( 1996), as obtained from DiToro (1985). We used K ow 

### values recommended in the HHRAP database to calculate K oc 

### values. For most semi-volatile nonionizing organic compounds -

C 

### DiToro, D.M. 1985. “A Particle Interac tion Model of Reversible Organic Chemical Sorption” Chemosphere . 14(10):1503-1538. For the purposes of applying Equation A-2-7, we define semi-volatile compounds as having a Henry’s Law Constant ( H ) value less than 10-3, consistent with ge neral descriptions provided in Lyman et al. (1990). For volatile nonionizing organics, chlorinated benzenes, and certain chlorinated pesticides -

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### Equation A-2-9 For the purposes of applying Equation A-2-8, we define volatile compounds as having a Henry’s Law Constant ( H ) value greater than 10-3, consistent with general descriptions provided in Lyman et al. (1990). PCDDs and PCDFs For PCDDs and PCDFs, we used the following correlation equation obtained from Karickhoff, et al. (1979), as cited by U.S. EPA (2000), , and K ow 

### values provided in the HHRAP database to calculate K oc 

### values.

C 

### Karickhoff, S.W., D.S. Brown, and T.A. Scott. 1979. “Sorption of Hydrophobic Pollutants on Natural Sediments.” Water Resources. 13:241-248. Metals We couldn’t find K oc 

### values for metals within the pref erred sources or available literature. Mercuric Compounds We couldn’t find K oc 

### values for mercury compounds within the preferred sources or available literature. A2-2.10 Partitioning Coefficients for Soil-Water ( Kd s 

### ), Suspended Sediment-Surface Water (Kd sw 

### ), and Bottom Sediment-Sediment Pore Water ( Kd bs 

### ) Partition coefficients ( Kd) describe the partitioning of a compound between sorbing material, such as soil, soil pore-water, surface water, suspended solid s, and bed sediments. For organic compounds, Kd is estimated to be a function of the organic-carbon partition coefficient and the fraction of organic carbon in the partitioning media. For metals, Kd is assumed to be independent of the organic carbon in the partitioning media and, therefore, partitioning is similar in all sorbing media. The soil-water partition coefficient ( Kd s 

### ) describes the partitioning of a compound between soil pore-water and soil particles, and strongly influen ces the release and movement of a compound into the subsurface soils and underlying aquifer. The susp ended sediment-surface water partition coefficient ( Kd sw 

### ) describes the partitioning of a compound between su rface water and suspended solids or sediments. The bed sediment-sediment pore-water partition coefficient ( Kd bs 

### ) describes the partitioning of a compound between the bed sediments and bed sediment pore-water. For most compounds (including PCDDs and PCDFs), we obtained Kd s 

### values from the following preferred sources: C 

### U.S. EPA. 2004b. Superfund Chemical Data Matrix (SCDM). OERR. Washington, D.C. January. C 

### U.S. EPA. 1996. Soil Screening Guidance: Technical Background Document and User’s Guide . Office of Solid Waste and Emergency Response. Washington, DC. EPA/540/R-95/128. May.

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### Equation A-2-10

Equation A-2-11

Equation A-2-12 C 

### Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. “Review and Analysis of Parameters and Assessing Transport of E nvironmentally Released Radionuclides through Agriculture.” Oak Ridge National Laboratory. Oak Ridge, Tennessee. C 

### RTI. 1996. Chemical Properties for SCDM Development. Prepared for U.S. EPA Office of Emergency and Remedial Response. Washington, DC. C 

### Calculated using procedures consistent with: U.S. EPA. 1993d. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions

. Office of Health and Environmental Assessment. Office of Research and Development. EPA-600-AP-93-003. November 10. We assume that soil organic carbon is the dominan t sorbing component in soils and sediments. Therefore, Kd values not directly available in the prefe rred sources were calculated using the following fraction organic carbon ( f

OC 

### ) correlation equations provi ded in U.S. EPA (1993d):

C 

### U.S. EPA. 1993d. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions . Office of Health and Environmental Assessment. Office of Research and Development. EPA-600-AP-93-003. November 10. U.S. EPA (1993d), based on literature searches, states that f OC



### could range as follows: C 

### 0.002 to 0.024 in soils—for which a mid-range value of f oc,s 

### = 0.01 generally can be used. C 

### 0.05 to 0.1 in suspended sediments—for which a mid-range value of f oc,sw 

### = 0.075 generally can be used. C 

### 0.03 to 0.05 in bottom sediments—for which a mid-range value of f oc,bs 

### = 0.04 generally can be used. We calculated Kd values using the K oc 

### values recommended in the HHRAP database, and mid-range f oc 

### values recommended by U.S. EPA (1993d).

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### Equation A-2-13 Metals For metals (except mercury), Kd is governed by factors other than organic carbon, such as pH, redox, iron content, cation exchange capac ity, and ion-chemistry. Therefore, Kd values for metals can’t be calculated using the same correlation equations specified for organic compounds. We obtained Kd values, except lead and mercury, from the preferre d sources listed above. SCDM obtained its values from U.S. EPA (1996), which provides values for Kd that are based on pH and are estimated using the MINTEQ2 geochemical speciation model. The MINTEQ2 model analyses were conducted under a variety of geochemical conditi ons and metal concentrations. The MINTEQ2 pH-dependent Kd values were estimated by holding constant the iron oxide at a medium value and the f oc 

### at 0.002. Because organic carbon does not play a major role in partitioning for the metals, U.S. EPA (1994b) assumed that the partitioning is the same, regardless of the soil, suspended sediment, or bottom sediment phase. Therefore, we assumed that th e values for partitioning coefficients Kd s 

### , Kd sw 

### , and Kd bs 

### for the metals are the same. We obtained the Kd value for lead from the following: C 

### Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. “Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides Through Agriculture.” Oak Ridge Na tional Laboratory, Oak Ridge, Tennessee. Mercuric Compounds We obtained Kd s 

### , Kd sw 

### , and Kd bs 

### values for mercury , mercuric chloride, and methyl mercury from U.S. EPA (1997b). A2-2.11 Soil Loss Constant Due to Degradation ( ksg ) Soil loss constant due to degradation ( ksg ) reflects loss of a compound from the soil by processes other than leaching. Degradation rates in the soil media include biotic and abiotic mechanisms of transformation. Abiotic degradation includes photolys is, hydrolysis, and redox reactions. Hydrolysis and redox reactions can be significant abiotic mechanisms in soil (U.S. EPA 1990). Lyman et al. (1990) states that degradation rates can be assumed to follow first order kinetics in a homogenous media. Therefore, the half-life ( t1⁄2 

### ) of compounds can be related to the degradation rate constant ( ksg ) as follows:

Ideally, ksg is the sum of all biotic and abiotic rate constants in the soil. Therefore, if the t1⁄2

### for all of the mechanisms of transformation are known, the degrada tion rate can be calculated using Equation A-2-13. However, literature sources don’t generally provide suffi cient data for all such mechanisms, especially for soil. For most compounds (except PCDDs and PCDFs, PCBs, metals, and mercury), we calculated ksg values using half-life soil values obtained from the following preferred sources:

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### C 

### Howard, P.H., Boethling, R.S., Jarvis, W.F., Meylan, W.M., and Michalenko, E.M. 1991. Handbook of Environmental Degradation Rates. Lewis Publishers. Chelsea, Michigan. C 

### Recommended value reported in published sources or literature other than the preferred sources listed above. When multiple parame ter values were reported in a particular source (e.g., database), we selected the recommended value in most cases. Half-life values provided in Howard et al. (1991) indicate the disappearance of a substance in ground water or soil; with the principal degradation mechan isms being biodegradation and hydrolysis. Values reported were highly variable because of the different methods used for measurements, in addition to the various controlling factors that could affect them. Therefore, Howard et al. (1991) provided a range of half-life values found in the literature, usually for th e fastest reaction mechanism. We used high-end half-life values to calculate ksg values. For half-life values obtained from literature sources, if more than one value was recommended by the source, then we selected the value falling closest to the average of the recommended values. This value was used to calculate the ksg value recommended in the HHRAP database. If no recommended values were available, we used a value measured at 25 / 

### C. If more than one value measured at 25 / 

### C was available, then we used the value falling closest to the average of the availabl e values to calculate the ksg value recommended in the HHRAP database. If no value was available at 25 / 

### C, we used values determined within the range of 20 to 30 / 

### C following the same method. For contaminants with no reported soil degradation rates, we recommend a default value of zero. PCDDs, PCDFs, and PCBs For PCDDs, PCDFs, and PCBs, we obtained ksg values from U.S. EPA (2000); which discussed experimental studies that were conducted on PCDDs and PCDFs degradation mechanisms. U.S. EPA (2000) stated th at based on available studies, it appears reasonable to assign a uniform rate of degradation for all PCDD/F congeners, and PCBs. The specific degradation rate provided by U.S. EPA (2000) was 0.0277 yr -1 

### , which translates to a half-life of 25 years. Metals For the metals , literature states that the metals are transformed, but not degraded, by such mechanisms; therefore, we assume ksg values are zero for metals with no reported half-life values in soil. Mercuric Compounds For mercury, mercuric chloride, and methylmercury, U.S. EPA (1997b) recommended ksg values of zero. A2-2.12 BIOCONCENTRATION AND BIOTRANSFER FACTORS FOR PLANTS A2-2.12.1 Root Concentration Factor ( RCF ) The root concentration factor ( RCF ) is used to calculate the belowg round transfer of contaminants from soil to a root vegetable. The RCF was developed based on experiment s conducted by Briggs et al. (1982) which measured uptake of compounds into barley roots from growth solution. For compounds with log K ow 

### values of 2.0 and higher, we used the following correlation equation to obtain RCF values:

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### Equation A-2-14

Equation A-2-15 For compounds with log K ow 

### values less than 2.0, we used the following correlation equation to obtain RCF values:

We obtained these equations from the following document: C 

### Briggs, G.G., R.H. Bromilow, and A.A. Evans, 1982. “Relationships Between Lipophilicity and Root Uptake and Translocati on of Non-ionized Chemicals by Barley.” Pesticide Science . Volume 13. Pages 495-504. These equations estimate a RCF value in fresh weight (FW) units, which was then converted to dry weight (DW) units using a moisture content of 87 percent in root vegetables (U.S. EPA 1997c; Pennington 1994). Briggs et al. (1982) derived the correlation e quations above from studies using 18 compounds with log K ow 

### values ranging from -0.57 to 4.6. In addition, a validation exercise, in which predictions of dioxin-like compounds (log Kow values from 6.0 to 8.2) in carrots were compared with observations, shows this factor to adequately perform for this class of compounds (Muller et al. 1994). Therefore, RCF values for compounds with outlying log K ow 

### values have been capped in line with the test data used to formulate the correlation equation. We assigned compounds with log K ow 

### values less than -0.57 an RCF value corresponding to a log K ow 

### value of -0.57. At the high end of the range, we assigned compounds with log K ow 

### values greater than 8.2 (considering the validation studies using dioxin-like compounds) an RCF value corresponding to a log K ow 

### value of 8.2. As in previous U.S. EPA guidance (U.S. EPA 1994a), we recommend using Equation A-2-14 in calculating exposure to dioxin-like compounds. We used K ow 

### values available in the HHRAP database to calculate each RCF value. Metals For metals, no referenced RCF values were available in publishe d literature. However, plant-soil biotransfer factors for root vegetables ( Brrootveg 

### ) were available in the literature and, therefore, RCF values, normally used to calculate Brrootveg 

### values, aren’t needed for the metals. Mercuric Compounds No RCF values were available in the literatu re for mercury, mercuric chloride, and methyl mercury. However, plant-soil biotransfer factors for root vegetables ( Brrootveg 

### ) were available in U.S. EPA (1997b) and, therefore, RCF values, normally used to calculate Brrootveg 

### values, aren’t needed for the mercuric compounds.

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### Equation A-2-16 A2-2.12.2 Plant-Soil BCFs in Root Vegetables (Br rootveg 

### ) The plant-soil bioconcentration factor for compounds in root vegetables ( Brrootveg 

### ) accounts for uptake from soil to the belowground root vegetables or produce. For most compounds, we used the following equati on from U.S. EPA (1995b) to calculate values for Brrootveg 

### on a dry weight basis:

We calculated Brrootveg 

### values using the RCF and Kd s 

### values listed in the HHRAP database. Metals We obtained the Brrootveg 

### values for metals (except nickel, cadmium, selenium, and arsenic) from Baes et al. (1984) . Br values in Baes et al. (1984) are dry weight values provided for nonvegetative (reproductive) growth, such as tubers. For nickel, cadmium, selenium, and arsenic , we obtained Brrootveg 

### values from the following document: C 

### U.S. EPA. 1992b. Technical Support Document for the Land Application of Sewage Sludge. Volumes I and II . EPA 822/R-93-001a. Office of Water. Washington, D.C. For nickel, cadmium, selenium, and arsenic —Brroot veg 

### values were calculated by multiplying the uptake slope factors [( : 

### g COPC/g DW plant)/(kg COPC applied/hect are)] for root vegetables by a conversion factor of 2x10 9 

### g/hectare soil. In deriving the conversion factor, U.S. EPA (1992b) assumed a soil average dry bulk density of 1.33 g/cm 3 

### and a soil incorporation depth of 15 cm. Mercuric Componds We obtained Brrootveg 

### values for mercuric chloride and methyl mercury from U.S. EPA (1997b) on a dry weight basis. The HHRAP methodolgy assumes elemental mercury doesn’t deposit onto soils, and therefore there’s no pl ant uptake through the soil. Therefore, a Brrootveg 

### value for elemental mercury isn’t applicable. A2-2.12.3 Plant-Soil BCFs for Aboveground Produce (Br ag 

### ) and Forage (Br forage 

### ) The plant-soil bioconcentration factor ( Br) for aboveground produce accounts for the uptake from soil and the subsequent transport of contaminants th rough the roots to the aboveground plant parts. As addressed in U.S. EPA (1995b), the Br value for most compounds is a function of water solubility, which is inversely proportional to K ow 

### . The Br value for metals is a function of the bioavailability of the metals in soil. For all compounds, including PCDDs and PCDFs, (1) the subscript “ ag ” represents aboveground produce which applies to exposed fruits and vegetables, and pr otected fruits and vegetables, and (2) the subscript

“ forage ” represents forage, but the values also apply to silage and grain. For metals, (1) aboveground fruits (both exposed and protected) are represented by Br ag (fruit) 

### ; (2) aboveground vegetables (both exposed and protected) are represented by Br ag(veg) 

### , (3) forage is represented by Br forage 

### , but the values also apply to silage, and (4) grains are represented by Br grain 

### .

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### Equation A-2-18 Equation A-2-17 For most compounds, we used the following co rrelation equations to calculate values for Br ag 

### and Br forage 

### on a dry weight basis:

We obtained these correlation equations from; C 

### Travis, C.C. and A.D. Arms. 1988. Bioconcentration of Organics in Beef, Milk, and Vegetation. Environmental Science and Technology. 22:271-274. Travis and Arms (1988) developed a correlation equation for vegetation that doesn’t distinguish between aboveground produce and forage or silage or grain. Due to lack of literature data, we used the Travis and Arms (1988) correlation equation to calculate Br values for both aboveground produce and forage. The above correlation equations for Br values were derived from e xperiments conducted on compound classes such as DDT, pesticides, PCDDs, PCDFs, and PCBs, representing compounds with log K ow 

### values ranging from 1.15 to 9.35. Therefore, Br values for compounds with outlying log K ow 

### values have been capped in line with the test data used to formul ate the correlation equation. Compounds with log K ow 

### values less than 1.15 we assigned a Br value corresponding to a log K ow 

### value of 1.15. At the high end of the range, compounds with log K ow 

### values greater than 9.35 we assigned a Br value corresponding to a log K ow 

### value of 9.35. We used the log K ow 

### values listed in the HHRAP database to calculate each Br value. Metals For metals, we derived Br values from uptake slope factors provided in the following document: C 

### U.S. EPA. 1992b. Technical Support Document for the Land Application of Sewage Sludge . Volumes I and II. EPA 822/R-93-001a. Office of Water. Washington, DC. Uptake slopes provided in U.S. EPA (1992b) are the ratio of contaminant concentration in dry weight plant tissue to the mass of contaminant applied pe r hectare soil. These uptake slopes were multiplied by 2 x 10 9 

### g/hectare soil to convert to Br values. The conversion factor was derived using the U.S. EPA (1992b) assumed soil bulk density of 1.33 g/cm 3 

### , and an incorporation depth of 15 cm. For other metals, we obtained Br values from Baes et al. (1984). Baes et al. (1984) described biotransfer factors (on a dry weight basis) from plant-soil uptak e for (1) vegetative growth (leaves and stems) “Bv”; and (2) nonvegetative or reproductive growth (fru its, seeds, and tubers) “Br”. Note that Bv is defined as the air-to-plant biotransfer factor. We used the following methodology to derive Br values on a dry weight basis: a. For nickel, cadmium, selenium, zinc, and arsenic , Br ag (fruit) 

### values were calculated by multiplying the uptake slope factors with a conversion factor of 2 x10 9 

### g/ha soil (uptake

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### slope factor and the conversion factor we re obtained from U.S. EPA (1992b) for garden fruits). All other metals were obtained by selecting “Br” values for nonvegetative growth (reproductive) provided in Baes et al. (1984). b. For nickel, cadmium, selenium, zinc, and arsenic, Br ag (veg) 

### values were calculated by weighting the uptake slope factors for garden fruits (75%) and leafy vegetables (25%) and multiplying the result with a conversion factor of 2 x10 9 

### g/ha soil. The uptake slope factors and the conversion factor were obt ained from U.S. EPA (1992b). For other metals, “Br” values for nonvegetative (repr oductive) growth and “Bv” values for vegetative growth—obtained from Baes et al. (1984)—were weighted as 75% (reproductive) and 25% vegetative. The resulting values were adopted as Br ag (veg) 

### values. c. For nickel, cadmium, selenium, zinc, and arsenic, Br forage 

### values were calculated by multiplying the uptake slope factors with a conversion factor of 2x10 9 

### g/ha soil. The uptake slope factors and the conversion fact or were obtained from U.S. EPA (1992b) for leafy vegetables. For other metals, Br forage 

### values were obtained from Baes et al. (1984). “Bv” values for vegetative growth (such as leaves and stems) in Baes et al. (1984) were used for Br forage 

### . d. For nickel, cadmium, selenium, zinc, and arsenic, Br grain 

### values were calculated by multiplying the uptake slope factors with a conversion factor of 2 x10 9 

### g/ha soil. The uptake slope factors and the conversion fact or were obtained from U.S. EPA (1992b) for grains/cereals. For other metals, Br grain 

### value was obtained from Baes et al. (1984). “Br” values for nonvegetative growth as recommended by Baes et al. (1984) were used for Br grain 

### . e. Consumption rates used to obtain the weighted average Br ag 

### value for aboveground produce are as follows: (1) Br ag 

### values for fruits combined with a human consumption rate of fruits of 1.44E-03 kg/kg/day, and (2) Br ag 

### values for vegetables combined with a human consumption rate of ve getables of 1.49E-03 kg/kg/day. Mercuric Compounds We obtained Br ag 

### values for mercuric chloride and methyl mercury as described above. We obtained Br forage 

### values on a dry weight basis for mercuric chloride and methyl mercury from U.S. EPA (1997b). The HHRAP methodology assumes that elemental mercury doesn’t deposit onto soils. Therefore, it’s assumed that th ere’s no plant uptake through the soil. A2-2.12.4 Air-to-Plant BTFs for Aboveground Produce ( Bv ag 

### ) and Forage (Bv forage 

### ) The air-to-plant biotransfer factor ( Bv ) is defined as the ratio of contaminant concentration in aboveground plant parts to the contaminant concentration in air. We calculated Bv values only for aboveground exposed produce (both fruits and vege tables). We assume that aboveground protected produce (both fruits and vegetables) and belowground produce are protected from air-to-plant transfer. According to U.S. EPA (1995b), root vegetables are assumed to be also protected from air-to-plant transfer. For most compounds (excluding PCDDs and PCDFs), we calculated the air-to-plant biotransfer factor for aboveground produce ( Bv ag 

### ) and forage ( Bv forage 

### ) using correlation equations derived for azalea leaves in the following documents:

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### Equation A-2-19

Equation A-2-20 C 

### Bacci E., D. Calamari, C. Gaggi, and M. Vi ghi. 1990. “Bioconcentration of Organic Chemical Vapors in Plant Leaves: Experimental Measurements and Correlation.” Environmental Science and Technology . Volume 24. Number 6. Pages 885-889. C 

### Bacci E., M. Cerejeira, C. Gaggi, G. Chemello, D. Calamari, and M. Vighi. 1992. “Chlorinated Dioxins: Volatilization from Soils and Bioconcentration in Plant Leaves.” Bulletin of Environmental Contamination and Toxicology . Volume 48. Pages 401-408. Bacci et al. (1992) developed a correlation e quation using data collected for the uptake of 1,2,3,4-tetrachlorodibenzo-p-dioxin (TCDD) in azalea leaves, and data obtained from Bacci et al. (1990). The Bv obtained was then evaluated for 14 organic co mpounds to develop a correlation equation with K ow 

### and H . Bacci et al. (1992) derived the following equations without distinguishing between forage and aboveground produce:

where B vol 

### = Volumetric air-to-plant biotransfer factor (fresh-weight basis) Bv = Mass-based air-to-plant biotransfer factor (dry-weight basis) D

air



### = 1.19 g/L (Weast 1981) D forage 

### = 770 g/L (Macrady and Maggard 1993) f

water 

### = 0.85 (fraction of forage that is water—Macrady and Maggard [1993]) We calculated Bv vlaues using Equations A-2-19 and A-2-20, and the values for H and K ow 

### listed in the HHRAP database; based on a T of 25°C or 298.1 K. We adopted the resulting Bv values for both forage ( Bv forage 

### ) and aboveground produce ( Bv ag 

### ). Please note the following uncer tainty associated with these variables: C 

### For organics (except PCDDs and PCDFs) , U.S. EPA (1993d) recommended reducing Bv values by a factor of 10 before use. This was based on the work conducted by U.S. EPA (1993d) for U.S. EPA (1994a) as an interim correction factor. Welsch-Pausch et al (1995) conducted experiments to determine c oncentrations of PCDDs and PCDFs in air and resulting biotransfer to welsh ray grass. This was documented in the following: - Welsch-Pausch, K.M. McLachlan, and G. Umlauf. 1995. “Determination of the Principal Pathways of Polych lorinated Dibenzo-p-dioxins and Dibenzofurans to Lolium Multiflorum (Welsh Ray Grass)”. Environmental Science and Technology . 29: 1090-1098.

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### A follow-up study based on Welsch-Pausch et al. (1995) was conducted by Lorber (1995) (see discussion below for PCDDs and PCDFs). In a following publication, Lorber (1997) concluded that the Bacci factor reduced by a factor of 100 was close in line with observations made by him through various studies, including the Welsch-Pausch et al. (1995) experiments. Therefore, we calculated Bv values using the Bacci et al. (1992) correlation equations and then reduced by a factor of 100 for all organics, excluding PCDDs and PCDFs. PCDDs and PCDFs For PCDDs and PCDFs, we obtained Bv values, on a dry weight basis, from the following: C 

### Lorber, M. and P. Pinsky. 1999. “An Evaluation of Three Empirical Air-to-Leaf Models for Polychlorinated Dibenzo-p-Dioxins a nd Dibenzofurans”. National Center for Environmental Assessment (NCEA). U.S. EPA. Washington D.C. Accepted for publication in Chemosphere

. U.S. EPA (1993d) stated that, for dioxin-like com pounds, using the Bacci et al. (1992) equations may overpredict Bv values by a factor of 40. This was because the Bacci et al. (1990) and Bacci et al. (1992) experiments did not take photodegradation eff ects into account. Therefore, U.S. EPA (1993d) recommended that Bv values calculated using Equations A-2-19 a nd A-2-20 be reduced by a factor of 40 for dioxin-like compounds. However, according to Lorber (1995), the Bacci algorithm divided by 40 may not be appropriate because • the physical and chemical properties of di oxin congeners are generally outside the range of the 14 organic compounds used by Bacci (1990), and • the factor of 40 derived from one experi ment on 2,3,7,8-TCDD may not apply to all dioxin congeners. Welsch-Pausch et al. (1995) conducted experiments to obtain data on uptake of PCDDs and PCDFs from air to Lolium Multiflorum (Welsh Ray grass). The data includes grass concentrations and air concentrations for dioxin congener groups, but not the invidual congeners . Lorber (1995) used data from Welsch-Pausch et al.(1995) to develop an air-to-leaf transfer factor for each dioxin-congener group. Bv values developed by Lorber (1995) were about an order of magnitude less than values calculated using the Bacci et al. (1990) and (1992) correlation equations . Lorber (1995) speculated that this difference could be attributed to several factors including experi mental design, climate, and lipid content of plant species used. We obtained the Br values for PCDDs and PCDFs listed in the HHRAP database from the experimentally derived values of Lorber (1995). However, Lorber (1995) stated that these values should be considered carefully by users of this methodology because of th e inherent uncertainties associated with the data. Metals For metals, we found no literature sources for the Bv values. U.S. EPA (1995b) quoted from the following document, that metals were assumed not to experience air to leaf transfer: C 

### Belcher, G.D., and C.C. Travis. 1989. “Modeling Support for the RURA and Municipal Waste Combustion Projects: Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food Chain Model.” Interagency Agreement No. 1824-A020-A1. Office of Risk Analysis, Health and Safety ResearchDivision. Oak Ridge National Laboratory. Oak Ridge, Tennessee. October.

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### As with the above cited references, we assumed Bv values for metals (excluding elemental mercury) are zero. Mercury The HHRAP assumes that mercury emissions consist of both the elemental and divalent forms. However, only small amounts of elemental mercury is assumed to be deposited based on its behavior in the atmosphere. Elemental mercury either dissipates in to the global cycle or is converted to the divalent form. The HHRAP assumes methyl mercury doesn’t exist in air emissions or in the air phase. Additional basis for the assumption regarding mercury transfer from air to plants includes • elemental mercury reaching or depositing onto the plant surfaces is negligible, and • biotransfer of methyl mercury from air is zero. This is based on assumptions made regarding speci ation and fate and transport of mercury from emissions. Therefore, we assume the Bv values for elemental and methyl mercury are zero. The Bv value for mercuric chloride (dry weight basis) comes from U.S. EPA (1997b). If field data suggests otherwise, Bv values (1) provided in U.S. EPA (1997b) for methyl mercury can be used, and (2) need to be determined for elemental mercury. Please note that uptake of mercury from air into the aboveground plant tissue is primarily in the diva lent form. We assume that a part of the divalent form of mercury is converted to methyl mercury once in the plant tissue. A2-2.13 BIOTRANSFER FACTORS FOR ANIMALS The biotransfer factor for animals ( Ba ) is the ratio of contaminant concentration in fresh weight animal tissue to the daily intake of contaminant by the animal. A2-2.13.1 BTFs for Beef (Ba beef 

### ) and Milk (Ba milk 

### ) The main route of human exposure to many highly lipophilic compounds is through ingestion of contaminated agricultural products such as b eef and milk (McLachlan 1993). The transfer of contaminants from environmental media (e.g., air, soil, water) and food (e.g. grain, silage) into livestock products (e.g., beef, milk) has historically been either determined by direct measurement of contaminants in livestock products, or predic ted using regression models. Organic Compounds When empirical data are lacking for biotransfer of organc chemicals, one of the most widely used approaches to predict contaminant transfer from envir onmental media and food to beef tissue and milk are the regression models developed by Travis and Ar ms (1988), which relate chemical octanol-water partition coefficient (K ow 

### ) to biotransfer into beef and milk. These regressions, however, are hampered by the limited log K ow 

### range and questions surrounding the validity of the underlying biotransfer data set. In response, EPA developed a new methodology for predic ting beef and milk biotransfer factors (See report entitled: “Methodology for Predicting Cattle Biotransfe r Factors” (RTI 2005) for complete documentation of the approach). Using EPA’s updated methodology, we predicted biotransfer factors for organic chemicals with the following single equation:

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### Equation A-2-21
where Ba fat 

### = Biotransfer factor ([mg /kg Fat]/[mg/day]) K ow 

### = Octanol-water partition coefficient (unitless). Values for Ba fat

### were adjusted to account for the assumed fat content of milk and beef as shown below: 

# Ba milk Ba fat 

# = × 10 0 04 log



# . Equation A-2-22


# Ba beef Ba fat 

# = × 10 019 log



# . Equation A-2-23 The log K ow 

### ’s of the chemicals used to derive the equati on ranged from -0.67 to 8.2. Therefore we used equation A-2-21 for organic chemicals having a l og Kow between -0.67 and 8.2. Compounds with log K ow 

### values less than -0.67 were assigned Ba beef 

### and Ba milk 

### values corresponding to a log K ow 

### value of - 0.67. At the high end of the range, compounds with log K ow 

### values greater than 8.2 were assigned Ba beef 

### and Ba milk 

### values corresponding to a log K ow 

### value of 8.2. We used the K ow 

### values in the HHRAP database to calculate Ba beef 

### and Ba milk 

### values. Highly Metabolized Organic Compounds As discussed in RTI (2005), Equation A-2-21 might overestimate biotransfer of highly metabolized chemicals, producing an upper bound estimate for these chem icals. Of those chemicals relevant to the HHRAP (and therefore included in the HHRAP comp anion database), Phthalates and PAHs fall within this group (see HHRAP Chapter 2 for more information on the phthalate and PAH chemical categories). One way to account for this potential overestimati on is to rely upon a metabolism factor to improve model predictions. For example, EPA developed a me tabolism factor of 0.01 (i.e., 99% of the chemical ingested is metabolized) for bis-ethylhexyl phthalate (BEHP, See Chapter 2). When this factor is applied to the biotransfer factors predicted using the regression equation recommended above for BEHP, the biotransfer factors are reduced by two orders of magnitude. These metabolism-adjusted predicted biotransfer factors are close in magnitude to the empirically derived biotransfer factors found in the literature, which supports using this metabolism factor. Unfortunately, EPA has not developed metabolism factors for other organic chemicals, due to limited availability of empirically derived data (see Chapter 2). For those highly metabolized chemicals that don’t have metabolism factors, we still consider it reasonable to use estimated Ba values for the following reasons: • Few chemicals have had all their degradation products identified; • If identified, the degradation products may in fact be as toxic as, or even more toxic than, the parent compound (the degradation products of PAHs, for example, are toxic). Unless data demonstrates that all degradation products are nontoxic (as is the case for BEHP), the only way to address toxic degradation products in the HHRAP is to include their mass in the mass of the parent chemical; and

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### • the metabolic degradation products may them selves be persistent. For example, DDT is metabolized to DDD and DDE, which remain persistent. It should also be noted that not all chemicals are me tabolized at the same rate and may remain in animal tissue as the parent compound through establishment of steady state concentrations. In fact, many of the chemicals in the biotransfer data set that are well predicted by Equation A-2-21 are metabolized to other compounds. DDT is metabolized to DDE, and lindane (used to derive the regression, but not in the HHRAP) is metabolized to many different compounds. For DDT and lindane, biotransfer factors are well predicted using Equation A-2-21. Thus, just because a chemical undergoes biotransformation to other compounds, doesn’t necessarily mean Equation A-2-21over-estimates its biotransfer. Lacking sufficient data to identify all degradati on products, characterize all degradation products as nontoxic, and ensure that all potentially toxic degrad ation products are less persistent than the parent chemical, we consider it reasonably protective to use the Ba beef 

### and Ba milk 

### values for the parent chemical as predicted, without adjustment. If a highly metabo lized chemical is found to drive the risk assessment, then we recommend re-evaluating the appropriateness of the Ba beef 

### and Ba milk 

### values. Ionizing Organic Compounds To improve BTF estimates for organic acids, we used the first-order dissociation constant (pKa) to account for chemical ionization. For these chemicals, K ow 

### is a weighted value calculated based on the fraction of the chemical in the neutral form such that: 

# K K n FracNeutral K i FracNeutral ow ow ow 

# = × + ×
− ( )( ) 1 Equation A-2-24
where K ow 

### n = partition coefficient for the neutral species (unitless), K ow 

### i = partition coefficient for the ionized species (mol/L), FracNeutral = fraction of neutral species present for organic acids (unitless). Accounting for the fraction of ionizable organics in the neutral form is important because K ow 

### can vary considerably depending on pH. The cow’s small intes tine, where chemicals can be absorbed, has a near neutral pH (Umphrey and Staples, 1992). Thus, the neutral fraction is determined using a pH equal to 7 in the following equation (Lee et al., 1990): 

# [ ] [ ][ ] 

# ( ) FracNeutral HA HA A pH pKa =

− − =+ − 1 10 Equation A-2-25

where [HA] = equilibrium concentration of organic acid (mol/L), [A-] = equilibrium concentration of anion (mol/L), and pKa = acid dissociation constant (unitless). If a value for log K ow 

### i wasn’t available, we estimated log K ow 

### i assuming a ratio of log K ow 

### i to log K ow 

### n of 0.015. This ratio is a conservative va lue developed by EPA to apply to organic acids without data for log K ow 

### i (U.S. EPA, 1996).

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### Metals We obtained Ba beef 

### and Ba milk 

### values for metals (except cadmium, mercury, selenium, and zinc), on a fresh weight basis, from Baes et al. (1984). For cadmium, selenium, and zinc, U.S. EPA (1995a) cited Ba values derived by dividing uptake slopes [(g COPC/kg DW tissue)/(g COPC/kg DW feed)], obtained from U.S. EPA (1992b), by a daily consumption rate of 20 kg DW per day for beef and dairy cattle. We obtained our recommended values from Baes et al. (1984) for all metals except cadmium, selenium, and zinc. We calculated Ba values for cadmium, selenium, and zinc using uptake slope factors and consumption rates provided in U.S. EPA (1992b) and U.S. EPA (1995a), converting the result to a fresh weight basis by assuming a moisture content of 87 pe rcent in milk and 70 percent in beef. Moisture content in beef and milk were obtained from the following: C 

### U.S. EPA. 1997c. Exposure Factors Handbook . “Food Ingestion Factors”. Volume II. EPA/600/P-95/002Fb. August. C 

### Pennington, J.A.T. 1994. Food Value of Portions Commonly Used . Sixteenth Edition. J.B. Lippincott Company, Philadelphia. We provide the calculated fresh weight Ba beef 

### and Ba milk 

### values in the HHRAP database. Mercuric Compounds The HHRAP assumes that elemental mercury neither deposits onto soils nor transfers to aboveground plant parts. Therefore, there’s no transfer of el emental mercury into animal tissue. Therefore, we recommend Ba values of zero for elemental mercury. This based on assumptions made regarding speciation and fate and transport of mercury from emission sources. If field data suggests otherwise, Ba beef 

### and Ba milk 

### values for elemental mercury can be derived from the uptake slope factors provided in U.S. EPA (1992b) and U.S. EPA (1995a); using the same consumption rates discussed earlier for metals like cadmium, selenium, and zinc. We derived the Ba beef 

### and Ba milk 

### values listed in the HHRAP database for mercuric chloride and methyl mercury from data in U.S. EPA (1997b). U.S. EPA (1997b) provided Ba beef 

### and Ba milk 

### values for mercury, but did not specify for which form of mercury. As in U.S. EPA (1997b), we assume mercury speciates into 87 percent divalent mercury and 13 percent meth yl mercury in herbivore animal tissue. Also, assuming that the Ba beef 

### and Ba milk 

### values provided in U.S. EPA (1997b) were for total mercury in animal tissue, the biotransfer factors in U.S. EPA (1997b) can be apportioned in the fractions assumed to be found in animal tissue. Therefore, we based the values reported in the HHRAP database on the following: C 

### We converted the default Ba milk 

### value of 0.02 day/kg DW for mercury to a fresh weight basis assuming a 87 percent moisture content in milk (U.S. EPA 1997c; and Pennington 1994). We multiplied the resulting Ba milk 

### (fresh weight) value by (1) 0.13 to obtain a value for methyl mercury, and (2) 0.87 to obtain a value for mercuric chloride (divalent mercury). C 

### We converted the default Ba beef 

### value of 0.02 day/kg DW for mercury to a fresh weight basis assuming a 70 percent moisture content in beef (U.S. EPA 1997c; and Pennington 1994). We multiplied the resulting Ba beef 

### (fresh weight) value by (1) 0.13 to obtain a value for methyl mercury, and (2) 0.87 to obtain a value for mercuric chloride (divalent mercury).

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### A2-2.13.2 Biotransfer Factors for Pork ( Ba pork 

### ) For most compounds we derived Ba pork 

### values using the same method used to estimate Ba beef 

### values (see Section A2-2.13.1 above for a detailed description of the method & its limitations), modifying to reflect an assumed fat content of pork of 23%. Specifi cally, we used equation A-2-21 to generate Ba fat

### values, which were then adjusted to account for the assumed fat content of pork as shown below: 

# Ba pork Ba fat 

# = × 10 0 23 log



# . Equation A-2-26 The log K ow 

### ’s of the chemicals used to derive the equati on ranged from -0.67 to 8.2. Therefore we used equation A-2-21 for organic chemicals having a l og Kow between -0.67 and 8.2. Compounds with log K ow 

### values less than -0.67 were assigned Ba pork 

### values corresponding to a log K ow 

### value of -0.67. At the high end of the range, compounds with log K ow 

### values greater than 8.2 were assigned Ba pork 

### values corresponding to a log K ow 

### value of 8.2. We used the K ow 

### values in the HHRAP database to calculate Ba pork 

### values. This calculation is limited by the assumptions that: • contaminants bioconcentrate in the fat tissues; and • effects from differences in metabolism, dig estive system, and feeding characteristics between beef cattle and pigs are minimal. Metals For metals (except cadmium, selenium, and zinc) , no data was available in the literature to calculate Ba pork 

### values. For cadmium, selenium, and zinc, U.S. EPA (1995b) reported Ba values derived by dividing uptake slopes [(g COPC/kg DW tissue)/(g COPC/kg DW feed)], obtained from U.S. EPA (1992b), by a daily consumption rate of 4.7 kg DW per day for pigs provided in U.S. EPA (1995a). The dry weight Ba pork 

### values (for cadmium, selenium, and zinc) were conve rted to a fresh weight basis assuming a moisture content of 70 percent in pork (U.S. EPA 1997c; and Pennington 1994). Mercuric Compounds The HHRAP assumes that elemental mercury neither deposits onto soils nor transfers to the aboveground plant parts; therefore, there’s no transfer of elemental mercury into the animal tissue. Therefore, we recommend Ba values of zero for elemental mercury. This is based on the assumptions made regarding speciation and fate and transport of mercury from emissions. If field data suggests otherwise, Ba pork 

### values for elemental mercury can be derived from the uptake slope factors provided in U.S. EPA (1992b) and U.S. EPA (1995a), using the same consumption rates discussed earlier for metals like cadmium, selenium, and zinc. We derived Ba pork 

### values for mercuric chloride and methyl mercury from data in U.S. EPA (1997b). U.S. EPA (1997b) provided Ba pork 

### values for mercury, but did not specify for which form of mercury. As in U.S. EPA (1997b), the HHRAP assumes that mercury speciates into 87 percent divalent mercury and 13 percent methyl mercury in herbivore animal tissue. Also, assuming that the Ba pork 

### values provided in U.S. EPA (1997b) were for total mercury in animal ti ssue, biotransfer factors in U.S. EPA (1997b) can be apportioned in the fractions it is assumed to be found in animal tissue. Therefore, we converted the U.S. EPA (1997b) Ba pork 

### value of 0.00013 day/kg DW for mercury to a fresh weight basis assuming a 70 percent moisture c ontent in pork (U.S. EPA 1997c; and Pennington 1994).

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## Ba chicken Ba fat 

## = × 10 014 log



## . Equation A-2-27


## Ba egg Ba fat 

## = × 10 0 08 log



## . Equation A-2-28 We multiplied the resulting Ba pork 

### (fresh weight) value by (1) 0.13 to obtain a value for methyl mercury, and (2) 0.87 to obtain a value for mercuric chloride (divalent mercury). A2-2.13.3 BTFs for Chicken (Ba chicken 

### ) and Poultry Eggs (Ba egg 

### ) Biotransfer factors for chicken ( Ba chicken 

### ) and poultry eggs ( Ba egg 

### ) are expressed as the ratio of the contaminant concentration in the fresh weight tissue to the contaminant intake from the feed. Biotransfer factors are calculated from bioconcentration factors for chicken and poultry eggs. BCFs are expressed as the ratio of the contaminant concentration in the fr esh weight tissue to the contaminant concentration in dry weight soil. For most compounds we derived Ba pork 

### values using the same method used to estimate Ba beef 

### values (see Section A2-2.13.1 above for a detailed description of the method & its limitations), modifying to reflect an assumed fat content of chicken of 14%, and eggs of 8%. Specifically, we used equation A-2-21 to generate Ba fat

### values, which were then adjusted to account for the assumed fat content of chicken and eggs as shown below:

The log K ow 

### ’s of the chemicals used to derive the equati ons ranged from -0.67 to 8.2. Therefore we used equation A-2-21 for organic chemicals having a l og Kow between -0.67 and 8.2. Compounds with log K ow 

### values less than -0.67 were assigned Ba chicken 

### and Ba egg 

### values corresponding to a log K ow 

### value of - 0.67. At the high end of the range, compounds with log K ow 

### values greater than 8.2 were assigned Ba chicken 

### and Ba egg 

### values corresponding to a log K ow 

### value of 8.2. We used the log K ow 

### values in the HHRAP database to calculate Ba chicken 

### and Ba egg 

### values. These calculations are limited by the assumptions that: • contaminants bioconcentrate in the fat tissues; and • effects from differences in metabolism, dig estive system, or feeding characteristics between beef cattle and chickens are minimal. Please note that the scenario of principal concern fo r chicken and egg contamination is for home grown chickens. The raising of home gr own chickens would be characteris tic of free range and semi-free range housing conditions where poultry do come in contact with soil, and possibly vegetation, insects, and benthic organisms. The applicability of this scenar io to commercial poultry operations characterized by housing conditions that do not provide chicke ns access to soil would need to be assessed on a case-by-case basis. Metals Ba chicken 

### and Ba egg 

### values for all metals except cadmium, selenium, and zinc, weren’t available in the literature. For cadmium, selenium, and zinc, U.S. EPA (1995a) cited Ba values that were derived by dividing uptake slopes [(g COPC/kg DW tissue)/(g COPC/kg DW feed)], obtained from U.S. EPA (1992b), by a daily consumption rate of 0.2 kilogram s DW per day by chicken. To obtain values listed in the HHRAP database, we converted the dry weight Ba value to a fresh weight value by assuming a moisture content of 75 percent in eggs and chicken (U.S. EPA 1997c; and Pennington 1994).

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### Mercury The HHRAP assumes that elemental mercury neith er deposits onto soils nor transfers to the aboveground plant parts or grains. Therefore, there’s no transfer of elemental mercury into animal tissue. Therefore, we recommend Ba values of zero for elemental mercury. This is based on the assumptions made regarding speciation and fate and tr ansport of mercury from emission sources. If field data suggests otherwise, Ba chicken 

### and Ba egg 

### values for elemental mercury can be derived from the uptake slope factors provided in U.S. EPA (1992b) and U.S. EPA (1995a), using the same consumption rates discussed earlier for metals like cadmium, selenium, and zinc. We derived Ba chicken 

### and Ba egg 

### values for mercuric chloride and methyl mercury from data in U.S. EPA (1997b). U.S. EPA (1997b) provided Ba chicken 

### and Ba egg 

### values for mercury, but did not specify for which form of mercury. As in U.S. EPA (1997b), the HHRAP assumes mercury speciates into 87 percent divalent mercury and 13 percent methyl mercury in herbivore animal tissue. Also, assuming that the Ba chicken 

### and Ba egg 

### values provided in U.S. EPA (1997b) were for total mercury in animal tissue, then biotransfer factors in U.S. EPA (1997b) can be appor tioned in the fractions it is assumed to be found in animal tissue. Therefore, we based the values reported in the HHRAP database on the following: C 

### We converted the U.S. EPA (1997b) Ba chicken 

### value of 0.11 day/kg DW for mercury to a fresh weight basis assuming a 75 percent mois ture content in chicken (U.S. EPA 1997c; and Pennington 1994). We multiplied the resulting Ba chicken 

### (fresh weight) value by (1) 0.13 to obtain a value for methyl mercury, and (2) 0.87 to obtain a value for mercuric chloride (divalent mercury). C 

### We converted the U.S. EPA (1997b) Ba egg 

### value of 0.11 day/kg DW for mercury to a fresh weight basis assuming a 75 percent mois ture content in eggs (U.S. EPA 1997c; and Pennington 1994). We multiplied the resulting Ba egg 

### (fresh weight) value by (1) 0.13 to obtain a value for methyl mercury, and (2) 0.87 to obtain a value for mercuric chloride (divalent mercury). A2-2.13.4 Bioconcentration and Bi oaccumulation Factors for Fish Bioconcentration and bioaccumulation factors for fi sh are used for various compounds, depending on the K

ow 

### value of the compound. We recommend using bioconcentration factors for fish ( BCF fish 

### ) for compounds (except PCDDs, PCDFs, and PCBs) with a log K ow 

### value less than 4.0; and for metals (except lead and mercury). We recommend using bioaccumulation factors for fish ( BAF fish 

### ) for compounds (except PCDDs, PCDFs, and PCBs) with a log K ow 

### value greater than 4.0, lead, and mercuric compounds. We recommend also using biota-sediment accumulation factors for fish ( BSAF fish 

### ) for PCDDs, PCDFs, and PCBs. A2-2.13.4.1 Bioconcentration Factors for Fish ( BCF fish 

### ) BCF fish 

### is the ratio of the contaminant concentration in fish to the contaminant concentration in the water column where the fish is exposed. It accounts for uptake of contaminants by fish from water passing across the gills. We derived BCF values for fish for all organic compounds with a log K ow 

### of less than 4.0 (cutoff value with BAF fish 

### ) and for all metals, except lead and mercury, as cited in U.S. EPA (1995b). This implies that the concentration of contaminant in the fish is only due to water intake by the fish, and compounds with a log K ow 

### of less than 4.0 are assumed not to significantly bioaccumulate.

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### Equation A-2-27
Equation A-2-28
Equation A-2-29
Equation A-2-30 It is generally assumed that field measured BCFs ar e based on total (dissolved and suspended) water column concentrations, and laboratory measu red BCFs are based on dissolved water column concentrations. This distinction is important for compounds with a log K ow 

### of greater than or equal to 4.0, because significant amounts of a contaminant can partition into the suspended sediment organic carbon (or particulate phase) of the water column. For compounds with a log K ow 

### of less than 4.0, most of the contaminant is associated with th e dissolved phase of the water colu mn and negligible amounts of the contaminant is associated with the suspended sedim ent phase in the water column. Therefore, for compounds with a log K ow 

### of less than 4.0, BCF values b ased on dissolved contaminant water concentrations in the water column are essentially the same as BCF values based on total (dissolved + suspended) contaminant water concen trations in the water column. Our recommended BCF values don’t recognize differences in total versus dissolved water concentrations when calculating fish concentrations from BCF fish 

### values for compounds with a log K ow 

### of less than 4.0. Since, dissolved water concentrations is the ma jor contributing factor from compounds with a log K ow 

### of less than 4.0, all BCF fish 

### values (regardless of whether they were derived using total or dissolved water concentrations) can be multiplied by the contaminan t concentration in the dissolved water column ( C dw 

### ) to calculate fish concentrations. This assumption is necessary because (1) literature data is often unclear if the water concentrations are dissolved or total con centrations, and (2) most of the literature reviewed indicated that laboratory experiments were conducted us ing filtered or distilled water; or the experiments were conducted using fresh water, but were filte red before analyses for water concentrations. For most compounds, we calculated BCF values using best fit log K ow 

### correlation equations derived by Meylan et al. (1999): C 

### Meylan, W., P.H. Howard, R.S. Boethling, D. Aronson, H. Printup, and S. Gouchie. 1999. “Improved Method for Estimating Bioc oncentration/Bioaccumulation Factor from Octanol/Water Partition Coefficient”. Environmental Toxicology and Chemistry

. 18(4):664-672. Meylan et al. (1999) collected information on measu red BCF and other key expe rimental details for 694 chemicals. Log BCF was then regressed against log K ow 

### , and chemicals with significant deviations from the line of best fit were analyzed by chemical st ructure. The resulting algorithm classifies a substance as either nonionic or ionic, the latter group including carboxylic acids, sulfonic acids and their salts, and quaternary N compounds. Log BCF for nonionics was estimated from log K ow 

### and a series of correction factors if applicable; different equations apply for log K ow 

### 1.0 to 7.0 and >7.0 (Meylan et al. 1999). These equations are as follows: For log K ow 

### < 1 :
For log K ow 

### 1 to 7 :
For log K ow 

### > 7 : For log K ow 

### >10.5 :

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### Equation A-2-31
Equation A-2-32
Equation A-2-33
Equation A-2-34 Equation A-2-35 For ionic compounds (carboxylic acids, sulfonic acids and salts, compounds with N of +5 valence), were categorized by log K ow 

### , and a log BCF in the range 0.5 to 1.75 was assigned as follows: For log K ow 

### < 5 :
For log K ow 

### 5 to 6 :
For log K ow 

### 6 to 7 :
For log K ow 

### 7 to 9 :
For log K ow 

### > 9 :

We assume that BCF fish 

### values calculated using the above co rrelation equations were (1) based on dissolved water concentrations, and (2) not lipid-normalized. Metals We obtained measured BCF fish 

### values for metals (except lead and mercury) from various literature studies, as cited in U.S. EPA (1999a). Values not av ailable in U.S. EPA (1999a) we estimated using the correlation equations above. BCF fish 

### values obtained from U.S. EPA (1999a) were characterized as follows: C 

### Field-measured or laboratory-measured values from various experimental studies were evaluated by U.S. EPA (1999a). This information is summarized in the following document: U.S. EPA. 1999a. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities. Peer Review Draft. August. Field-measured data is only (1) available for a limited number of compounds, and (2) based on a single study. In such cases, the field-measured value or the geometric mean of field-measured values were compared with the geometric mean of laboratory-measured values, and the higher one used. A detailed discussion on sources of BCF values and methodology followed were provided in Appendix C of U.S. EPA (1999a). Measured values from various experimental studies we re evaluated by U.S. EPA (1999a). Detailed discussion and sources of measured values were provi ded in U.S. EPA (1999a). For lead and some mercury compounds, a BAF was determined to be more applicable than a BCF , since those compounds tends to bioaccumulate. Mercury As in U.S. EPA (1997b), elemental mercury isn’t expected to deposit significantly onto soils and surface water. Therefore, it’s assumed that there is no transfer of elemental mercury into fish. Fish are assumed to be exposed only to the divalent and or ganic forms of mercury that exist in the water and soil/sediment media. However, as with the con servative approach adopted by previous guidance documents, all of mercury in the fish is assumed to ex ist or be converted to the methyl mercury (organic) form after uptake into the fish tissue. Therefore, BCF and BAF values are not considered applicable for

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### Equation A-2-36 divalent mercury (mercuric chloride). For methyl mercury, a BAF was determined to be more applicable than a BCF , since mercury tends to bioaccumulate. A2-2.13.4.2 Bioaccumulation Factors for Fish (BAF fish 

### ) BAF fish 

### is the ratio of the contaminant concentration in fish to the contaminant concentration in the water body where the fish are exposed. The BAF fish 

### accounts for uptake of contaminants by fish from water and sediments passing across the gills, and from consump tion of various foods in cluding plankton, daphnids, and other fish. For compounds with a log K ow 

### of greater than or equal to 4.0, contaminants can significantly partition into the suspended sediment organic carbon (or particul ate phase) of the water column. Therefore, BAF values should generally be based on total (dissolvedand suspended) water column concentrations. BAF values for fish reported in the HHRAP database were used for organic compounds (except PCBs, PCDDs, and PCDFs) with a log K ow 

### greater than 4.0, lead and some mercuric compounds. In general we assumed that: • Field-measured BAFs were based on total (dissolved and suspended) water column concentrations; • Laboratory-measured BCFs, and therefore the BAFs predicted from them, were based on dissolved water column concentrations; and • BCFs estimated using correlation Equations A-2-24 through A-2-32, and therefore the BAFs predicted from them, were based on di ssolved water column concentrations. In addition, we assumed that field-measured BCFs for compounds with a log K ow 

### greater than 4.0 were equal to BAFs, because the tissue concentrations are a result of uptake of water (dissolved and suspended), sediment, and various trophic level food. For most organic compounds (except PCBs, PCDDs and PCDFs) with a log K ow 

### greater than 4.0, the FCM, which accounts for accumulation through the food ch ain in addition to water, becomes greater than 1. Therefore, a BAF fish 

### , which takes the food chain into consid eration, is more appropriate than a BCF fish 

### (U.S. EPA 1995c; 1998). As in U.S. EPA (1995c; 1998), we assumed that BAF values for inorganic chemicals equal BCFs (i.e., the FCM is 1.0), unless chemical specific biomagnification data support using a FCM other than 1.0. For consistency, we adjusted all field-measure d BAF (or BCF) values using the methodology suggested in U.S. EPA (1998), to include only the dissolved wa ter column fractions; (i.e., the BAFs based on total water concentrations were converted to BAFs based on dissolved water concentrations). This was done so that all BAF fish 

### values (based on dissolved water concentra tions) can be multiplied by the contaminant concentration in the dissolved water column ( C dw 

### ) to calculate fish concentrations. We used the following equation cited in U.S. EPA (1998) to convert the BAF based on total water concentrations to a BAF based on dissolved water concentrations:

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### Equation A-2-37 where f fd



### = fraction of COPC that is freely dissolved in water DOC = concentration of dissolved organic carbon, kg organic carbon / L water POC = concentration of particulate organic carbon, kg organic carbon / L water Since, the Gobas (1993) model was derived from a study conducted at Lake Ontario, DOC and POC values for Lake Ontario were used. Values cited in U.S. EPA (1998) were: DOC = 2 x 10 -6 

### kg/L POC = 7.5 x 10 -9 

### kg/L A BAF based on dissolved water concentr ations can be calculated from a BAF based on total water concentrations as follows:

Metals (lead) For lead, the food-chain multiplier becomes greater than 1; therefore, a BAF is more appropriate. We obtained the BAF fish 

### value reported in the HHRAP database for lead as a geometric mean from various literature sources described in U.S. EPA (1999a). Since we recommend assuming that metals are insoluble under neutral conditions, the di ssolved and total water concentrations are almost equal. However, for consistency, we adjusted the BAF fish 

### value for lead for dissolved fractions. Mercuric Compounds As in U.S. EPA (1997b), we don’t expect elemental mercury to deposit significantly onto soils and surface water. Therefore, there it is assumed that there is no transfer of elemental mercury into fish. Fish are assumed to be exposed only to the divalent and organic forms of mercury that exists in the water and soil/sediment me dia. However, consistent with the conservative approach adopted by previous guidance documents, all of mercury in the fish is assumed to exist or be converted to the methyl mercury (organic) form after uptake into the fish tissue. Therefore, we obtained the BAF fish 

### value for methyl mercury from U.S. EPA (1997b) for a trophic level 4 fish. A2-2.13.4.3 Biota-Sediment Accumulation Factor for Fish (BSAF fish 

### ) PCDDs, PCDFs, and PCBs BSAF fish 

### accounts for the transfer of cont aminants from the bottom sediment to the lipid in fish. U.S. EPA (2000) and (1993d) recommended using BSAF fish 

### values for dioxin-like compounds, including PCBs, because of their lipophilic nature. U.S. EPA (1995b) also stated that BSAF fish 

### values (1) were used for 2,3,7,8-TCDD and PCBs to estimate protective sediment concentrations instead of surface water concentrations, and (2) were a more reliable measure of bioaccumulation potential because of the analytical difficulties in m easuring dissolved concentrations in surface water. Therefore, for PCDDs, PCDFs, and PCBs, The HHRAP database includes BSAF fish 

### values instead of BAFs for fish. We obtained the BSAF fish 

### values from U.S. EPA (2000). U.S. EPA (2000) provided exposure scenarios for conducting site-specific assessments to dioxin-like compounds. For each scenario, U.S. EPA (2000) recommended the use of the following BSAF fish 

### values based on the amount of chlorination of the PCDD or PCDF: C 

### For TetraCDDs and TetraCDFs, BSAF fish 

### = 9.0 x 10 -02 

### C 

### For PentaCDDs and PentaCDFs, BSAF fish 

### = 9.0 x 10 -02

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### C 

### For HexaCDDs and HexaCDFs, BSAF fish 

### = 4.0 x 10 -02 

### C 

### For HeptaCDDs and HeptaCDFs, BSAF fish 

### = 5.0 x 10 -03 

### C 

### For OctaCDDs and OctaCDFs, BSAF fish 

### = 1.0 x 10 -04 

### Homologue group BSAF fish 

### values obtained from U.S. EPA (2000) were either measured or estimated values that were based on a whole fish lipid cont ent of 7 percent and an organic carbon content of 3 percent. A2-3 TOXICITY BENCHMARKS The following sections discuss carcinogenic and noncar cinogenic toxicity benchmarks of compounds. The toxicity information provided in the HHRAP is for informational purposes to help permitting authorities explain the basis for selecting contaminants of concern. Since toxicity benchmarks and slope factors may change as additional toxicity research is conducted, we highl y recommend consulting with the most current versions of the sources listed belo w before completing a risk assessment, to ensure that the toxicity data used in the risk assessment is based upon the most current Agency consensus.

A2-3.1 Prioritization of Data Sou rces for Chronic Toxicity Benchmarks In December 2003, the Office of Superfund Remedia tion and Technology Innovation distributed OSWER Directive 9285.7-53, (U.S. EPA 2004a) updating the hierach y of sources of human health toxicity values originally distributed in Risk Assessment Guidan ce for Superfund Volume I, Part A, Human Health Evaluation Manual (RAGS) (U.S. EPA 1989). We r ecommend using the same heirarchy of sources for acquiring human health toxicity data to be usedin performing risk assessments of hazardous waste combustion facilities. We gathered the following parameter values for the database: • Chronic Oral Toxicity Benchmarks:



## S Oral Reference Doses ( RfD s) for effects other than cancer (non-cancer)



## S Oral Cancer Slope Factors ( CSF s) for cancer • Chronic Inhalation Toxicity Benchmarks:



## S Inhalation Reference Concentrations ( RfC s) for effects other than cancer (non-cancer)



## S Unit Risk Factors ( URF s) for cancer As with other Agency applications (i.e., U.S. EPA Superfund, 

## Resource Conservation and Recovery Act [RCRA] , and Air Toxics), toxicity benchmarks available in the U.S. EPA Integrated Risk Information System (IRIS) (U.S. EPA 2005) were given first priority. For contaminants lacking current IRIS assessments, we obtained toxicity benchmar k values from one of the following data sources: • Provisional Peer-Reviewed Toxicity Values (PPRTVs) • Other Peer Reviewed Values:

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## S California Environmental Protection Agency (CalEPA) chronic Reference Exposure Levels (RELs) and Unit Risk Estimate (UREs)



## S U.S. Agency for Toxic Substances and Disease Registry (ATSDR) chronic Minimum Risk Levels (MRLs)



## S U.S. EPA. 1997a. Health Effects Assessment Summary Tables (HEAST) and older health effects assessment documents not incorporated into HEAST - U.S. EPA Office of Research and Development (ORD)-National Center for Environmental Assessment (EPA-NCEA) Dose-response assessments that have achieved full intr a-agency consensus are incorporated in IRIS, which is regularly updated and available on-line (U .S. EPA 2005). As of 1996, benchmark values placed on IRIS have undergone external peer review a nd Agency consensus review. Both the U.S. EPA Superfund and RCRA programs accept the primacy of human health toxicity values contained in U.S. EPA's IRIS. The primacy of IRIS toxicity values is also identified in Ri sk Assessment Guidance for Superfund (RAGS) hierarchy (U.S. EPA 1989). A Provisional Peer-Reviewed Toxicity Value (PPRTV) is a toxicity value derived for use in the U.S. EPA Superfund Program when such value is not available in U.S. EPA's IRIS (PPRTVs currently represent the second tier of human health toxicity values for the U.S. EPA Superfund and RCRA hazardous waste programs). PPRTVs are derived after a review of th e relevant scientific literature using the methods, sources of data, and guidance for value derivation used by the U.S. EPA IRIS Program. All provisional toxicity values receive internal review by two EPA sci entists and external peer review by at least two scientific experts. A third scientific review is perfo rmed if there is a conflict between the two original external reviewers. PPRTVs differ in part from IRIS values in that PPRTVs do not receive the multiprogram consensus review provided for IRIS values. This is because IRIS values are generally intended to be used in all U.S. EPA programs, while PPRTVs are developed specifically for the Superfund Program. In general, the need for a PPRTV is eliminated once an analogous IRIS value becomes available. Once IRIS values become availabl e, PPRTVs are generally removed from the PPRTV database. U.S. EPA ORD is concerned that PPRTV’s may be seen (and used) as equivalent to IRIS values, and has restricted direct access to the PPRTV values database to only EPA employees. EPA employees can access the PPRTV database directly via the EPA intranet web site. All others wishing to gain access to PPRTV values need to register as approved users. If you are on an approved or registered user list, and contact the EPA Center which derives PPRTVs they would email PPRTV assessments you request to you. Plus , if you are on this list, they would periodically email you a list of what contaminants are in the PPRTV database. If you think that you would like to be on this list, please contact a risk assessor or toxicologist in an EPA Superfund or hazardous waste program in the EPA Regional Office containing sites y ou are working on or expect to work on. You may also apply to be put on the list by sending an email, with “PPRTV Approved User Application” in the subject line, to HHRAPFeedback@EPA.GOV. Please include the following information in the body of the email: • Your name • Your affiliation (e.g. company or regulatory agency you work for, or civic/public organization, or other entity interested in a risk assessment using PPRTVs) • Email address (if it’s different than the address form which you send the application)

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### As described on the U.S. EPA ORD Air Toxics web site ( http://www.epa.gov/ttn/atw ), the California Environmental Protection Agency (CalEPA) Office of Environmental Health Hazard Assessment has developed dose-response assessments for many subs tances, based both on carcinogenicity and health effects other than cancer. The process for developi ng these assessments is similar to that used by U.S. EPA to develop IRIS values and incorporates signifi cant external scientific peer review. The non-cancer information includes available inhalation health ri sk guidance values expressed as chronic inhalation and oral reference exposure levels (RELs). CalEPA de fines the REL as a concentration level at (or below) which no health effects are anticipated, a concept th at is substantially similar to U.S. EPA's non-cancer dose-response assessment perspective. The HHRAP database shows the chronic REL when no IRIS RfC/RfD or PPRTV exists. CalEPA's quantitative dose-response information on carcinogenicity by inhalation exposure is expressed in terms of the URE, defined similarly to EPA's URE. The HHRAP database shows specific CalEPA UREs where no IRIS or PPRTV values exist. Ca lEPA's dose response assessments for carcinogens and noncarcinogens are available on-line. As with U.S. EPA ORD Air Toxics, ATSDR chronic MRL values were listed in the HHRAP database for assessing noncancer effects. As described on the U.S. EPA ORD Air Toxics web site ( http://www.epa.gov/ttn/atw ), U.S. Agency for Toxic Substances and Disease Registry (ATSDR) develops and publishes Minimum Risk Levels (MRLs) for many toxic substances. The MRL is defined as an estimate of daily human exposure to a substance th at is likely to be without an appreciable risk of adverse effects (other than cancer) over a specified duration of exposure. MR Ls can be derived for chronic exposures by the inhalation and oral rout es. ATSDR describes MRLs as substance-specific estimates to be used by health assessors to select e nvironmental contaminants for further evaluation. MRLs are presented with only 1 significant figure a nd are considered to be levels below which contaminants are unlikely to pose a health threat . Exposures above an MRL do not necessarily represent a threat, and MRLs are therefore not intended for use as predictors of adverse health effects or for setting cleanup levels. ATSDR publishes MRLs as part of po llutant-specific toxicological profile documents, and also in a regularly updated on-line table. Health Effects Assessment Summary Tables (HEA ST) (U.S. EPA. 1997a) cons ist of dose-response assessments for some substances that were prepared by the EPA Office of Research and Development (ORD), but not submitted for internal U.S. EPA consen sus. For some substances, older health effects assessment documents omitted from HEAST also exist and are generally cited in Table A-1 as ORDNational Center for Environmental Assessment (EPA-NCEA) values. In 1989 and for several years thereafter, HEAST was updated on a quarterly basis. HEAST is no longer updated with new values, but existing values are deleted as revised values become available on IRIS.
A2-3.2 Explanation of Calculated Toxicity Benchmark Values In the assessment of risk from contaminants, EPA-deriv ed or reviewed toxicity benchmarks values are recommended. However, for numerous compounds, a co mplete set of inhalation and oral EPA-derived toxicity benchmarks are not available. In such cases, toxicity benchmark values were calculated based on available EPA-derived benchmarks values. For instance, if the oral RfD (mg/kg/day) was available and the inhalation RfC (mg/m 3 

### ) was not; the RfC was calculated by dividing the RfD by an average human inhalation rate of 20 m 3 

### /day and multiplying by the average human body weight of 70 kg. This conversion is based on a route-to-route extrapolati on, which assumes that the toxicity of the given chemical is equivalent over all routes of exposure.

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### Equation A-2-38

Equation A-2-39 Although conversion based on a route-to-route extrapolation of oral dose-response or inhalation information is not optimal risk assessment practice, the alternative would be to omit these substances altogether from any quantitative risk estimate, and th ereby, providing a de facto false negative result of potential risk for the considered route or pathway. Therefore, using route-to-route extrapolation of oral dose-response or inhalation information when applyi ng the HHRAP is preferable when no toxicological benchmark value is available in the peer review ed data sources listed. However, assumptions and uncertainties involved when using toxicity benchmarks calculated based on route-to-route extrapolation should limit their use to screening-level or priority type risk assessments. The following methodology was used to calculate mi ssing toxicity benchmark values using available benchmarks that are based on route-to-route extrapolation: 1) Oral RfD s presented in the peer reviewed sources cited above were used if available. Missing Oral RfD s were calculated from the RfC assuming route-to-route extrapolation using the following equation:

RfC s presented in the peer reviewed sources cite d above were used when available. If RfC s were not available they were calculated from the RfD assuming route-to-route extrapolation and using the i nverse of the equation above. 2) For Inhalation URF s, values were obtained from the p eer reviewed sources cited above. If the Inhalation URF s were not available they were calculated from Oral CSF , using the following equation:

Oral CSF s presented in the peer reviewed sources c ited above were used when available. Missing Oral CSFs were calculated from Inhalation URF values assuming route-to-route extrapolation and using the i nverse of the equation above. A2-3.3 Uncertainties Involved when using Toxicity Benchmarks Calculated based on Route-to-Route Extrapolation The conversion based on a route-to-route extrapolation, which assumes that the toxicity of the given chemical is equivalent over all routes of exposur e, does introduce uncertainty into the assessment. By using this method, it is assumed that the qualitativ e data supporting the benchmark value for a certain route also applies to the route in question. For example, if an RfD is available and the RfC is calculated from that value, the assumption is made that the t oxicity seen following oral exposure will be equivalent to toxicity following inhalation exposure. This assumption could overestimate or underestimate the toxicity of the given chemical following inhalation exposure.

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### Additional information regarding what to consider in the evaluation of route-to-route extrapolations can be found in the U.S. EPA (1994c) document Methods for Derivation of Inhalation Reference Concentrations and App lication of Inhalation Dosimetry . A2-3.4 Prioritization of Data Sources for Acute Toxicity Benchmarks Acute inhalation exposure guidelines and criteria are (1 ) designed to protect a variety of exposure groups including occupational workers, military personne l, and the general public, (2) based on varying exposure durations up to 24 hours in length, and (3) intended to protect against a variety of toxicity endpoints ranging from discomfort or mild adverse hea lth effects to serious, debilitating, and potentially life-threatening effects, up to and including death. Because of the daily operations of most emission sources and the potential for upset conditions to sometimes occur during operations, acute values de veloped to include intermittent exposures were considered more appropriate and more protective than values which are based on the strict assumption that acute exposures will be one-time only. Ther efore, we recommend the Acute Reference Exposure Levels (Acute REL) developed by Cal/EPA, as th e first choice for acute inhalation values (Cal/EPA 1999). Additional acute reference values which also do not exclude intermittent exposures are anticipated to be available from the EPA Office of Research a nd Development. When available, we recommend using those values (referred to as Acute Reference Con centrations [A-RfCs]) as the first choice, with the Cal/EPA acute RELs second in the hierarchy. Pl ease note that the values we recommend using from all of the sources are based on one-hour exposures. 1. Cal/EPA Acute RELs – an acute REL represents the concentration in air at or below which no adverse health effects are anticip ated in the general population, including sensitive individuals, for a specified exposure period (Cal/EPA 1999) 2. Acute inhalation exposure guidelines (AEGL-1) – an AEGL-1 value represents “the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals , could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and revers ible upon cessation of exposure.” (NAC 2002) 3. Level 1 emergency planning guidelines (ERPG-1) – an ERPG-1 value represents “the maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experienci ng other than mild transient adverse health effects or perceiving a clearly defined objectionable odor.” (AIHA 2004; SCAPA 2004) 4. Temporary emergency exposure limits (TEEL-1) – a TEEL-1 value represents “the maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined odor.” (SCAPA 2004) It should be noted that the TEEL-1 values (SCAPA 2004) are calculated based on an assumed exposure period of 15-minutes. To evaluate risks due to acu te exposure based on the highest 1-hour average air concentrations, the TEEL-1 values were extrapolated from a 15-minute to a 1-hour exposure basis using a modification to Haber’s Rule devel oped by ten Berge (1986) and used by Cal/EPA to develop acute RELs (Cal/EPA 1999), as shown below.

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# C T K n 

# × = Equation A-2-40
where C = Concentration (mg/m 3 

### ) n = Constant greater than zero (unitless) T = Time of exposure (hour) K = Constant level or severity of response (unitless)
Where available, chemical-sp ecific values for the parameter n as selected and recommended by Cal/EPA’s Office of Environmental Health Hazard Assessment (OEHHA) based on the work of ten Berge (1986) and the open literature were used to make th e extrapolations (Cal/EPA 1999). For chemicals for which a chemical-specific value of n was not available, extrapolations were made using a value of n = 1, as recommended by OEHHA, because the extrapolations were all based on an initial exposure period (15- minutes) of less than 1 hour duration (Cal/EPA 1999). Use of the modified form of Haber’s Rule allows contributions by both concentration and time to the overall severity of effect to be considered. Howeve r, the extrapolated air concentrations are to be interpreted carefully, and should not be interpreted to be absolutes. For example, chemical-specific values of the exponent n are sometimes based on a rela tively limited set of dose-response data. Also, the majority of extrapolated TEEL-1 values were calculate d using default exponent values and, therefore, are likely to be even less certain than exponent values based on limited data sets. The hierarchy is presented in order of preference, fro m 1 (most preferred) to 4 (least preferred). If no acute REL value is available for a given contaminant, one can work down the list in order. If no AEGL-1 value is available, but an AEGL-2 value is availabl e, the AEGL-2 can be selected as the AIEC only if it is a more protective value (lower in concentration) th an an ERPG-1 or a TEEL-1 value if either of these values is available.U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-2-39 

# REFERENCES APPENDIX A-2

Agency for Toxic Substances and Disease Registry (ATSDR). 1987. Draft Toxicological Profile for Di(2-ethylhexyl) Phthatlate. Oak Ridge National Laboratory. December. ATSDR. 1993. Toxicological Profile for Selected PCBs (Aroclor-1260, -1254, -1248, -1242, -1232, –1221, and -1016). ATSDR. Atlanta, GA. Bacci E., D. Calamari, C. Gaggi, and M. Vighi. 1990. “Bioconcentration of Organic Chemical Vapors in Plant Leaves: Experimental Measurements and Correlation.” Environmental Science and Technology . Volume 24. Number 6. Pages 885-889. Bacci E., M. Cerejeira, C. Gaggi, G. Chemello, D. Calamari, and M. Vighi. 1992. “Chlorinated Dioxins: Volatilization from Soils and Bioconcentration in Plant Leaves.” Bulletin of Environmental Contamination and Toxicology . Volume 48. Pages 401-408. Baes, C.F. 1982. “Prediction of Radionuclide K d

### values from Soil-Plant Concentration Ratios.” Tran. American Nuclear Society. 41:53-54. Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor . 1984. “Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides through Agriculture.” Oak Ridge National Laboratory. Oak Ridge, Tennessee. Banerjee, S., P.H. Howard, and S.S. Lande. 1990. “General Structure Vapor Pressure Relationships for Organics.” Chemosphere . 21(10-11). Pages 1173-1180. Belcher, G.D., and C.C. Travis. 1989. “Mode ling Support for the RURA and Municipal Waste Combustion Projects: Final Report on Sensitivity and Uncertainty Analysis for the Terrestrial Food Chain Model.” Interagency Agreement No. 1824-A020-A1. Office of Risk Analysis, Health and Safety Research Division. Oak Ri dge National Laboratory. Oak Ridge, Tennessee. October. Bidleman, T.F. 1984. “Estimation of Vapor Pr essures for Nonpolar Organic Compounds by Capillary Gas Chromatography. Analytical Chemistry. Volume 56. Pages 2490-2496. Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology. Volume 22. Number 4. Pages 361-367. Billington, J.W., G. Huang, F. Szeto, W.Y. Shiu , and D. Mackay. 1988. “Preparation of Aqueous Solutions of Sparingly Soluble Organic Substances: I. Single Component Systems.” Environmental Toxicology and Chemistry. Volume 7. Pages 117-124. Bintein, S., J. Devillers, and W. Karcher. 1993. “Nonlinear Dependence of Fish Bioconcentration on n-Octanol/Water Partition Coefficient.” SAR and QSAR in Environmental Research . Volume 1. Pages 29-39.

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### Boyd, S.A. 1982. “Adsorption of Substituted Phenols by Soil.” Soil Science . 134(5):337-343. Briggs, G.G., R.H. Bromilow, and A.A. Evans. 1982. “Relationships Between Lipophilicity and Root Uptake and Translocation of Nonionized Chemicals by Barley.” Pesticide Science . Volume 13. Pages 495-504. Bruggeman, W.A., J. Van Der Steen, and O. Hutzinger. 1982. “Reversed-Phase Thin-Layer Chromatography of Polynuclear Aromatic Hydrocarbons and Chlorinated Biphenyls. Relationship with Hydrophobicity as Measured by Aqueous Solubility and Octanol-Water Partition Coefficient.” Journal of Chromatography . Volume 238. Pages 335-346. Budavari, S., M.J. O’Neil, A. Smith, and P.E. Heckelman. 1989. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th Edition. Merck and Company, Inc. Rahway, New Jersey. California Environmental Protection Agency (Cal/EPA). 1993. “Parameter Values and Ranges for CALTOX.” Draft. Office of Scientific Affairs. California Department of Toxic Substances Control. Sacramento, CA. July. Cal/EPA. 1999. “Air Toxics Hot Spot Program RiskAssessment Guidelines, Part I, The Determination of Acute Reference Exposure Levels for Airborne Toxicants.” Office of Environmental Health Hazard Assessment. March. On-Line Address: http://www.oehha.ca.gov/air/pdf/acuterel.pdf Callahan, M.A., M.W. Slimak, N.W. Gabel, I.P. May, C.F. Fowler, J.R. Freed, P. Jennings, R.L. Dorfee, F.C. Whitmore, B. Maestri, W.R. Mabey, B.R. Holt, and C. Gould. 1979. Water-Related Environmental Fate of 129 Priority Pollutants, Volume I . EPA 440/4-79-029ab. Chamberlain, A.C. 1970. “Interception and Rete ntion of Radioactive Aerosols by Vegetation.” Atmospheric Environment . Pergamon Press. Great Britain. Volume 4. Pages 57-78. Chiou, C.T., V.H. Freed, D.W. Schmedding, and R.L. Kohnert. 1977. “Partition Coefficient and Bioaccumulation of Selected Organic Chemicals.” Environ. Sci. Technol. 11(5):475-478. Di Toro, D.M. 1985. “A Particle Interaction Model of Reversible Organic Chemical Sorption.” Chemosphere. 14(10):1503-1538. DiToro, D.M., C.S. Zarba, D.J. Hansen, W.J. Berry, R.C. Swartz, C.E. Cowan, S.P. Pavlou, H.E. Allen, N.A. Thomas, and P.R. Paquin. 1991. “Technical Basis for Establishing Sediment Quality Criteria for Nonionic Compounds Using Equilibrium Partitioning.” Environmental Toxicology and Chemistry . 10:1541-1583. Eadie, B.J., N.R. Morehead, and P.F. Landrum. 1990. “Three-Phase Partitioning of Hydrophobic Organic Compounds in Great Lakes Waters.” Chemosphere . Volume 20. Pages 161-178. Ellegehausen, H., J.A. Guth, and H.O. Esser. 1980. “Factors Determining the Bioaccumulation Potential of Pesticides in the Individual Compar tments of Aquatic Food Chains.” Ecotoxicology and Environmental Safety . 4:134.

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### Foreman, W.T., and T.F. Bidleman. 1985. “Vapor Pressure Estimates of Individual Polychlorinated Biphenyls and Commercial Fluids Using G as Chromatographic Retention Data.” J. Chromatogr. 330:203-216. Gobas, F.A.P.C. 1993. “A Model for predicting the bioaccumulation of hydrophobic organic chemicals in aquatic food-webs: appli cation to Lake Ontario.” Ecological Modeling . 69:1-17. Griffin, R.A., R. Clark, M.C. Lee, and E.S.K. Chia n. 1978. “Disposal and Removal of Polychlorinated Biphenyls in Soil.” In Land Disposal of Hazardous Waste . EPA-600/9-78-016. Pages 169-181. Hagenmaier, H.; She, J.; Linidig, C. (1992) Pers istence of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in contaminated soil at Maulach and Rastatt in Southwest Germany. Chemosphere . 25(7-10):1449-1456. Hansch, C., and A. Leo. 1985. Medchem Project . Pomona College. Clairemont, California. Issue No. 26. Haque, R., and D. Schmedding. 1975. “A Method of Measuring the Water Solubility of Hydrophobic Chemicals: Solubility of Five Polychlorinated Biphenyls.” Bulletin of Environmental Contamination and Toxicology. Volume 14. Pages 13-18. Hinckley, D.A., T.F. Bidleman, and W.T. Foreman. 1990. “Determination of Vapor Pressures for Nonpolar and Semipolar Organic Compounds fro m Gas Chromatographic Retention Data.” Journal of Chemical Engineering Data. Volume 35. Pages 232-237. Hodson, J., and N.A. Williams. 1988. “The Estimati on of the Adsorption Coefficient (Koc) for Soils by High Performance Liquid Chromatography.” Chemosphere. 17(1):67-77. Hoffman, F.O., K.M. Thiessen, M.L. Frank, and B.G. Blaylock. 1992. “Quantification of the Interception and Initial Retention of Radioac tive Contaminants Deposited on Pasture Grass by Simulated Rain.” Atmospheric Environment. 26A(18):3313-3321. Hollifield, H.C. 1979. “Rapid Nephelometric Estimat e of Water Solubility of Highly Insoluble Organic Chemicals of Environmental Interests.” Bull. Environ. Contam. Toxicol. 23:579-586. Howard, P.H. 1989-1993. Handbook of Environmental Fate and Exposure Data For Organic Chemicals

. Volume I: Large Production and Priority Pollutants (1989). Volume II: Solvents (1990). Volume III: Pesticides (1991). Volume IV: Solvents2 (1993) . Lewis Publishers. Chelsea, Michigan. Howard, P.H., R.S. Boethling, W.F. Jarvis, W.M. Meylan, and E.M. Michalenko, 1991. Handbook of Environmental Degradation Rates. Lewis Publishers. Chelsea, Michigan. Iaacson, P.J., and C.R. Frink. 1984. “Nonrever sible Sorption of Phenolic Compounds by Sediment Fractions: The Role of Sediment Organic Matter.” Environ. Sci. Technol. 18:43-48. Junge, C. E. 1977. Fate of Pollutants in the Air and Water Environments, Part I . Suffet, I. H., Ed. Wiley. New York. Pages 7-26.

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### Karickhoff, S.W., D.S. Brown, and T.A. Scott. 1979. “Sorption of Hydrophobic Pollutants on Natural Sediments.” Water Resources. 13:241-248. Kenaga, E.E., and C.A.I. Goring. 1980. “Rel ationship between Water Solubility, Soil Sorption, Octanol-water Partitioning, and Concentration of Chemicals in Biota.” Aquatic Toxic. Pages 78-115. Karickhoff, S.W., and J.M. Long. 1995. “ Intern al Report on Summary of Measured, Calculated, and Recommended Log K ow 

### Values.” Environmental Research Laboratory. Athens, Georgia. April 10. Kollig, H.P. 1993. Environmental Fate Constants for Organic Chemicals Under Consideration for EPA’s Hazardous Waste Identification Projects. U.S. EPA Office of Research and Development. Environmental Research Laboratory. Athens, Georgia. Landrum, P.F., S.R. Nihart, B.J. Eadie, and W.S. Gardner. 1984. “Reverse-Phase Separation Method for Determining Pollutant Binding to Aldrich Humic Acid and Dissolved Organic Carbon of Natural Waters.” Environmental Science and Technology. 18(3):187-192. Lawrence, J., and H.M. Tosine. 1976. “Adsor ption of Polychlorinated Biphenyls from Aqueous Solutions and Sewage.” Environmental Science and Technology . 10:381-383. Lee, M.C., S.K. Chian, and R.A. Griffin. 1979. “Solubility of Polychlorinated Biphenyls and Capacitor Fluid in Water.” Water Res . 13:1249-1258. Lorber, M. 1995. “Development of an Air-to-plant Vapor Phase Transfer for Dioxins and Furans. Presented at the 15th International Symposium on Chlorinated Dioxins and Related Compounds”. August 21-25, 1995 in Edmonton, Canada. Abstract in Organohalogen Compounds

. 24:179-186. Lorber, M., and P. Pinsky. 1999. “An Evaluation of Three Empirical Air-to-Leaf Models for Polychlorinated Dibenzo-p-Dioxi ns and Dibenzofurans.” National Center for Environmental Assessment (NCEA). U. S. EPA, 401 M St. SW, Washington, DC. Accepted for Publication in Chemosphere

. Lucius, J.E., R.O. Olhoeft, P.L. Hill, and S.K. Duke. 1992. Properties and Hazards of 108 Selected Substances - 1992 Edition. U.S. Department of the Interior Geological Survey. U.S. Geological Survey Open-File Report 92-527. September. Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1982. Handbook of Chemical Property Estimation Methods: Environmental Behavior of Organic Compounds. McGraw-Hill Book Company. New York, New York. Ma, K.C., W.Y. Shiu, and D. Mackay. 1990. A Critically Reviewed Compilation of Physical and Chemical and Persistence Data for 110 Selected EMPPL Substances. Prepared for the Ontario Ministry of Environment. Water Resources Branch. Toronto, Ontario.

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### Mabey, W.R., J.H. Smith, R.T. Podoll, H.L. Johnson, H. L. Mill, T.W. Chiou, J. Gate, I. Waight-Partridge, H. Jaber, and D. Vanderberg. 1982. Aquatic Fate Process Data for Organic Priority Pollutants

. U.S. EPA Report Number 440/4-81-014. December. McCarthy, J.F., and B.D. Jimenez. 1985. “Interac tions Between Polycyclic Aromatic Hydrocarbons and Dissolved Humic Material: Binding and Dissociation.” Environmental Science and Technology. 19(11):1072-1076. Mackay, D., and S. Paterson. 1991. “Evaluating the Multimedia Fate of Organic Chemicals: A Level III Fugacity Model.” Environmental Science and Technology. Volume 25(3). Pages 427-436. Mackay, D., and W.Y. Shiu. 1975. “The Aqueous Solubility and Air-Water Exchange Characteristics of Hydrocarbons under Environmental Conditions.” In Chemistry and Physics of Aqueous Gas Solutions. Electrochem. Soc., Inc. Princeton, New Jersey. Mackay, D. W.Y. Shiu, and K.C. Ma. 1992. Illustrated Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals. Volume I—Monoarom atic Hydrocarbons, Chlorobenzenes, and PCBs. Volume II—Polynuc lear Aromatic Hydrocarbons, Polychlorinated Dioxins, and Dibenzofurans. Volu me III—Volatile Organic Chemicals. Lewis Publishers. Chelsea, Michigan. Mackay, D., and A.W. Wolkoff. 1973. “Rate of Evaporation of Low-Solubility Contaminants from Water Bodies to Atmosphere.” Environmental Science and Technology. Volume 7. Pages 611-614. McLachlan, M.S., H. Thoma, M. Reissinger, and O. Hutzinger. 1990. “PCDD/F in an Agricultural Food Chain. Part I: PCDD/F Mass Balance of a Lactating Cow.” Chemosphere. Volume 20 (Numbers 7-9). Pages 1013-1020.McLachlan, M.S.; Sewart, A.P.; Bacon, I.R.; Jones, K.C. (1996). “Persistence of PCDD/Fs in a sludgeamended soil”. Environ. Sci. Technol. 30(8):2567-2571. Macrady, J.K., and S.P. Maggard. 1993. “Uptake and Photodegradation of 2,3,7,8-Tetrachlorodibenzo-p-dioxin Sorbed to Grass Foliage.” Environmental Science and Technology . 27:343-350. Mallon, B.J., and F.I. Harrison. 1984. “Octanol -Water Partitioning Coefficient of Benzo(a)pyrene: Measurement, Calculation, and Environmental Implications.” Bulletin of Environmental Contamination and Toxicology . New York. Pages 316-323. Metcalfe, D.E., G. Zukova, D. Mackay, and S. Pate rson. 1988. “Polychlorinated Biphenyls (PCBs), Physical and Chemical Properties”. In: Hazards, Decontamination and Replacement of PCB, A Comprehensive Guide . Pages 3-33. J.P. Crine Editor. Plenum Press. New York, N.Y. Meylan, W., P.H. Howard, and R.S. Boethling. 1992. “Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients.” Environmental Science and Technology

. 26(8):1560-1567.

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### Miller, M.M., S.P. Wasik, G.L. Huang, W.Y. Shiu, and D. Mackay. 1985. “Relationships Between Octanol-Water Partition Coefficient and Aqueous Solubility.” Environmental Science and Technology . 19(6):522-529. Mills, W.B., J.D. Dean, D.B. Porcella, S.A. Gherini, R.J.M. Hudson, W.E. Frick, G.L. Rupp, and G.L. Bowie. 1982. Water Quality Assessment: A Screeni ng Procedure for Toxic and Conventional Pollutants . Part 1. EPA 600/6-82-004a. Monsanto Co. 1972. Presentations to the independent task force on PCB, May 15, 1972. Washington D.C. Montgomery, J.H., and L.M. Welkom. 1991. Groundwater Chemicals Desk Reference. Lewis Publishers. Chelsea, Michigan. Murray, J.M., R.F. Pottie, and C. Pupp. 1974. “The Vapor Pressures and Enthalpies of Sublimation of Five Polycyclic Aromatic Hydrocarbons.” Can. J. Chem . 52:557-563. Moses, A.J. 1978. The Practicing Scientist’s Handbook. A Gu ide for Physical and Terrestrial Scientists and Engineers. Van Nostrand Reinhold Company. New York, NY. Nelson, N., P.B. Hammond, I.C.T. Nisbel, A.F. Sarofim, and W.H. Drury. 1972. “Polychlorinated Biphenyls: Environmental Impact.” Environ. Res . 5:249-362. Nisbet, J.C.T., and A.F. Sarofim. 1972. “Rates and Routes of Transport of PCBs in the Environment.” Environ. Health Perspectives . 1:21-38. North Carolina Department of Environment, H ealth, and Natural Resources (NC DEHNR). 1997. North Carolina Protocol for Performing Indirect Ex posure Risk Assessments for Hazardous Waste Combustion Units . January. Ogata, M., K. Fujisawa, Y. Ogino, and E. Mano. 1984. “Partition Coefficients as a Measure of Bioconcentration Potential of Crude O il Compounds in Fish and Shellfish.” Bulletin of Environmental Contaminant Toxicology . Volume 33. Page 561. Paris, D.F., W.C. Steen, and G.L. Baughman. 1978. “Role of Physico-Chemical Properties of Arochlors 1016 and 1242 in Determining their Fate and Transport in Aquatic Environments.” Chemosphere. 4:319-325. Paustenbach, D.J., R.J. Wenning, V. Lau, N.W. Harrington, D.K. Rennix, A.H. Parsons. 1992. “Recent Developments on the Hazards Posed by 2,3,7,8- Tetrachlorobenzo-p-dioxin in Soil: Implications for Setting Risk-based Cleanup Levels at Residential and Industrial Sites.” J. Toxicol. and Environ. Health . 36:103-149. Pennington, J.A.T. 1994. Food Value of Portions Commonly Used . Sixteenth Edition. J.B. Lippincott Company, Philadelphia. Rao, P.S.C., A.G. Hornsby, D.P. Kilcrease, and P. Nkedi-Kizza. 1985. “Sorption and Transport of Hydrophobic Organic Chemicals in Aqueous and Mixed Solvent Systems: Model Development and Preliminary Evaluation.” J. Environ. Qual. 14(3):376-383.

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### Research Triangle Institute (RTI). 1992. Preliminary Soil Action Level for Superfund Sites, Draft Interim Report. Prepared for U.S. Environmental Protection Agency (EPA) Hazardous Site Control Division, Remedial Operations Guidance Branch. Arlington, Virginia. EPA Contract No. 68-W1-0021. Work Assignment No. B-03. Work Assignment Manager, Loren Henning. December. RTI. 1994. “Draft Report—Chemical Properties for Soil Screening Levels.” North Carolina. July 26. RTI. 2005. Methodology for Predicting Cattle Biotransfer Factors. Prepared for U.S. Environmental Protection Agency (EPA) Office fo Solid Waste. EPA Contract No. 68-W-03-042. August. Subcommittee on Consequence Assessment and Protec tive Actions (SCAPA). 2001a. “Revision 17 ofERPGs and TEELs for Chemicals of Concern.” U.S. Department of Energy. January 10. OnLine Address: http://tis-hq.eh.doe.gov/web/Chem_Safety/teel.htm SCAPA. 2001b. “SCAPA ERPG Working List.” August 13. On-Line Address: http://www.bnl.gov/scapa/scapawl.htm Smith, J.H., W.R. Mabey, N. Bahonos, B.R. Holt, S.S. Lee, T.W. Chou, D.C. Venberger, and T. Mill. 1978. Environmental Pathways of Selected Chemic als in Fresh Water Systems: Part II, Laboratory Studies. Interagency Energy-Environment Research Program Report. Environmental Research Laboratory. Office of Research and Development. U.S. EPA. Athens, Georgia. EPA-600/7-78-074. Page 304. Southworth, G.R., and J.L. Keller. 1986. “Hyd rophobic Sorption of Polar Organics by Low Carbon Soils.” Water, Air, and Soil Pollution. 28:239-248. Stephenson, R.M., and S. Malanowski. 1987. Handbook of the Thermodynamics of Organic Compounds. Elsevier Publishing Company, Inc. New York. Stephan, C.E., and others. 1993. “Derivation of Proposed Human Health and Wildlife Bioaccumulation Factors for the Great Lakes Initiative.” Office of Research and Development, U.S. Environmental Research Laboratory. PB93-154672. Springfield, Virginia. Stephens, R.D., M. Petreas, and G.H. Hayward. 1995. “Biotransfer and Bioaccumulation of Dioxins and Furans from Soil: Chickens as a Model for Foraging Animals.” The Science of the Total Environment. 175: 253-273. July 20. Thomann, R.V. 1989. “Bioaccumulation Model of Organic Chemical Distribution in Aquatic Food Chains.” Environmental Science and Technology . 23(6):699-707. Thomann, R.V., J.P. Connolly, and T.F. Parkerton. 1992. “An Equilibrium Model of Organic Chemical Accumulation in Aquatic Food Webs with Sediment Interaction.” Environmental Toxicology and Chemistry. 11:615-629. Thompson, S.E., C.A. Burton, D.J. Quinn, and Y.C. Ng. 1972. “Concentration Factors of Chemical Elements in Edible Aquatic Organisms.” La wrence Radiation Laboratory. Livermore, CA. UCRL-50564, Revision 1. (Reference cited in updated version of Chapman, W.H., H.L. Fisher, and M.W. Pratt. 1968).

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### Travis, C.C. and A.D. Arms. 1988. “Bioconcentr ation of Organics in Beef, Milk, and Vegetation.” Environmental Science and Technology. 22:271-274. U.S. EPA. 1978. Environmental Pathways of Selected Chem icals in Freshwater Systems: Part II. Laboratory Studies. Interagency Energy-Environment Research and Development Program Report. Environmental Research Laboratory. Athens, GA. EPA 600/7-78-074. May. U.S. EPA. 1986. Superfund Public Health Evaluation Manual. Office of Emergency and Remedial Response (OERR). Washington, D.C. October. U.S. EPA. 1989. Risk Assessment Guidance for Superfund: Vo lume I. Human Health Evaluation Manual (Part A) . OERR. Washington, D.C. OERR 9200 6-303-894. U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions . EPA/600/6-90/003. January. U.S. EPA. 1992a. Handbook of Resource Conservation and Recovery Act (RCRA) Ground Water Monitoring Constituents: Chemical and Physical Properties. EPA/530-R-92/022. Office of Solid Waste. Washington, D.C. U.S. EPA. 1992b. Technical Support Document for the Land A pplication of Sewage Sludge. Volumes I and II . EPA 822/R-93-001a. Office of Water. Washington, D.C. U.S. EPA. 1992c. Risk Reduction Engineering Laboratory Treatability DataBase. Version 5.0. U.S. EPA. 1993a. Assessment Tools for the Evaluation of Risk. U.S. EPA. 1993b. Derivation of Proposed Human Health and Wildlife Bioaccumulation Factors for the Great Lakes Initiative. Office of Research and Development, U.S. Environmental Research Laboratory. Duluth, Minnesota. March. U.S. EPA. 1993c. “Proposed Water Quality Guidance for the Great Lakes System.” Federal Register. 58:20802. April 16. U.S. EPA. 1993d. Review Draft Addendum to the Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions . Office of Health and Environmental Assessment. Office of Research and Development. EPA-600-AP-93-003. November 10. U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compounds . Draft Report. Office of Research and Development. Washington, D.C. EPA/600/6-88/005Ca,b,c. June. U.S. EPA. 1994b. Revised Draft Guidance for Performing S creening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes: Attachme nt C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . OERR. Office of Solid Waste. December 14. U.S. EPA. 1994c. Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry . ORD. EPA/600/8-90/066F.

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### U.S. EPA. 1995a. Memorandum regarding Further Studies for Modeling the Indirect Exposure Impacts from Combustor Emissions. From Mathew Lorber, Exposure Assessment Group, and Glenn Rice, Indirect Exposure Team, Environmental Criteria and Assessment Office. Washington, D.C. January 20. U.S. EPA. 1995b. Review Draft Development of Human He alth-Based and Ecologically-Based Exit Criteria for the Hazardous Waste Identification Project . Volumes I and II. Office of Solid Waste. March 3. U.S. EPA. 1995c. Great Lakes Water Quality Initiative. Tec hnical Support Document for the Procedure to Determine Bioaccumulation Factors . Office of Water. EPA-820-B-95-005. March. U.S. EPA. 1996. Soil Screening Guidance: Technical Background Document and User’s Guide . Office of Solid Waste and Emergency Response. Washington, D.C. EPA/540/R-95/128. May. U.S. EPA. 1997a. “Health Effects Assessment Summary Tables (HEAST). Fiscal Year 1997 Update”. Office of Solid Waste and Emergency Res ponse. EPA-540-R-97-036. PB97-921199. July. U.S. EPA. 1997b. Mercury Study Report to Congress. Volu me III: Fate and Transport of Mercury in the Environment. OAQPS and ORD. EPA-452/R-97-005. December. U.S. EPA. 1997c. Exposure Factors Handbook . “Food Ingestion Factors”. Volume II. EPA/600/P-95/002Fb. August. U.S. EPA. 1998. “Methodology for Assessing Health Risks Associated with Multiple Pathways of Exposure to Combustor Emissions (MPE)”. U pdate to EPA/600/6-90/003. Office of Research and Development, National Center for Environmental Assessment, U.S. EPA. EPA/600/R-98/137. December. U.S. EPA. 1999a. Screening Level Ecological Risk Assessmen t Protocol for Hazardous Waste Combustion Facilities. Peer Review Draft. August

. U.S. EPA. 1999b. “Toxicological Review of Acet aldehyde, CAS No. 75-07-0, In Support of Summary Information on the Integrated Risk Information System (IRIS).” Superfund Technical Support Center. NCEA. NCEA-S-0687. December. U.S. EPA. 2004a. Memorandum Regarding Huma n Health Toxicity Values in Superfund Risk Assessments. From Michael B. Cook, Director, Office of Superfund Remediation and Technology Innovation (OSRTI). To Superfund National Policy Managers, Regions 1 - 10. OSWER Directive 9285.7-53. December. U.S. EPA. 2004b. Superfund Chemical Data Matrix. OERR. Washington, D.C. January. U.S. EPA. 2004c. WATER9—Air Emissions Models Wastewater Treatment . Version 2.0.0. OAQPS. Research Triangle Park. North Carolina. July 1 U.S. EPA. 2005. Integrated Risk Information System (IRIS). Values updated monthly on line at http://www.epa.gov/iris/ . Values presented in the HHRAP database are current as of August 2005.

### Human Health Risk Assessment Protocol Appendix A-2 September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-2-48 

### Veith, G.D., N.M. Austin, and R.T. Morris. 1979a. “A Rapid Method for Estimating Log P for Organic Chemicals.” Water Res. 13:43-47. Veith, G.D., D.L. DeFoe, and B.V. Bergstedt. 1979b. “Measuring and Estimating the Bioconcentration Factor of Chemicals in Fish.” Journal of Fish. Res. Board Can. 26:1040-1048. Veith, G.D., K.J. Macek, S.R. Petrocelli, and J. Caroll. 1980. “An Evaluation of Using Partition Coefficients and Water Solubility to Estimate Bi oconcentration Factors for Organic Chemicals in Fish.” Journal of Fish. Res. Board Can. Prepublication Copy. Verschueren, K. 1983. Handbook of Environmental Data on Organic Chemicals . Second Edition. Van Nostrand Reinhold Company. New York. Weast, R.C. 1981. Handbook of Chemistry and Physics . 62nd Edition. Cleveland, Ohio. CRC Press. Welsch-Pausch, K.M. McLachlan, and G. Umlauf. 1995. “Determination of the Principal Pathways of Polychlorinated Dibenzo-p-dioxins and Dibe nzofurans to Lolium Multiflorum (Welsh Ray Grass)”. Environmental Science and Technology . 29: 1090-1098. Zitko, V. 1971. “Polychlorinated Biphenyls and Organochlorine Pesticides in Some Fresh Water and Marine Fishes.” Bull. Contam. Toxicol . 6:464-470.

### CHEMICALS OF POTENTIAL CONCERN INCLUDED IN THE COMPANION DATABASE CAS# Compound CAS# Compound Human Health Risk Assessment Protocol Appendix A-2 September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-2-49 

### 83-32-9 Acenaphthene 75-07-0 Acetaldehyde 67-64-1 Acetone 75-05-8 Acetonitrile 98-86-2 Acetophenone 107-02-8 Acrolein 107-13-1 Acrylonitrile 309-00-2 Aldrin 62-53-3 Aniline 120-12-7 Anthracene 7440-36-0 Antimony compounds 12674-11-2 Aroclor 1016 11097-69-1 Aroclor 1254 7440-38-2 Arsenic Compounds 1912-24-9 Atrazine 7440-39-3 Barium 100-52-7 Benzaldehyde 71-43-2 Benzene 56-55-3 Benzo(a)anthracene 50-32-8 Benzo(a)pyrene 205-99-2 Benzo(b)fluoranthene 207-08-9 Benzo(k)fluoranthene 65-85-0 Benzoic acid 100-47-0 Benzonitrile 100-51-6 Benzyl alcohol 100-44-7 Benzyl chloride 7440-41-7 Beryllium compounds 319-84-6 BHC, alpha- (alpha-Hexachlorocyclohexane) 319-85-7 BHC, beta- (beta-Hexachlorocyclohexane) 111-44-4 Bis(2-chlorethyl)ether 75-27-4 Bromodichloromethane 75-25-2 Bromoform (Tribromomethane) 101-55-3 Bromophenyl-phenylether, 4- 7440-43-9 Cadmium compounds 75-15-0 Carbon disulfide 56-23-5 Carbon tetrachloride 57-74-9 Chlordane 7782-50-5 Chlorine 59-50-7 Chloro-3-methylphenol, 4-106-47-8 Chloroaniline, p108-90-7 Chlorobenzene 510-15-6 Chlorobenzilate 75-45-6 Chlorodifluoromethane 75-00-3 Chloroethane 67-66-3 Chloroform (Trichloromethane) 39638-32-9 Chloroisopropyl ether, bis-1,2- 91-58-7 Chloronaphthalene,2- 95-57-8 Chlorophenol, 2- 7005-72-3 Chlorophenyl-phenylether, 4- 2921-88-2 Chlorpyrifos 7440-47-3 Chromium compounds 18540-29-9 Chromium, hexavalent 218-01-9 Chrysene 108-39-4 Cresol, m- (3-Methylphenol)95-48-7 Cresol, o106-44-5 Cresol, p98-82-8 Cumene (Isopropylbenzene) 57-12-5 Cyanide Compounds 72-54-8 DDD, 4,4'- 72-55-9 DDE, 4,4'- 50-29-3 DDT, 4-4'- 333-41-5 Diazinon 53-70-3 Dibenz(a,h)anthracene 96-12-8 Dibromo-3-chloropropane, 1,2- 124-48-1 Dibromochloromethane 95-50-1 Dichlorobenzene, 1,2- 541-73-1 Dichlorobenzene, 1,3- 106-46-7 Dichlorobenzene,1,4- 91-94-1 Dichlorobenzidine, 3,3'- 75-71-8 Dichlorodifluoromethane 75-34-3 Dichloroethane 1,1- 107-06-2 Dichloroethane, 1,2- (Ethylene Dichloride) 75-35-4 Dichloroethylene 1,1- 156-59-2 Dichloroethylene, cis-1,2- 156-60-5 Dichloroethylene-1,2 (trans) 120-83-2 Dichlorophenol, 2,4- 78-87-5 Dichloropropane, 1,2- 542-75-6 Dichloropropene, 1,3- 62-73-7 Dichlorvos 60-57-1 Dieldrin 84-66-2 Diethyl phthalate 131-11-3 Dimethyl phthalate 105-67-9 Dimethylphenol, 2,4- 119-90-4 Dimethyoxybenzidine, 3,3'-

### CHEMICALS OF POTENTIAL CONCERN INCLUDED IN THE COMPANION DATABASE CAS# Compound CAS# Compound Human Health Risk Assessment Protocol Appendix A-2 September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-2-50 

### 84-74-2 Di-n-butyl phthalate 99-65-0 Dinitrobenzene, 1,3- 51-28-5 Dinitrophenol, 2,4- 121-14-2 Dinitrotoluene, 2,4- 606-20-2 Dinitrotoluene, 2,6- 117-84-0 Di-n-octylphthalate 123-91-1 Dioxane, 1,4- 646-06-0 DIOXOLANE,1,3- 122-66-7 Diphenylhydrazine,1,2- 298-04-4 Disulfoton 115-29-7 Endosulfan I 72-20-8 Endrin 106-89-8 Epichlorohydrin (1-Chloro-2,3- epoxypropane) 97-63-2 Ethyl methacrylate 62-50-0 Ethyl methanesulfonate 100-41-4 Ethylbenzene 106-93-4 Ethylene Dibromide 75-21-8 Ethylene oxide 117-81-7 Ethylhexyl phthalate, bis-2- 206-44-0 Fluoranthene 86-73-7 Fluorene 50-00-0 Formaldehyde 64-18-6 Formic acid 35822-46-9 HeptaCDD, 1,2,3,4,6,7,8- 67562-39-4 HeptaCDF, 1,2,3,4,6,7,8- 55673-89-7 HeptaCDF, 1,2,3,4,7,8,9- 76-44-8 Heptachlor 1024-57-3 Heptachlor epoxide 39227-28-6 HexaCDD, 1,2,3,4,7,8- 57653-85-7 HexaCDD, 1,2,3,6,7,8- 19408-74-3 HexaCDD, 1,2,3,7,8,9- 70648-26-9 HexaCDF, 1,2,3,4,7,8- 57117-44-9 HexaCDF, 1,2,3,6,7,8- 72918-21-9 HexaCDF, 1,2,3,7,8,9- 60851-34-5 HexaCDF, 2,3,4,6,7,8- 87-68-3 Hexachloro-1,3-butadiene (Perchlorobutadiene) 118-74-1 Hexachlorobenzene 77-47-4 Hexachlorocyclopentadiene 67-72-1 Hexachloroethane (Perchloroethane) 70-30-4 Hexachlorophene 7647-01-0 Hydrogen chloride (Hydrochloric acid) 193-39-5 Indeno(1,2,3-cd) pyrene 78-59-1 Isophorone 7439-92-1 Lead compounds 121-75-5 Malathion 7487-94-7 Mercuric chloride 7439-97-6 Mercury (elemental) 126-98-7 Methacrylonitrile 67-56-1 Methanol 72-43-5 Methoxychlor 79-20-9 Methyl acetate 74-83-9 Methyl bromide (Bromomethane) 74-87-3 Methyl chloride (Chloromethane) 78-93-3 Methyl ethyl ketone (2-Butanone) 108-10-1 Methyl isobutyl ketone 22967-92-6 Methyl mercury 298-00-0 Methyl parathion 74-95-3 Methylene bromide 75-09-2 Methylene chloride 91-20-3 Naphthalene 7440-02-0 Nickel 88-74-4 Nitroaniline, 2- 99-09-2 Nitroaniline, 3- 100-01-6 Nitroaniline, 4- 98-95-3 Nitrobenzene 88-75-5 Nitrophenol, 2- 100-02-7 Nitrophenol, 4-924-16-3 Nitroso-di-n-butylamine, n86-30-6 Nitrosodiphenylamine, n621-64-7 Nitrosodipropylamine, n3268-87-9 OctaCDD, 1,2,3,4,6,7,8,9- 39001-02-0 OctaCDF, 1,2,3,4,6,7,8,9- 40321-76-4 PentaCDD, 1,2,3,7,8-

### CHEMICALS OF POTENTIAL CONCERN INCLUDED IN THE COMPANION DATABASE CAS# Compound CAS# Compound Human Health Risk Assessment Protocol Appendix A-2 September 2005

U.S. EPA Region 6 U.S. EPA Multimedia Planning and Permitting Division Office of Solid Waste Center for Combustion Science and Engineering A-2-51 

### 57117-41-6 PentaCDF, 1,2,3,7,8- 57117-31-4 PentaCDF, 2,3,4,7,8- 608-93-5 Pentachlorobenzene 82-68-8 Pentachloronitrobenzene (PCNB) 87-86-5 Pentachlorophenol 85-01-8 Phenanthrene 108-95-2 Phenol 298-02-2 Phorate 85-44-9 Phthalic anhydride (1,2-Benzene dicarboxylic anhydride) 

### 23950-58-5 Pronamide 129-00-0 Pyrene 110-86-1 Pyridine 299-84-3 Ronnel 94-59-7 Safrole 7782-49-2 Selenium 7440-22-4 Silver 57-24-9 Strychnine 100-42-5 Styrene 1746-01-6 TetraCDD, 2,3,7,8- 51207-31-9 TetraCDF, 2,3,7,8- 95-94-3 Tetrachlorobenzene, 1,2,4,5- 630-20-6 Tetrachloroethane, 1,1,1,2- 79-34-5 Tetrachloroethane, 1,1,2,2- 127-18-4 Tetrachloroethylene (Perchloroethylene) 58-90-2 Tetrachlorophenol, 2,3,4,6- 109-99-9 Tetrahydrofuran 7440-28-0 Thallium (l) 108-88-3 Toluene95-53-4 Toluidine, o87-61-6 Trichlorobenzene, 1,2,3- 120-82-1 Trichlorobenzene, 1,2,4- 71-55-6 Trichloroethane, 1,1,1- 79-00-5 Trichloroethane, 1,1,2- 79-01-6 Trichloroethylene 75-69-4 Trichlorofluoromethane (Freon 11) 95-95-4 Trichlorophenol, 2,4,5- 88-06-2 Trichlorophenol, 2,4,6- 96-18-4 Trichloropropane, 1,2,3- 108-67-8 Trimethylbenzene, 1,3,5- 99-35-4 Trinitrobenzene, 1,3,5 (sym-) 118-96-7 Trinitrotoluene, 2,4,6- 108-05-4 Vinyl acetate 75-01-4 Vinyl chloride108-38-3 Xylene, m95-47-6 Xylene, o106-42-3 Xylene, p7440-66-6 Zinc

## B - i 

# APPENDIX B ESTIMATING

MEDIA CON CENTRATION EQUATIONS A

ND VARIA

BLE VALUES 

# Table Equation SOIL INGESTION EQUATIONS B-1-1 Soil Concentration Due to Deposition B-1-2 COPC Soil Lo ss Constant B-1-3 COPC Loss Co nstant Due to Soil Ero sion B-1-4 COPC Loss C onstant Due to Soil R unoff B-1-5 COPC Loss Co nstant Due to Soil Le aching B-1-6 COPC Loss Co nstant Due to Soil Volatiliz ation PRODUCE INGESTION EQUATIONS B-2-1 Soil Concentration Due to Deposition B-2-2 COPC Soil Lo ss Constant B-2-3 COPC Loss Co nstant Due to Soil Ero sion B-2-4 COPC Loss C onstant Due to Soil R unoff B-2-5 COPC Loss Co nstant Due to Soil Le aching B-2-6 COPC Loss Co nstant Due to Soil Volatiliz ation B-2-7 Abovegroun d Produce Concentration

Due to Direct Dep osition B-2-8 Abovegroun d Produce Concentration

Due to Air-to-Plant Transfer B-2-9 Abovegrou nd Prod uce Conc entra tion Du e to Root Uptake B-2- 10 Belowgr ound Pr oduce Co ncent ratio n Due to Ro ot Upta ke ANIMAL PRODUCTS INGESTION EQUATIO NS B-3-1 Soil Concentration Due to Deposition B-3-2 COPC Soil Lo ss Constant B-3-3 COPC Loss Co nstant Due to Soil Ero sion B-3-4 COPC Loss C onstant Due to Soil R unoff B-3-5 COPC Loss Co nstant Due to Soil Le aching B-3-6 COPC Loss Co nstant Due to Soil Volatiliz ation B-3-7 Forage and Silage Concentration Due to Direct Deposition B-3-8 Forage and Silage Concentration Due to Air-to- Plant Transfer B-3-9 Forage/ Silage /Grai n Concen trati on Due to Root Upt ake B-3- 10 Beef Concentration Du e to Plant & Soil I

ngestion B-3- 11 Milk Concentration D ue to Plant & Soil Ingestion B-3- 12 Pork Concentration Due to Plant & S oil Ingestion B-3- 13 COPC Conc entra tion i n Eggs B-3- 14 Concentration in Chick en DRINKING WATER AND FISH INGESTION EQUATI ONS B-4-1 WATERSHED Soil C oncentration Due to D eposition B-4-2 COPC Soil Lo ss Constant B-4-3 COPC Loss Co nstant Due to Soil Ero sion B-4-4 COPC Loss C onstant Due to Soil R unoff B-4-5 COPC Loss Co nstant Due to Soil Le aching B-4-6 COPC Loss Co nstant Due to Soil Volatiliz ation B-4-7 Total Water Body Load B-4-8 Deposition to Water Body B-4-9 Imperv

ious Runoff Load to Water Body B-4- 10 Pervious Runoff Load to Water Body B-4- 11 Erosion Load to Water B ody

## B-ii

DRINKI NG WATER AND

FISH I NGESTION

EQUATIO

NS (cont’d)
B-4- 12 Diffusion Load to Water B ody B-4- 13 Universal Soil Los s Equation (USLE) B-4- 14 Sedim

ent Del ivery

Ratio B-4- 15 Total Water Body Conc entration B-4- 16 Fraction in Water Colum n & Benthic Sedim

ent B-4- 17 Overall Total Water Body Dissipation Rate Con stant B-4- 18 Water Column Volatiliz ation Loss Rate Con stant B-4- 19 Overall COPC Transfer Rate Coefficient B-4- 20 Liquid Phase Transfer Coefficien t B-4- 21 Gas Phase Transfer Coefficient B-4- 22 Benthic Burial Rate C onstant B-4- 23 Total Water Column C oncentration B-4- 24 Dissolved Phase Water Concentration B-4- 25 COPC Concentration Sorbed to Bed S ediment B-4- 26 Fish Concentration From Bioconcentration Factors Using Dissolved-Phase Water Concentration B-4- 27 Fish Concentration From Bioaccumulation Factors Using D issolved-P hase Water Concentration B-4- 28 Fish Concentration From Biota-to- Sediment Accum ulation Factors Using

COPC Sorbed to Bed Sediment DIREC T INHA

LATION EQUAT ION B-5-1 Air Concentration ACUT E EQUATION B-6-1 Acute Air Concentration

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 1 of 9)

B-1 Description Use the equations in this

table to c alculate

an aver age COPC s oil concentr

ation result

ing from wet and dry depos ition of par ticles a nd vapors to s oil over the exposure duration. We

recom mend assumi ng that COPCs are incor

porated only

to a finit e depth (the soil mix

ing zone de

pth, Z

s ). Us e th e COP C so il c onc ent rat ion aver aged over the expo sur e du rat ion , re pre sen ted by Cs , for carcinogenic COPCs, where r isk is a veraged over the lifetim

e of an i ndividual. Because the

hazard quotie

nt associa ted with nonc arcinoge

nic COPCs is

based on a r

efere nce dose ra

ther than a lifetime exposure, we recommend using the highest annual average COPC soil concentration occurring during the exposure duration period for non carcinogenic COPCs. The highest annual aver age C OPC soi l co nce ntr ati on wo uld most like ly oc cur at th e end of th e ti me pe rio d of comb ust ion and is re pre sen ted by Cs tD . The following uncertainties are associated with this variable: (1) We assume that the time period for deposition of COPCs resulting from hazardous waste combustion is a conservative, long-term value. T his assumption may overestim ate Cs and Cs tD . (2) Exposure duration values ( T 2 ) are based o n histo rical mobil ity studies and won’t necessarily remain constant . Specifical ly, mobility stu dies ind icate that mos t recepto rs that move remai n in the vic inity of

the com bustion unit; how

ever, it is impos sible to ac curately predict the

probability

that these

short-dista

nce mov es will influence exposure,based on f

actors such as atmospheric transport of pollutants. (3) A value

of zero for T

1 doesn’t account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may underestimate Cs and Cs tD . (4) For soluble COPCs, leaching might lead to movement below the 2 centimeters, res ulting in lower concentrations within the mixing depth. This uncertainty may overe stimate Cs and Cs tD . (5) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This m ay underestimate Cs and Cs tD . Equation for Carcinogens Soil Concentra

tion Ave raged Ov er Exposure

Duration

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 2 of 9)

B-2 Equation for Noncarcinogens Highest A

nnual Ave

rage Soil Concentrat

ion

where

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation to calculate Ds. Apportion the calculat ed Ds value into the divalent mercury (Hg 2+ ) and methyl mercur y (MHg) forms based on the assumed 98% Hg 2+ and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg 0 ) occurs in very

small amounts in the vapor

phase and doe s not exis

t in the particle or particle -bound phase. T herefore , assum

e elem ental m ercury deposition onto s oils is neg ligible or zero. Eva

luate ele mental mercur

y for the direct

inhalation pa

thway only (Table B-5-1).
Ds (Hg2+) = 0.98 Ds (Mercu ry) Ds (MH G) = 0.02 Ds (Mercu ry) Ds (Hg0) = 0.0 Evaluate divalent and methyl me rcury as individual COPCs. Calculate Cs for diva lent and m

ethyl m ercury using the c orresponding ( 1) fate and transport param eters f or merc uric chloride (divalent mercury, Hg 2+ ) and me

thyl m ercury provided in A

ppendix A- 2, and (2) Ds (Hg 2+ ) and Ds (MHg) as calculat ed above.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 3 of 9)

B-3 Varia ble Description Units Value 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Cs tD Soil concentration at time tD mg COPC/kg soil 

### Ds Deposition te rm mg COPC/kg soi l-yr 

### Varies

U.S. EPA (1994a) and NC DEHNR (1997) recommend incorporating a deposition term into the Cs equation. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Five of the varia bles in the equation for Ds (Q, Cywv, Dywv , Dydp , and Dywp ) are COPC- and site-s pecific

. Values for these variables are estima ted through modeling. The direction and magnitude of any uncertainties shouldn’t be ge

neralize d. (2) Based on the

narrow r ecomm ended range s, we e

xpect unce

rtainties associat

ed with Vdv, F v , and BD to be low. (3) Values for Z s vary by about one

order of m

agnitude. U

ncertainty is grea tly re duced if y

ou know w

hether soils are tilled or untilled. 

### tD Time

period over

which deposition occurs (ti me per iod of com

bustion) yr 

### 30 U.S. EPA (1998) suggest s that tD can be 

### $ 30 year s. We r ecomm end using 30 y

ears unles s site-s

pecific inform ation is available indicating

that this a

ssumption i s unreasona

ble (see Chapter 6 of

the HHRA

P). 

### ks COPC soil loss constant due

to all processes yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-1-2. T

he COPC soil loss consta nt is the sum

of all C OPC remov

al process es. Uncertain ty associated wit h this vari able incl udes the fo llowing:

COPC-specif

ic value s for ksg

(one of the variables in the equation in Table B-1-2) are empirically determ ined from f ield studies . No inform

ation is av

ailable r egarding the applica

tion of thes e values

to the site -specif

ic conditions associated with affected facilities.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 4 of 9)

Varia ble Description Units Value



### B-4 T 2 Length of

exposure duration yr 

### 6, 30, or 40 We rec omme

nd reasonable

maxi mum e xposure (R

ME) value s for T 2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure dura

tion rates are based on historica l mobility rates a nd may not rema in constant. This ass

umption may overestim

ate or underestimate Cs and Cs tD . (2) Mobility s

tudies indica

te that m ost recept ors that m

ove rem ain in the v

icinity of the e mission s ources. How

ever, it is impossible to accurately predict the likelihood that these short-distance moves will influence exposure, based on factors such as atmospheric transport of pollutants. This assumption may overes timate or underestimate Cs and Cs tD . 

### T 1 Time

period at the

beginning of combustion yr 

### 0 Consistent w

ith U.S. EPA ( 1994c), we recom mend a v alue of 0 for T

1 . The following uncertainty is associated w ith this variable: A T 1 of 0 does not

account f or exposure

that ma y have occurred f

rom histor

ical opera tions or em

issions f rom burning hazardous waste. This may underestim ate Cs and Cs tD .

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 5 of 9)

Varia ble Description Units Value



### B-5 100 Units conve

rsion fac tor mg-cm 2 /kg-cm

2 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 of the H

HRAP for

guidance on calculat

ing this v ariable. Uncertainties associated with this variable are site-specific. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998),which f urther sta tes that l eaching s oluble com pounds might

lead to m

oveme nt below a

1-cm de pth. A default v alue of 2 cm f

or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brzuzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrat

ions within the Z s . This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, based on a mean value for loam soil obtained from Ca rsel et al. (1988). U.S. EPA (1998) stated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 6 of 9)

Varia ble Description Units Value



### B-6 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This va riable is COPC-specif

ic. We discuss this

variable and off er COPC-spe cific v

alues in A

ppendix A- 2. The ra

nge is based on the values pr

esented in Appendix A

-2. Values a

re also pre sented in U. S. EPA (1994c) a nd NC DEHNR

(1997).
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) st

ates that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) Our F v calculat ions assum

e a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urban sources. If y

our site is located in an urban are a, using the latter ST valu e may be more app rop ria te. Spe cifi call y, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources, a nd it would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid-phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Dydv Unitized y

early averag e dry deposition from vapor phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dywv Unitized yearly ave rage wet deposition from vapor phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dydp Unitized y

early averag e dry deposition from particle phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dywp Unitized yearly ave rage wet deposition from particle phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 7 of 9)

B-7 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. This reference is for the statem ent that the equation used to calculate the fraction of air concentration in vapor phase ( F v ) assumes that the variable c (the Junge constant) i s constant f

or all chemicals. However , Bidleman (1 988) n otes that the value of cdepends on the chemical (sorbate) molecular weight, the surface concentration for monolayer coverage, and the differe nce betwee n the heat of

desorption f

rom the pa

rticle sur face a nd the heat of

vaporiza tion of the l

iquid phase sor

bate. The followi ng equation, pr

esented in Bidlema

n (1988), is cit

ed by U. S. EPA (1994b) and NC DEHNR (1997) for calculating the variable F v :

where F

v = Fraction of chemical air concentration in vapor phase (unitless) c = Junge cons tant = 1.7 x

10 -04 (atm-cm) ST = Whitby’ s avera ge surf ace area of part

iculates = 3.5 x 10 -06 cm 2 /cm 3 air (corresponds to background plus local sources)

= Liquid-phase

vapor pres sure of c

hemica l (atm) (see A ppendix A- 2)

If the chemical is a solid at am bient temperatures, the solid-phase vapor pressure is converted to a liquid-phase vapor pressure as follows: where

= Solid-phase v apor pressur

e of che mical (atm) (see A

ppendix A- 2)

= Entropy of fusion over the universal gas constant = 6.79 (unitless)
T m = Melting point of chem ical (K) (see A

ppendix A- 2) T a = Ambient air temperature = 284 K (11°C) Brzuzy, L.P. and R.A. Hites. 1995. “Estimating the Atmospheric Deposition of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Soils.” Environmental Science and Technology

. Volume 29. Pag

es 2090-2098. This reference presents soil profiles for dioxin mea surements.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 8 of 9)

B-8 Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. Cited by U.S. EPA (1994b)

as the sour

ce for a mean s oil bulk densi

ty va lue, BD , of 1.5 g soil/cm 3 soil for loam soil

. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Press, Inc. New York.

Cited by U.S. EPA (1998)

for the s tateme nt that BD is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and c lay c ontent of the soil. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -1-1. This document a lso recom mends us ing (1) a de

position term

, Ds , and (2) COPC-specific F v values.
Researc h Triang le Institute

(RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepa

red for U .S. EPA Haz

ardous Site C ontrol Divis ion, Remedial Opera tions Guidance Branch. A

rlington, Virg

inia. EPA C ontract 68-W 1-0021. Work Assig nment No. B-03, Work

Assig nment Ma

nager Loren Henning . Decem ber. This document is a reference source f or COPC-specific F v values. U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compo unds. Draft Report. Of

fice of Resear ch and Dev

elopment. Washing

ton, D.C. EPA

/600/6-88/005b. The Exte rnal Rev iew Dr aft of the MPE docum

ent (the f inal is U.S. EPA 1998) cite s this docum ent as the source of values f or soil m ixing zone

depth, Z

s , for tilled and untilled soils. U.S. EPA. 1993. Addendum to the M ethodology for As

sessing He

alth Risks Associated w

ith Indirect

Exposure to Combustor Emi ssions . Working

Group Rec omme

ndations. Of

fice of Solid Was

te. Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This docum

ent is a r efere nce for t he equation in Table B- 1-1. It rec omme nds using a deposition ter m, Ds , and COPC-specific F v values in the Cs equation. U.S. EPA 1994a. Draft Guidanc e for Perf orming Scre

ening Level

Risk Analys

es at Combus tion Facilitie s Burning Hazar

dous Wastes. Attachment C, Draft Ex

posure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. Offic e of Em

ergency and Rem edial Res ponse. Of

fice of Solid Was

te. April. This document is a reference f or the equation in Table B-1-1; it recommends using the following in the Cs equation: (1) a deposition t

erm, Ds , and (2) a de fault soil bulk densit y val ue of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil from Carsel e t al. (1988). U.S. EPA. 1994b. Estimating Ex posure to Diox

in-Like Com

pounds

. Volume III: Site-Specific Assessment Procedures. Externa l Review Draft. Off

ice of R esearc h and Development. W

ashington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent recom mends v alues f or length of

exposure duration, T 2 , for the farm

er.

### TABLE B-1-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (SOIL INGESTION EQUATIONS)

(Page 9 of 9)

B-9 U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes . Off ice of E merge ncy and R

emedia l Response. Offic e of Solid W

aste. Decembe

r. This docu ment recommends th e following:

C Values for

the length of expos

ure duration, T 2
C Value of 0 f

or the tim e period of

the beginning

of com bustion, T

1
C F

v values that range from 0.27 to 1 for organic COPCs

C Default soil bulk density value of 1.5 g soil/cm 3 soil, base d on a me an for loa m soil f rom Car sel et a l. (1988) U.S. EPA. 1997a

. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Office of A

ir Quality and Planning and Standards and Office of Research and Development. E

PA 452/R-97-005. D ecem ber. U.S. EPA. 1997b. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002Fc . August

. This docum

ent is a r efere nce source

for va lues for length of

exposure duration, T 2 . U.S. EPA. 1998. Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions (MPE ) . Update to EPA/600/6-90/003. Of fice of Resear ch and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber.

### TABLE B-1-2 COPC SOIL LOSS CONSTANT (SOIL INGESTION EQUATIONS)

(Page 1 of 4)

B-10 Description This equa tion calcula

tes the CO

PC soil loss c onstant, w

hich accounts

for the loss of COPCs from soil by s everal

mecha nisms. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) COPC-specif

ic value s for ksg

are em pirically determ ined from field st udies. No inf

ormation i s available regarding the application of these va lues to the site-spec ific condi tions associated with affected f acilities. (2) The sourc e of the equations in T ables B-1- 3 through B-1-5 ha ve not bee

n identified.

Equation

Varia ble Description Units Value 

### ks COPC soil loss constant due

to all processes yr -1



### ksg COPC loss cons tant due to biotic and abiotic degradation yr -1 

### Varies This va riable is COPC-specif

ic. Values

are av ailable in the COPC table s in Appendi x A-2. “Degra dation rate ” values

are als o presented in NC DEHN R (1997); howe

ver, no re ferenc e or source is provided for the v

alues. U.S. EPA (1994a) and U.S. EP A (1994b) state thatksg values a re COPC-spe cific; howeve r, all ksg values a re prese nted as ze ro (U.S. EPA 1994a

) or as “N A” (U.S . EPA 1994b); the basis of these as sumptions i s not addres sed. The following uncertainty is associated w ith this variable: COPC-specif

ic value s for ksg

are determined empirically from field studies; no information is available on applying these values to the site-specific conditions associated with affected f acilities.

### TABLE B-1-2 COPC SOIL LOSS CONSTANT (SOIL INGESTION EQUATIONS)

(Page 2 of 4)

Varia ble Description Units Value



### B-11 kse COPC loss cons tant due to soil erosion yr -1 

### 0 Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is fur ther dis cus sed

in T able B-1 -3. Cons ist

ent wit h U.S . EPA

(199 4a) , U. S. EPA (1994b) and NC DEHNR (1997), w e recom mend a de fault v

alue of z ero for ksebecause contamina ted soil er odes both onto the site and away from

the site. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The sourc e of the equation in Table B-1-3 ha s not been ide

ntified. (2) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrations within the Z s . This uncertainty may ove

restimate kse

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate kse

. 

### ksr COPC loss constant due to surface

runoff yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-1-4. N

o refer ence docum

ent is cit ed for this equation; howeve

r, using this

equation is c onsistent w

ith U.S. EPA ( 1998). U.S. EPA (1994a) assum ed that all ksr

values a re zero but didn’t explain the basis f or this ass umption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-1 -4) incl ude the fol lowing: (1) The sourc e of the equation in Table B-1-4 ha s not been ide

ntified. (2) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrations within the Z s . This uncertainty may ove

restimate ksr

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksr

. 

### ksl COPC lo ss constan t due to l eaching yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-1-5. U sing this equation is cons istent w ith U.S. EPA (1998),U.S. EPA (1994b) , and NC DEH NR (1997). U.S . EPA (1994a) a ssumed that ksl is zero but didn’t expla in the basis of this assum

ption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-1 -5) incl ude the fol lowing: (1) The sourc e of the equation in Table B-1-5 ha s not been ide

ntified. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksl

.

### TABLE B-1-2 COPC SOIL LOSS CONSTANT (SOIL INGESTION EQUATIONS)

(Page 3 of 4)

Varia ble Description Units Value



### B-12 ksv COPC loss cons tant due to volatilization yr -1 

### Varies Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is calcula ted usin g the eq uation in Ta ble B-1- 6. T

his equa tion cal cula tes the COPC loss consta

nt from soil due to v

olatilizat ion, and wa

s obtained f

rom U.S. EPA (1998). T he soil loss

constant due

to volatili

zation ( ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eter in untilled soils, r

esulting in a great

er mix ing depth. This uncertainty may overes timate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksv

.

REFERENCES AND DISCUSSION Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is one of the reference documents f or the equations in Tables B-1-4 and B-1-5. This document is also cited as (1) the source for a range of COPC-specific degradation rates ( ksg), and (2) one of the sour ces that recomm

end assum

ing that the

loss resul

ting from erosion ( kse ) is zero because of contaminated soil eroding both onto the site and away from the site. U.S. EPA. 1994a

. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analyse

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. This docum

ent is cit ed as a s ource for

the assum

ptions that los ses res

ulting fr om erosion ( kse ), surface ru noff ( ksr ), degrada tion ( ksg), leachin g ( ksl

), and vola

tilization (

ksv ) are all zero. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This document is one of the reference documents f or the equations in Tables B-1-4 and B-1-5. This document is also cited as one of the sources that recommend using the assumption that the loss re sulting f

rom eros ion ( kse ) is zero and the loss resulting from de gradation (

ksg) is “NA” or zero for all com pounds.

### TABLE B-1-2 COPC SOIL LOSS CONSTANT (SOIL INGESTION EQUATIONS)

(Page 4 of 4)

B-13 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence doc

uments f or the equations for ksr , ksl , and ksv

.

### TABLE B-1-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (SOIL INGESTION EQUATIONS)

(Page 1 of 5)

B-14 Description This equa tion calcula

tes the c onstant for

COPC loss re sulting f

rom eros ion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), we recomm

end a def ault value of zero f or ksebecause of contaminated soil eroding onto the site and away from the site. In site-specific cases w here the permitting authority considers it appropriate to calculate a kse , we recommend usin g the equat ion pres ented in this tabl e along with associated uncertai nties. Yo u can find ad dition al discuss ion on determinin g ksein U.S. EPA (1998). Uncertainties associated with this equation include: (1) For soluble COPCs, leaching might lead to movement below 2 centimeter in untilled soils, resulting in a greater m ixing depth. This uncertainty may ove restimate kse

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) in c omparison to that of ot her residue s. This uncertainty may underestim ate kse

. Equation

Varia ble Description Units Value 

### kse COPC loss cons tant due to soil erosion yr -1 

### 0 Consistent with U.S. EPA (1994), U.S. EP A (1994b), and NC DEHNR (1997), we recommend that the default value assumed for kseis zero because contaminated soil erodes both onto the site and away from the site. uncertainty may ove restimate kse

. 

### 0.1 Units conve

rsion fac tor g-kg/cm 2

- m 2 

### X e Unit soil loss kg/m 2 -yr 

### Varies This va riable is site-specific and is calculated by using the equation in Ta

ble B-4-13. The following uncertainty is associated w ith this variable: All of the equation v

ariables are site -specif

ic. Using default values r

ather than site-spec ific v

alues f or any or all of these variables will result in unit soil loss ( X e ) estim ates that are under-

or overes timated to some

degree. Based on default v alues, w e expec t X e estimates to vary

over a range of less than two orders of magnitude.

### TABLE B-1-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (SOIL INGESTION EQUATIONS)

(Page 2 of 5)

Varia ble Description Units Value



### B-15 SD Sediment

delivery ratio unitless 

### Varies This va lue is site -specif

ic, and is c alculate d by using the equation in Table B -4-14. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The rec omme

nded defaul

t values for the e mpirica l interce pt coeff icient, a , are av

erage v alues bas ed on studies of sedime nt yields from various w

atersheds . Theref

ore, those de fault v

alues m ay not a ccuratel y repre sent site -specif

ic watershed conditions. As a result, using these default values may under- or overestimate SD

. (2) The rec omme

nded defaul

t value f or the em pirical slope coeff

icient, b , is based on a revie w of s ediment yields

from various watersheds. This single default value m ay not accurately represent site-specif ic watershed conditions. As a result, using the default value may under- or overestim ate SD

. 

### ER Soil enrichm ent ratio unitless 

### Inorga nics: 1 Organic s: 3 COPC enrichm

ent occurs because ( 1) lighter soil partic les erode more quic kly tha n heavier soil particles, and (2)

concentra

tion of organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded mater ial than in in-situsoil (U.S. E PA 1998). In the

absence of site- specific data, w e recom mend a default v

alue of 3 for organic COPCs and 1 for inorganic COPCs. This is consistent with other Agency guidance (1998), which recommends a range of 1 to 5 and a v

alue of 3 as a “reasonable f irst esti mate.” This ra nge has be en used f

or organic matter

, phosphorus, and other soil-bound C OPCs (U.S. EPA 1998); howev

er, no source s or ref

erences were provided f

or this range. ER is gener ally higher in sa

ndy soils than in silty

or loamy soils (U.S. EPA 1998). The following uncertainty is associated w ith this variable: The def ault ER value m

ay not a ccuratel y ref lect site -specif

ic conditions; therefor

e, ksemay

be over- or underestimated to an unknown extent. Using county-specific ER values will reduce the extent of any uncertainties. 

### BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions. It m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree.

### TABLE B-1-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (SOIL INGESTION EQUATIONS)

(Page 3 of 5)

Varia ble Description Units Value



### B-16 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrations within the Z s . This uncertainty may

overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient ml wa

ter/g soil (or cm 3 water/ g soil) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### 2 sw Soil volum

etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure; you can estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. Howe

ver, w e recom mend using 0.2 ml/cm 3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soil s) r ecomm ended by U.S . EPA

(199 8) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksemay

be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-1-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (SOIL INGESTION EQUATIONS)

(Page 4 of 5)

B-17 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agric ultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density, BD , value of 1.5 g soil/cm 3 soil for loam soil

. Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, I nc. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is one of

the source s that rec omme nd assum ing that the

loss resul

ting from erosion ( kse ) is zero because contaminated soil erodes both onto the site and away from the site. U.S. EPA. 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analyse

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revise d Draft Guidanc

e for Perf orming Scre

ening Level

Risk Analys

es at Combus tion Facilitie s Burning Hazar

dous Wastes. Attachment C, Draft Ex

posure Asse

ssment Guidance for RCRA Hazardous Waste Combustio n Facilities. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber 14. This document recommends (1) a def ault soil bulk density value of 1.5 g soil/cm3 soil, base d on a me an value for loam soil that is

taken f rom Car sel et a l. (1988), and (2)

a defa ult soil volumet ric wa ter content, 2 sw , value of 0.2 ml water/cm 3 soil.

### TABLE B-1-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (SOIL INGESTION EQUATIONS)

(Page 5 of 5)

B-18 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is the s ource of a

range of COPC enrichm

ent ratio, ER , values. The recomme nded range,

1 to 5, was

used for organic m

atter, phosphor

ous, and other s oul-bound COPCs. This docum

ent recom mends a value of 3 as a “r easonable first e stimat

e,” and st ates that COPC enrichm

ent occurs because l

ighter soil particle s erode m ore quickly

than heav

ier soil particles . Lighte

r soil particles hav

e higher r atios of s urface area to v olume and are highe

r in organic

matte r content. T

herefore , concentra

tion of orga

nic COPCs, w

hich is a f unction of the organic c arbon content of sorbing m

edia, is e xpected t o be higher in eroded m

aterial than in in situsoil. This docu ment is also a so urce of the fol lowing:

C A range of soil volumet ric wa ter content

( 2 sw ) values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heavy loam/clay soils). However, no source or reference is provided for this range.

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil

C The equat

ions in Tables B-1-3 a

nd B-1-5.

### TABLE B-1-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (SOIL INGESTION EQUATIONS)

(Page 1 of 4)

B-19 Description This equat ion calcu lates the CO PC loss constant due to ru noff of soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might result in movement to below 2 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty m ay overestimate ksr

. (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestim ate ksr

. Equation

Varia ble Description Units Value 

### ksr COPC lo ss constan t due to r unoff yr -1 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994b), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, s ite-spec ific proc edures f or estim ating the a

mount of surfac e runoff

, such as t hose based on the U.S. Soil Conserva tion Service curve number equation (CNE). U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, ksr may be under- or overestimated to an unknown degree.

### TABLE B-1-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (SOIL INGESTION EQUATIONS)

(Page 2 of 4)

Varia ble Description Units Value



### B-20 2 sw Soil volum

etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure; you can estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a def ault value . This v

alue is the

midpoint of

the range 0.1 (very sandy s oils) to 0.3 (he avy loam/cla y soils), recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range) , and is cons istent w ith U.S. EPA ( 1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksr

may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrations within the Z s . This uncertainty may

overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient ml wa

ter/g soil (or cm 3 water/ g soil) Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

### TABLE B-1-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (SOIL INGESTION EQUATIONS)

(Page 3 of 4)

Varia ble Description Units Value



### B-21 BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1998), U .S. EPA (1994), a nd NC DEHNR

(1997) as a refere

nce to calculate av

erage a nnual runoff

, RO . This re ferenc e provides maps w ith isolines of annual average surface w ater runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because these values are to tal contr ibutio ns and no t only surface ru noff, U.S. EPA (199 4) recommends t hat the vo lumes be redu ced by 50 per cent in o rder to est imate surface run off. Hillel, D. 1980. Fundament als of Soil Physics. Acade mic Press, In c. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is one of

the source

documents

that recom

mends us ing Table

B-1-4; howe

ver, this document i s not the orig inal source

of this e quation (the s ource is unk nown). T his document also recommends the followin g:

C Estima

ting annual c

urrent runof

f, RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.

C Default value of 0.2 (ml w ater/cm3 soil) for

soil volum

etric w ater conte nt ( 2 sw )

### TABLE B-1-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (SOIL INGESTION EQUATIONS)

(Page 4 of 4)

B-22 U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edure for Tox

ic and Conventi

onal Pollutants in Sur

face and Ground W

ater—Part I (Revised. 1985) . Environmental Research Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This docum

ent is cit ed by NC DEHNR (1997)

as an ex ample of the use of

the U.S. Soil Conserva

tion Servic e CNE to e stimat e site-s pecific surfac e runoff

. U.S. EPA. 1994a

. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

II: Site-s pecific As

sessme nt Procedure

s. External Review

Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s a range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes . Attac hment C, Draft E

xposure Assessm

ent Guidance for RCRA

Hazardous

Waste Combustion Facilitie s. Off ices of Emerg ency a nd Reme dial Respons e. Off ice of Sol id Waste . Decem

ber. This docu ment recommends th e following:

C Estima

tion of av erage a nnual runoff

, RO , by using the Water Atlas of the United States (Gera ghty e t al. 1973)

C Default

soil bulk de

nsity, BD , value of 1.5 g soil/cm 3 soil, base d on the me an for loa m soil tha t is take n from Carsel e

t al. (1988)

C Default

soil volum

etric w ater conte nt, 2 sw , value of 0.2 (ml water/cm 3 soil)

U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of soil volumet ric wa ter content, 2 sw , values of 0.1 (ve ry sa ndy soils) to 0.3 (heav

y loam /clay soils) (the

original s ource of, or refe rence f or, these v

alues is not

identified)

C A range of va

lues for soil mix

ing depth, Z

s , for tilled and untilled s oil (the orig inal source

of, or re ferenc e for, the se value s is not ident ified)

C Using the Water Atlas of the United States (Gera ghty e t al. 1973) to c alculate

averag e annual runof

f, RO

### TABLE B-1-5 COPC LOSS CONSTANT DUE TO LEACHING (SOIL INGESTION EQUATIONS)

(Page 1 of 5)

B-23 Description This equat ion calcu lates the co nstant for COPC lo ss resulti ng from leachin g of soil. Un certainti es associated with this eq uation includ e the follo wing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overes timate ksl

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to that

of other r

esidues. T

his uncertainty may underestim ate ksl

. (3) The original source of this equation has not been identified. U.S. EPA (1998 ) presents the equation as shown here. U.S. EPA (1994b) and NC DEHNR (1997 ) replaced the numerator as

shown w ith “ q ”, defined as ave

rage annua

l recharg e (cm /yr). Equation

Varia ble Description Units Value 

### ksl COPC loss cons tant due lea

ching yr -1 

### P Avera

ge annual precipitat

ion cm/yr 

### 18.06 to 164.19 This variable is site-specific. T his range is based on information presented in U.S. EPA (1998), representing data for 69 selected cities (U .S. Bureau of

Census 1987; B aes et a

l. 1984). The

69 select ed cities are not ide

ntified; how

ever, the y appea r to be located throughout the contin ental United States. We recomme nd using site-specific data. The following uncertainty is associated w ith this variable: To the ex tent that a site is not

located ne ar an est

ablished m

eteorologic al data s

tation, and si

te-speci fic data

are not available, defa

ult avera ge annual precipitat

ion data m

ay not a ccuratel y ref lect site -specif

ic conditions. As a r

esult, ksl may be un der- or ove resti mated. However , avera ge ann ual p recip itati on d ata are reaso nabl y availab le; th erefor e, we expect unc ertainty

introduced by

this variable to be m

inimal.

### TABLE B-1-5 COPC LOSS CONSTANT DUE TO LEACHING (SOIL INGESTION EQUATIONS)

(Page 2 of 5)

Varia ble Description Units Value



### B-24 I Avera

ge annual irrigation cm/yr 

### 0 to 100 This variable is site-specific. T his range is based on information presented in U.S. EPA (1998), representing data for 69 selected cities (Baes et al. 1984). The 69 selected cities are not identified; however, they a ppear to be located throughout the cont inental United States. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l irrigat ion inform

ation is not a

vailable , default

values ( generally based on the closest c omparable location) may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be under- or overestimated to an unknown degree. 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994b), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, site-specific procedures, such as those based on the U.S. Soil Conservation Service CNE. U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual surface runoff information is not available, default or estim ated values m ay not a ccuratel y repre sent site -specif

ic or local conditions. A

s a resul t, ksl may be under- or overestim ated to an unknown degree. 

### E v Avera

ge annual evapotra

nspiration cm/yr 

### 35 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U. S. EPA ( 1998), repres enting data from 69 selected cities. The 69 selected cities are not identified; however, they appear to be located throughout the contin ental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual evapotranspiration information is not available, default values may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be un der- or ove resti mated t o an u nkno wn degree.

### TABLE B-1-5 COPC LOSS CONSTANT DUE TO LEACHING (SOIL INGESTION EQUATIONS)

(Page 3 of 5)

Varia ble Description Units Value



### B-25 2 sw Soil volum

etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure. You can estimate 2 sw as the m idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range)

and is consi stent wi

th U.S. EPA (1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value may not accurately reflect site-specif ic or local conditions; therefore, ksl may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in lower concentrations within the Z s . This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD .

### TABLE B-1-5 COPC LOSS CONSTANT DUE TO LEACHING (SOIL INGESTION EQUATIONS)

(Page 4 of 5)

Varia ble Description Units Value



### B-26 BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of

1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The rec omme

nded soil bulk density

value m ay not a ccuratel y repre sent site -specif

ic soil condi

tions. 

### Kd s Soil-wat

er partiti on coeff

icient cm 3 water/ g soil Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

REFERENCES AND DISCUSSION Baes, C.F., R.D. Sharp, A.L. Sjoreen and R.W. Shor. 1984. “A Review and Analysis of Parameters for Asse ssing Transport of Environmentally Released Radionuclides through Agriculture.” Prepared f

or the U.S. D epartm

ent of Ene

rgy unde r Contract No. DEAC 05-840R21400. For the contine

ntal United S tates, as cited in U .S. EPA (1998), t his docume

nt is the sour

ce of a series of ma

ps showing : (1) ave

rage annua

l precipita

tion ( P ), (2) ave

rage annua

l irrigat ion ( I ), and (3) average annual evapotranspiration isolines. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density value, BD , of 1.5 g soil/cm 3 soil for loam soil

. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1998), U .S. EPA (1994b), a nd NC DEHNR

(1997) as a refere

nce for c alculating

averag e annual runof

f, RO . This docum

ent provides

maps w ith isolines of annual average surface runoff, w hich is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Bec ause these volumes are total contributions and not only surface runoff, U.S. EPA (1994b) recommends that the volumes be reduced by 50 percent in order to estimate averag e annual surface runoff.

### TABLE B-1-5 COPC LOSS CONSTANT DUE TO LEACHING (SOIL INGESTION EQUATIONS)

(Page 5 of 5)

B-27 Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the source documents that cites the use of the equation in Table B-1-5. However, the document is not the original source of this equation. This document also recommends the following:

C Estima

tion of av erage a nnual surfa

ce runoff , RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.

C A default value of 0.2 (ml w ater/cm3 soil) for

soil volum

etric w ater conte nt, 2 sw U.S. Burea

u of the Ce

nsus. 1987. Statistical Abstract of t he United State

s: 1987. 107th editi on. Washington, D.C. This docum

ent is a s ource of a

verage annual prec ipitation (

P ) inform ation for 69 selected cites, a s cited in U .S. EPA (1990); t hese 69 cit

ies are not identifi ed. U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventiona l Pollutants in Surface an d Groundwater . Part I (Revised 1985). Environmental Research

Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This document is cited by NC DEHNR (1997) as an exam ple of the use of the U.S. Soil Conservation Service CNE to estimate RO

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s values for soil m

ixing depth, Z s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docum

ent recom mends (1)

a defa ult soil volum

etric w ater conte nt, 2 sw , value of 0.2 (ml water/cm 3 soil), and (2)

a defa ult soil bulk density , BD , value of 1.5 (g soil/cm 3 soil), based on a mean v alue for loam soil from

Carsel e t al. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence s ource docum

ents for the equation i

n Table B -1-5. The or

iginal sour

ce of thi s equation is

not identif

ied. This document also prese

nts a range of values f or soil m ixing depth, Z, for tilled and untilled s oil; the orig inal source

of these values i s not identif

ied.

### TABLE B-1-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (SOIL INGESTION EQUATIONS)

(Page 1 of 5)

B-28 Description This eq uati on cal culat es the COPC loss c onst ant fro m soil d ue to volat iliza tion , and comes fro m Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Exposure Pat

hways to Combus tor Emissions

(U.S. EPA 1998) . The soil loss consta

nt due to vola

tilization (

ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by adapt ing the Hw

ang and Falco equation f

or soil vapor

phase dif fusion (Hw

ang and Falco 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overes timate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to that

of other r

esidues. T

his uncertainty may underestim ate ksv

. Equation

Varia ble Definition Units Value 

### ksv COPC loss cons tant due to volatilization yr -1

3.1536 x 10 +7 Units conve rsion fac tor s/yr 

### H Henry’ s Law constant atmm 3 /mol 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail, a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated by using

the param

eters and algorithm

s in Appendi

x A-2, m ay under - or overesti mate t he actual COPC-specif

ic value s. As a

result, ksv

may be under- or ov

erestim ated.

### TABLE B-1-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (SOIL INGESTION EQUATIONS)

(Page 2 of 5)

Varia ble Definition Units Value



### B-29 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), which further states that leaching soluble compounds might lead to movement below a 1-cm depth. Additional informa tion on this subject can be obtained fr om Brzuz y and Hi tes (1995), w

hich present

s soil prof iles for dioxin measur ements . A def

ault value of 2 cm for soil m

ixing depth for untille d soils is ba sed on a study

that profiled dioxin measur ements within soil (Brzuzy

et al. 1995). A def

ault value of 20 cm for soil m

ixing depth for tille d soils is ba sed on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeter in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient cm 3

water/ g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### R Universa l gas cons tant atmm 3 /mol-K 

### 8.205 x 10 -5

There a re no uncert

ainties a ssociate d with this

param eter.

### TABLE B-1-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (SOIL INGESTION EQUATIONS)

(Page 3 of 5)

Varia ble Definition Units Value



### B-30 T a Ambie

nt air tem perature K 

### 298 This variable is site-specific. U.S. EPA (1998) recommends a def ault ambient air temperature of 298 K. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for t he varia ble are not available, defa ult values may not accura

tely represent site-spe cific c onditions. We expect the uncerta

inty as sociated w

ith the sel ection of a single value f rom within the temper

ature rang

e at a s ingle loca

tion to be m

ore signif icant than t

he uncerta

inty as sociated w

ith choosing a single ambient temper ature to re

present al l localitie s. 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions. 

### D soil Solids partic le density g/cm3 

### 2.7 We rec omme

nd using this v

alue, based on Blake and Hartag e (1996) and Hillel (1980). The solids particle density will vary with location and soil type. 

### D a Diffus ivity of COPC in a ir cm 2 /s 

### Varies This va lue is COPC-s

pecific . We dis cuss this v ariable i n detail, a nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: The def ault D a values m

ay not a ccuratel y repre sent the be

havior of COPCs under s ite-spec ific condi tions. How

ever, we ex pect the degree of

uncertaint

y to be m inimal.

### TABLE B-1-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (SOIL INGESTION EQUATIONS)

(Page 4 of 5)

Varia ble Definition Units Value



### B-31 2 sw Soil volum etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This va riable depe

nds on the av

ailable w ater and on s oil structure . You can e stimat e 2 sw as the m

idpoint betwe

en a soil’s

field capacity and wilting point, if you can identify a representative watershed soil. Howev er, we recomm

end using 0.2 ml/cm 3 as a default v alue. Thi s value i s the m idpoint of the

range 0.1 (

very sandy s oils) to 0.3 (he avy loam/cla y soils) recom

mended by U.S. EPA (1998) (no source or refer ence is pr ovided for

this range

) and is cons istent w

ith U.S. EPA ( 1994b). The following uncertainty is associated w ith this variable: (1) The def

ault 2 sw values may

not accurately reflect site-specif ic or local conditions; therefore, ksv may be under- or overestimated to a small e xtent, based on the limited range of values.

REFERENCES AND DISCUSSION Blake, G R. and K.H. H

artge. 1996. Particle D

ensity. M ethods of Soil Anal

ysis, Part 1: Physical

and Mineralogic

al Methods . Se con d Ed iti on. Arno ld K lut e, E d. Ame ric an S oci ety o f Agro nomy, Inc. Madison,WI., p. 381. Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density value, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk. Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. Miller, R.W . and D.T. Gardiner . 1998. In: Soils in Our Env ironment . J.U. Mille

r, Ed. Prentice

Hall. Uppe

r Saddle Riv

er, NJ. pp. 80-123. U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compou nds. Volume III: Site-specific Assessment Procedures External Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s value f or soil, m ixing depth, Z s , for tilled and untilled s oil.

### TABLE B-1-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (SOIL INGESTION EQUATIONS)

(Page 5 of 5)

B-32 U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docum

ent recom mends a default soil density

, BD , value of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled soil; however, the source or basis for these values is not identified

C A def

ault am bient air te

mperat ure of 298 K

C A range of soil volumet ric wa ter content, 2 sw

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 8)

B-33 Description Use the equations in this

table to c alculate

an aver age COPC s oil concentr

ation result

ing from wet and dry depos ition of par ticles a nd vapors to s oil over the exposure duration. We

recom mend assumi ng that COPCs are incor

porated only

to a finit e depth (the soil mix

ing zone de

pth, Z

s ). Us e th e COP C so il c onc ent rat ion aver aged over the expo sur e du rat ion , re pre sen ted by Cs , for carcinogenic COPCs, where r isk is a veraged over the lifetim

e of an i ndividual. Because the

hazard quotie

nt associa ted with nonc arcinoge

nic COPCs is

based on a r

efere nce dose ra

ther than a lifetime exposure, we recommend using the highest annual average COPC soil concentration occurring during the exposure duration period for non carcinogenic COPCs. The highest annual aver age C OPC soi l co nce ntr ati on wo uld most like ly oc cur at th e end of th e ti me pe rio d of comb ust ion and is re pre sen ted by Cs tD . The following uncertainties are associated with this variable: (1) We assume that the time period for deposition of COPCs resulting from hazardous waste combustion is a conservative, long-term value. T his assumption may overestim ate Cs and Cs tD . (2) Exposure duration values ( T 2 ) are based o n histo rical mobil ity studies and won’t necessarily remain constant . Specifical ly, mobility stu dies ind icate that mos t recepto rs that move remai n in the vic inity of

the com bustion unit; how

ever, it is impos sible to ac curately predict the

probability

that these

short-dista

nce mov es will influence exposure,based on f

actors such as atmospheric transport of pollutants. (3) A value

of zero for T

1 doesn’t account for exposure that may have occurred from historic operations and emissions from burning hazardous waste. This may underestimate Cs and Cs tD . (4) For soluble COPCs, leaching might lead to movement to below the mixing depth, resulting in lower concentrations within the mixing depth. This may overestimate Cs and Cs tD . (5) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This m ay underestimate Cs and Cs tD . Equation for Carcinogens Soil Concentra

tion Ave raged Ov er Exposure

Duration

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 8)

B-34 Equation for Noncarcinogens Highest A

nnual Ave

rage Soil Concentrat

ion

where

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation to calculate Ds. Apportion the calculat ed Ds value into the divalent mercury (Hg 2+ ) and methyl mercur y (MHg) forms based on the assumed 98% Hg 2+ and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg 0 ) occurs in very

small amounts in the vapor

phase and doe s not exis

t in the particle or particle -bound phase. T herefore , assum

e elem ental m ercury deposition onto s oils is neg ligible or zero. Eva

luate ele mental mercur

y for the direct

inhalation pa

thway only (Table B-5-1).
Ds (Hg2+) = 0.98 Ds (Mercu ry) Ds (MHg) = 0.02 Ds (Mercu ry) Ds (Hg0) = 0.0 Evaluate divalent and methyl me rcury as individual COPCs. Calculate Cs for diva lent and m

ethyl m ercury using the c orresponding ( 1) fate and transport param eters f or merc uric chloride (divalent mercury, Hg 2+ ) and me

thyl m ercury provided in A

ppendix A- 2, and (2) Ds (Hg 2+ ) and Ds (MHg) as calculat ed above.

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 8)

B-35 Varia ble Description Units Value 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Cs tD Soil concentration at time tD mg COPC/kg soil 

### Ds Deposition te rm mg COPC/kg soi l-yr 

### Varies

U.S. EPA (1994a) and NC DEHNR (1991) recommend incorporating the use of a deposition term into the Cs equation. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Five of the varia bles in the equation for Ds (Q, Cyv, Dywv , Dywp , and Dydp ) are COPC- and site-s pecific

. Values of these variables are estima ted through modeling. The direction and magnitude of any uncertainties shouldn’t be ge

neralize d. (2) Based on the

narrow r ecomm ended range s, we e

xpect unce

rtainties associat

ed with Vdv, F v , and BD to be low. (3) Values for Z s vary by about one

order of m

agnitude. U

ncertainty is grea tly re duced if y

ou know w

hether soils are tilled or untilled. 

### tD Time

period over

which deposition occurs (ti me per iod of com

bustion) yr 

### 30 U.S. EPA (1998) suggests that this period of time can be 

### $ 30 year s. We r ecomm end using 30 y

ears unles s site-s

pecific informa tion is ava

ilable indic ating that

this assum

ption is unreasonable (see Chapter 6 of the HH RAP). 

### ks COPC soil loss constant due

to all processes yr -1 

### Varies This variable is COPC- and site-specific, and is calculated by using the equation in Table B-1-2. The COPC soil loss constant is

the sum of all C OPC remov

al process es. Uncertain ty associated wit h this vari able incl udes the fo llowing:

COPC-specif

ic value s for ksg

(one of the variables in the equation in Table B-1-2) are empirically determ ined from field studies. No information is available on applying these values to the site-specific conditions associated with affected f

acilities.

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 8)

Varia ble Description Units Value



### B-36 T 2 Length of

exposure duration yr 

### 6, 30, or 40 We rec omme

nd the follow

ing reas onable ma

ximum exposure (RME) val

ues for T

2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure dura

tion rates are based on historica l mobility rates a nd may not rema in constant. This ass

umption may overestim

ate or underestimate Cs and Cs tD . (2) Mobility s

tudies indica

te that m ost recept ors that m ove rem ain in the v

icinity of the e mission s ources; how

ever, it is impossible to accurately predict the likelihood that these short-distance moves will influence exposure, based on factors such as atmospheric transport of pollutants. This assumption may overes timate or underestimate Cs and Cs tD . 

### T 1 Time

period at the

beginning of combustion yr 

### 0 Consistent w

ith U.S. EPA ( 1994bc), we recom mend a v alue of 0 for T

1 . The following uncertainty is associated w ith this variable: A T 1 of zero doesn’t account for ex posure that m

ay hav e occurre d from historical operation or e missions from the combustion of hazardous waste. This may underestimate Cs and Cs tD . 

### 100 Units conve

rsion fac tor mg-cm 2 /kg-cm

2

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 5 of 8)

Varia ble Description Units Value



### B-37 Q COPC emis sion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 of the H

HRAP for

guidance regarding

the calc ulation of this vari able. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998),which f urther sta tes that l eaching s oluble com pounds might

lead to m

oveme nt below a

1-cm de pth. A default v alue of 2 cm f

or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brzuzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution in compa rison to that of other residues. This uncertainty may underestim ate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, based on a mean value for loam soil obtained from Ca rsel et al. (1988). U.S. EPA (1998) stated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree.

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 6 of 8)

Varia ble Description Units Value



### B-38 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This va riable is COPC-specif

ic. We discuss this

variable and off er COPC-spe cific v

alues in A

ppendix A- 2. This ra

nge is based on the values pr

esented in Appendix A

-2. Values a

re also pre sented in U. S. EPA (1994c) a nd NC DEHNR

(1997).
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) st

ates that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) Our F v calculat ions assum

e a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urban sources. If y

our site is located in an urban are a, using the latter ST valu e may be more app rop ria te. Spe cifi call y, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources, a nd it would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Dydv Unitized y

early averag e dry deposition from vapor phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dywv Unitized yearly ave rage wet deposition from vapor phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dydp Unitized y

early averag e dry deposition from particle phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dywp Unitized yearly ave rage wet deposition from particle phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific.

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 7 of 8)

B-39 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Brzuzy, L.P. and R.A. Hites. 1995. “Estimating the Atmospheric Deposition of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Soils.” Environmental Science and Technology

. Volume 29. Pag

es 2090-2098. This reference presents soil profiles for dioxin mea surements. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This ref erence i s cited by

U.S. EPA (1994b)

as the sour

ce for a mean s oil bulk densi

ty va lue, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Press, Inc. New York.

Cited by U.S. EPA (1998)

for the s tateme nt that BD is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and c lay c ontent of the soil. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -1-1. This document a lso recom mends us ing (1) a de

position term

, Ds , and (2) COPC-specific F v values.
Researc h Triang le Institute

(RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepa

red for U .S. EPA Haz

ardous Site C ontrol Divis ion, Remedial Opera tions Guidance Branch. A

rlington, Virg

inia. EPA C ontract 68-W 1-0021. Work Assig nment No. B-03, Work

Assig nment Ma

nager Loren Henning . Decem ber. This document is a reference source f or COPC-specific F v values. U.S. EPA. U.S. EPA. 1992. Estimating Ex posure to Diox

in-Like Com

pounds. Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/005b. The Exte rnal Rev iew Dr aft of the MPE docum

ent (the f inal is U.S. EPA 1998) cite s this docum ent as the source of values f or soil m ixing zone

depth, Z

s , for tilled and untilled soils.

### TABLE B-2-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 8 of 8)

B-40 U.S. EPA. 1993b. Addendum to the M ethodology for As

sessing He

alth Risks Associated w

ith Indirect

Exposure to Combustor Em issions . Working Group Rec omme

ndations. Of

fice of Solid Waste. Office of Re search a nd Developm

ent. Was hington, D.C. Septembe

r 24. This docum

ent is a r efere nce for t he equation in Table B- 2-1. It rec omme nds using a deposition ter m, Ds , and COPC-specific F v values in the Cs equation. U.S. EPA. 1994a. Draft Guidanc e for Perf orming Scre

ening Level

Risk Analys is at Combusti on Facilities

Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. Offic e of Em

ergency and Rem edial Res ponse. Of

fice of Solid Was

te. April 15. This document is a reference f or the equation in Table B-2-1; it recommends that the following be used in the Cs equation: (1) a deposition t

erm, Ds , and (2) a de fault soil bulk densit y value of 1.5 g/cm 3 , based on a mean v

alue for loam soil from

Carsel e t al. (1988). U.S. EPA. 1994b. Estimating Ex posure to Diox

in-Like Com

pounds

. Volume III: Site-Specific Assessment Procedures. External Review Draft. Off

ice of R esearc h and Development. W

ashington, D.C. EPA/600/6- 88/005Cc. June. This docum

ent recom mends v alues f or length of

exposure duration, T 2 , for the farm

er. U.S. EPA. 1994c

. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes . Off ice of E merge ncy and R

emedia l Response. Offic e of Solid W

aste. Decembe

r. This docu ment recommends th e following:

C Values for

the length of expos

ure duration, T 2
C Value of 0 f

or the tim e period of

the beginning

of com bustion, T

1
C F

v values that range from 0.27 to 1 for organic COPCs

C Default soil bulk density value of 1.5 g/cm 3 , based on a mean f

or loam s oil from

Carsel e t al. (1988) U.S. EPA. 1997a

. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment. Office of A

ir Quality and Planning and Standards and Office of Research and Development. E

PA 452/R-97-005. D ecem ber. U.S. EPA. 1997b. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002Fc . August

. This docum

ent is a r efere nce source

for va lues for length of

exposure duration, T 2 . U.S. EPA. 1998. Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions (MPE ) . Update to EPA/600/6-90/003. Of fice of Resear ch and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/ 137. Decem ber.

### TABLE B-2-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 4)

B-41 Description This equa tion calcula

tes the CO

PC soil loss c onstant, w

hich accounts

for the loss of COPCs from soil by s everal

mecha nisms. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) COPC-specif

ic value s for ksg

are em pirically determ ined from field st udies. No inf

ormation i s available regarding the application of these va lues to the site-spec ific condi tions associated with affected f acilities. (2) The sourc e of the equations in T ables B-2- 3 through B-2-5 ha s not been ide

ntified. Equation

Varia ble Description Units Value 

### ks COPC soil loss constant due

to all processes yr -1



### ksg COPC loss cons tant due to biotic and abiotic degradation yr -1 

### Varies This va riable is COPC-specif

ic. Values

are av ailable in the COPC table s in Appendi x A-2. “Degra dation rate ” values

are als o presented in NC DEHN R (1997); howe

ver, no re ferenc e or source is provided for the v

alues. U.S. EPA (1994a) and U.S. EP A (1994b) state thatksg values a re COPC-spe cific; howeve r, all ksg values a re prese nted as ze ro (U.S. EPA 1994a

) or as “N A” (U.S . EPA 1994b); the basis of these as sumptions i s not addres sed. The following uncertainty is associated w ith this variable: COPC-specif

ic value s for ksg

are em pirically determ ined from field st udies; no inf

ormation i s available regarding the application of these values to the site-specific conditions associated with affected f acilities.

### TABLE B-2-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-42 kse COPC loss cons tant due to soil erosion yr -1 

### 0 Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is fur ther dis cus sed

in T able B-2 -3. Cons ist

ent wit h U.S . EPA

(199 4a) , U. S. EPA (1994b) and NC DEHNR (1997), w e recom mend a de fault v

alue of z ero for ksebecause contamina ted soil er odes both onto the site and away from

the site. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The sourc e of the equation in Table B-2-3 ha s not been ide

ntified. (2) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a gre ater m

ixing depth. This uncertainty may overes timate kse

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate kse

. 

### ksr COPC loss constant due to surface

runoff yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-2-4. N

o refer ence docum

ent is cit ed for this equation. Using this equation is c onsistent w

ith U.S. EPA ( 1998) and NC DE HNR (1997). U .S. EPA (1994a) assume s that all ksr values a

re zero but

does not ex

plain the bas is of this

assum ption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-2 -4) incl ude the fol lowing: (1) The sourc e of the equation in Table B-2-4 ha s not been ide

ntified. (2) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a gre ater m

ixing depth. This uncertainty may overes timate ksr

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksr

. 

### ksl COPC loss cons tant due to le aching yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-2-5. U sing this equation is consistent w ith U.S. EPA (1998),U.S. EPA (1994b) , and NC DEH NR (1997). U.S . EPA (1994a) s tates tha t ksl is zero but doesn’t ex plain the bas is of this as sumption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-2 -5) incl ude the fol lowing: (1) The sourc e of the equation in Table B-2-5 w asn’t identi fied. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksl

.

### TABLE B-2-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-43 ksv COPC loss cons tant due to volatilization yr -1 Varies Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is calcula ted usin g the eq uation in Ta ble B-2- 6. T

his equa tion cal cula tes the COPC loss consta

nt from soil due to v

olatilizat ion, and wa

s obtained f

rom U.S. EPA (1998). T he soil loss

constant due

to volatili

zation ( ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a gre ater m

ixing depth. This uncertainty may overes timate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksv

.

REFERENCES AND DISCUSSION
Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is one of the reference documents f or the equations in Tables B-2-4 and B-2-5. This document is also cited as (1) the source for a range of COPC-specific degradation rates ( ksg), and (2) one of the sour ces that recomm

end assum

ing that the

loss resul

ting from erosion ( kse ) is zero because of contaminated soil eroding both onto the site and away from the site. U.S. EPA. 1994a

. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. This docum

ent is cit ed as a s ource for

the assum

ptions that los ses res

ulting fr om erosion ( kse ), surface ru noff ( ksr ), degrada tion ( ksg), leachin g ( ksl

), and vola

tilization (

ksv ) are all zero. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber 14. This document is one of the reference documents f or the equations in Tables B-2-4 and B-2-5. This document is also cited as one of the sources that recommend assuming that the loss resulting from e

rosion ( kse ) is zero and the loss resulting from de gradation (

ksg) is “NA” or zero for all com pounds.

### TABLE B-2-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 4)

B-44 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence doc

uments f or the equations for ksr , ksl , and ksv

.

### TABLE B-2-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 5)

B-45 Description This equa tion calcula

tes the c onstant for

COPC loss re sulting f

rom eros ion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), we recomm

end a def ault value of zero f or ksebecause of contaminated soil eroding onto the site and away from the site. In site-specific cases w here the permitting authority considers it appropriate to calculate a kse , we recommend usin g the equat ion pres ented in this tabl e along with associated uncertai nties. Yo u can find ad dition al discuss ion on determinin g ksein U.S. EPA (1998). Uncertainties associated with this equation include: (1) For soluble COPCs, leaching might lead to movement below 2 centimeter in untilled soils, resulting in a greater m ixing depth. This uncertainty may ove restimate kse

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) in c omparison to that of ot her residue s. This uncertainty may underestim ate kse

. Equation

Varia ble Description Units Value 

### kse COPC loss cons tant due to soil erosion yr -1 

### 0 Consistent w

ith U.S. EPA ( 1994), U.S. EPA ( 1994b), and NC DE HNR (1997), w

e recom mend as suming a

default value f

or kseof zero because contaminated soil erodes both onto the site and away from the site. Uncertainty may overestimate kse

. 

### 0.1 Units conve

rsion fac tor g-kg/cm 2

- m 2 

### X e Unit soil loss kg/m 2 -yr 

### Varies This va riable is site-specific and is calculated by using the equation in Ta

ble B-4-13. The following uncertainty is associated w ith this variable: All of the equation v

ariables are site -specif

ic. Using default values r

ather than site-spec ific v

alues f or any or all of these variables will result in unit soil loss ( X e ) estim ates that are under-

or overes timated to some

degree. Based on default v alues, X

e estimates can vary

over a range of less than two orders of magnitude.

### TABLE B-2-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 5)

Varia ble Description Units Value



### B-46 SD Sediment

delivery ratio unitless 

### Varies This va lue is site -specif

ic and is c alculate d by using the equation in Table B -4-14. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The rec omme

nded defaul

t values for the e mpirica l interce pt coeff icient, a , are av

erage v alues that are based on studies of sedime nt yields from various w

atersheds . Theref

ore, those de fault v

alues m ay not a ccuratel y repre sent site-specific watershed conditions. As a result, use of these def ault values may under- or overestim ate SD

. (2) The rec omme

nded defaul

t value f or the em pirical slope coeff

icient, b , is based on a revie w of s ediment yields

from various watersheds. This single default value m ay not accurately represent site-specif ic watershed conditions. As a result, use of this default value may under- or overestimate SD

. 

### ER Soil enrichm ent ratio unitless 

### Inorga nics: 1 Organic s: 3 COPC enrichm

ent occurs because ( 1) lighter soil partic les erode more quic kly tha n heavier soil particles, and (2)

concentra

tion of organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded mater ial than in in-situsoil (U.S. E PA 1998). In the

absence of site- specific data, w e recom mend a default v

alue of 3 for organic COPCs and 1 for inorganic COPCs. This is consistent with other Agency guidance (1998), which recommends a range of 1 to 5 and a v

alue of 3 as a “reasonable f irst esti mate.” This ra nge has be en used f

or organic matter

, phosphorus, and other soil-bound C OPCs (U.S. EPA 1998); howev

er, no source s or ref

erences were provided f

or this range. ER is gener ally higher in sa

ndy soils than in silty

or loamy soils (U.S. EPA 1998). The following uncertainty is associated w ith this variable: The def ault ER value m

ay not a ccuratel y ref lect site -specif

ic conditions; therefor

e, ksemay

be over- or underestimated to an unknown extent. Using county-specific ER values will reduce the extent of any uncertainties. 

### BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree.

### TABLE B-2-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 5)

Varia ble Description Units Value



### B-47 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient ml wa

ter/g soil (or cm 3 water/ g soil) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### 2 sw Soil volum

etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure; you can estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. Howe

ver, w e recom mend using 0.2 ml/cm 3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soil s) r ecomm ended by U.S . EPA

(199 8) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksemay

be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-2-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 5)

B-48 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agric ultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, I nc. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is one of

the source s that rec omme nd assum ing that the

loss resul

ting from erosion ( kse ) is zero because contaminated soil erodes both onto the site and away from the site. U.S. EPA. 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil, as cit ed in U.S. EPA

(1993). U.S. EPA. 1994b. Revise d Draft Guidanc

e for Perf orming Scre

ening Level

Risk Analys

es at Combus tion Facilitie s Burning Hazar

dous Wastes. Attachment C, Draft Ex

posure Asse

ssment Guidance for RCRA Hazardous Waste Combustio n Facilities. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber 14. This document recommends (1) a def ault soil bulk density value of 1.5 (g soil/cm3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988), and (2)

a defa ult soil volumet ric wa ter content, 2 sw , value of 0.2 (ml water/cm 3 soil), based on U.S. EPA (1993)

.

### TABLE B-2-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 5 of 5)

B-49 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is the s ource of a

range of COPC enrichm

ent ratio, ER , values. The recomme nded range,

1 to 5, was

used for organic m

atter, phosphor

ous, and other s oul-bound COPCs. This docum

ent recom mends a value of 3 as a “r easonable first e stimat

e,” and st ates that COPC enrichm

ent occurs because l

ighter soil particle s erode m ore quickly

than heav

ier soil particles . Lighte

r soil particles hav

e higher r atios of s urface area to v olume and are highe

r in organic

matte r content. T

herefore , concentra

tion of orga

nic COPCs, w

hich is a f unction of the organic c arbon content of sorbing m

edia, is e xpected t o be higher in eroded m

aterial than in in situsoil. This docu ment is also a so urce of the fol lowing:

C A range of soil volumet ric wa ter content

( 2 sw ) values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heavy loam/clay soils). However, no source or reference is provided for this range.

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil

C The equat

ions in Tables B-1-3 a

nd B-1-5.

### TABLE B-2-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 4)

B-50 Description This equat ion calcu lates the CO PC loss constant due to ru noff of soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might result in movement to below 2 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty m ay overestimate ksr

. (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestim ate ksr

. Equation

Varia ble Description Units Value 

### ksr COPC lo ss constan t due to r unoff yr -1 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994b), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, s ite-spec ific proc edures f or estim ating the a

mount of surfac e runoff

, such as t hose based on the U.S. Soil Conserva tion Service curve number equation (CNE). U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, ksl may be under- or overestimated to an unknown degree.

### TABLE B-2-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-51 2 sw Soil volum

etric w ater conte nt ml

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure; you can estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a def ault value . This v

alue is the

midpoint of

the range 0.1 (very sandy s oils) to 0.3 (he avy loam/cla y soils), recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range) , and is cons istent w ith U.S. EPA ( 1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksr

may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient ml wa

ter/g soil (or cm 3 water/ g soil) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

### TABLE B-2-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-52 BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1998), U .S. EPA (1994), a nd NC DEHNR

(1997) as a refere

nce to calculate av

erage a nnual runoff

, RO . This re ferenc e provides maps w ith isolines of annual average surface w ater runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because these values are to tal contr ibutio ns and no t only surface ru noff, U.S. EPA (199 4) recommends t hat the vo lumes be redu ced by 50 per cent in o rder to est imate surface run off. Hillel, D. 1980. Fundament als of Soil Physics. Acade mic Press, In c. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is one of

the source

documents

that recom

mends us ing Table

B-2-4; howe

ver, this document i s not the orig inal source

of this e quation (this s ource is unk nown). T his document also recommends the followin g:

C Estima

ting annual c

urrent runof

f, R O (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.

C Default value of 0.2 (ml w ater/cm3 soil) for

soil volum

etric w ater conte nt ( 2 sw )

### TABLE B-2-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 4)

B-53 U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edure for Tox

ic and Conventi

onal Pollutants in Sur

face and Ground W

ater—Part I (Revised. 1985) . Environmental Research Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This docum

ent is cit ed by NC DEHNR (1997)

as an ex ample of the use of

the U.S. Soil Conserva

tion Servic e CNE to e stimat e site-s pecific surfac e runoff

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6- 88/005Cc June.. This docum

ent present

s a range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil as cit ed in U.S. EPA

(1993). U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes . Attac hment C, Draft E

xposure Assessm

ent Guidance for RCRA

Hazardous

Waste Combustion Facilitie s. Off ices of Emerg ency a nd Reme dial Respons e. Off ice of Sol id Waste . Decem

ber 14. This docu ment recommends th e following:

C Estima

tion of av erage a nnual runoff

, RO , by using the Water Atlas of the United States (Gera ghty e t al. 1973)

C Default

soil bulk de

nsity, BD , value of 1.5 (g soil/cm 3 soil), based on the me an for loa m soil tha t is take n from Carsel e

t al. (1988)

C Default

soil volum

etric w ater conte nt, 2 sw , value of 0.2 (ml water/cm 3 soil), based on U.S. EPA (1993) U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of soil volumet ric wa ter content, 2 sw , values of 0.1 (ve ry sa ndy soils) to 0.3 (heav

y loam /clay soils) (the

original s ource of, or refe rence f or, these v

alues is not

identified)

C A range of va

lues for soil mix

ing depth, Z

s , for tilled and untilled s oil (the orig inal source

of, or re ferenc e for, the se value s is not ident ified)

C Using the Water Atlas of the United States (Gera ghty e t al. 1973) to c alculate

averag e annual runof

f, RO

### TABLE B-2-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 5)

B-54 Description This equat ion calcu lates the co nstant for COPC lo ss resulti ng from leachin g of soil. Un certainti es associated with this eq uation includ e the follo wing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksl

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to other

residues. This unce

rtainty may underestimate ksl

. (3) The original source of this equation hasn’t been identified. U.S. EPA (1998) p resents the equation as shown here. U.S. EPA (1994b) and NC DEHNR (1997 ) replaced the numerator as

shown w ith “ q ”, defined as ave

rage annua

l recharg e (cm /yr). Equation

Varia ble Description Units Value 

### ksl COPC loss cons tant due to le aching yr -1 

### P Avera

ge annual precipitat

ion cm/yr 

### 18.06 to 164.19 This va riable is site-specific. T

his range is based on informa

tion presented in U.S. EPA ( 1998), repres enting data for 69 selected cities (U.S. Bureau of Census 1987; Baes et al. 1984). The 69 selected cities are not identified; however, they appear to be located throughout the conti nental United States. We recommend using site-specific data. The following uncertainty is associated w ith this variable: (1) To the ex

tent that a site is not

located ne ar an est

ablished m

eteorologic al data s

tation, and si

te-speci fic data

are not available, defa

ult avera ge annual precipitat

ion data m

ay not a ccuratel y ref lect site -specif

ic conditions. As a r

esult, ksl may be un der- or ove resti mated. However , avera ge ann ual p recip itati on d ata are reaso nabl y availab le; th erefor e, we expect unc ertainty

introduced by

this variable to be m

inimal.

### TABLE B-2-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 5)

Varia ble Description Units Value



### B-55 I Avera

ge annual irrigation cm/yr 

### 0 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U.S. EPA ( 1998), repres enting data for 69 selected cities (

Baes et al. 1984). T

he 69 selec

ted cities are not ide

ntified; how

ever, the y appea r to be loca

ted throughout t

he continental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual irrigation information is not available, default values (genera lly bas ed on the clos est com parable loc ation) ma

y not ac curately

refle ct site-s

pecific conditions. A

s a resul t, ksl may be under- or overestim ated to an unknown degree. 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This va riable is site-specific. A

ccording to U.S. EPA (1998),U.S. EPA (1994b) , and NC DEH NR (1997), y

ou can esti

mate RO by using the Water Atlas of the United States (Geraghty et a l. 1973). According to NC DEHNR (1997), you can also use more de tailed, si te-speci fic procedures, such as those ba sed on the U. S. Soil Conser vation Ser

vice CN E. U.S. EPA ( 1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, ksl may be under- or overestimated to an unknown degree. 

### E v Avera

ge annual evapotra

nspiration cm/yr 

### 35 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U. S. EPA ( 1998), repres enting data from 69 selected cities. The 69 selected cities are not identified; however, they appear to be located throughout the contin ental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual evapotranspiration information is not available, default values may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be un der- or ove resti mated t o an u nkno wn degree.

### TABLE B-2-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 5)

Varia ble Description Units Value



### B-56 2 sw Soil volum

etric w ater conte nt (ml

water/cm

3 soil) 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure. You can estimate 2 sw as the m idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range)

and is consi stent wi

th U.S. EPA (1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 s w value may not accurately reflect site-specif ic or local conditions; therefore, ksl may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestimate Cs and Cs tD .

### TABLE B-2-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 5)

Varia ble Description Units Value



### B-57 BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value may not accurately represent site-specific soil conditions. 

### Kd s Soil-wat

er partiti on coeff

icient cm 3 water/ g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

REFERENCES AND DISCUSSION Baes, C.F., R.D. Sharp, A.L. Sjoreen and R.W. Shor. 1984. “A Review and Analysis of Parameters for Asse ssing Transport of Environmentally Released Radionuclides through Agriculture.” Prepared f

or the U.S. D epartm

ent of Ene

rgy unde r Contract No. DEAC 05-840R21400. For the contine

ntal United S tates, as cited in U .S. EPA (1998), t his docume

nt is the sour

ce of a series of ma

ps showing : (1) ave

rage annua

l precipita

tion ( P ), (2) ave

rage annua

l irrigat ion ( I ), and (3) average annual evapotranspiration isolines. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density value, BD , of 1.5 g/cm3 for loam soil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by NC DEHNR (1997) , U.S. EPA (1994b) , and U.S. EPA (1998) as a refere

nce for c alculating

averag e annual runof

f, RO . This docum

ent provides

maps w ith isolines of annual average surface runoff, w hich is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Bec ause these volumes are total contributions and not only surface runoff, U.S. EPA (1994b) recommends that the volumes be reduced by 50 percent in order to estimate averag e annual surface runoff.

### TABLE B-2-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 5 of 5)

B-58 Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the source documents that cites the use of the equation in Table B-2-5. However, the document is not the original source of this equation. This document also recommends the following:

C Estima

tion of av erage a nnual surfa

ce runoff , RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.

C A default value of 0.2 (ml w ater/cm3 soil) for

soil volum

etric w ater conte nt, 2 sw U.S. Burea

u of the Ce

nsus. 1987. Statistical Abstract of t he United State

s: 1987. 107th editi on. Washington, D.C. This docum

ent is a s ource of a

verage annual prec ipitation (

P ) inform ation for 69 selected cites, a s cited in U .S. EPA (1990); t hese 69 cit

ies are not identifi ed. U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventiona l Pollutants in Surface an d Groundwater . Part I (Revised 1985). Environmental Research

Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This document is cited by NC DEHNR (1997) as an exam ple of the use of the U.S. Soil Conservation Service CNE to estimate RO

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft Offi ce of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6- 88/005Cc June.. This docum

ent present

s values for soil m

ixing depth, Z s , for tilled and untilled s oil, as cit ed in U.S. EPA

(1998). U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docum

ent recom mends (1)

a defa ult soil volum

etric w ater conte nt, 2 sw , value of 0.2 (ml water/cm 3 soil), and (2)

a defa ult soil bulk density , BD , value of 1.5 (g soil/cm 3 soil), based on a mean v alue for loam soil from

Carsel e t al. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence s ource docum

ents for the equation i

n Table B -2-5. The or

iginal sour

ce of thi s equation is

not identif

ied. This document also prese

nts a range of values f or soil m ixing depth, Z, for tilled and untilled s oil; the orig inal source

of these values i s not identif

ied.

### TABLE B-2-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 4)

B-59 Description This eq uati on cal culat es the COPC loss c onst ant fro m soil d ue to volat iliza tion , and was obt ained from Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Exposure Pat

hways to Combustor Emi

ssions(U.S. EPA 1998) . The soil loss consta

nt due to vola

tilization (

ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by

adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to other

residues. This unce

rtainty may underestimate ksv

. Equation

Varia ble Definition Units Value 

### ksv COPC loss cons tant due to volatiliz ation yr -1

3.1536 x 10 +07 Units conve rsion fac tor s/yr 

### H Henry’ s Law constant atmm 3 /mol 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail, a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated by using

the param

eters and algorithm

s in Appendi

x A-2, m ay under - or overesti mate t he actual COPC-specif

ic value s. As a

result, ksv

may be under- or ov

erestim ated.

### TABLE B-2-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 4)

Varia ble Definition Units Value



### B-60 Z s Soil mix ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient cm 3

water/ g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### R Universa l gas cons tant atmm 3 /mol-K 

### 8.205 x 10 -5

There a re no uncert

ainties a ssociate d with this

param eter. 

### T a Ambie

nt air tem perature K 

### 298 This variable is site-specific. U.S. EPA (1990) also recomme nds an ambient air temperature of 298 K. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for t he varia ble are not available, defa ult values may not accura

tely represent site-spe cific c onditions. We expect the uncerta

inty as sociated w

ith the sel ection of a single value f rom within the temper

ature rang

e at a s ingle loca

tion to be m

ore signif icant than t

he uncerta

inty as sociated w

ith choosing a single ambient temper ature to re

present al l localitie s.

### TABLE B-2-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 4)

Varia ble Definition Units Value



### B-61 BD Soil bulk density g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions. 

### D soil Solids particle density g/cm3 

### 2.7 We rec omme

nd using this v

alue, based on Blake and Hartag e (1996) and Hillel (1980). The solids particle density will vary with location and soil type. 

### D a Diffusivity of COPC in a ir cm 2 /s 

### Varies This va lue is COPC-s

pecific . We dis cuss this v ariable i n detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The def ault D a values m

ay not a ccuratel y repre sent the be

havior of COPCs under s ite-spec ific condi tions. How

ever, we ex pect the degree of

uncertaint

y to be m inimal. 

### 2 sw Soil volum etric w ater conte nt ml/cm

3 soil 

### 0.2 This variable depends on the available water and on soil structure. You can estimate 2 sw as the m idpoint betwe

en a soil’s

field capacity and wilting point, if you can identify a representative watershed soil. Howev er, we recomm

end using 0.2 ml/cm 3 as a default v alue. Thi s value i s the m idpoint of the

range 0.1 (

very sandy s oils) to 0.3 (he avy loam/cla y soils) recom

mended by U.S. EPA (1998) (no source or refer ence is pr ovided for

this range

) and is cons istent w

ith U.S. EPA ( 1994b). The following uncertainty is associated w ith this variable: (1) Default 2 sw values may not accurately reflect site-specif ic or local conditions; therefore, ksv may be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-2-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 4)

B-62 REFERENCES AND DISCUSSION
Blake, G R. and K.H. H

artge. 1996. Particle D

ensity. M ethods of Soil Anal

ysis, Part 1: Physical

and Mineralogic

al Methods . Se con d Ed iti on. Arno ld K lut e, E d. Ame ric an S oci ety o f Agro nomy, Inc. Madison,WI., p. 381. Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density value, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk. Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. Miller, R.W . and D.T. Gardiner . 1998. In: Soils in Our Env ironment . J.U. Mille

r, Ed. Prentice

Hall. Uppe

r Saddle Riv

er, NJ. pp. 80-123. U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compou nds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s value f or soil, m ixing depth, Z s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docum

ent recom mends a default soil density

, BD , value of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled soil; however, the source or basis for these values is not identified

C A def

ault am bient air te

mperat ure of 298 K

C A range of soil volumet ric wa ter content, 2 sw

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 12)

B-63 Description This equa tion calcula

tes the CO

PC concentrat

ion in aboveg

round vege

tation, due to w

et and dry deposition of

COPCs onto plant

surfac es. The

limita tions and unce

rtainty in calcula

ting this v

alue includ e the follo wing: (1) Uncertainties associated with the variables Q, Dydp , and Dywp are site-specific. (2) The recommended equatio n for calcul ating kp values doe s not consider chemic al degra

dation proces ses. Inc luding chem ical deg radation w

ould decrease the am

ount of tim

e that a chemical remains on plant surfaces (half -life) and thereby increase kp values. Pd decreas es with increased kp values. Reduction of half-lif e from the assum

ed 14 days

to 2.8 days , for example, would decrease Pd about 5-fold. (3) Calculati

ng other par

amete r values (for ex ample, Fwand Rp ) is base d directly or indirectl

y on studie s of vegetation ot her than abov

eground produce

(prima rily g rasses) . To the e

xtent that the ca

lculated pa

ramet er value s don’t acc

urately represe nt aboveg round produce-specific v alues, unce

rtainty is introduce d. (4) The uncertainties associated with the variables F v , Tp , and Yp are not ex

pected to be

significant. As highl ighted abov

e, Pd is most significantly

affected by

the value s assum

ed for kp and the extent to which parameter values (assum ed based on studies of pasture grass) accurately ref lect aboveground produce-specific values. Equation

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation above to calculate Pd. Apportion the calculat ed Pd value into the divalent mercury (Hg 2+ ) and me

thyl m ercury (MHg) forms based on the 78% Hg 2+ and 22% MHg

speciation split in abov

eground produce

(see Cha pter 2). Pd (Hg2+) = 0.78 Pd (Mercu ry) Pd (MH G) = 0.22 Pd (Mercu ry) Evaluate divalent and methyl me rcury as individual COPCs. Calculate Pd for divalent and methyl m ercury using the corresponding equations above.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 12)

B-64 Varia ble Description Units Value 

### Pd Concentration of COPC in

aboveground produce due to direct (wet a nd dry) de

position mg COPC/kg DW


### 1000 Units conve rsion fac tor mg/g 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This value is COPC- and site-specific and is determined by air dispersion modeling. See Chapters 2 and 3 for guidance on calculating this variable. Uncertainties associated with this variable are also COPC- and site-specific. 

### F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in detail in Appendix A -2, and off

er COPC-spe cific v

alues in the HHRAP companion database. This range is based on values presented in Appendix A-2. U.S. EPA (1994b) and NC DEHNR (1997) also present values.
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) states

that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) The F v calculat ion uses a de fault

ST value f or backg round plus local

sources, rather tha

n an ST value for urban sources. If a specific site is loc ated in an ur ban area,using the latter ST value m ay be m ore appropria

te. Specifically, the ST

value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local s ources, and it would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only a f ew perc ent lowe

r. (2) According to Bidleman (1988), the F v equation assumes that the variable c (Junge c onstant) is constant for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . (3) Based on U.S. EPA (1994a), the F v value for dioxins (PCDD/PCDF) is intended to represent 2, 3, 7, 8-TCDD TEQs by weight ing data f or all dioxi

n and furan congeners

with nonze

ro TEFs. U

ncertainty is introduce d, because t he Age ncy has been unable to verif

y the recomm

ended F

v value for dioxins. 

### Dydp Unitized y early averag e dry deposition from particle phase s/m 2 -yr 

### Varie s

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 12)
Varia ble Description Units Value



### B-65 Rp Interception fraction of the e dible

portion of pla

nt unitless 

### 0.39 We rec omme

nd using this default Rp valu e bec aus e it rep rese nts the most cur ren t in form ati on a vail abl e; sp ecif ical ly, productivity

and relati

ve inge stion rates

. As sum marized in Baes

et al. (1984) , experim

ental studie s of past

ure gras ses identi fied a c orrelation be tween i nitial Rp values and productivity (standing crop biomass [ Yp ]) (Chambe rlain 1970): Rp = 1 - e - ( @ Yp
where Rp = Interception fraction of the edible portion of plant (unitl ess)

( = Empirical constant. Chamberlain (1970) presented a range of 2.3 to 3.3; Baes et al. (1984) used 2.88, the midpoint for pasture grasses. Yp = Yield or sta

nding crop biom

ass (product

ivity) (kg W W/m 2 ); the use o f Yp value on a wet w eight basis is in contrast to the equation presented in this table, which presents Yp on a dry weight basis. Baes et al. (1984) proposed using the same empirical relationship developed by Chamberlain (1970) for other vegeta tion class es. Clas s-specif ic estim ates of the em pirical c onstant, ( , were developed by forcing an ex ponential regression equatio n throu gh several po ints, in cludin g average and th eoretical maximum estimates of Rp and Yp (Baes et al. 1984) . The class-specific Rp estim ates w ere then w

eighted, by

relativ e ingest ion of eac h class, t o arrive at the weighted average Rp value of 0.39. U.S. EPA (1994b) and U.S. EP A (1995) recommended a weighted av erage Rp value of 0.0 5. However, th e relative ingestion rates used in U.S. EPA (1994b) and U.S . EPA (1995) to weight the average Rp value w ere deriv ed from U.S. EPA (1992) and U .S. EPA (1994b). T he most current guidance av ailable f or ingestion rates of

homegr own produce is the 1997 Exposure Factors Handbook (U.S. EPA 1997) . The def ault Rp value of 0.3 9 was weighted by rel ative ingestion r

ates of homegr own expos ed fruit a

nd exposed v

egetable s found in U.S . EPA (1997). Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The em

pirical relationship dev

eloped by Chambe rlain (1970) on the

basis of a study of pastur e grass may not accurately represent aboveground produce. (2) The em

pirical c onstants dev

eloped by Baes et al. (1984) f

or use in the

empiric al relat

ionship deve loped by Chamberlain (1970) may not accurately represe nt site-specific mixes of aboveground produce.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 12)
Varia ble Description Units Value



### B-66 Fw Fraction of COPC wet

deposition that adheres to plant surfaces unitless 

### 0.2 for anions 0.6 for cations and most o rganics We recomme

nd using the chemical class-specific values of 0.2 for anions and 0.6 for cations and most organics, as estima ted by U .S. EPA (1994b) a nd U.S. EPA (1995) . These values a re the bes t availa ble inform

ation, base d on a review of the c urrent sci entific literature , with the followi ng exce ption: We r

ecomm end using an Fwvalue of 0.2 for the three organic COPCs that ionize to anionic forms. These include (1) 4-chloroaniline, (2) n-n itrosodiphenylamine, and (3) n-nitros odi-n-proplya mine (s ee Appe

ndix A-2)

. The values estimated by

U.S. EPA (1994b) and U.S. EP A (1995) were based on information presented in Hoffman, et al. (1992), w

hich present

ed values for a pa ramet er ( r) term

ed the “inte

rception f raction.” These v

alues w ere based on a study in w

hich soluble r

adionuclides and insoluble pa rticles labeled w

ith radionuclide s were

deposited onto pa

sture grass v ia sim ulated rai n. The par

amete r ( r) is def

ined as “t he frac tion of m aterial in rain inter

cepted by veget ation and initial ly retained” o r, essenti ally, the pro duct of Rp and Fw, as def ined: r = Rp @ Fw Ther values de

veloped by

Hoffm an, et al. (1992) were

divided by

an Rp value of

0.5 for f orage (U .S. EPA 1994b). The Fwvalues de

veloped by

U.S. EPA (1994b)

are 0.2 f or anions and 0.6 for cations and insoluble particle s. U.S. EPA (1994b) and U .S. EPA (1995) recomm ended using t

he Fw value c alculate d by using the r value f or insoluble particles to represe

nt organic compounds; how ever, no r ationale f or this rec omme

ndation was provided. Interception values ( r)—as def ined by Hoffm

an, et al. (1992)—have not been ex perime ntally de termined for aboveground produce. The refore,U.S. EPA (1994b) and U.S. EPA (1995) apparent ly def aulted and a

ssumed that the Fwvalues c alculate d for past ure gras s (sim

ilar to f orage) a lso apply to aboveg

round produce. T

he rational e for this recomm endation w

as not provided. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Values of

r developed e

xperim entally for past ure gras s may

not accura

tely r epresent a boveground produce-specific r

values. (2) Values o f r

assum ed for m ost organic

compounds, ba

sed on the be

havior of insoluble poly

styre ne microsphe

res tag ged wit h radionuclide s, may

not accura

tely r epresent t he behavior

of orga nic compounds under site-specific conditions. 

### Dywp Unitized y early wet deposition in particle phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 5 of 12)
Varia ble Description Units Value



### B-67 kp Plant surfa ce loss c oefficient yr -1 

### 18 We recomme

nd the kp value of

18 recom

mended by

U.S. EPA (1998)

and U.S. EPA (1994b). The r ecomm ended value is the midpoint of a possible range of values (7.44 to 90.36). U.S. EPA (1998) iden tified several processes— including wind removal, water remova l, and growth dilution—that reduce the amount of COPC that has been deposited on a p lant surfac e. The t erm kp is a m easure of the am ount of conta

minant los

t to these phy

sical proc esses ov

er time

. U.S. EPA (1998) cites Miller and Hoffman (1983) for the following equation used to estimate kp : kp = ( ln 2 / t 1/2 ) @ 365 days /yr where t 1/2 = half-life (day s) Miller and Hoffm

an (1983) report

half-lif e values ranging f rom 2.8 to 34 da

ys f or a vari ety of

COPCs on herba

ceous vegeta tion. Thes e half-l

ife va lues resul t in kp valu es o f 7.4 4 to 90. 36 ( yr -1 ). U.S. EPA (1998) and U.S. E PA (1994b) recommend a kp value of 18, based on a generic 14-day half-life, corresponding to physical processes only. You can also calculate site- and compound-specific kp values using the equa tion from Miller and H

offm an (1983). Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The recommended equatio n for calcul ating kp does not consider chem ical deg radation proc esses. Adding chemical degradation processes would decrease half-lif es and thereby increase kp values; plant conce ntration decreases as kp increases. Using a kp value tha t does not cons ider chem

ical deg radation proc esses i s protective. (2) The half

-life v alues repor

ted by Miller and Hof

fman (1983) may

not accura

tely r epresent t he behavior

of compounds on aboveground prod uce. (3) Based on this

range (7. 44 to 90.36), plant c oncentrations could range

from about 1.8 tim

es higher to about 5 times lower than the plant concentrations, based on a kp value of 18.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 6 of 12)
Varia ble Description Units Value



### B-68 Tp Length of

plant expos

ure to deposition per harvest of edible portion of pla

nt yr 

### 0.16 We recomme

nd using a Tp value of 0.16 years; this is consistent with U.S. EPA (1998), U.S. EPA (1994b), and NC DEHNR (19 97), whic h recommended treating Tp as a constant, based on the average period between successive hay harvests . Belcher

and Trav is (1989) est

imated this period a

t 60 days

. Tp is calculated as follows: 60 days ÷ 365 days/yea

r = 0.16 y

ears The following uncertainty is associated w ith this variable: The av erage pe riod betwe en succes sive hay harvest s (60 days) may

not reflect the leng

th of the g

rowing season or t

he length be

tween s uccessiv e harves ts for si te-speci fic abov

eground produce

crops. Pd

will be (1) und erestimated if th e site-speci fic value of Tp is less than 60 days, or (2) ov erestim ated if the site-s

pecific value of Tp is more than 60 days.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 7 of 12)
Varia ble Description Units Value



### B-69 Yp Yield or sta nding crop biom

ass of the edible por

tion of the plant (pr odu cti vit y) kg DW /m 2 

### Aboveground Produ ce: 2.24 We recomme

nd using the Yp value of

2.24. Based on a revie

w of the availa ble litera ture, this v

alue appea

rs to be represent ative of the mos t comple te and thoroug

h inform ation. U.S. EP A (1998) s tates that the best est imate of Yp is productivity. Baes et al. (1984) and Shor et al. (1982) define Yp as follows as: Yp = Yh i / Ah i where Yh i = Harv est yi eld of

i th crop ( kg DW) Ah i = Are a planted to i th crop (m 2 ) U.S. EPA (1994a) and NC DEHNR (1997) recommended using this equation. Class-specific Yp values were estim ated by using averag e U.S. va lues for Yh and Ah for a variety of fruits and vegetables for 1993 (USDA 1994a and USDA 1994b). Yh values were converted to dry w eight by using average conversion fa ctors for fruits, fruiting vegetables, legume s, and lea

fy v egetable s (Baes

et al. 1984). Class-specific Yp values were grouped to reflect ex posed fruits or exposed vegetables. Exposed fruit and exposed vegetable Yp values w

ere then w

eighted by

relativ e ingest ion rates de

rived f rom the hom

egrown produce table s in U.S. EPA (1997). T

he avera ge inge stion-weighted Yp value w as 2.24. U.S. EPA (1994b) and U .S. EPA (1995) recomm end a Yp value of 1.6; however, the produce classes and relative ingestion rates used to derive this Yp value a re inconsis

tent with U.S. EPA (1997). The following uncertainty is associated w ith this variable: The harv est yi eld ( Yh ) and area

planted ( Ah ) may not reflect site-s

pecific conditions. T

his may under- or overestimate Yp

.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 8 of 12)

B-70 REFERENCES AND DISCUSSION Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and Analysis of Parameters and Assessing Transpo rt of Environmentally Released Radion uclides through Agriculture

. ORNL-5786. Oak Ridge National Laborator

y. Oa k Ridge,Tenness ee. Septe mber. This docum

ent proposed us ing the sa me em pirical relationship dev

eloped by Chambe rlain (1970) f

or other vegetation classes. Class-s pecific estim ates of the em pirical c onstant, ( , were develope d by forcing an exponent ial regressio n equati on thro ugh several p oints, includ ing average and theoreti cal maximum estimates of Rp and Yp

. The class-specific em

pirical constants developed are as follows: Exposed produce

— 0.0324 Leafy v egetables

— 0.0846 Silage

— 0.769 Beecher , G.D., a nd C.C. Tra

vis. 1989. “

Modeling Support for the RU RA and Municipal Was

te Combus

tion Projects: Final Report on Sensitivi ty and U ncertainty Analy sis for t he Terre strial Food Chain Model.”

Interagency A

greem ent No. 1824-A

020-A1, Of

fice of Risk A nalysi s, Health and Safe

ty Res earch Div

ision, Oak

Ridge Na

tional La boratory. Oak Ridg

e, Tenne ssee. October. This document recommends Tp values based on the avera ge period between succes sive hay harvests an d successive gr azing. Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Pages 361-367. N ovembe r 4. This docu ment is cited b y U.S. EPA (1 994a) an d NC DEHNR (1 997) as t he source of the equat ion for cal culatin g F v . For discus sion, see R

efere nces and D iscussion, T

able B-1-1. Chamberlain, A.C. 1970. “Interception and Retention of Radioactive Aerosols by Vegetation.” Atmospheric Environment

. 4:57 to 78. Experim ental studie s of past

ure gras ses identi fied a c orrelation be tween i nitial Rp values and productivity (standing crop biomass [ Yp ]): Rp = 1-e
- ( @ Yp where ( = Empirica l constant; range prov

ided as 2.3 to 3.3 Yp = Yield or sta nding crop biom

ass (product

ivity) (kg DW /m 2 )

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 9 of 12)

B-71 Hoffm an, F.O., K.M . Thiess en, M.L. Fr ank, and B.G . Blay

lock. 1992. “ Quantific ation of the Intercept ion and Initial

Retention of

Radioacti

ve Contam

inants Depos ited on Pasture Grass by Simulated Rain.” Atmospheric Environment. Vol. 26A. 18:3313 to 3321. This docum

ent developed values

for a pa ramet er ( r) that it termed “interception fraction,” based on a study in which soluble gamma -emitting radionuclides and insoluble particles tagged with ga mma -emitt ing radionucl

ides we re deposited onto pasture grass ( specifically , a com bination of f

escues, clover, a

nd old field v

egetation, including f

escue) v ia sim ulated rai n. The parame ter, r , is defined as “the fractio n of material in rain int ercepted b y vegetation an d initi ally retained ” or, essent ially, the p roduct of Rp and Fw, as d ef ined for the HHR AP: r = Rp @ Fw Experim ental r values obt ained in clude th e following:

C A range of 0.006 to 0.3 for anions (based on the soluble radionuclide iodide- 131 [ 131 I]); when calculatin g Rp values for anions, U.S. EPA (1994a) used the highest geometric mean r valu e (0 .08 ) ob serv ed i n th e stu dy.

C A range of 0.1 t o 0.6 for cations (b ased on th e solubl e radion uclide b eryllium-7 [ 7Be]; when calculatin g Rp values for cations, U.S. EPA (1994a) used the highest geometric mean r valu e (0 .28 ) ob serv ed i n th e stu dy.

C A geom

etric ra nge of v alues f rom 0.30 to 0.37 for insoluble polysty rene m icro sphere s (IPM) rang

ing in diam

eter fr om 3 to 25 m

icrome ters, labeled with c erium-141 [ 141 Ce], [ 95 N]b, and strontium

-85 85 Sr; when calc ulating Rp values f or organics

(other than t

hree orga nics that i onize to anionic form s: 4-chloroa

niline, n-nitr

osodiphenylamine, and n-nitrosodi-n-propy

lamine [see Appe

ndix A-2]), U.S. EPA (1994a ) used the g

eometr ic mea n r value f or IPM with a

diamet er of 3 m icrome ters; how ever, no r ationale f or this selection was prov

ided. The authors concluded that, for the soluble 131 I anion, inter ception fr action r is an inve

rse func tion of rai n amount, w

hereas f or the soluble

cation 7 Be and the IPMs, r depends m

ore on biomass than on amount of rainfall. The authors also concluded that (1) the anionic 131 I is esse ntially remov ed with the

water after the vegetation surf

ace has become

saturated, and (2) the cationic 7 Be and the IPMs are ad sorbed t o or settl e out on to the pl ant surface. This discrep ancy between the behavior of the anio nic and cat ionic sp ecies is con sistent wit h a negative ch arge on the plant surface. As sum marized in U.S. EPA

(1994a), this doc

ument is the source

of the recomm

ended F

v value of 0.27 for diox

ins (polyc hlorinated dibe

nzodioxins/poly

chlorinated dibenzofura

ns [ PCDD/PCDF

]). This v alue is int ended to repr

esent 2,3,7,8-t

etrachlorodi

benzo-p-dioxi

n (2,3,7,8-TCDD) equiva lents (T EQ) by w eighting a ll dioxin and f

uran congene

rs with nonz

ero toxicity equivale ncy f actors (T EF). U.S. EPA

is inves tigating the appropria

teness of the use of

recom mended F

v value f or PCDD/PCDF

s . Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. Miller, C.W. and F.O. Hoffman. 1983. “An Examination of the Environmental Half -Time for Radionuclides Deposited on Vegetation.” Health Physics . 45 (3): 731 to 744. This document is the source of the equation used to calculate kp : kp = (ln 2/ t 1/2 ) @ 365 days/year where t 1/2 = half-life (days) The study reports half-life

values r anging f rom 2.8 to 34 da

ys f or a vari ety of

COPCs on herba

ceous vegetation.

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 10 of 12)

B-72 NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -2-7. Shor, R.W., C .F. Baes, and R.D. Shar p. 1982. Agricultural P

roduction in the

United States

by County: A Compilation of Inf ormation from the 1974 Census of Agricultur

e for Use in Terres trial Food-Chain Tran sport and Assessment Models. Oak Ridg e National

Laborator

y Publication. ORNL- 5786. This document is the source of the equation used to calculate Yp :

Yp . P i = Yh / Ah i where P i = productivity of i th crop ( kil ogr am dry we igh t [kg DW ]/sq uar e m ete r [m 2 ])

Yh = harvest yield of i th crop ( kg DW) Ah i = area pla nted to crop I

(m 2 ) using the f

ollowing i

nforma tion:

Produce Categ ory Empirical

Constant (unitless) Rp

(unitless) Yp

(kg DW /m 2 ) Yp (kg WW /m 2 ) Intake (g/ kg-d ay) Exposed Fruit

s 0.0324 0.053 0.252 1.68 0.19 Exposed Vegetables

-- 0.982 5.660 89.4 0.11 Leafy Vege

tables 0.0846 0.215 0.246 2.86

-- Fruiting Vegetables 0.0324 0.996 10.52 167

-- Using the empirical relationship developed by Baes et al. (1984) to estimate Rp based on Yp requires t hat Yp term to be in whole-weight units. However, in Equation B-2-7, the Yp term s hould be in dry-weight units. For expose d veget

ables, Rp was derived from a weighted average of leafy v egetable and fruiting vegetable Rp values. This w eighted a verage was ba sed on whole -weig

ht Yp values f

or leafy and fruiting veg

etables. In addition, the exposed vegetable Yp value, bo th whole- an d dry-weight, was derived by the following:

The fo llo wing pro duc e it ems wer e in clu ded in e ach cate gor y:

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 11 of 12)

B-73 Exposed Fruit

s—apple, a

pricot, berr

y, cher ry, cr anberry, grape, peach, pear , plum/prune , straw

berry Exposed Vegetables—asparagus, cucumber, eggplant, sweet pepper, tomato, snap beans, broccoli, brussel sprouts, cauliflower, celery, lettuce, and spinach The ingestion rates for exposed fruits and exposed vegetables w ere based on U.S. EPA (1997), homegrown intake rates.
Howeve r, U.S. EPA ha

s revie wed Bae s et al. ( 1984), which a lso present

s and discus ses this equation. U.S. Depar

tment of Agric ulture (USD

A). 1994a. Vegetables 1993 Summary . National Agric ultural Stat

istics Se rvice, A gricultura l Statistic s Board. W

ashington, D .C. Vg 1-2 (94). USDA. 1994b. Noncitrus Fruits and Nuts 199 3 Summary . National Agric ultural Stat

istics Se rvice, A gricultura l Statistic s Board, W

ashington, D .C. Fr Nt 1-3 (94). One of the so urces of Yh (harves t yield) and Ah (area planted for harvest) values for f ruits, fruiting vegetables, legumes, and leafy vegetables used to calculate Yp (yield or standing crop biomass). Yh values w

ere conve rted (for use in the equations) to dry weight by using averag e conversion factor

s for the se sam

e aboveg round produce classes, a

s presented in Baes e

t al. (1984). The fruits and vegetables considered in each category are as follows: Exposed f

ruits—apple , apricot, be

rry, c herry, cranberry

, grape, peach, pear

, plum/prune , and straw

berry Exposed vegetables—asparagus, cucumber, eggplant, sw eet pepper, tomato, snap beans, broccoli, brussel sprouts, cauliflower, celery, lettuce, and spinach U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge , Volumes I and II. Office of W ater. Washington, D.C. EPA 822/R-93-001a. This docum

ent is the s ource of i

ngestion ra

tes (g D W/day ) for abov eground produce

classe s—fruiti

ng vege tables (4.2) , leafy

veget ables (2.0),and legum

es (8.8)— tha

t U.S. EPA (1994b) used to calculate Rp and Yp

. U.S. EPA. 1994a

. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

II: Site-Spe

cific Assessment Procedures

. External Re view Draft

. Office of R esearc h and Development. W

ashington, D.C. EPA/600/6-88/00 5Cc. June. This is t he source of

ingestion r

ate for fruits, ba

sed on whole

weight (88 g/day

) and conve

rted to dry

weight by using an aver age w hole-weight to dry

-weig ht convers ion factor

for fr uits (excluding plums/prunes, which had an extreme value) of 0.15 taken from Baes et al. (1984), used to calculate Rp and Yp

. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This is one

of the sour

ce docum ents for the equation i

n Table B -2-7. This document also recommended we ighted average Rp and Yp values of 0.05 and 1.6, res

pectivel y, based on the em

pirical relationships ide

ntified by Chambe rlain (1970) a

nd Shor et al. (1982). Rp = 1 - e - ( @ Yp
where ( = Empirica l constant; range prov

ided as 2.3 to 3.3

### TABLE B-2-7 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O DIRE CT DE POSITION (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 12 of 12)

B-74 Yp = Standing cr op biomass

(productivit

y) (k g DW/m

2 ) and Shor et a

l. (1982): Yp = Yh / Ah i where
Yh = Harves t yield of i th crop ( kg DW) Ah i = Area planted to crop I (m 2 ) U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3. This is one

of the sour

ce docum ents for the equation i

n Table B -2-7.

U.S. EPA. 1997. Exposure Factors Handbook. Office of Re search a nd Developm

ent. EPA/600/P-95/002F. August

. This document is the source of relative ingestion rates. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This is one of the sour ce document s for the equ ation in Table B-2-7 . This docu ment also stat es that the best estimate o f Yp (yield or standing crop biomass) is productivity, as defined under Shor et al. ( 1982).

### TABLE B-2-8 ABOVEGROUND PRODUCE CONCENTRATIO N DUE TO AIR-TO-PLANT TRANSFER

(CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 5)

B-75 Description This equa tion calcula

tes the CO

PC concentrat

ion in aboveg

round produce re sulting f rom dire ct uptake

of vapor phase COPCs

onto plant surf

aces. The limitatio ns and un certainty in trodu ced in calcu lating th is value inc lude th e following: (1) The range of values f or the variable Bv

(air-to-pla

nt biotransf

er fac tor) is about 19 orders of

magni tude for org

anic COPCs (

this range may change on t

he basis of

the tables

in Appendix A-2). COPC-specific Bv values f or nondioxin-lik

e compounds

may be overe stimat

ed by up to one

order of m

agnitude, ba

sed on expe

rimenta l conditions used to develop t he algorithm used to estimate Bv values. (2) The algorithm used to calculate values for the va riable F

v assum es a def ault value for the pa

ramet er ST (Whitby’s average s

urface area of particulates [aerosols]) of background plus local sources, r ather than a

n ST value for urban sources. If a specific site is located in an urban area, using the latter ST value m

ay be m ore appropria

te. The ST value f

or urban sourc es is about one order of

magni tude grea ter than tha

t for bac kground plus local source s and would result in a lower F

v value; how

ever, the F v value is likely to be only

a few percent low

er. As highl ighted by uncertaint

ies desc ribed above , Pv

is most affected by

the value calculat ed for Bv

. Equation

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation to calculate Pv. Apportion the calculat ed Pv value into the divalent mercury (Hg 2+ ) and methyl mer cury (M HG) forms based on the 78% Hg 2+ and 22% MHG speciation split in abov

eground produce

. Pv (Hg2+) = 0.78 Pv (Mercu ry) Pv (MHg) = 0.22 Pv (Mercu ry) Evaluate divalent and methyl me rcury as individual COPCs. Calculate Pv for divalent and methyl m ercury using the equations above.

### TABLE B-2-8 ABOVEGROUND PRODUCE CONCENTRATIO N DUE TO AIR-TO-PLANT TRANSFER

(CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 5)

B-76 Varia ble Description Units Value 

### Pv Concentration of COPC in

aboveground produce due to air-toplant transfer μ g COPC/g DW (equivale nt to mg COPC/kg DW) 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This va riable is COPC- and site -specif ic, and is de

termined by air dispersion m odeling. Se e Chapters

2 and 3 of the HHRAP for guidance on calculating this variable. Uncertainties associated with this variable are site-specif ic. 

### F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion database. This range is based on values presented in Appendix A-2. U.S. EPA (1994b) and NC DEHNR (1997) also pre sent val

ues. F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) st

ated that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It is based on the assum ption of a de fault

ST value f or backg round plus local

sources, rather tha

n an ST value f or urban source s. If a

specif ic site i s located in an urban ar ea, using the latter ST

value m ay be m ore appropria

te. Specifically, the ST

value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local s ources, and it would re sult in a low er calc ulated F

v value; however, the F v valu e is l ikel y to b e on ly a few percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Cyv Unitized y

early averag e air concentration from vapor phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-2-8 ABOVEGROUND PRODUCE CONCENTRATIO N DUE TO AIR-TO-PLANT TRANSFER

(CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 5)
Varia ble Description Units Value



### B-77 Bv ag COPC air-to-plant biotransf er fac tor for aboveground produce unitless ([mg COPC/g DW plan t]/ [(mg COPC/g air]) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP companion database. Uncertain ty associated wit h this vari able incl ude the fol lowing: (1) The studies that formed the basis of the algorithm used to estim ate Bv values were conducted on azalea leaves and grass es, and m

ay not a ccuratel y repre sent Bv

for aboveground produce other than leafy vegetables. 

### VG ag Empirica

l correct ion factor for aboveground produce unitless 

### 0.01 or 1.0 We recomme

nd using a VGag value of 0.0 1 for COP Cs with a log K ow greate r than 4 and a

value of 1.0 for COPCs

with a log K ow less than 4. This va riable is an empir

ical corr ection fa ctor that reduces abov

eground produce

concentra

tion. The equation in this t able was developed to estimate the transfe r of COPCs into leafy vegetation rather than into bulkier aboveground produce, such as apples. Because of the p rotective o uter skin, size, and sh ape of bulky pr oduce, t ransfer of lip ophil ic COPCs ( log K ow greater than 4) to the center of th e produ ce is not li kely. In addi tion, t ypical prepa ration t echniqu es, such as wash ing, peeling, and cooking, will further reduce residues. U.S. EPA (1994b) recommended a value of 0.01, based on U.S. EPA (1994a), bu t made no distinction between fruits, vegeta bles, and le afy

veget ation. NC DEHNR (1997), a lso citing U.S. EPA (1994a ), recom mended v alues of (1) 0.01 for fruits a nd fruiting

veget ables, and (2) 1.0 for leafy veget ables. T he values cited f rom U.S. EPA (1994a) a

re also ba sed on informa tion from Riederer (1990) and Wipf

, et al. (1982)

. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) U.S. EPA (1994a ) assum ed that tra nslocation of

compounds de

posited on the s

urface of aboveground vegetation to inner parts of aboveground produce would be insignificant. This may underestimate Pv. (2) U.S. EPA (1994a) assumed that the density of the skin and the whole vegetable are equal. This m ay overestimate Pv

. (3) U.S. EPA (1994a ) assum ed that the thickness

of veg etable sk in and broadlea

f tree skin are

equal. T he eff ect of this assum

ption on Pv

is unknow

n. 

### D a Density

of air g/m 3 

### 1200.0

We rec omme

nd using this v

alue based on Weast

(1986). This

refer ence indica

tes that a ir density varies with tem perature. The densi ty of air at both 20° C and 25°C ( rounded to two signifi cant fig ures) is 1. 2 x 10 +3

. U.S. EPA (1994b) and NC DEHN R (1997) recom

mended thi s sam

e value but stated t

hat it wa s calcula ted at sta ndard conditions (20° C and 1 atm osphere).

### TABLE B-2-8 ABOVEGROUND PRODUCE CONCENTRATIO N DUE TO AIR-TO-PLANT TRANSFER

(CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 4 of 5)

B-78 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technol ogy. Volume 22. N umber 4. Pag

es 361-367. For discussion, see Re ferenc es and Dis cussion in Table B-1-1. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -2-8. This document a lso recom mends tha

t (1) F

v values be based on the work of Bidleman (1988), and (2) an empirical correction factor ( VGag

) be used to reduce concentrations of COPCs in specific vegetation types—specifically, a VGag value of 0.5 is recom

mended f or silage . Howev

er, no rationa

le is provided f

or this val ue. This f

actor is us ed to reduce

estim ated COPC conc entrations i n specif ic vegetation ty

pes, beca use (1) Bv

was developed for azalea lea ves, and (2) it is assumed that there is insignificant translocation of compounds deposited on the surface of some vegetation types to the inner parts of this vege tation because of the lipophilicity of the COPC. Riederer, M. 1990. “Estimating Partitioning and Transport of Organic Chemicals in the Foliage/Atmosphere System : Discussion of a Fugacity-Based Model.” Environmental Science and Technology . 24: 829 to 837. This is t he source of

the leaf thicknes s estim

ate used t o estim ate the e mpirica l correct ion factor ( VGag ). U.S. EPA. 1994a

. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

I: Propert

ies, Source

s, Occurr ence, and Bac

kground Exposur

es. External Review

Draft. Office of Re search a nd Development. Washington, DC. EPA/600/6-88/005Cc. Jun e. This docum

ent recom mends a n empiric al correc

tion fact or of 0.01 to reduce estim ated veg etable conc entrations on the basis of the assum

ption that ther

e is insig nificant transloca

tion of compounds de

posited on the s

urface of aboveground vegetation to inne r parts f or aboveg round produce. N

o refer ence or dis cussion reg

arding the validity

of this a ssumption w

as give n. The factor of 0.01 is based on a similar correction factor f or belowground produce ( VG bg ), which i s estim ated on the ba

sis of a ratio of the vegetable sk

in mass to vege table total mass . The document assumes that the densities of the skin and vegetable are equal. The document also assumes an ave rage vegetable skin leaf

that is based on Rierderer (1990). Based on these assumpt ions, U.S. EPA

(1994a) calculated VG bg for carrots an d potat oes of 0.0 9 and 0. 03, resp ectively. By comparin g these values to conta mination reductio n research co mpleted by Wipf, et al. (1982),U.S. EPA (1994a ) arrived at the re comm

ended VG ag value of

0.01. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This is one of the sour ce document s for the equ ation in Table B-2-8 . This docu ment also pr esents a range (0.27 t o 1) of F v values for organic COPCs, based on the work of Bidleman (1988); F

v for all inorganics

is set e qual to zero. U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3.

### TABLE B-2-8 ABOVEGROUND PRODUCE CONCENTRATIO N DUE TO AIR-TO-PLANT TRANSFER

(CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 5 of 5)

B-79 U.S. EPA. 1997. Mercury Study Re port to Congre ss. Volume III: Fate and Trans

port of Mer

cury in t he Environm

ent. Off ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. Based on at

tempts to model ba

ckground c oncentrations

of dioxin-l

ike com pounds in beef

on the basis

of know n air conce

ntrations, thi s docume

nt recom mends reducing, by

a fac tor of 10, Bv values c alculate d by using the Bacci,et al. (1992)

algorithm

The use of this f actor “m ade predic

tions [of bee f concent

rations] com

e in line w

ith observa

tions.” Weast,R.C. 1986. Handbook of Chemistry and Physics . 66th Edition. Cleveland, Ohio. CRC P ress.

This docum

ent is a r efere nce for a ir density values, and is an upda

te of W east (1981). Wipf, H.K., E. Homberger, N. Neuner, U.B. Ranalder, W. Vetter, and J.P. Vuilleumier. 1982. “TCDD Levels in Soil and Plant Samples from the Seveso A rea.” In: Chlorinate

d Dioxins and Related Compounds : Impact on the Environment. Eds. Hutzinger, O. et al. Pergamon, NY.

### TABLE B-2-9 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O ROOT UPTAKE (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 1 of 3)

B-80 Description This equa tion calcula

tes the CO

PC concentrat

ion in aboveg

round produce due t

o direct upta

ke of C OPCs from

soil through plant roots. T he limit ations and unc ertainty

introduced in c alculating this valu e includ e the follo wing: (1) The availabil ity of site-spe cific informati on, such as meteorolo gical data, will affect the accur acy of Cs estimates. (2) Estimated COPC-specific soil-to-plant bioconcentration factors ( Br) don’t ref lect site -specif

ic conditions. This m

ay be e specially

true for inorganic C OPCs for w hich you c ould more accurately estima

te Br by using site-specific BCFsrather tha n BCF s presented in Baes e

t al. (1984). W

e theref ore recom mend using

plant uptake

response s lope fac

tors deriv ed in U.S. EPA (1992) for arsenic, cadmium, selenium, nickel, and zinc. Equation

For mercury modeling, calculate aboveg round produce concentratio n due to root uptake using the respective Cs and Br values for divalent mercury (Hg 2+ ) and me

thyl m ercury (MHg).

Varia ble Description Units Value 

### Pr ag Concentration of COPC in

aboveground produce due to r oot uptake mg COPC/kg DW



### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies This va lue is COPC-a

nd site-spe cific a

nd calculat

ed using the

equation in Table B-2-1. Uncertai nties ass ociated w

ith this variable are site-specific.

### TABLE B-2-9 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O ROOT UPTAKE (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 2 of 3)
Varia ble Description Units Value



### B-81 Br ag Plant-soil bioconc entration f actor for aboveground produce unitless ([mg COPC/kg DW plant]/[mg COPC/ kg soil]) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRA

P companion da

tabase. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Estimates of Br for som e inorganic

COPCs, based on plant uptak e response

slope fa ctors, m ay be m ore accurate than those ba

sed on BCF

s from Baes et al. (1984). (2) We rec omme

nd that uptake

of orga nic COPCs f

rom soil and transport

of the COPCs to aboveg round plant parts be c alculate d on the basis of a regression equation dev eloped in a s

tudy of the uptake

of 29 orga

nic compounds. T

his regre ssion equation, develope d by Tr avis and A

rms (1988) , may

not accura

tely r epresent the behavior of all organic COPCs under site-specific conditions.

REFERENCES AND DISCUSSION Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and A nalysis of Par ameters and Assessi

ng Transport of Env

ironmentally

Released Radionuclides t hrough Agricultur

e. ORNL-5786. Oak Ridge National Laborator

y. Oa k Ridge,Tenness ee. Septe mber. Element-specific bioconcentration factors ( BCF ) were developed by Baes e t al. (1984)—for both vegetative (stems and leaves) portions of food crops (Bv) and non vegetative (reproductive—fruits, seeds, and tubers) portions of food crops ( Br)—on the basi s of a r eview and compilation of a

wide v ariety of me asured, em

pirical, a nd compar

ative da ta. Inorganic-specific Br

values were calculated as a weighted average of

vegetative (

Bv ) and reproductive ( Br) BCF s. We recomm

end calculating inorganic-specific Br values as a weig

hted averag e of vegetativ

e and reproduc

tive BCFs . Relativ

e ingest ion rates de

termined from U.S. EPA (1997a ) are 75 per

cent reproduc

tive and 25 pe

rcent vegetativ

e for hom egrown produce. Howeve r, for ex posed fruit

s only the reproductiv

e BCFs should be used. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -2-9. Travis, C.C. and A.D. Arm s. 1988. “Bioconcentration of Organics in Beef, Milk, and Vegetation.” Environmental Science and Technology . 22:271 to 274. Based on pai

red soil and plant concent ration data

for 29 organic com

pounds, this docum

ent developed a reg

ression equa

tion relating

soil-to-plant BCF

( Br) to K

ow ; log Br = 1.588 - 0.578 log K ow

### TABLE B-2-9 ABOVEG

ROUNDPRODUC E CONC ENTR ATION DUE T O ROOT UPTAKE (CONSUMPTION OF ABOVEGROUN D PRODUCE EQUATIONS) (Page 3 of 3)

B-82 U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge , Volumes I and II. Office of W ater. Washington, D.C. EPA 822/R-93-001 a. Source of plant uptake response factors for arsenic, cadmium, nicke l, selenium, and zinc. Plant uptake response factors are converted to BCFs by multiplying the plant uptake response factor by 2. U.S. EPA. 1994. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-Specific Assessment Procedures. External Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/0 05Cc. June. This is t he source f

or ingestion rate f

or fruits,based on w

hole weight (88 g/da

y), and c onverted to dry w eight by using an a

verage whole-w eight to dry

-weig ht convers ion factor

for fr uits (excluding plums/prunes, which had an extreme value) of 0.15 from Ba es et al. (1984)—used to calculate Br

. U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3. This document recommends using the BCFs , Bv , and Br from Baes et

al. (1984) f

or calcula ting the upta

ke of inor ganics i nto vege tative g rowth (st ems a nd leaves) and nonvegetative growth (fru its , see ds, and tub ers) , re spe cti vely. Although m

ost BCFsused in th is documen t come from Baes et al. (1 984), values for some in organics were ap parentl y obtained from plant up take respon se slope facto rs. These up take response s lope fac

tors deriv ed from U.S. EPA (1992)

. U.S. EPA. 1997a

. Exposure Factors Handbook . Off ice of R esearc h and Development. E

PA/600/P-95/002F. A

ugust. This document is the source for relative intake rate split of 75 percent reproductive and 25 percent vegetative f or homegrown produce.

U.S. EPA. 1997b. Mercury Study Re port to Congre ss. Volume III: Fate and Trans

port of Mer

cury in t he Environm

ent. Off ice of A ir Quality and Planning and Standards a nd Offi ce of Re search and Development. E

PA 452/R-97-005. D ecem ber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This is one

of the sour

ce docum ents for the equation i

n Table B -2-9.

### TABLE B-2-10 BELOWGR

OUND PR

ODUCECONCE NTRA TION D UE TO R OOT UPTA

KE (CONSUMPTION OF BELOWGROUND PRODUCE EQUAT IONS) (Page 1 of 5)

B-83 Description This equa tion calcula

tes the CO

PC concentrat

ion in belowg

round vege

tation due to dir

ect uptak e of COPCs

from soil. The

limita tions and unce

rtainty introduced in calculating this value

include the follo wing: (1) The availabil ity of site-spe cific informati on, such as meteorolo gical data, will affect the accur acy of Cs estimates. (2) Estimated COPC-specific soil-to-plant biotransfer factors ( Br) don’t nece ssarily

reflec t site-specific c onditions. This may be espec ially t

rue for inor

ganic COPCs for w

hich estim

ates of Br would be more accurately estimate d by using si te-specific B CFs from Baes et al. (1984 ). Hence, for arsenic, cad mium, seleniu m, nickel, and zinc, we recommend u sing plan t uptake response s lope fac

tors deriv ed from U.S. EPA (1992)

.

For mercury modeling, belowground produce concentration due to root uptake is calculated using the respective Cs and Br values for divalent mercury (Hg 2+ ) and me

thyl m ercury (MHg). Varia ble Description Units Value 

### Pr bg Concentration of COPC in

belowgr ound produce due to root uptake mg COPC/kg DW



### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies This va lue is COPC-a

nd site-spe cific a

nd calculat

ed using the

equation in Table B-2-1. Uncertai nties ass ociated w

ith this variable are site-specific.

### TABLE B-2-10 BELOWGR

OUND PR

ODUCECONCE NTRA TION D UE TO R OOT UPTA

KE (CONSUMPTION OF BELOWGROUND PRODUCE EQUAT IONS) (Page 2 of 5)
Varia ble Description Units Value



### B-84 Br rootveg Plant-soil bioconc entration f actor for belowground produce unitless ([mg COPC/ kg plan t DW]/ [mg COPC/ kg soil]) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP companion database. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Estimates of Br for som e inorganic

COPCs, based on plant uptak e response

slope fa ctors, m ay be m ore accurate than those ba

sed on BCFs f

rom Bae s et al. ( 1984). (2) We rec omme

nd that you calculat

e uptake of organic COPCs f rom soil and the trans

port of COPCs

to belowgr ound produce on the basis of a regre ssion equation developed by Brig gs et al (1982). This

regres sion equation m

ay not a ccuratel y repre sent the be

havior of all clas ses of or

ganic COPCs under site -specif ic conditions.

### TABLE B-2-10 BELOWGR

OUND PR

ODUCECONCE NTRA TION D UE TO R OOT UPTA

KE (CONSUMPTION OF BELOWGROUND PRODUCE EQUAT IONS) (Page 3 of 5)
Varia ble Description Units Value



### B-85 VGrootveg Empirica

l correct ion factor for belowground produce unitless 

### 0.01 or 1.0 We recomme

nd that you use a VGrootvegvalue of 0.0 1 for COP Cs with a log K ow greater than 4 and use a VGrootvegvalue of 1.0 for CO PCS with a log K ow less than 4. This va riable is an empir

ical corr ection fa ctor that reduces produce concentra

tion. Beca

use of the protectiv e outer sk in, size, and sh ape of bulky pr oduce, t ransfer of lip ophil ic COPCs ( log K ow greate r than 4) to the

center of the produce i sn’t likely. In addition, typical preparation techniques, such as washing, peeling, and cooking, will further reduce residues. U.S. EPA (1994) recommended a VGrootvegvalue of 0.0 1 for lipo philic C OPCs (lo g K ow greater than 4) to reduce estima ted below ground produce c oncentrations . This es timate for unspecified v

egetable s is based on:

where M

skin = Mass of thin (skin) layer of an below grou nd vegetabl e (g) M vegetable = Mass of enti re vegetable (g) If y ou assum e that the density

of the sk in and the w

hole vegetable ar

e the sam e, this equa

tion can bec ome a r

atio of the volume of the sk

in to that of

the whole

veget able. Wi th this ass umption, U.S. EPA (1994) ca lculated VGrootvegvalues of 0.09 an d 0.03 for carrots an d potat oes, respe ctively. U.S. EPA (199 4) ident ified oth er processe s, such as p eeling, cooking, a

nd cleaning , that will further reduce the

veget able conce

ntration. Be cause of

these othe

r processe s, U.S. EPA (1994) recommended a VGrootvegvalue of 0.01 for lipophilic COPCs. The following uncertainty is associated w ith this variable: U.S. EPA (1994) assumed that the density of the skin and the whole vegetable are equal. This m ay overestimate Pr. However, based on the li mited range of VGrootveg(compa red to Br), it appears that in most cases, these u ncertain ties will have a l imited impact o n the calcu lation o f Pr and, ult imately, risk. 

### Kd s Soil-wat

er partiti on coeff

icient cm 3 water /g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A

-2.

### TABLE B-2-10 BELOWGR

OUND PR

ODUCECONCE NTRA TION D UE TO R OOT UPTA

KE (CONSUMPTION OF BELOWGROUND PRODUCE EQUAT IONS) (Page 4 of 5)

B-86 REFERENCES AND DISCUSSION Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and A nalysis of Par ameters and Assessi

ng Transport of Env

ironmentally

Released Radionuclides t hrough Agricultur

e. ORNL-5786. Oak Ridge National Laborator

y. Oa k Ridge,Tenness ee. Septe mber. For discussion, see Re ferenc es and Dis cussion in Table B-2-10. Briggs,G.G.,R.H. Brom ilow, and A .A. Eva

ns. 1982. Rela

tionships betw

een lipophilic ity and r

oot uptake a

nd transloca

tion of non-ioniz

ed chem icals by barley

. Pesticide Science 13:495-504. This docum

ent present

s the rela tionship betw

een RCF and K

ow presented in the equation in Table B-2-10.. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is a source docum

ent for the

equation in Table B-2-10. Travis, C.C. and A.D. Arm s. 1988. “Bioconcentration of Organics in Beef, Milk, and Vegetation.” Environmental Science and Technology . 22:271 to 274. Based on pai

red soil and plant concent ration data

for 29 organic com

pounds, this docum

ent developed a reg

ression equa

tion relating

soil-to-plant BCF

( Br) to K

ow log Br = 1.588 - 0.578 log K ow U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge , Volumes I and II. Office of W ater. Washington, D.C. EPA 822/R-93-001 a. Source of plant uptake response factors for arsenic, cadmium, nicke l, selenium, and zinc. Plant uptake response factors are converted to BCFs by multiplying the plant uptake response factor by 2. U.S. EPA. 1993. Review D raft Addendum to the Methodology for Asses sing Health Ri

sks Associated with Indir ect Exposur

e to Combustor

Emissions . Off

ice of Health and Env

ironmenta

l Asses sment. Offi ce of Re search a nd Developm

ent. EPA-600-A

P-93-003. Novem

ber 10. This document is a source of COPC-specific Kd s values. U.S. EPA. 1994. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-Specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/0 05Cc. June. This is a source docum

ent for Vg

rootvegvalues.

### TABLE B-2-10 BELOWGR

OUND PR

ODUCECONCE NTRA TION D UE TO R OOT UPTA

KE (CONSUMPTION OF BELOWGROUND PRODUCE EQUAT IONS) (Page 5 of 5)

B-87 U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3. This document recommends using the BCFs , Bv , and Br from Baes et

al. (1984) f

or calcula ting the upta

ke of inor ganics i nto vege tative g rowth (st ems a nd leaves) and nonvegetative growth (fru its , see ds, and tub ers) , re spe cti vely. Although m

ost BCFsused in th is documen t come from Baes et al. (1 984), values for some in organics were ap parentl y obtained from plant up take respon se slope facto rs. These up take response s lope fac

tors we re calc ulated fr om field data, suc

h as me tal me thodologies. Refere

nces used to calcula

te the uptak

e response

slope fa ctors are not clearl

y identif ied. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment. Office of A

ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 8)

B-88 Description Use the equations in this

table to c alculate

an aver age COPC s oil concentr

ation result

ing from wet and dry depos ition of par ticles a nd vapors to s oil over the exposure duration. We

recom mend assumi ng that COPCs are incor

porated only

to a finit e depth (the soil mix

ing zone de

pth, Z

s ). Us e th e COP C so il c onc ent rat ion aver aged over the expo sur e du rat ion , re pre sen ted by Cs , for carcinogenic COPCs, where r isk is a veraged over the lifetim

e of an i ndividual. Because the

hazard quotie

nt associa ted with nonc arcinoge

nic COPCs is

based on a r

efere nce dose ra

ther than a lifetime exposure, we recommend using the highest annual average COPC soil concentration occurring during the exposure duration period for non carcinogenic COPCs. The highest annual aver age C OPC soi l co nce ntr ati on wo uld most like ly oc cur at th e end of th e ti me pe rio d of comb ust ion and is re pre sen ted by Cs tD . The following uncertainties are associated with this variable: (1) We assume that the time period for deposition of COPCs resulting from hazardous waste combustion is a conservative, long-term value. T his assumption may overestim ate Cs and Cs tD . (2) Exposure duration values ( T 2 ) are based o n histo rical mobil ity studies and won’t necessarily remain constant . Specifical ly, mobility stu dies ind icate that mos t recepto rs that move remai n in the vic inity of

the com bustion unit; how

ever, it is impos sible to ac curately predict the

probability

that these

short-dista

nce mov es will influence exposure,based on f

actors such as atmospheric transport of pollutants. (3) Using a v

alue of z ero for T

1 doesn’t account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may underestimate Cs and Cs tD . (4) For soluble COPCs, leaching might lead to movement to below the mixing depth, resulting in lower concentrations within the mixing depth. This uncertainty m ay overestimate Cs and Cs tD . (5) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This m ay underestimate Cs and Cs tD . Equation for Carcinogens Soil Concentra

tion Ave raged Ov er Exposure

Duration

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 8)

B-89 Equation for Noncarcinogens Highest A

nnual Ave

rage Soil Concentrat

ion

where

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation to calculate Ds. Apportion the calculat ed Ds value into the divalent mercury (Hg 2+ ) and methyl mercur y (MHg) forms based on the assumed 98% Hg 2+ and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg 0 ) occurs in very

small amounts in the vapor

phase and doe s not exis

t in the particle or particle -bound phase. T herefore , assum

e elem ental m ercury deposition onto s oils is neg ligible or zero. Eva

luate ele mental mercur

y for the direct

inhalation pa

thway only (Table B-5-1).
Ds (Hg2+) = 0.98 Ds (Mercu ry) Ds (Mhg) = 0.02 Ds (Mercu ry) Ds (Hg0) = 0.0 Evaluate divalent and methyl me rcury as individual COPCs. Calculate Cs for diva lent and m

ethyl m ercury using the c orresponding ( 1) fate and transport param eters f or merc uric chloride (divalent mercury, Hg 2+ ) and me

thyl m ercury provided in A

ppendix A- 2, and (2) Ds (Hg 2+ ) and Ds (MHg) as calculat ed above.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 8)

B-90 Varia ble Description Units Value 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil


### Cs tD Soil concentration at time tD mg COPC/kg soil 

### Ds Deposition te rm mg COPC/kg soilyr 

### Varies

U.S. EPA (1994a) and NC DEHNR (1997) recommended incorporating a depositio n term into the Cs equation. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Five of the varia bles in the equation for Ds (Q, Cyv, Dywv , Dywp , and Dydp ) are COPC- and site-s pecific

. Values for these variables are estima ted through modeling. The direction and magnitude of any uncertainties shouldn’t be ge

neralize d. (2) Based on the

narrow r ecomm ended range s, we e

xpect unce

rtainties associat

ed with Vdv, F v , and BD to be low. (3) Values for Z s vary by about one

order of m

agnitude. U

ncertainty is grea tly re duced if y

ou know w

hether soils are tilled or untilled. 

### tD Time

period over

which deposition occurs (ti me per iod of com

bustion) yr 

### 30 U.S. EPA (1998) suggests that this period of time can be 

### $ 30 year s. We r ecomm end using 30 y

ears unles s site-s

pecific informa tion is ava

ilable indic ating that

this assum

ption is unreasonable (see Chapter 6 of the HH RAP). 

### ks COPC soil loss constant due

to all processes yr -1 

### Varies This variable is COPC- and site-specific, and is calculated by using the equation in Table B-3-2. The COPC soil loss constant is

the sum of all C OPC remov

al process es. Uncertain ty associated wit h this vari able incl udes the fo llowing:

COPC-specif

ic value s for ksg

(one of the variables in the equation in Table B-3-2) are empirically determ ined from f ield studies . No inform

ation is av

ailable r egarding the applica

tion of thes e values

to the site -specif

ic conditions associated with affected facilities.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 8)
Varia ble Description Units Value



### B-91 T 2 Length of

exposure duration yr 

### 6, 30, or 40 We rec omme

nd reasonable

maxi mum e xposure (R

ME) value s for T 2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure dura

tion rates are based on historica l mobility rates a nd may not rema in constant. This ass

umption may overestim

ate or underestimate Cs and Cs tD . (2) Mobility studies indicate that most receptors that move remain in the vicinity of the emission sources; however, it is impossible to accurately predict the likelihood that these short-distance moves will influence exposure, based on f

actors suc h as atm ospheric tr

ansport of pollutants. T

his assum ption may

overest imate or underestimate Cs and Cs tD . 

### T 1 Time

period at the

beginning of combustion yr 

### 0 Consistent w

ith U.S. EPA ( 1994c), we recom mend a v alue of 0 for T

1 . The following uncertainty is associated w ith this variable: A T 1 of zero doesn’t account for ex posure that m

ay hav e occurre d from historical operation or e missions from burning hazardous waste. This may underestim ate Cs and Cs tD . 

### 100 Units conve

rsion fac tor mg-cm 2 /kg-cm

2

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 8)
Varia ble Description Units Value



### B-92 Q COPC emis sion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 of the H

HRAP for

guidance on calculat

ing this v ariable. Uncertainties associated with this variable are site-specific. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998),which f urther sta tes that l eaching s oluble com pounds might

lead to m

oveme nt below a

1-cm de pth. A default v alue of 2 cm f

or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brzuzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a greater mixing depth. This uncertainty m ay overestimate Cs and Cs tD . (2) Deposition to hard surfaces may result in dust residues that have negligible dilution compared to other residues. This uncertainty may underestimate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This va riable is affected by

the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) stated tha t a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended

BDvalue m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overesti mate site-spec ific soil conditions to a n unknown deg

ree.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 of 8)
Varia ble Description Units Value



### B-93 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP companion database. This range is based on values presented in Appendix A-2. Values are also presented in U.S. EPA (1994b)

and NC DEH

NR (1997).
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) states

that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It assum

es a def ault ST value or background plus local s ources, ra ther than an ST

value f or urban sourc es. If your site is located in an urban a

rea, using the latte r ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources, and would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only

a few percent low

er. (2) According to Bidleman (1988), the F v equation assumes that the variable c (Junge c onstant) is constant for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid-phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Dydv Unitized y

early averag e dry deposition from vapor phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air m odeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### Dywv Unitized yearly ave rage wet deposition from vapor phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air m odeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### Dydp Unitized y

early averag e dry deposition from particle phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air m odeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### Dywp Unitized yearly ave rage wet deposition from particle phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air m odeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 7 of 8)

B-94 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Brzuzy, L.P. and R.A. Hites. 1995. “Estimating the Atmospheric Deposition of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Soils.” Environmental Science and Technology

. Volume 29. Pag

es 2090-2098. This reference presents soil profiles for dioxin mea surements. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This reference is cited by U.S. EPA (1994b) as the source for a mean soil bulk density value of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Press, Inc. New York.

Cited by U.S. EPA (1998)

for the s tateme nt that BD is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and c lay c ontent of the soil. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -3-1. This document a lso recom mends us ing (1) a de

position term

, Ds , and (2) COPC-specific F v values.
Researc h Triang le Institute

(RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepa

red for U .S. EPA Haz

ardous Site C ontrol Divis ion, Remedial Opera tions Guidance Branch. A

rlington, Virg

inia. EPA C ontract 68-W 1-0021. Work Assig nment No. B-03, Work

Assig nment Ma

nager Loren Henning . Decem ber. This document is a reference source f or COPC-specific F v values. U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compo unds. Draft Report. Of

fice of Resear ch and Dev

elopment. Washing

ton, D.C. EPA

/600/6-88/005b. The Exte rnal Rev iew Dr aft of the MPE docum

ent (the f inal is U.S. EPA 1998) cite s this docum ent as the source of values f or soil m ixing zone

depth, Z

s , for tilled and untilled soils.

### TABLE B-3-1 SOIL CO NCEN TRAT ION DUE TO DE POSITION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 8 of 8)

B-95 U.S. EPA. 1993b. Addendum to the M ethodology for As

sessing He

alth Risks Associated w

ith Indirect

Exposure to Combustor Em issions . Working Group Rec omme

ndations. Of

fice of Solid Waste. Office of Re search a nd Developm

ent. Was hington, D.C. Septembe

r. This docum

ent is a r efere nce for t he equation in Table B- 3-1. It rec omme nds using a deposition ter m, Ds , and COPC-specific F v values in the Cs equation. U.S. EPA 1994a. Draft Guidanc e for Perf orming Scre

ening Level

Risk Analys is at Combusti on Facilities

Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Was te Combustion Facilities

. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. April 15. This document is a reference f or the equation in Table B-3-1; it recommends that the following be used in the Cs equation: (1) a deposition t

erm, Ds , and (2) a de fault soil bulk densit y value of 1.5 g/cm 3 , based on a mean v

alue for loam soil from

Carsel e t al. (1988). U.S. EPA. 1994b. Estimating Ex posure to Diox

in-Like Com

pounds

. Volume III: Site-Specific Assessment Procedures. Externa l Review Draft. Off

ice of R esearc h and Development. W

ashington, D.C. EPA/600/6- 88/005Cc. June. This docum

ent recom mends v alues f or length of

exposure duration, T 2 , for the farm

er. U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes . Office of Em ergency and Remedial Re sponse. Office of Solid W

aste. Decembe

r 14. This docu ment recommends th e following:

C Values for

the length of expos

ure duration, T 2
C Value of 0 f

or the tim e period of

the beginning

of com bustion, T

1
C F

v values that range from 0.27 to 1 for organic COPCs

C Default soil bulk density value of 1.5 (g soil/cm 3 soil), based on a me an for loa m soil f rom Car sel et a l. (1988) U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1997b. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002Fc . August

. This docum

ent is a r efere nce source

for va lues for length of

exposure duration, T 2 . U.S. EPA. 1998. Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions (MPE ) . Update to EPA/600/6-90/003. Of fice of Resear ch and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/ 137. Decem ber.

### TABLE B-3-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 4)

B-96 Description This equat ion calcu lates the CO PC soil loss cons tant, whic h accoun ts for the lo ss of COPCs fro m soil by several mechan isms. Uncertai nties asso ciated with this equ ation in clude th e following: (1) COPC-specif

ic value s for ksg

are empirically determ

ined from field studies; no information is available regarding the application of these values to the site-specif ic conditions associated with affected f

acilities. (2) The sourc e of the equations in T ables B-3- 3 through B-3-5 ha s not been ide

ntified.
Equation

Varia ble Description Units Value 

### ks COPC soil loss constant due

to all processes yr -1



### ksg COPC soil loss constant due

to biotic and abiotic degra

dation yr -1 

### Varies This va riable is COPC-specif

ic and should be

determ ined from the COPC tables in Appe ndix A-2. “Degra dation rate ” values

are als o presented in NC DEHN R (1997); howe

ver, no re ferenc e or source is provided for the v

alues. U.S. EPA (1994a) and U.S. EP A (1994b) state thatksg values a re COPC-spe cific; howeve r, all ksg values a re prese nted as ze ro (U.S. EPA 1994a) or a

s “NA” (U.S. EPA 1994b) ; the basis of these assum ptions is not a

ddressed. The following uncertainty is associated w ith this variable: COPC-specif

ic value s for ksg

are empirically determ

ined from field studies; no information is available on applying these values to the site-specific conditions associated with affected f acilities.

### TABLE B-3-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 4)
Varia ble Description Units Value



### B-97 kse COPC loss cons tant due to soil erosion yr -1 

### 0 Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is fur ther dis cus sed

in T able B-3 -3. Cons ist

ent wit h U.S . EPA

(199 4a) , U. S. EPA (1994b) and NC DEHNR (1997), w e recom mend a de fault v

alue of z ero for ksebecause contamina ted soil er odes both onto the site and away from

the site. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The sourc e of the equation in Table B-3-3 ha s not been ide

ntified. (2) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting a grea ter mix ing depth. This uncertainty may overes timate kse

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate kse

. 

### ksr COPC loss constant due to surface

runoff yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-3-4. N

o refer ence docum

ent is cit ed for this equation; using this equation is cons istent w ith U.S. EPA ( 1998). U.S. EPA (1994a) assum es that a ll ksr values a

re zero but does not explain the bas is of this assum ption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-3 -4) incl ude the fol lowing: (1) The sourc e of the equation in Table B-3-4 ha s not been ide

ntified. (2) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a gre ater m

ixing depth. This uncertainty may overes timate ksr

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksr

. 

### ksl COPC lo ss constan t due to l eaching yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-3-5. U sing this equation is cons istent w ith U.S. EPA (1998),U.S. EPA (1994b) , and NC DEH NR (1997). U.S . EPA (1994a) a ssumes that ksl is zero but

does not ex

plain the basis of this assum

ption. Uncertain ties associ ated with th is variable ( calculated by using the eq uation in Table B-3 -5) incl ude the fol lowing: (1) The sourc e of the equation in Table B-3-5 ha s not been ide

ntified. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksl

.

### TABLE B-3-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 4)
Varia ble Description Units Value



### B-98 ksv COPC loss cons tant due to volatilization yr -1 

### Varies Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is calcula ted usin g the eq uation in Ta ble B-3- 6. T

his equa tion cal cula tes the COPC loss consta

nt from soil due to v

olatilizat ion, and wa

s obtained f

rom U.S. EPA (1998). T he soil loss

constant due

to volatili

zation ( ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to m

oveme nt to below 2 centim

eters in unt

illed soils,

resulting in a gre ater m

ixing depth. This uncertainty may overes timate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksv

.

REFERENCES AND DISCUSSION Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the reference documents f or the equations in Tables B-3-4 and B-3-5. This document is also cited as (1) the source for a range of COPC-specific degradation rates ( ksg), and (2) one of the sour ces that recomm

end assum

ing that the

loss resul

ting from erosion ( kse ) is zero because of contaminated soil eroding both onto the site and away from the site. U.S. EPA. 1994a

. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. This docum

ent is cit ed as a s ource for

the assum

ptions that los ses res

ulting fr om erosion ( kse ), surface ru noff ( ksr ), degrada tion ( ksg), leachin g ( ksl

), and vola

tilization (

ksv ) are all zero. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This document is one of the reference documents f or the equations in Tables B-3-4 and B-3-5. This document is also cited as one of the sources that recommend using the assumption that the loss re sulting f

rom eros ion ( kse ) is zero and the loss resulting from de gradation (

ksg) is “NA” or zero for all com pounds.

### TABLE B-3-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 4)

B-99 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. Envir

onmental Criteria and Ass essme nt Off ice. ORD . Cincinnati , Ohio. This docum

ent is one of

the ref erence doc

uments f or the equations for ksr , ksl , and ksv

.

### TABLE B-3-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 5)

B-100 Description This equa tion calcula

tes the c onstant for

COPC loss re sulting f

rom eros ion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), we recomm

end a def ault value of zero f or ksebecause of contaminated soil eroding onto the site and away from the site. In site-specific cases w here the permitting authority considers it appropriate to calculate a kse , we recommend usin g the equat ion pres ented in this tabl e along with associated uncertai nties. Yo u can find ad dition al discuss ion on determinin g ksein U.S. EPA (1998). Uncertainties associated with this equation include: (1) For soluble COPCs, leaching might lead to movement below 2 centimeter in untilled soils, resulting in a greater m ixing depth. This uncertainty may ove restimate kse

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) in c omparison to that of ot her residue s. This uncertainty may underestim ate kse

. Equation

Varia ble Description Units Value 

### kse COPC loss cons tant due to soil erosion yr -1 

### 0 Consistent with U.S. EPA (1994), U.S. EP A (1994b), and NC DEHNR (1997), we recommend that the default value assumed for kseis zero because contaminated soil erodes onto the site and away f rom the site. Uncertainty ma y overestimate kse

. 

### 0.1 Units conve

rsion fac tor g-kg/cm 2

- m 2 

### X e Unit soil loss kg/m 2 -yr Varies This va riable is site-specific and is calculated by using the equation in Ta

ble B-4-13. The following uncertainty is associated w ith this variable: All of the equation v

ariables are site -specif

ic. Using default values r

ather than site-spec ific v

alues f or any or all of these variables will result in unit soil loss ( X e ) estim ates that are under-

or overes timated to some

degree. Based on default v alues, X

e estimates can vary

over a range of less than two orders of magnitude.

### TABLE B-3-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 5)
Varia ble Description Units Value



### B-101 SD Sediment

delivery ratio unitless 

### Varies This va lue is site -specif

ic and is c alculate d by using the equation in Table B -4-14. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The rec omme

nded defaul

t values for the e mpirica l interce pt coeff icient, a , are av

erage v alues that are based on studies of sedime nt yields from various w

atersheds . Theref

ore, those de fault v

alues m ay not a ccuratel y repre sent site-specific watershed conditions. As a result, using these default values m ay under- or overestimate SD

. (2) The rec omme

nded defaul

t value f or the em pirical slope coeff

icient, b , is based on a revie w of s ediment yields

from various watersheds. This single default value m ay not accurately represent site-specif ic watershed conditions. As a result, using this default value may under- or overestim ate SD

. 

### ER Soil enrichm ent ratio unitless 

### Inorga nics: 1 Organic s: 3 COPC enrichm

ent occurs because ( 1) lighter soil partic les erode more tha n heavier soil particles, and (2)

concentra

tion of organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded material than in in-situsoil (U.S. E PA 1998). In the

absence of site- specific data, w e recom mend a de fault v

alue of 3 for orga

nic COPCs an d 1 for ino rganic COP Cs. This is co nsistent with other U.S. EP A guidance (1 998), which recommends a range of 1 to 5 and a va

lue of 3 as a “rea

sonable f irst esti mate.” This ra nge has be en used f

or organic matter

, phosphorus, and ot

her soilbound COPCs (U.S. E

PA 1998); howe

ver, no sour

ces or re ferenc es we

re provided for this r

ange. ER is gener

ally hig her in sandy s oils than in s ilty or loamy soils (U.S. EPA 1998). The following uncertainty is associated w ith this variable: The def ault ER value m

ay not a ccuratel y ref lect site -specif

ic conditions; therefor

e, ksemay

be over- or underestimated to an unknown extent. Using county-specific ER values will reduce the extent of any uncertainties. 

### BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

### TABLE B-3-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 5)
Varia ble Description Units Value



### B-102 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient mL w

ater/g soil (or cm 3 water/ g soil) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This va riable is site-specific, a

nd depends on the

availa ble wat er and on soil

structure ; you ca

n estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. Howe

ver, w e recom mend using 0.2 ml/cm 3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soil s) r ecomm ended by U.S . EPA

(199 8) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 s w value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksemay

be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-3-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 5)

B-103 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agric ultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, I nc. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is one of

the source s that rec omme nd assum ing that the

loss resul

ting from erosion ( kse ) is zero because contaminated soil erodes both onto the site and away from the site. U.S. EPA. 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This document recommends (1) a def ault soil bulk density value of 1.5 (g soil/cm3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988), and (2)

a defa ult soil volumet ric wa ter content, 2 sw , value of 0.2 (mL wa ter/cm 3 soil).

### TABLE B-3-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 5)

B-104 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is the s ource of a

range of COPC enrichm

ent ratio, ER , values. The recomme nded range,

1 to 5, was

used for organic m

atter, phosphor

ous, and other s oul-bound COPCs. This docum

ent recom mends a value of 3 as a “r easonable first e stimat

e,” and st ates that COPC enrichm

ent occurs because l

ighter soil particle s erode m ore quickly

than heav

ier soil particles . Lighte

r soil particles hav

e higher r atios of s urface area to v olume and are highe

r in organic

matte r content. T

herefore , concentra

tion of orga

nic COPCs, w

hich is a f unction of the organic c arbon content of sorbing m

edia, is e xpected t o be higher in eroded m

aterial than in in situsoil. This docu ment is also a so urce of the fol lowing:

C A range of soil volumet ric wa ter content

( 2 sw ) values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heavy loam/clay soils). However, no source or reference is provided for this range.

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil

C The equat

ions in Tables B-3-3 a

nd B-3-5.

### TABLE B-3-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 4)

B-105 Description This equat ion calcu lates the CO PC loss constant due to ru noff of soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeter in untilled soils, resulting in a greater mixing depth. This uncertainty may overes timate ksr

. (2) Deposition to hard surfaces may result in dust residues that have negligible dilution in comparison to that of other residues. This uncertainty may underestim ate ksr

. Equation

Varia ble Description Units Value 

### ksr COPC lo ss constan t due to r unoff yr -1 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994b), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, s ite-spec ific proc edures f or estim ating the a

mount of surfac e runoff

, such as t hose based on the U.S. Soil Conserva tion Service curve number equation (CNE). U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, ksr may be under- or overestimated to an unknown degree.

### TABLE B-3-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 4)
Varia ble Description Units Value



### B-106 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This va riable is depends on the available wate r and soil st

ructure; y ou can esti

mate 2 sw as the m

idpoint between a soil’s

field capacity and wilting point, if you can identify a representative watershed soil. We recommend using 0.2 (mL w ater/cm3 soil) as a def ault value . This v

alue is the

midpoint of

the range 0.1 (very sandy s oils) to 0.3 (he avy loam/cla y soils), which i s recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range) , and is cons istent w ith U.S. EPA ( 1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 s w value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksr

may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient mL w

ater/g soil (or cm 3 water/ g soil) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

### TABLE B-3-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 4)
Varia ble Description Units Value



### B-107 BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1998), U .S. EPA (1994), a nd NC DEHNR

(1997) as a refere

nce to calculate av

erage a nnual runoff

, RO . This re ferenc e provides maps w ith isolines of annual average surface w ater runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because these values are to tal contr ibutio ns and no t only surface ru noff, U.S. EPA (199 4) recommends t hat the vo lumes be redu ced by 50 per cent in o rder to est imate surface run off. Hillel, D. 1980. Fundament als of Soil Physics. Acade mic Press, In c. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is one of

the source

documents

that cite s the use of

Table B -3-4; howev

er, this doc

ument is not the origi

nal source of this equa

tion (this sour

ce is unknow

n). This doc

ument also recommend s the follo wing:

C Estima

tion of annua

l current r unoff, RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.

C Default value of 0.2 (mL w ater/cm3 soil) for

soil volum

etric w ater conte nt ( 2 sw )

### TABLE B-3-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 4)

B-108 U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edure for Tox

ic and Conventi

onal Pollutants in Sur

face and Ground W

ater—Part I (Revised. 1985) . Environmental Research Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This docum

ent is cit ed by NC DEHNR (1997)

as an ex ample of the use of

the U.S. Soil Conserva

tion Servic e CNE to e stimat e site-s pecific surfac e runoff

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s a range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes . Attachment C, Draft Ex posure Assessment Guidance for RCRA

Hazardous

Waste Combustion Facilitie s. Off ices of Emerg ency a nd Reme dial Respons e. Off ice of Sol id Waste . Decem

ber. This docu ment recommends th e following:

C Estima

tion of av erage a nnual runoff

, R O, by using the Water Atlas of the United States (Gera ghty e t al. 1973)

C Default

soil bulk de

nsity, BD , value of 1.5 (g soil/cm 3 soil), based on the me an for loa m soil tha t is take n from Carsel e

t al. (1988)

C Default

soil volum

etric w ater conte nt, 2 sw , value of (0.2 mL wa ter/cm 3 soil) U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of soil volumet ric wa ter content, 2 sw , values of 0.1 (ve ry sa ndy soils) to 0.3 (heav

y loam /clay soils) (the

original s ource of, or refe rence f or, these v

alues is not

identified)

C A range of va

lues for soil mix

ing depth, Z

s , for tilled and untilled s oil (the orig inal source

of, or re ferenc e for, the se value s is not ident ified)

C Using the Water Atlas of the United States (Gera ghty e t al. 1973) to c alculate

averag e annual runof

f, RO

### TABLE B-3-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 5)

B-109 Description This equat ion calcu lates the CO PC loss constant due to leac hing of soi l. Uncertai nties asso ciated with this equ ation in clude th e following: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksl

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ithin situmater

ials) com pared to other

residues. This unce

rtainty may underestimate ksl

. (3) The orig

inal source

of this e quation has not been identif ied. U.S. EPA

(1998) prese

nts the equa

tion as show

n here. U.S . EPA (1994b) and NC DEHNR (1997) replac ed the num erator as shown with “ q ”, defined as ave rage annua

l recharg e (cm /yr). Equation

Varia ble Description Units Value 

### ksl Constant f

or COPC loss due

to soil leaching yr -1



### P Avera

ge annual precipitat

ion cm/yr 

### 18.06 to 164.19 This va riable is site-specific. T

his range is based on informa

tion presented in U.S. EPA ( 1998), repres enting data for 69 selected cities (U.S. Bureau of Census 1987; Baes et al. 1984). The 69 selected cities are not identified; however, they appear to be located throughout the conti nental United States. We recommend using site-specific data. The following uncertainty is associated w ith this variable: To the ex tent that a site is not

located ne ar an est

ablished m

eteorologic al data s

tation, and si

te-speci fic data

are not available, defa

ult avera ge annual precipitat

ion data m

ay not a ccuratel y ref lect site -specif

ic conditions. As a r

esult, ksl may be un der- or ove resti mated. However , avera ge ann ual p recip itati on d ata are reaso nabl y availab le; th erefor e, we expect unc ertainty

introduced by

this variable to be m

inimal.

### TABLE B-3-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 5)
Varia ble Description Units Value



### B-110 I Avera

ge annual irrigation cm/yr 

### 0 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U.S. EPA ( 1998), repres enting data for 69 selected cities (

Baes et al. 1984). T

he 69 selec

ted cities are not ide

ntified; how

ever, the y appea r to be loca

ted throughout t

he continental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual irrigation information is not available, default values (genera lly bas ed on the clos est com parable loc ation) ma

y not ac curately

reflec t site-specific c onditions. As a result, ksl may be under- or overestim ated to an unknown degree. 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This va riable is site-specific. A

ccording to U.S. EPA (1998),U.S. EPA (1994b) , and NC DEH NR (1997), y

ou can esti

mate RO by using the Water Atlas of the United States (Geraghty et a l. 1973). According to NC DEHNR (1997), you can also use more de tailed, si te-speci fic procedures, such as those ba sed on the U. S. Soil Conser vation Ser

vice CN E. U.S. EPA ( 1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, ksl may be under- or overestimated to an unknown degree. 

### E v Avera

ge annual evapotra

nspiration cm/yr 

### 35 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U. S. EPA ( 1998), repres enting data from 69 selected cities. The 69 selected cities are not identified; however, they appear to be located throughout the contin ental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual evapotranspiration information is not available, default values may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be un der- or ove resti mated t o an u nkno wn degree.

### TABLE B-3-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 5)
Varia ble Description Units Value



### B-111 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure. You can estimate 2 sw as the m idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range)

and is consi stent wi

th U.S. EPA (1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value may not accurately reflect site-specif ic or local conditions; therefore, ksl may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

### TABLE B-3-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 5)
Varia ble Description Units Value



### B-112 Kd s Soil-wat

er partiti on coeff

icient cm 3 water

/g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

REFERENCES AND DISCUSSION Baes, C.F., R.D. Sharp, A.L. Sjoreen and R.W. Shor. 1984. “A Review and Analysis of Parameters for Asse ssing Transport of Environmentally Released Radionuclides through Agriculture.” Prepared f

or the U.S. D epartm

ent of Ene

rgy unde r Contract No. DEAC 05-840R21400. For the contine

ntal United S tates, as cited in U .S. EPA (1998), t his docume

nt is the sour

ce of a series of ma

ps showing : (1) ave

rage annua

l precipita

tion ( P ), (2) ave

rage annua

l irrigat ion ( I ), and (3) average annual evapotranspiration isolines. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density value, BD , of 1.5 g soil/cm 3 soil for loam soil

. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1998), U .S. EPA (1994b), a nd NC DEHNR

(1997) as a refere

nce for c alculating

averag e annual runof

f, RO . This docum

ent provides

maps w ith isolines of annual average surface runoff, w hich is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Bec ause these volumes are total contributions and not only surface runoff, U.S. EPA (1994b) recommends that the volumes be reduced by 50 percent in order to estimate averag e annual surface runoff. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil.

### TABLE B-3-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 5)

B-113 NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the source documents that cites the use of the equation in Table B-1-5. However, the document is not the original source of this equation. This document also recommends the following:

C Estima

tion of av erage a nnual surfa

ce runoff , RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.

C A default value of 0.2 (mL water/cm

3 soil) for soil volum

etric w ater conte nt, 2 sw U.S. Burea

u of the Ce

nsus. 1987. Statistical Abstract of t he United State

s: 1987. 107th editi on. Washington, D.C. This docum

ent is a s ource of a

verage annual prec ipitation (

P ) inform ation for 69 selected cites, a s cited in U .S. EPA (1998); t hese 69 cit

ies are not identifi ed. U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventiona l Pollutants in Surface an d Groundwater . Part I (Revised 1985). Environmental Research

Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This document is cited by NC DEHNR (1997) as an exam ple of the use of the U.S. Soil Conservation Service CNE to estimate RO

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docum

ent recom mends (1)

a defa ult soil volum

etric w ater conte nt, 2 sw , value of 0.2 (mL wa ter/cm 3 soil), and (2)

a defa ult soil bulk density , BD , value of 1.5 (g soil/cm 3 soil), based on a mea n value f or loam s oil from

Carsel e t al. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence s ource docum

ents for the equation i

n Table B -3-5. The or

iginal sour

ce of thi s equation is

not identif

ied. This document also prese

nts a range of values f or soil m ixing depth, Z, for tilled and untilled s oil; the orig inal source

of these values i s not identif

ied.

### TABLE B-3-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 4)

B-114 Description This eq uati on cal culat es the COPC loss c onst ant fro m soil d ue to volat iliza tion , and was obt ained from Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Exposure Pat

hways to Combustor Emi

ssions(U.S. EPA 1998) . The soil loss consta

nt due to vola

tilization (

ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by

adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to other

residues. This unce

rtainty may underestimate ksv

. Equation

Varia ble Definition Units Value 

### ksv COPC loss cons tant due to volatilization yr -1

3.1536 x 10 +7 Units conve rsion fac tor s/yr 

### H Henry’ s Law constant atmm 3 /mol 

### Varies

This variable is COPC-specific. We discuss this variable in detail in detail in Appendix A-2, and offe r COPC-specific values in the HHRA

P companion da

tabase. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated using the pa

ramet ers and al gorithms in Appendix

A-2, m ay under - or overesti mate t he actual COPC-specif

ic value s. As a

result, ksv

may be under- or ov

erestim ated.

### TABLE B-3-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 4)

Varia ble Definition Units Value



### B-115 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient cm 3

water/ g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s value s are cal culat ed as d escri bed i n Appe ndix A2. 

### R Universa l gas cons tant atmm 3 /mol-K 

### 8.205 x 10 -5

There a re no uncert

ainties a ssociate d with this

param eter. 

### T a Ambie

nt air tem perature K 

### 298 This variable is site-specific. U.S. EPA (1998) recommends an am bient air temperature of 298 K. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for T

a are not av

ailable, de fault v

alues m ay not a ccuratel y repre sent site-specific condi

tions. We expect t

he uncerta

inty as sociated w

ith the sel ection of a single value f rom w ithin the temper ature rang

e at a s ingle loca

tion to be m

ore signif icant than t

he uncerta

inty as sociated w

ith choosing a

single ambient temperature to represent all localities.

### TABLE B-3-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 4)

Varia ble Definition Units Value



### B-116 BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions. 

### D soil Solids partic le density g/cm3 

### 2.7 We rec omme

nd the use of

this value , based on Bla

ke and Ha

rtage (1996)

and Hillel (1980). The solids particle density will vary with location and soil type. 

### D a Diffus ivity of COPC in a ir cm 2 /s 

### Varies This va lue is COPC-s

pecific . We dis cuss this v ariable i n detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The def ault D a values m

ay not a ccuratel y repre sent the be

havior of COPCs under s ite-spec ific condi tions. Howeve r, we e xpect the degree of uncerta

inty to be minim al. 

### 2 sw Soil volum etric w ater conte nt mL/cm 3 soil 

### 0.2

This va riable depe

nds on the av

ailable w ater and on s oil structure . You can e stimat e 2 sw as the m

idpoint between a soil’s field ca pacity and wilti ng point, if

you can identify

a repres entative

water shed soil. Howeve

r, we recomm

end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soils) rec omm ended by U.S . EPA

(199 8) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: (1) The def

ault 2 sw values may

not accurately reflect site-specif ic or local conditions; therefore, ksv may be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-3-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 4)

B-117 REFERENCES AND DISCUSSION
Blake, G R. and K.H. H

artge. 1996. Particle D

ensity. M ethods of Soil Anal

ysis, Part 1: Physical

and Mineralogic

al Methods . Se con d Ed iti on. Arno ld K lut e, E d. Ame ric an S oci ety o f Agro nomy, Inc. Madison,WI., p. 381. Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density value, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk. Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. Miller, R.W . and D.T. Gardiner . 1998. In: Soils in Our Env ironment . J.U. Mille

r, Ed. Prentice

Hall. Uppe

r Saddle Riv

er, NJ. pp. 80-123. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docum

ent recom mends a default soil density

, BD , value of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled soil; however, the source or basis for these values is not identified

C A def

ault am bient air te

mperat ure of 298 K

C A range of soil volumet ric wa ter content, 2 sw

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 o f 10)

B-118 Description This equa tion calcula

tes the CO

PC concentrat

ion in forag

e and sila ge (abov eground vegetation) due to wet and dry de

position of C OPCs onto plant s urface s. The li

mitations and uncerta

inty introd uced in cal culatin g this variab le includ e the follo wing: (1) Uncertainties associated with the variables Q, Dydp , and Dywp are COPC - are site-specific. (2) In calculating the variable Fw , values of r assumed for most organic com pounds—based on the behavior of insolu ble polystyrene micro spheres tagg ed with radionuclides— may accurately represent the behavior of organic com pounds under site-specific conditions. (3) The empirical relationship used to calculate the variable Rp , and the empirical constant for use in the relationship, may not accurately represe nt site-specific silage types. (4) The recommended equatio n for calcul ating kp does not consider chem ical deg radation proc esses. This conse rvative approach c ontributes to t he possible ov

erestim ation of pla

nt concentrations. (5) The harv

est yi eld ( Yh ) and area

planted ( Ah ) values used to estimate the variable Yp may not reflec t site-specific conditions. Equation

For merc ury m odeling Forage and silage concen tration s due to d irect dep ositio n are calcul ated usin g 0.48Q for total mercur y and F

v = 0.85 in the m

ercury modeling

equation. A

pportion the ca

lculated Pd values i

nto the divalent (Hg 2+ ) and methyl merc ury (MHg) forms based on the 78% divalent mercury (Hg 2+ ) and 22% m

ethyl m ercury (MHg) speciation spli

t in aboveg

round produce and f

orage. Pd (Hg2+) = 0.78 Pd (Mercu ry) Pd (Mhg) = 0.22 Pd (Mercu ry) Evaluate divalent and methyl me rcury as individual COPCs. Calculate Pd for divalent and methyl m ercury using the corresponding equations above.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 o f 10)

B-119 Varia ble Description Units Value 

### Pd Concent ration o f COPC in for age

and silage due to dire ct deposition mg COPC/kg DW 

### 1000 Units conve

rsion fac tor mg/g 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This va lue is COPC- and site-s

pecific , and is dete

rmined by

air disper

sion model

ing. See C

hapters 2 a

nd 3 for guida

nce on calculating this variable. Uncertainties associated with this variable are site-specif ic. 

### F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion da

tabase. This rang

e is based on values presented i n Appendix A-2. U.S. EPA (1994b) and N C DEHNR ( 1997) also present values.
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) st

ates that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urb an source s. If a specific site is

located in an urban are a, using the latter ST value may be more appropriate. Specifically, the ST value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local source s, and it would res ult in a low

er calc ulated F

v value; however, the F v value is likely to be only

a few percent low

er. (2) According to Bidleman (1988), the F v equation assumes that the variable c (Junge c onstant) is constant for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfac e and the he at of va porization of

the liquid phas e sorbate. To the e xtent that site- or C OPC-specif

ic condit ions may cause the value of c to vary, uncer tainty is in trodu ced if a const ant value o f c is used to calculate F v . (3) Based on U.S. EPA (1994a), the F v value for dioxins (PCDD/PCDF) is intended to represent 2, 3, 7, 8-TCDD TEQs by weig

hting data for all dioxin and furan congeners with nonzero TEFs. Uncertainty is introduced, because the Age ncy has been unable to verif

y the recomm

ended F

v value for dioxins. 

### Dydp Unitized y

early averag e dry deposition from particle phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 o f 10)

Varia ble Description Units Value



### B-120 Fw Fraction of

COPC wet

deposition that adheres to plant surfaces unitless 

### 0.2 for anions 0.6 for cations and most o rganics We recomme

nd using the chemical class-specific values of 0.2 for anions and 0.6 for cations and most organics, as estimated by U.S. E PA (1994b) and U. S. EPA (1995). T hese va lues are the best a

vailable inform ation, based on a revi ew of the curre nt scientif ic litera ture, wit h the follow

ing exc eption: We

recom mend using

an Fwvalue of 0.2 for the three organic COPCs that ionize to anionic form

s. Thes e include (1)

4-chloroanili

ne, (2) n-nitros odiphenyla mine, a nd (3) n-nitrosodi-

n-proplyam

ine (see A ppendix A- 2). The va lues esti mated by U.S. EPA (1994b)

and U.S. EPA (1995) are ba sed on infor

mation pre sented in Hof

fman, Thiesse n, Frank, and B layloc

k (1992), w

hich present

ed values for a pa ramet er ( r) termed the “interception fraction.” These values were ba sed on a study

in which s oluble radionuc lides and ins oluble partic les labeled with ra dionuclides w

ere deposit

ed onto pasture g rass vi a simulated rain. The para meter ( r) is def ined as “t he frac tion of m aterial in rain inter

cepted by veget ation and ini tially retain ed” or, esse ntially, th e produ ct of Rp and Fw, as def ined: r = Rp @ Fw Ther values de

veloped by

Hoffm an, Thies sen, Frank

, and Blay

lock (1992) w

ere divided by an Rp value of 0.5 for forage (U.S. EPA 1994b). The Fwvalues de veloped by

U.S. EPA (1994b)

are 0.2 f or anions and 0.6 for cations and insoluble particles . U.S. EPA ( 1994b) and U.S. EPA (1995) recom

mended us ing the

Fw value c alculate d by using the r value f or insoluble part

icles to r epresent or

ganic com

pounds; howev

er, no rationa

le for thi s recom

mendation was prov

ided. Uncertain ties associ ated with th is variable i nclude t he followin g:

Values o f r

assumed for most organic com pounds, based on the behavior of insolu ble polystyrene micro spheres tagged with radi onuclides, m ay not a ccuratel y repre sent the be

havior of organic c ompounds under site-specific conditions. 

### Dywp Unitized yearly ave rage wet deposition from particle phase s/m 2



### - yr 

### Varies

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 o f 10)

Varia ble Description Units Value



### B-121 Rp Interception fraction of the e dible

portion of pla

nt unitless 

### Forage: 0.5 Silage: 0.46 We rec omme

nd using thes e defaul

t Rp valu es b ecau se th ey rep rese nt t he mo st cu rre nt i nfo rmat ion avai lab le; spe cifi call y, productivity

and relati

ve inge stion rates

. As sum marized in Baes

et al. (1984) , experim

ental studie s of past

ure gras ses identi fied a c orrelation be tween i nitial Rp values and productivity (standing crop biomass [ Yp ]) (Chambe rlain 1970): Rp = 1 - e - ( @ Yp
where Rp = Interception fraction of the edible portion of plant (unitl ess)

( = Empirica

l constant. C

hamberlain (1970) pres ents a ra nge of 2.3 to 3.3; Baes

et al. (1984)

uses 2.88, the midpoint for pasture grasses. Yp = Yield or sta

nding crop biom

ass (product

ivity) (kg DW /m 2 )
Baes et al. (1984) propos ed using the same empiric al relat

ionship deve loped by C

hamberlain (1970) for

other veg

etation classes . Class- specific estim ates of the em pirical c onstant, ( , were

developed by for

cing an e xponential r

egress ion equation throu gh several po ints, in cludin g average and th eoretical maximum estimates of Rp and Yp (Baes et al. 1984) . The classspecific Rp estimates were then weighted, by relative ingestion of each clas s, to arrive at the weighted averag e Rp value of 0.5 for forage and 0.46 for silage. U.S. EPA (1994b) and U.S. EP A (1995) recommend a weig hted average Rp value of

0.05. Howe

ver, the relative

ingestion rates used in U.S. EPA (1994b) and U.S. EP A (1995) to weight the average Rp value w ere deriv ed from U.S. EPA (1992) and U.S. EPA ( 1994b). The m ost current

guidance available for ingestion rate s of hom egrown produce is the

1997 Exposure Factors Handbook

(U.S. EPA 1997) . The def ault Rp values of 0.5 for forage and 0 .46 for si lage were weighted b y relative ingestion r

ates of homegr own expos ed fruit a

nd exposed v

egetable s found in U.S . EPA (1997). Uncertain ties associ ated with th is variable i nclude t he followin g:

The em pirical c onstants dev

eloped by Baes et al. (1984) to us e in the em pirical relationship dev

eloped by Chamberlain (1970) may not accurately represe nt site-specific mixes of forage or silage.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 o f 10)

Varia ble Description Units Value



### B-122 kp Plant surfa

ce loss c oefficient yr -1 

### 18 This value is site-specific. We recommend the kp value of 18 recom

mended by

U.S. EPA (1998)

and U.S. EPA (1994b). The kp value selected is the midpoint of a possible range of values (7.44 to 90.36). U.S. EPA (1998) identified several processes—including wind removal, water rem oval, and growth dilution—that reduce the amount of COPC that has been depo sited on a p lant surfac e. The t erm kp is a measure of the am ount of contaminant lost to these physical processes over time. U.S. EPA (1998) cites Miller and Hoffman (1983) for the following equation used to estimate kp : kp = (ln 2/ t 1/2 ) @ 365 days/year where t 1/2 = half-life (days) Miller and Hoffm

an (1983) report

half-lif e values ranging f rom 2.8 to 34 da

ys f or a vari ety of

COPCs on herba

ceous vegeta tion. Thes e half-l

ife va lues conve

rt to kp valu es o f 7.4 4 to 90. 36 yr -1 . U.S. EPA ( 1998) and U.S. EPA (1994b) recommend a kp value of 18, based on a generic 14 -day half-life, co rrespon ding to p hysical pro cesses only. The 1 4-day halflife is approxim

ately the midpoi

nt of the r ange (2.8 t

o 34 days)

estim ated by Miller and H

offm an (1983). Uncertain ties associ ated with th is variable i nclude t he followin g: (1) the recommende d equati on for calcu lating kp does not consider chemical degradation processes. Adding chemical degradation processes would decrease half-lives and thereby increase kp values; plant concentration decreases as kp increases. Therefore, using a kp value that does not consider chemical degradation processes is conservative. (2) Based on this range (7.44 to 90.36), plant concentrations could range from about 1.8 times higher to about 5 times lower than the plant concentrations, based on a kp value of 18.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 o f 10)

Varia ble Description Units Value



### B-123 Tp Length of

plant expos

ure to deposition per harvest of edible portion of pla

nt yr 

### Forage: 0.12 Silage: 0.16 This va riable is site-specific. W

e recom mend the using these

default values i

n the absenc e of site -specif ic inform ation. U.S. EPA (199 8), U.S. EPA (199 4b), an d NC DEHNR (1 997) rec ommended treat ing Tp as a constan t, based o n the average period s between succe ssive hay harvests and success ive grazing. For forage, the average of the a verage period between successive hay harvests (60 days) and the average period betwee n success ive gra

zing (30 day

s) is used (that is, 45 da

ys). Tp is calculated as follows: Tp = (6 0 da ys + 30 days )/ 2 ÷ 36 5 da ys/yr = 0. 12 yr Use these average periods from Beecher and Travis (1989) when calculating the COPC concentration in cattle forage. When calculating t

he COPC conce

ntration in silage f

ed to cattle, the av

erage pe riod betwe en succes sive hay harvest s (60 days) is used (Beecher and Travis 1989). Tp is calculated as follows: Tp = 60 days ÷ 365 days/y ear = 0.16 year The following uncertainty is associated w ith this variable: Using hay harvest cy

cles to estimate silage Tp values may underestimate COPC uptakes if silage ty pes differ significantly from hay, and have longer actual harvest cy cles (for example, if

grains or other feeds with longer harvest cycle s are used as silag e). This underestim

ation will increase as actua l harves t cyc les incre ase, up to a

bout 3 months. Beyond that time fram e, if the kp value re

mains unc

hanged at 18. Higher Tp values w ill have l ittle effect on predicted COPC concentrations in plants.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 7 o f 10)

Varia ble Description Units Value



### B-124 Yp Yield or sta

nding crop biom

ass of the edible por

tion of the plant kg DW /m 2 

### Forage: 0.24 Silage: 0.8 This va riable is site-specific. W

e recom mend the use of the se defa ult values in the abse

nce of s ite-spec ific inf

ormation. U.S. EPA (199 0) states th at the best estimate of Yp is productivity, which Baes et al. (1984) and Shor et al. (1982) define as follows: Yp . Yh /Ah i where

Yh = Harves t yield of i th crop ( kg DW) Ah i = Area planted to crop i (m 2 ) U.S. EPA (1994b) and NC DEHN R (1997) recom

mended us ing either

previously

calculat ed Yp values or

the equation presented above to calculate a Yp value.
We recomme

nd that the forage Yp valu e be c alcu lat ed as a weig hte d ave rage of pa stu re gr ass a nd h ay Yp values. Weights (0.75 for f

orage and 0.25 for hay

) are bas ed on (1) the f

raction of a yea r during w

hich cattle

are ass umed to be

pastured a

nd eating g rass (9 m o/yr), a nd (2) the f

raction of a yea r during w

hich cattle

are ass umed to not be

pastured a

nd to be fe d hay (3 mo/y r). An unw

eighted Yp value f

or pasture g

rass of 0.15 kg DW

/m 2 is assum ed (U.S. EPA

1994b). An unw

eighted Yp value f or hay of 0.5 kg DW

is calc ulated by the above

equation, using

the follow

ing dry harvest yield ( Yh ) and area harvested ( Ah ) values: Yh = 1.22 x 10 +11 kg DW ; from 1993 U.S. ave

rage w et weight Yh of 1.35 x 10 11 kg (USD A 1994) and conversion factor

of 0.9 (A gricultura l Resea rch Service 1994) Ah = 2.45 x 10 +11 m 2 ; from 1993 U.S. ave

rage f or hay ( USDA 1994). The u nwei ght ed p ast ure gras s an d ha y Yp values a re multi plied by 3/

4 and 1/4, respectively . They are then a

dded to calc

ulate the weighted forage Yp of 0.24 kg DW. We recom mend that a production weighted U.S. average Yp of 0.8 be assumed for silage (Shor et al. 1982). The following uncertainty is associated w ith this variable: The harv est yi eld ( Yh ) and area

planted ( Ah ) may not reflect site-s

pecific conditions. T

his may under- or overestimate Yp

.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 8 o f 10)

B-125 REFERENCES AND DISCUSSION Agricultur al Research S ervice. 199 4. Perso nal communicat ion regard ing the dr y weight fraction val ue for hay between G.F. Fries, and Glenn Ri ce and Jenn ifer Windho lz, U.S. E PA Office of

Researc h and Development. March 22. Thi s co mmun icat ion is ci ted by NC DEHN R (1 997 ) for the frac tio n of 0.9 use d to con vert wet we igh t to dry we igh t for hay. Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and Analysis of Parameters and Assessing Transpo rt of Environmentally Released Radion uclides through Agriculture

. ORNL-5786. Oak Ridge National Laborator

y. Oa k Ridge,Tenness ee. Septe mber. This document proposes using the empirical relationship developed by Chamberlain (1970) (see further discussion in reference section of Table B-2-7) that identifies a correlation between initial Rp values and productivity (standing crop biomass [ Yp ]). It uses this relationship to calculate Rp values for forage and silage. Beecher , G.D., a nd C.C. Tra

vis. 1989. Modeling Support f or the RURA and Municipal W aste Combust

ion Projects : Final Report on Sensitivit y and Uncer

tainty Analys is for the Te rrestri al Food Chain Model . Interag

ency A greem ent No. 1824-A

020-A1, Of

fice of Risk A nalysi s, Health and Safe

ty Res earch Div

ision, Oak

Ridge Na

tional La boratory. Oak Ridg

e, Tenne ssee. October. This document recommends Tp values based on the avera ge period between succes sive hay harvests an d successive gr azing. Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Chamberlain, A.C. 1970. “Interception and Retention of Radioactive Aerosols by Vegetation.” Atmospheric Environment

. 4:57 to 78. Cited by Baes et al. (1984) as

a source for an em

pirical c orrelation be

tween i nitial Rp values and productivity (standing crop biomass [ Yp ]) Hoffm an, F.O., K.M . Thiess en, M.L. Fr ank, and B.G . Blay

lock. 1992. “ Quantific ation of the Intercept ion and Initial

Retention of

Radioacti

ve Contam

inants Depos ited on Pasture Grass by Simulated Rain.” Atmospheric Environment. Vol. 26A, 18:3313 t o 3321. For discussion, see Re ferenc es and Dis cussion, T able B-2-7. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. Miller, C.W., and F.O. Hoffman. 1983. “An Examination of the Environmental Half-T ime for Radionuclides Deposited on Vegetation.” Health Physics . 45 (3): 731 to 744. For discussion, see Re ferenc es and Dis cussion, T able B-2-7.

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 9 o f 10)

B-126 NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This a s ource docum

ent for the

equation in Table B-3-7. This docu ment also reco mmends the follo wing:

C Rp values of

0.5 (forag

e) and 0.46 (s ilage), based on the correlation from Chamber lain (1970)

C Treating Tp as a cons tant, base d on the ave

rage per iods between succes sive hay harvest s and succ essive

grazing

C Bidleman (1 988) as so urce of equa tion for ca lculatin g F v Shor, R.W., C .F. Baes, and R.D. Shar p. 1982. Agricultural P

roduction in the

United States

by County: A Compilation of Inf ormation from the 1974 Census of Agricultur

e for Use in Terres trial Food-Chain Tran sport and Assessment Models. Oak Ridg e National

Laborator

y Publication. ORNL- 5786. For discussion, see Re ferenc es and Dis cussion in Table B-2-7. U.S. Depar

tment of Agric ulture (USD

A). 1994. Vegetables 1993 Summary . National Agric ultural Stat

istics Se rvice, A gricultura l Statistic s Board. W

ashington, D .C. Vg 1-2 (94). This docum

ent is cit ed by NC DEHNR (1997)

as the sour

ce for t he avera ge we t weig ht harves t yield ( Yh ) for hay

. U.S. EPA. 1994a

. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

II: Site-Spe

cific Assessment Procedures

. External Re view Draft

. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent recom mends a n unweight

ed estim ate of y ield or sta nding crop biom

ass of 0. 15 kg DW

/m 2 for pasture grass. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This is one

of the sour

ce docum ents for the equation i

n Table B -3-7. This document a lso (1) developed and recommends Fwvalues of 0.2 for anion s and 0.6 for cation s and inso luble p articles, b ased on d ividing “ r ” values developed by Hof

fman, Thiesse n, Frank, a

nd Blayloc k (1992) and a

n Rp value of

0.5 for f orage; (2) recommends Rp values of 0.5 (forag

e) and 0.46 (s ilage); (3) recommends a kp valu e of 1 8, b ased on a gene ric 14- day h alf- time , co rre spo ndi ng t o ph ysic al p roc esse s on ly; (4) recommend s treating Tp as a cons tant ,base d on the ave

rage per iods between succes sive hay harvest s and succ essive

grazing ; and (5) cites Bi dleman (19 88) as th e source of th e equatio n for calcul ating F v . U.S. EPA. 1995. Review Draft Development of Human Health-Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3. This is one of the source documents for the equation in Table B-2-6. This document also recommends (1) using the Fwvalue calculated by using the r value for insoluble particles (see Hoffm an, Thies sen, Frank

, and Blay

lock 1992) to r

epresent or

ganic com

pounds; howev

er, no rationa

le for thi s recom

mendation is provided, and (2) Rp values of 0.5 (forag

e) and 0.46 (silage ), based on the

correlat ion from Chambe rlain (1970).

### TABLE B-3-7 FORAGEAND S ILAGECONCE NTRA TION D UE TO D IRECT DEPOSIT ION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS)

(Page 10of 10)

B-127 U.S. EPA. 1997. Exposure Factors Handbook . “Food Inge stion Factor s”. Volume

II. SABReview

Draft. EPA/600/P-95/002F. A ugust. This document is the source of relative ingestion rates. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This is one of the sour ce document s for the equ ation in Table B-3-7 . This docu ment also stat es that the best estimate o f Yp (yield or standing crop biomass) is productivity, as defined under Shor et al. ( 1982).

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 5)

B-128 Description This equa tion calcula

tes the CO

PC concentrat

ion in forag

e and sila ge (abov eground vegetation) resulting from di rect uptak

e of va por phase COPCs onto plant surf aces. Uncertain ties associ ated with th e use of this eq uation includ e the follo wing: (1) The range of values f or the variable Bv

(air-to-plant biotransfer factor) is about 19 orders of magnitude for organic COPCs. COPC-specific Bv values f or nondioxin-lik

e compounds may be overes

timated by up to one order of magnitude, based on experimental conditions used to develop the algorithm used to estimate Bv values. (2) The algorithm used to calculate values for the va riable F

v assum es a def ault value for the pa

ramet er ST (Whitby’s average s

urface area of particulates [aerosols]) of background plus local sources, r ather than a

n ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, using the latter ST

value may be more appropriate. The ST value f or urban sourc es is about one order of

magni tude grea ter than tha

t for bac kground plus local source s and would result in a lower Fv value; however, the F v value is likely to be only

a few percent low

er. Equation

For merc ury m odeling

Use 0.48Q

for total merc ury and F

v = 0.85 in the mercury modeling equation to calculate Pv . Apportion t he calcula

ted Pv value into the divalent (Hg 2+ ) and methyl merc ury (MHg) forms based on the 78% Hg 2+ and 22% MHg speciation split in abov

eground produce

and forag

e. Pv (Hg2+) = 0.78 Pv (Mercu ry) Pv (Mhg) = 0.22 Pv (Mercu ry) Varia ble Description Units Value 

### Pv Forage a

nd silage concentra

tion due to air-to-plant transfer μ g COPC/g DW plant tissue (equivale nt to mg/kg DW)

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 5)

Varia ble Description Units Value



### B-129 Q COPC-specif ic emi ssion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 for guida

nce on calc

ulating this

variable

. Uncertainties associated with this variable are also COPC- and site-specific. 

### F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRAP companion database. This range is based on values presented in Appendix A-2. U.S. EPA (1994b) and NC DEHNR (1997) also present values.
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) states

that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an S

T value f or urban sourc es. If a specif ic site i s located in an urban ar ea, using the latter ST

value m ay be m ore appropria

te. Specif

ically, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources, a nd it would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfa ce conce ntration for

monolay er cover age, and t he diff erence be tween t he heat of desorption f

rom the partic le surfa

ce and the heat of v

aporization of the liquid-phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Cyv Unitized y

early averag e air concentration from vapor phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 5)

Varia ble Description Units Value



### B-130 Bv forage Air-to-pla

nt biotransf

er fac tor for forage and sil age (mg CO PC/g plant tissue DW

)/ (mg CO PC/g air) 

### Varies

This variable is COPC-specific. We discuss this variable in detail in Appendix A-2, and off er COPC-specific values in the HHRAP companion database. Uncertain ty associated wit h this vari able incl ude the fol lowing:

The studies that formed the basis of the algorithm used to estim ate Bv values were conducted on azalea leaves and gras ses, and m

ay not a ccuratel y repre sent Bv

for abovegro und pr oduce ot her than leafy vegetables. 

### VG ag Empirica

l correct ion factor for forage and sil age unitless 

### Forage: 1.0 Silage: 0.5 This variabl e is site-sp ecific. In th e absence of sit e-specific in formation, we recommend usin g VGag values of 1.0 for forage and 0.5 for silage. U.S. EPA (1994a), U.S. EPA (199 4b), and NC DEHNR (1997) recommended an empirical correction factor to reduce estimated con centratio ns of const ituents in specific veget ation types . This factor is used to red uce estimated b ulky silage concentrat

ions, becaus e (1) Bv

was de veloped f or azale a leave s, and (2) it was assumed that there is insigni ficant translocation of compounds deposited on th e surface of specific vegetation types (such as bulky silage) to the inner parts of this vegetation. U.S. EPA (1994a) and U.S. EP A (1994b) recommended a VGag of 1.0 for pasture g rass and ot

her leaf y veg etation because of

a direct analogy

to exposed azalea

and gras s leave s. Pasture g rass is de scribed as

“leaf y veg etation.” U.S. EPA (1994a) and U.S. EP A (1994b) didn’t recommend a VGag value f or silage . NC DEHN

R (1997) recommended a VGag factor of 0.5 for bulky s ilage but didn’t present a specif ic rationa le for thi s recom

mendation. U.S. EPA (1995) noted that a volume ratio of out er surfa ce area volume to whole v

egetation volume

could be use d to assign a value to VGag for sila

ge, if specific assum

ptions concer

ning the proport

ions of ea ch type of veg etation of which silage m

ay cons ist of w

ere know n (for ex ample, corn and other

grains). In the abse

nce of s pecific assum ptions concerning hay/silage/grain intake, however, U.S. EPA (1995) recommended assum ing a VGag of 0.5 for si lage without rig

orous justif

ication. The following uncertainty is associated w ith this variable: The VGag value of

0.5 for silage is r

ecomm ended wit hout vigorous justific ation. Depe nding on the composition of site-specific silage, the recomm ended value may under- or overestima te the actual value.

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 5)

Varia ble Description Units Value



### B-131 D a Density

of air g/m 3 

### 1200.0

We rec omme

nd using this v

alue based on Weast

(1986). This

refer ence indica

tes that a ir density varies with temper ature. T he density

of air a t both 20°C a

nd 25°C (rounde d to two sig nificant figures) is 1.2 x 10+3

. U.S. EPA (199 8) a lso rec omm

ends this val ue, but s tat es t hat is w as b ase d on a

tem per atur e of 25° C. U .S. E

PA (1994b) and NC DEHNR (1997) recomm ended this sa

me va lue but stat

ed that it w

as calc ulated at s

tandard condit

ions (20°C and 1 a

tmosphere

). Both docum

ents cite d Weast

(1981).

REFERENCES AND DISCUSSION Bidelman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technol ogy. Volume 22. N umber 4. Pag

es 361-367 For discussion, see Re ferenc es and Dis cussion in Table B-1-1. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is a source docum

ent for the

equation in Table B-3-8. This docum ent also recomm

ended (1) tha

t F v values be based on the work of Bidleman (1988) , and (2) the use of an empirical correction factor ( VGag ) to reduce concentrations of COPCs in some vegetation types- (specifically , a VGag value of

0.5 is recom

mended f or silage ; howeve

r, no rationale is provided for this value). This fa

ctor is used to reduce e stimat ed COPC conce

ntrations in s

pecific veget ation type s, becaus e (1) Bv was de veloped f or azale a leave s, and (2) it is assum ed that ther

e is signifi cant trans location of compounds de

posited on the s

urface of spec ific v

egetation types to the inner pa rts of thi s vege

tation. Riederer, M. 1990. “Estimating Partitioning and Transport of Organic Chemicals in the Foliage/Atmosphere: Discussion of a Fugacity-Based Model.” Environmental Science and Technology

. 24: 829 to 837. This is t he source of

the leaf thicknes s used to es

timate the em pirical c orrection f

actor ( VGag ).

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 5)

B-132 U. S. EPA 1994a. Estimating Exposure to Dioxin-Like Compo unds. Volume II: Properties, Sources, Occurrence, and Backgroun d Exposures. Externa l Review Draft. Office of Re search a nd Development. Washington, D.C. EPA/600/6-88/005 Cb. June. This docum

ent recom mends a n empiric al correc

tion fact or of 0.01 to reduce estim ated veg etable conc entrations, based on the assumpt ion that there

is insigni ficant t

ranslocat ion of compounds de

posited on the s

urface of aboveground vegetation to inne r parts f or aboveg round produce. T

he docume

nt provides no refere

nce or disc

ussion regarding the validity of this assumpt ion. The factor of 0.01 is based on a similar correction factor f or below ground produce ( VGag ), which i s estim ated based on a ratio of

the vegetable sk

in mass to vege table total mass . The document assumes that the density of the skin and veg etable are equal. The document also assumes a n average vegetable sk

in leaf based on Rierderer (1990). Based on these assumptions, U.S. EPA (1994a

) calcula ted VGag for car

rots and potat

oes of 0.09 a

nd 0.03, respec

tively . By c omparing

these va lues to conta

mination r

eduction res earch com

pleted by Wipf, e t al. (1982), U.S. EPA (1994a

) arrived at the re comm

ended VGag of 0.01. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This is one of the sour ce document s for the equ ation in Table B-3-8 . This docu ment also pr esents a range (0.27 t o 1) of F v values for organic COPCs, calculated on the basis of Bidleman (1988); F

v for all inorganics

is set e qual to zero. U.S. EPA. 1995. Review Draft Development of Human-Health Based and Ecolo gically-Based Exit Criteria for the Hazardous Waste Identificat ion Project . Volumes I and II. Of fice of Solid Waste. March 3. This docum

ent present

s estim ated VGag values. U.S. EPA (1995) notes that a

volume ratio of outer surf

ace area volum

e to whole

veget ation volum

e could be us ed to assig

n a value to VGag for sila ge, if specific assum

ptions (conce

rning the propor

tions of ea

ch type of veg etation of which silage m

ay cons ist of) w

ere know n (for ex ample, corn and other

grains). In the abse

nce of specific assumptions concerning hay/silage/grain intake, howe ver, U.S. EPA (1995) recommends assuming a VGag value of 0.5 for silage (for CO PCs with a l og K ow greate r than 4) w

ithout rigorous jus

tificat ion. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment. Office of A

ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. Based on at

tempts to model ba

ckground c oncentrations

of dioxin-l

ike com pounds in beef

on the basis

of know n air conce

ntrations, thi s docume

nt recom mends reducing, by

a fac tor of 10, Bv values c alculate d by using the Bacci, et al. ( 1992) algorithm The use of this f actor “m ade predic

tions [of bee f concent

rations] com

e in line w

ith observa

tions.” Weast,R.C. 1981. Handbook of Chemistry and Physics . 62nd Edition. Cleveland, Ohio . CRC Press.

This docum

ent is a r efere nce for a ir density values. Weast,R.C. 1986. Handbook of Chemistry and Physics . 66th Edition. Cleveland, Ohio. CRC P ress.

### TABLE B-3-8 FORAGE AND SILAGE CONCENTRATION DUE TO AIR-TO-P LANT TRANSFER

(CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 of 5)

B-133 This docum

ent is a r efere nce for a ir density values, and is an upda

te of W east (1981). Wipf, H .K., E. Ham

berger, N . Neuner, U .B. Ranalde r, W. Vette

r, and J.P. Vuilleum

ier. 1982 “TCDD Le

vels in Soil and Plant Sam ples from the Seve so Area .” In: Chlorinated Dioxins and Relat ed Compounds: Impact on the Envir onment . Eds. Hut zinger, O. et al. Pergan on. New York.

### TABLE B-3-9 FORAGE /SILAG

E/GRA IN CON CENT RATION DUE T O ROOT UPTAKE (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 o f 3)

B-134 Description This equation calculates the COPC concentration in forage/silage/grain (aboveground produce), due to di rect uptake of COPCs from soil through plant roots. Uncertainties associated with the use of this equ ation in clude th e following: (1) The availabil ity of site-spe cific informati on, such as meteorolo gical data, will affect the accur acy of Cs estimates. (2) Estimated COPC-specific soil-to-plant bioconcentration factors ( Br) don’t ref lect site -specif

ic conditions. This m

ay es pecially be true f or inorganic

COPCs for which Br

would be m

ore accurately estima

ted by using site-specific bioconcentration factors rather than bioconcentration factors from Baes et al. (1984). We therefore recom mend using plant uptake response slope factors derived from U.S. EPA (1992) for arsenic, cadmium, s elenium, nickel, and zinc. Equation

For mercury modeling, forag e/silage/grain concentration due to root uptake is calculated for divalent mercury (Hg 2+ ) and methyl merc

ury (MHg) using their respective Cs and Br values.

Varia ble Description Units Value 

### Pr Concentration of COPC in

forage /silage /grain due to root uptake mgCOPC/kg DW plant tissue


### Cs Average soil concentration over

exposure dur

ation mg/kg 

### Varies This va lue is COPC a

nd site-spe cific, and calcula ted using the

equation in Table B-3-1. Uncertai nties ass ociated w

ith this variable are site-specific.

### TABLE B-3-9 FORAGE /SILAG

E/GRA IN CON CENT RATION DUE T O ROOT UPTAKE (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 o f 3)

Varia ble Description Units Value



### B-135 Br forage 

### / Br grain Plant-soil bioconc entration f actor for fora ge/sila ge, or gr ain unitless

[(mg COPC/ kg plant DW)

/ (mg COPC/kg soil)] 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRA

P companion da

tabase. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Estimates of Br for som e inorganic

COPCs, based on plant uptak e response

slope fa ctors, m ay be m ore accurate than those ba

sed on BCF

s from Baes et al. (1984). (2) We rec omme

nd that you calculat

e uptake of organic COPCs f rom soil,and transport

of the COPCs to aboveground plant parts,by using a regre ssion equation developed in a study of the upta

ke of 29 or

ganic compounds. T

his regre ssion equation, develope d by Tr avis and A

rms (1988) , may

not accura

tely r epresent t he behavior of all classes of organic COPCs under site-specific conditions.

REFERENCES AND DISCUSSION Baes, C.F . R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and Analysis of Parameters and Assessing Transport o f Environmentally Released Radionu clides Through Agriculture

. ORNL-5786. Oak Ridge National Laborator

y, Oak Ridge, Tennessee . Septem ber. This document presents inorganic-specific transfer fac tors (Br) for both vegetative ( Bv ) portions of

food crops and nonvege

tative ( reproductiv

e—fruits , seeds, a

nd tubers) portions (Br) of food crops. These bioconcentration factors were developed based on review and compilation of a wide v ariety of measured, empirical, and comparative data. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is a source docum

ent for the

equation in Table B-3-9. Travis, C.C., and A.O. Arm s. 1988. “Bioconcentration of Organics in Beef, Milk, and Vegetation.” Environmental Science and Technol ogy. 22:271 to 274. This docum

ent developed the following re gression equation relating soil- to-plant bioconc entration f actor ( Br) to K

ow , based on paired soil and plant concentration data: log Br = 1.588 - 0.578 @ log K ow U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge . Volumes I and II. Office of W ater. Washington, D.C. EPA 822/R-93-001a. Source of plant uptake response factors for arsenic, cadmium, nicke l, selenium, and zinc. Plant uptake response factors can be converted to BCFs by multiplying the plant uptake response factor by a fac tor of 2.

### TABLE B-3-9 FORAGE /SILAG

E/GRA IN CON CENT RATION DUE T O ROOT UPTAKE (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 o f 3)

B-136 U.S. EPA. 1995. Review D raft Deve lopment of Hum an Health Base d and Ecologically

Based Exit Criteria f

or the Hazar

dous Waste I

dentification P

roject. Vol

umes I and II

. Office of Solid Waste

. March 3. This document recommends using the bioconcentration factors Bv and Br from Baes et

al. (1984) f

or calcula ting the upta

ke of inor ganics i nto vege tative a nd nonveget

ative g rowth, resp ecti vely. Although m

ost BCFsused in th is documen t came from Baes et al. (1 984), values for some in organics were ap parentl y obtained from plant up take respon se slope facto rs. These up take respons e slope facto rs were calculat ed from field dat a, such as metal l oading ra tes and so il metal conce ntratio ns. However, t he methodo logies and references used to calcula te the up take response s lope fac

tors we re not clea

rly ide ntified. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This is one

of the sour

ce docum ents for the equation i

n Table B -3-9.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 7)

B-137 Description This equa tion first estim ates the daily a

mount of COPCs cattle are e xposed to throug

h ingesting

contami nated plant a

nd soil ma

terial. T he equation the

n recom mends the

use of biot

ransfe r factor s to transf orm the da

ily anim al intake of a COPC (mg CO

PC/day) int

o an anim al COPC tiss

ue concentr

ation (mg COPC/kg FW

tissue). The limitatio ns and un certainty in trodu ced in calcu lating th is variable i nclude t he followin g: (1) Variables P i and Cs are COPC- and site-specific. Uncertainties associated with these variables a re site-specific. (2) Uncertainties associated with the variables F i , Qs, and Qp i are ex

pected to be

minim al. (3) Using a single Ba beef value for each COPC may not accurately reflect site-specif ic conditions. It is not clear whether the default values are likely to under - or overestim ate A beef . Based on the

inform ation below , A beef

is dependent

on the conce

ntrations of

COPCs esti

mated i n plant fe eds and soil,

and the biotra

nsfer f actor est imated for eac

h constituent. Equation

For mercury modeling, beef concentration due to plant and soil ingestion is calculated for divalent mercury (Hg 2+ ) and methyl merc

ury (MHg) using their respective P i , Cs , and Ba beef values. Varia ble Description Units Value 

### A beef Concentration of COPC in beef mg COPC/kg FW tissue 

### F i Fraction of plant type ( i) grown on

contamina

ted soil and i

ngested by the anim al unitless 

### 1 This variabl e is site- and plant type- specific. P lant types for cattle are typic ally identi fied as grain, forage, and si lage. We recomm end using a default v

alue of 1. 0 for all plant type s when s ite-spec ific inf ormation i s not available. T his is consistent with U.S. EPA (1998), U.S. EPA (1994a), U .S. EPA (1994b) a nd NC DEHNR

(1997), whic

h recom mend assuming that 100 percent of the plant materials ingested by ca ttle were grown on soil contaminated by em issions. The following uncertainty is associated w ith this variable: (1) Assuming 100 percent of the plant materials eaten by cattle were grown on soil contaminated by emissions may overestimate A beef

.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 7)

Varia ble Description Units Value



### B-138 Qp i Quantity of plant type ( i) ingested

by the animal per day kg DW plant/day 

### Forage: 8.8 Silage: 2.5 Grain: 0.47 This variabl e is site- and plant type- specific. P lant types for cattle are typic ally identi fied as grain, forage, and si lage. We recommend that you use the fol lowing Qp values when eval uating cat tle raised b y beef farmers: forage (8.8 ), silage (2.5), and gr

ain (0.47). T

hese va lues are consistent with U.S. EPA (1994c), a nd NC DEHNR

(1997). The ref erence doc

uments c ite Boone et

al. (1981), NAS (1987), McKone and Rya n (1989), and Ric e (1994) as pr imary references for plant ingestion rates. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) The rec omme

nded daily

grain ingestion rate

of 0.47 kg

dry w eight (DW

)/day i s calcula

ted indirec

tly f rom (1) a recomm ended total da

ily dry matte r intake of 11.8 kg

DW plant/

day, bas ed on NAS ( 1987) and McKone and Ryan (1989) , and (2) dail y inge stion rates

of fora ge (8.8 kg /day) a nd silage (2.5 kg DW

/day), r ecomm ended by Boone et al. (1981). How ever, Boone

et al. (1981)

recom mended a n alternat ive daily grain ingestion rate

of 1.9 kg DW /day, a bout four tim

es higher than the ra

te we r ecomm end. As s hown in Equations in Table s B-3-7 through B-3-9, t

he concentr

ations of C OPCs in fora

ge, sila ge, and g rain are calculat

ed similarly. Theref

ore, the relative amounts of fora

ge, sila ge, and g rain inges ted daily have a l imited e ffec

t on the intak

e of COPCs , if the total daily

intake of dry m atter is held constant . Theref ore, lim ited uncert

ainty is introduced. (2) The rec omme

nded daily

ingestion r

ates (tota l and plant ty

pe-specif ic) ma y not accurately

represe nt site-specific or local condi

tions. The

refore, A beef may be under- or overestima ted, but to a limited degree.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 7)

Varia ble Description Units Value



### B-139 P i Concentration of COPC in pla nt type (i) ingested by the animal mg/kg DW 

### Varies This va riable is COPC-, site- , and plant ty pe-specif ic; plant ty

pes for c attle ar

e typic ally ide

ntified a s grain, f orage, a nd silage. Values f

or Pd , Pv , and Pr

are calculated by using the equations in Tables B-3-7, B-3-8, and B-3-9; and then summed for each plant ty pe to determine P i . Uncertain ties intr oduced by this variab le includ e the follo wing: (1) Some of the varia bles in th e equatio ns in Table s B-3-7, B-3-8, an d B-3-9 —includ ing Cs, Cyv, Q, Dydp , and Dywp —are COPC- and site-specific. Uncertainties associated with these variables are site-specific. (2) In the equation in Table B-3-7, uncert ainties a ssociate d with other

variable s include the

followi ng: F

w (values for orga nic compounds

estim ated on the ba

sis of the behavior of

polysty rene m icro sphere s), Rp (estim

ated on the basis of

a gener alized em pirical relationship), kp (estimation process does not consider chemical degradat ion), and Yp (estimated on the basis of national harvest yield and area planted values). A ll of these uncertainti es contribute

to the over

all uncert ainty a ssociate d with P i . (3) In the equation in Table B-3-8, COPC-specific Bv values for nondioxin-like compounds may be overestima ted by up to one order of magnitude, based on experimental conditions used to develop the algorithm to estimate Bv values. (4) In the equation in Table B-3-9, COPC-specific plant-soil bio transfer factors ( Br) may not reflec

t site-speci fic condit ions. Thi s may be especially true for inorgan ic COPCs fo r which estimate s of Br would be more accurately es

timated by using plant uptake response slope factors. 

### Qs Quantity

of soil ing

ested by the animal kg/day 

### 0.5 This variable is site-specific. We recommend using a soil ingestion rate of 0.5 kg/day . This is consistent with NC DEHNR (1997) and U.S. EPA ( 1994c), whic h cite USD

A (1994), Ri ce (1994), and NAS (1987). Uncertain ties intr oduced by this variab le includ e the follo wing: (1) The rec omme

nded soil inge stion rate may not accura

tely r epresent site-spec ific or local conditions . Howev er, we ex pect any diffe rences be tween t he recom mended v alue and si

te-speci fic or loc al soil ingestion rate s to be small. Theref

ore, we likew ise expect any

uncertaint

y introduc ed to be lim

ited. 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies

This variable is COPC- and site-specific, and calculated using the equation in Table B-3-1. Uncertainties are site-specific.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 7)

Varia ble Description Units Value



### B-140 Bs Soil bioavailability factor unitless 

### 1.0 The soil bioavailability f

actor, Bs, can be thoug

ht of as t he ratio bet

ween bioc oncentration (or biotransf er) fa ctors for soil and vege tation for a give

n contami nant. The efficiency of transf er from soil ma y diff er from efficiency

or transf er from plant ma terial f or some COPCs. If

the transf

er eff iciency is lowe r for soil s, then this ratio would be less t han 1.0. If it is equal or greater than that of vegetation, the Bs would be e qual to or gr eater tha n 1.0. Since there

is not enough data regarding bioav ailability from soil, we

recom mend a de fault v

alue of 1. 0 for Bs, until more COPC data becomes a

vailable for this pa

ramet er. Ther e is a f air am ount of uncer

tainty a ssociate d with the use of this default value, because some COPCs may be much less bioavailable from soil than from plant tissues. 

### Ba beef Biotran sfer factor for bee f day/kg FW tissue 

### Varies

This variable is COPC-specific. We discuss this variable and COPC-specific v alues in Appendix A-2. Ba beef is defined as the ra tio o f the CO PC co ncen trati on in animal tissu e (mg COP C/kg an imal ti ssue) to th e dail y intak e of th e COP C (mg COPC/day)

by the a nimal. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) We recomme

nd using the regression equation developed by RTI (2005) to calculate Ba beef values f or organic COPCs. Unce

rtainties listed in RT

I (2005) in deriv

ing the regression equation include : 1) the nec esssity to extrapolate data to steady state conditions, 2) metabolism may not be accounted for equally for all data points, and 3) there is a +/- 0.5 variability in measured Log Kow values available in the literature. In addition, values calculated by using this regression equation may not accurately represent the behavior of organic COPCs under site-specific condi

tions. Ba beef

and subseque

nt A beef value s may ther efore b e und er- or overe stimat ed to some degree. (2) We recommend calcul ating Ba beef values f or meta ls be using

single C OPC-specif

ic uptake factors developed by Baes et al. (1984). These uptake factors ma y not accurately represent the behavior of inorganic COPCs under site-specific condi

tions. Ba beef

and subseque

nt A beef value s may ther efore b e und er- or overe stimat ed to some degree. 

### MF Metabolism factor unitless 

### 0.01 and 1.0 This variabl e is COPC- specific. Base d on a stu dy by Ikeda et al. (1 980), U.S. EP A (1995a) recommended us ing a metabolism factor to account for m etabolism in animals to offset the am ount of bioaccumulation suggested by biotransfer factors . MF applies

only to be ef, m

ilk, and pork . It does not a pply to direct exposur

es to air,soil, or w

ater, or to ingestion of produce, chicken, or fish. U .S. EPA (1995b) recomm ended an MF of

0.01 for bis(

2-ethylhe xyl)pht halate (B EHP) and 1.0 for all other contaminants.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 7)

B-141 REFERENCES AND DISCUSSION Baes, C.F., R.D. Sharp, A.L. Sjoreen, and R.W. Shor. 1984. “Review and Analysis of Parameters and Assessing Transport of Environmentally Released Radionuclides Through Agriculture.” Oak Ridge National Laboratory, Oak Ridge, Tennessee. U.S. EP A (1994c) recommends Baes et al . (1984 ) as a source o f Ba beef values for inorganics. Boone, F.W., Yook C. Ng, and John M. Palms. 1981. “Terrestrial Pathways of Radionuclide Particulates.” Health Physics , Vol. 41, No. 5, pp. 735-747. Novem ber. This document is identified as a source of plant ingestion rates. Boone et al. (1981) reports forage, grain, and silage ingestion rates of 8.8, 1.9, and 2.5 kg DW/day, respectively, for beef cattle. Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 198 0. “Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate in rats, dogs, and pigs.” Food Cosmet. T oxicology. 18:637- 642. McKone, T .E., and P.B. Ry an. 1989. Human Exposures to Chemicals Through Fo od Chains: An Uncertainty Anal ysis. Liver

more, Ca lifornia: Lawr

ence Li vermor e National

Laborator

y Report

. UCRL-99290. This docum

ent is cit ed as a s ource of plant inges tion rates. McKone and Ryan (1989) report an a

verage total inge stion rate of 12 kg DW/day for the t hree plant f

eeds, w hich is consi stent with the t otal recom

mended by

other guida

nce docum

ents for cattle (

that is, f orage, g rain, and silage tota

l of 11.8 kg

DW/day ). National A

cadem y of S ciences

(NAS). 1987. Predicting F eed Intake

of Food-Producing A nimals . National Research Council, Committee on Animal Nutrition, Washington, D.C. This document is identified as a source of food ingestion rates. NC DEHNR (1997) and U.S. EPA (1994c) note that NAS (1987) reports a daily dry matter intake that is 2 percent of an averag e beef cattle body

weight of 590 kilog

rams. This res

ults in a daily total

intake r ate of 11. 8 kg DW

/day, a nd the daily

soil inges

tion rate of

approxim

ately 0.5 kg soil

/day (ba sed on USDA [1994]). NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is a r efere nce source

for the equation in Ta

ble B-3-10. NC DEHNR

(1997) recom

mends f orage, g rain, and silage ingestion rate s of 3.8, 3.8, a nd 1.0 kg dry

weight /day, re spectively, f

or typic al farm

er beef cattle. NC DEHNR

(1997) reports Rice (1994) as a references for these va riable.
Researc h Triang le Institute

(RTI). 2005. Methodology for Predicting Cattl e Biotransfer Factors. Prepared for U.S. Environmental Protection Agency (EPA) Office f o Solid Waste. EPA Contract No. 68-W-03-042. August.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 of 7)

B-142 U.S. Department of Agriculture (USDA). 1994. Personal Communication Between G.F. Fries, and Gle nn Rice and Jennifer Windholtz, U.S. Environmental Protection Agency, Office of Researc h and Development. Agricultural Research Service. March 22. NC DEHNR

(1997) and U.S. E

PA (1994c) note

that this re ferenc e reports s oil ingestion for cat tle to be 4 pe

rcent of the total da

ily dry matte r intake. U.S. EPA. 1993. Technical Suppor t Document f

or Land Application of

Sewage Sludge. Volumes I and II. EPA 822/R-93-001 a. Office of W ater. Washington, D.C. U.S. EPA (1995) recommended that bioconcentration factors for the metals cadmium, m ercury, selenium, and zinc presented in this document be used to derive Ba beef values. Following the method recommended by U.S. EPA (1992) for dioxins, the bioconcentration factors—with units of (kilograms feed DW /kilogram tissue DW—are divided by feed ingestion rates (kilogram feed DW/day]) to calculate Ba beef valu es (d ay/ki log ram t iss ue D W). U .S. EP A (19 93) reco mmend ed a f eed ing est ion rate of 20 kg DW/ day. U.S. EPA. 1994a

. Estimating Ex posures to D ioxin-like

Compounds

. Volume III: Site-specific Assessment Procedures. Office of Re search and Development. EPA/600/6-88/005Cc. External Review Draft. June. This docum

ent recom mends a n F i value of 1; this value assumes that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by emissions. U.S. EPA. 1994b. Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustio n Facilities . Off ice of Sol id Waste and Eme rgency Response. EPA-530-R-94-021. April. This docum

ent recom mends a n F i value of 1; this value assumes that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by emissions. U.S. EPA. 1994c

. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docu ment is one o f the reference so urce docu ments for the eq uation in Table B-3 -10. This document al so recommends t he followin g:

C An F i value of 100 percent

C Qp i values for forage, silage , and grain of 8.8, 2.5 and 0.47 kg dry weight/day, respectively, based on Boone et al. (1981), NAS (1987), McKone and Ryan (1989), and Rice

(1994)

C A soil ingestion rate for cattle ( 2 sw ) of 0.5 kg /day, ba sed on USDA

(1994), Rice

(1994), and NA S (1987) U.S. EPA. 1995a

. Further Issues for Modeling the Indirect Exposure Impacts from Combusto r Emissions. Offic e of R esea rch and Deve lop ment . Was hin gto n, D .C. Janu ary.

This docu ment recommends u sing BCF for the metals cadm

ium, mercury, sele

nium, and zinc, presented in U.S. EPA (1993), to calculate Ba beef values f or these m

etals. Specifica

lly, the BCFsfrom U.S. EPA (1993)— which ar e in units of

kilogra m fe ed DW/k

ilogram tissue DW

are divided by a feed ing estion rate

of 20 kilog

rams D W/day to arrive at Ba beef values i n units of day/kilogram

tissue DW

, according

to the me thodology de

veloped f or dioxins (U .S. EPA 1992). U.S. EPA. 1995b. “Waste Technologies Industries Screening Human Health Risk Assessm ent (SHHRA): Evaluation of Potential Risk from Exposure to Routine Operating Emissions.” Volume V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois. U.S. EPA. 1997a

. Exposure Factors Handbook . “Food Inge stion Factor s”. Volume

II. SABReview

Draft. EPA/600/P-95/002F. A ugust.

### TABLE B-3-10 BEEF CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 7 of 7)

B-143 U.S. EPA. 1997b. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search and Development. E

PA 452/R-97-005. D ecem ber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent recom mends a n F i value of 1; this value assumes that 100 percent of the plant materials inge sted by cattle have been grown on soil contaminated by e missions.

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 7)

B-144 Description This equation first estimates the daily am ount of COPCs taken in by cattle through the ingestion of contaminated plant and soil material. The equation then recommends the use of biotransfer factors to transf orm the da

ily anim al intake of a COPC (mg CO

PC/day) int

o an anim al (dairy cattle) milk C OPC concentra

tion (mg COPC/kg FW

tissue). The limitatio ns and un certainty in trodu ced in calcu lating th is variable i nclude t he followin g: (1) Variables P i and Cs are COPC- and site-specific. Uncertainties associated with these variables are site-specific. (2) Uncertainties associated with the variables F i , Qs, and Qp i are expected to be m inimal. (3) Ba milk values may not reflect site-specific conditions— Ba milkvalues f

or nondioxin-lik

e organic s are bas ed on a gene ralized r egress ion equation; Ba milk values f or dioxins and furans a

re estima ted on the bas is of ex

perime ntal value s from

a single lactating cow; and Ba milkvalues f

or inorganic s are bas ed on integr ation of a wide v ariety of em pirical a nd experim

ental res ult which ca n mean t hat site-s pecific diffe rence ar e ignored. Based on the

inform ation below , A milkis dependent on the conce

ntrations of

COPCs esti

mated i n plant fe eds and soil,

and the biotra

nsfer f actor est imated for eac

h compound. Equation

For mercury modeling, calculate m ilk concentrations due to plant and soil ingestion for divalent mercury (Hg 2+ ) and methyl merc

ury (MHg) using their respective P i , Cs , and Ba milkvalues. Varia ble Description Units Value 

### A milk Concentration of COPC in m ilk mg COPC/kg

FW tissue 

### F i Fraction of plant type ( i) grown on

contamina

ted soil and i

ngested by the animal unitless 

### 1.0 This variabl e is site- and plant type- specific. P lant types for cattle are id entified as gr ain, forage, and silage. We recomm end using a default v

alue of 1. 0 for all plant type s. This i s consiste nt with U.S . EPA (1998), U. S. EPA (1994a), U.S. EPA (1994b) and NC DEHNR (1997 ), which recommend assum ing that 100 percent of the plant materials ingested by cat tle we re grow n on soil contam

inated by emiss ions. The following uncertainty is associated w ith this variable: (1) Assum

ing 100 perce

nt of the pla

nt mate rials ea ten by c attle w

ere grow n on soil contam

inated by facili ty emissions may

overestimate A milk .

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 7)

Varia ble Description Units Value



### B-145 Qp i Quantity of plant type ( i) ingested

by the animal per day kg DW plant/day 

### Forage: 13.2 Silage: 4.1 Grain: 3.0 This variabl e is site- and plant type- specific. P lant types for cattle are id entified as gr ain, forage, and silage. We recommend that you use the fol lowing Qp values when eval uating cat tle raised b y milk farmers: forage (13.2 ), silage (4.1), and gr

ain (3.0). The recommended plant type-specif ic Qp i values w

ere calculated as

follows

. First , tot al dry mat ter in take (D MI) was estimat ed as 2 0 kg DW/ day, b ased o n info rmatio n pre sent ed in NAS (1987). Second , data f rom Boone e

t al. (1981) w

ere used t o separate the total DMI into plant ty pe-specif ic frac tions. Finally , the recommended plant type-specific Qp i values w ere calculated by

multiply ing the es timated total DMI (20 kg DW

/day) by the plant ty

pe-specif ic frac tions. For example, the Qp i for fo rage was ca lcu lat ed as 20 k g DW/ day @ 0.65 = 13.2 kg DW/day . These

values a re consist ent with U.S. EPA (1993; 1994b; 1995), a nd NC DEHNR

(1997). Thes e refe

rence docum

ents cite Boone et al . (1981), NAS (1987), McKone and Ryan (1989), and Rice (1994) as primary references for plant ingestion rates. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) The plant type-specific Qp i values were calculated based on a total DMI of 20 kg D W/day (NAS 1987) rather than the tota

l DMI of 17 k

g DW/da y pres ented in Boone et al. (1981) and McKone a nd Ryan ( 1989). Sit e-sp ecif

ic t ota l DM I val ues may var y. (2) The plant t

ype-specific f

ractions c alculate d from Boone et al. (1981) may not accura

tely r epresent site-spec ific or local pla

nt type- specific frac

tions.

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 7)

Varia ble Description Units Value



### B-146 P i Concentration of COPC in pla nt type (i) ingested by the animal mg/kg DW 

### Varies This va riable is COPC-, site- , and plant ty pe-specif ic; plant ty

pes for c attle ar

e identif ied as gr ain, fora ge, and silage. Values for Pd , Pv , and Pr are ca lculated by

using the equations in T ables B-3- 7, B-3-8, and B- 3-9, and then sum med f or each plant type to determine P i . Uncertain ties intr oduced by this variab le includ e the follo wing: (1) Some of the varia bles in th e equatio ns in Table s B-3-7, B-3-8, an d B-3-9 —includ ing Cs, Cyv, Q, Dydp , and Dywp —are COPC- and site-specific. Uncertainties associated with these variables are site-specific. (2) In the equation in Table B-3-7, uncert ainties a ssociate d with other

variable s include the

followi ng: F

w (values for orga nic compounds

estim ated on the ba

sis of the behavior of

polysty rene m icro sphere s), Rp (estim

ated on the basis of

a gener alized em pirical relationship), kp (estimation process does not consider chemical degradat ion), and Yp (estimated on the basis of national harvest yield and area planted values). A ll of these uncertainti es contribute

to the over

all uncert ainty a ssociate d with P i . (3) In the equation in Table B-3-8, COPC-specific Bv values for nondioxin-like compounds may be overestima ted by up to one order of magnitude, based on experimental conditions used to develop the algorithm to estimate Bv values. (4) In the equation in Table B-3-9, COPC-specific plant-soil bio transfer factors ( Br) may not reflec

t site-speci fic condit ions. Thi s may be especially true for inorgan ic COPCs fo r which estimate s of Br would be more accurately es

timated by using plant uptake response slope factors. 

### Qs Quantity

of soil ing

ested by the animal kg/day 

### 0.4 This variable is site-specific. We recommend using a soil ingestion rate of 0.4 kg/day . This is consistent with NC DEHNR (1997) and U.S. EPA ( 1994b), which cite USDA (1994), Rice

(1994), and NA S (1987). Brie fly, the recomm ended Qs value w

as calc ulated as follows

. First , a total DMI was estima ted as 20 k

g DW/da y based on inform

ation prese

nted in NA S (1987). Second , USDA ( 1994) estim

ates that Qs equals 2 pe

rcent of the total DM

I. Finally , the recom

mended Qs valu e was c alcu lat ed as 20 k g DW/ day @ 0.0 2 = 0 .4 k g DW / day. Uncertainties introduced by this variable include: (1) The rec omme

nded Qs value w

as based on a total DM

I of 20 kg DW/day NAS (1987) rather tha

n the total DMI of 17 kg DW/day presented in Boone et al. (1981) and McKone and Ryan (1989). To the extent that site-specific or local total DMI value s may vary, A milk may be under- or overestima ted to a limited degree. (2) USDA (1994)

states t hat Qs equals 2 pe

rcent of the total DM

I for dair y cat tle on a f arm. A lthough the basis of the estim ate of 2 percent is

not known, i

t is appare

nt that to the extent tha

t site-specific or

local Qs values a

re differ ent than 2 per

cent, A milkmay be under- or overestim ated to some degree.

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 7)

Varia ble Description Units Value



### B-147 Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies

This variable is COPC- and site-specific, and calculated using the equation in Table B-3-1. Uncertainties are site-specific. 

### Bs Soil bioavailability factor unitless 

### 1.0 The soil bioavailability f

actor, Bs, can be thoug

ht of as t he ratio bet

ween bioc oncentration (or biotransf er) fa ctors for soil and vege tation for a give

n COPC. The efficiency of transf er from soil ma y diff er from efficiency

or transf er from plant material for some COPCs. If the transfer efficie ncy is lower for soils, then this ratio would be less than 1.0. If it is equal or greater than that of vegetation, the Bs would be e qual to or gr eater tha n 1.0. Due to lim

ited data r

egarding bioavaila bility f rom soil,we re comm

end a def ault value of 1.0 for Bs, until more COPCspecific data is

availa ble for thi s param

eter. Som

e COPCs m

ay be m uch less bioa

vailable from soil than f

rom plant tissues. This uncertainty may overestimate Bs

. 

### Ba milk Biotran sfer factor for milk day/kg FW tissue Varies

This va riable is COPC-specif

ic. A de tailed disc

ussion of thi s varia

ble and COPC-s

pecific values a re prese nted in Appendix A

-2. Ba milkis defined as the ra tio of the C OPC concentra tion in milk

(mg C OPC/kg tis sue) to the daily int ake of the COPC (m

g COPC/day

) by the animal. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) We recomme

nd using the regression equation developed by RTI (2005) to calculate Ba milkvalues f or organic COPCs. Unce

rtainties listed in RT

I (2005) in deriv

ing the regression equation include : 1) the nec esssity to extrapolate data to steady state conditions, 2) metabolism may not be accounted for equally for all data points, and 3) there is a +/- 0.5 variability in measured Log Kow values available in the literature. In addition, values calculated by using this regression equation may not accurately represent the behavior of organic COPCs under site-specific condi

tions. Ba milkand subseque nt A milkvalue s may ther efore b e und er- or overe stimat ed to some degree. (2) We recommend calcul ating Ba milkvalues f or meta ls be using

single C OPC-specif

ic uptake factors developed by Baes et al. (1984). These uptake factors ma y not accurately represent the behavior of inorganic COPCs under site-specific condi

tions. Ba milkand subseque nt A milkvalue s may ther efore b e und er- or overe stimat ed to some degree.

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 7)

Varia ble Description Units Value



### B-148 MF Metabolism factor unitless 

### 0.01 and 1.0 This variabl e is COPC- specific. Base d on a stu dy by Ikeda et al. (1 980), U.S. EP A (1995a) recommended us ing a metabolism factor to account for m etabolism in animals to offset the am ount of bioaccumulation suggested by biotransfer factors . MF applies

only to be ef, m

ilk, and pork . It does not a pply to direct exposur

es to air,soil, or w

ater, or to ingestion of produce, chicken, or fish. U .S. EPA (1995b) recomm ended an MF of

0.01 for bis(

2-ethylhe xyl)pht halate (B EHP) and 1.0 for all other COPCs.

REFERENCES AND DISCUSSION Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and Analysis of Parameters and Assessing Transpo rt of Environmentally Released Radion uclides through Agriculture. Oak Ridge National Laboratory, Oak Ridge, Tennessee. U.S. EPA (1994c) recom mends Ba es et al . (1984) as a

source of (1) Ba milkvalues f

or inorganic s, and (2) w

ater conte nt of 0.9 f or cow’s milk, which ca

n be used to c onvert Ba milkvalues i n dry w eight to w et weight. Beecher , G.D., a nd C.C. Tra

vis. 1989. Modeling Support f or the RURA and Municipal W aste Combust

ion Project F

inal Report on Se

nsitivity and Uncertaint

y Analysis

for the Ter

restrial F ood Chain Model . Prepared unde r IAG-1824-A020-A 1 by Oak Ridge Na

tional La boratory for U.S. EPA

Offi ce of Health and Env ironmenta

l Asse ssment, Environm

ental Crit eria and Asses sment O ffice . Cincinnati , Ohio. This docu ment was cited by U.S . EPA (19 90) as th e source of Ba milkvalues f or cadm ium. Boone, F.W., Yook C. Ng, and John M. Palms. 1981. “Terrestrial Pathways of Radionuclide Particulates.” Health Physics . Vol. 41, No. 5, pa ges 735-747. N

ovembe r. This docum

ent is ident

ified as a source of plant ing

estion rate s. Boone et al. (1981) repor ts a total forage, grain,and silage ingest ion rate of

17 kg DW

/day f or dairy cattle. Also, this document s

tates tha t this total DMI of 17 k

g DW/da y is m ade up of t

he follow ing plant ty

pe-specif ic frac tions: for age (65 pe

rcent), g rain (15 perc ent), and silage (20 pe rcent). Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 198 0. “Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate in rats, dogs, and pigs.” Food Cosmet. T oxicology. 18:637-642. McKone, T .E., and P.B. Ry an. 1989. Human Exposures to Chemicals Through Fo od Chains: An Uncertainty Anal ysis. Liver

more, Ca lifornia: Lawr

ence Li vermor e National

Laborator

y Report

. UCRL-99290. This document is cited as a source of plant ingestion rates. It reports an average total ingestion rate of 17 kg dry weig ht/day for the three plant feeds, which is consistent with the total recommended by Boone et al. (1981) for cattle.

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 of 7)

B-149 NAS. 1987. Predicting F eed Intake

of Food-Producing A nimals. National Research Council, Committee on Animal Nutrition. Washington, D.C. NC DEHNR

(1997) and U.S. E

PA (1994c) note

that this doc

ument re ports a dail

y DMI equal to 3.2 perc ent of an averag e dairy cattle body

weight of 630 kilog

rams; this result

s in a daily DMI of 630 kg DW @ 0.032 = 20. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. Grains such as c orn may

be grow n specif ically as catt le feed. COPC uptake

into these f

eed ma terials m ay occ ur through root upt

ake, w et and dry deposition of

particula te-bound COPCs on plants, and v

apor-phase uptake of

COPCs through plant folia ge. Plants are classifie d as “prote cted” if they ha ve an oute

r covering

that acts as a bar rier to direct deposition and vapor uptake of air contam

inants. NC DEHNR (1997) classif ies gra ins as protected, and recomm ends that only

root uptake

of COPCs be

evaluat ed for g rains. Be cause silage m

ay cons ist of forage mater ials that have bee

n stored and f

erment ed, it should be

treated a s forag e (that is , as unprotec

ted). This docum

ent is a r efere nce source

for the equation in Ta

ble B-3-11. T

his docume

nt also rec omme

nds the following: (1) An F i value of 1 (2) Forage, silage, and grain ingestion rates ( Qp i ) of 13.2, 4.1, and 3.0 kg DW/day for dairy farm er cattle, respectively, based on a total DMI of 20 kg D W/day calculated from N AS (1987) and plant type -specif ic frac tions from

Boone et al . (1981) (3) Forage, silage, and grain ingestion rates ( Qp i ) of 6.2, 1.9, a nd 12.2 kg DW

/day, re spectively for

typica l dairy farm er cattl e based on U SDA (1994) (4) A Qs value of

0.4 kg/day

, based on NAS (1987) and USD A (1994) (5) Ba milkvalues r

anging f rom 3.5 x 10 -10 to 4.8, based on Baes et al. (1984).
Researc h Triang le Institute

(RTI). 2005. Methodology for Predicting Cattl e Biotransfer Factors. Prepared for U.S. Environmental Protection Agency (EPA) Office f o Solid Waste. EPA Contract No. 68-W-03-042. August. USDA. 1 994 . Per sona l Commu nicat ion R egard ing S oil I ngest ion R ate for Dairy Ca ttle. Between G.F. F ries, Agricu ltur al Rese arch S ervice , and Glenn Rice an d Jen nifer Windh oltz , U.S . EP A,

Offic e of Res earch and Developm ent. March 22. NC DEHNR

(1997) and EPA ( 1994c) note that USDA (1994)

reports soil ingestion to be 2 perce nt of the tot

al DMI f or dairy cattle on farm

s. U.S. EPA. 1994a

. Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustio n Facilities . Off ice of Sol id Waste and Eme rgency Response. EPA-530-R-94-021. April. This document recommends a F i value of 1, assuming that 100 percent of the plant materials ingested by cattle have been grown on soil contaminated by combustion unit emissions. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docu ment is a reference so urce for the equatio n in Table B- 3-11. This documen t also reco mmends the follo wing: (1) An F i value of 1 (2) A forage ingestion rate ( Qp i ) value of 13.2 kg DW

/day, f rom NA S (1987) and Boone et al. (1981) (3) A quantity

of soil ing

ested ( Qs ) value of

0.4 kg/day

, based on NAS (1987) and USD A (1994) (4) Ba milkvalues r

anging f rom 3.5 x 10 -10 to 4.8, based on Baes et al. (1984)

### TABLE B-3-11 MILK CON CENT RATION DUE T O PLANT

AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 7 of 7)

B-150 U.S. EPA. 1994c

. Estimating Exposures to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures . Externa l Review Draft. Office of Re search a nd Developm

ent. EPA/600/6-88/0 05Cc. June. This docum

ent reporte d bioconcentra tion fact ors for diox

in-like c ompounds (diox

in and fura

n congeners) calcula

ted on the bas is of ex

perime ntal data de

rived by McLachlan et al. ( 1990). U.S. EPA. 1995a

. Further Issues for Modeling the Indirect Exposure Impacts from Combusto r Emissions. Offic e of R esea rch and Deve lop ment . Was hin gto n, D .C. Janu ary. U.S. EPA. 1995b. “Waste Technolog

ies Industri es Scree

ning Huma

n Health Ri sk As sessm

ent (SHHRA

): Evalua tion of Potentia

l Risk f rom Expos

ure to Routine Operating Emissions.” Volume

V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment. Offic e of A

ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent recom mends a n F i value of 1; this value assumes that 100 percent of the plant materials inge sted by cattle have been grown on soil contaminated by e missions.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 7)

B-151 Description This equa tion first estim ates the daily int

ake of COPCs through t

he ingest ion of conta

minated plant and soil

mater ial. The equation use s biotransf

er fac tors to trans form t

he daily animal intake of a COPC (m

g COPC/day

) into an anim

al COPC tiss

ue concentr

ation (mg COPC/kg ti ssue). The limitatio ns and un certainty in trodu ced in calcu lating th is variable i nclude t he followin g: (1) Uncertainties associated with the variables P i and Cs are COPC- and site-specific. (2) Uncertainties associated with the variables F i , Q, and Qp i are ex

pected to be

minim al. (3) Uncertai

nties ass ociated w

ith Ba

pork values m

ay be signific ant for tw

o primar y reasons: (a) Ba pork for di oxin s are cal culat ed fro m Ba milkvalues t hat are ba sed on catt

le met abolism of dioxins rather than a sow metabolism, and (b) the source or methodology used to calculate the Ba pork valu es fo r or gan ics oth er th an d iox ins and ino rgan ics oth er th an ca dmiu m, mer cur y, selenium, and zinc a

s reported i

n NC DEHNR

(1997) is not k

nown. The

refore,the ma

gnitude and dir

ection of the assoc iated uncer tainties c annot be specified. Based on the

inform ation below , A porkis dependent on the conce

ntrations of

COPCs esti

mated i n plant fe eds and soil,

and the biotra

nsfer f actor est imated for eac

h COPC. Equation

For mercury modeling, pork concentration due to plant and soil ingestion is calculated for divalent mercury (Hg 2+ ) and methyl merc

ury (MHg) using their respective P i , Cs , and Ba porkvalues. Varia ble Description Units Value 

### A pork Concentration of COPC in por k mg COPC/kg FW

tissue 

### F i Fraction of plant type (i) grown on

contamina

ted soil and i

ngested by the anim al unitless 

### 1.0 This variabl e is site- and plant type- specific; pl ant types for swin e are typically ide ntified as gr ain and si lage. We recomm end using a default v

alue of 1. 0 for all plant type s. This i s consiste nt with U.S . EPA (1998; 1994a; 1994c), and NC DEHN

R (1996), whi ch recom

mend as suming t

hat 100 perce

nt of the pla

nt mate rials ingested by

swine w ere grown on s oil contam

inated by emiss ions. The following uncertainty is associated w ith this variable: Assum ing 100 perce

nt of the pla

nt mate rials ingested by

swine w ere grow n on soil contam

inated by facility em

issions may overestim

ate A pork .

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 7)

Varia ble Description Units Value



### B-152 Qp i Quantity of plant type ( i) ingested

by the animal each day kg DW plant/day 

### Silage: 1.4 Grain: 3.3 This variabl e is site- and plant type- specific; pl ant types for swin e are typically ide ntified as gr ain and si lage. We recommend that you use the fol lowing Qp values w hen evalua

ting sw ine raised by fa

rmers : silage

(1.4) and gr

ain (3.3). These Qp i values a re based on a total DMI

value of 4.7 kg DW

/day, a nd plant ty

pe-specif ic diet f ractions (70 percent grain and 30 percent silage) a re based on U.S. EPA (1982). NC DEHNR (19 97) and U.S. EP A (1990) r ecommend silage an d grain in gestion ra tes of 1.3 an d 3.0 kg dry/day , respect ively, for sw

ine. NC DE

HNR (1997) re ferenc es U.S. EPA (1990) as the

source of these ingestion rates. T he diff erence be tween t he defaul t Qp i values a

nd values r

ecomm ended by N

C DEHNR ( 1997) and U.S. EPA (1990) is t

he total DMI

upon which the

y are based. Spe cifica

lly, w e recom mend the use of a

total DMI f

or swine of 4.7 kg DW

/day, ba sed on U.S. EPA

(1995), wher

eas NC DEHNR (1997) a nd U.S. EPA (1990)

recom mend a to tal DMI of 4. 3 kg d ry wei ght /da y. NC DEHNR

(1997) and U.S. E

PA (1990) don’t dif

ferenti ate betw

een subsis

tence and t

ypical hog far mers a s they do for catt le, becaus e it is as sumed tha t forage is not a s ignific ant portion of a hog’s die

t. Uncertain ties intr oduced by this variab le includ e the follo wing:

The rec omme

nded grain a

nd silage ingestion r

ates m ay not a ccuratel y repre sent site -specif

ic or local conditions. There fore, Qp i and A porkvalues may be under- or overestimated to some degree.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 7)

Varia ble Description Units Value



### B-153 P i Concentration of COPC in pla nt type ( i) ingested by the animal mg/kg DW 

### Varies This va riable is COPC-, site- , and plant ty pe-specif ic; plant ty

pes for s wine ar e identif ied as gr ain and sila

ge. Values for Pd , Pv , and Pr are calculated by using the equations in Tables B-3-7, B-3-8, and B-3-9; and then summed for each plant ty pe to determine P i . Uncertain ties intr oduced by this variab le includ e the follo wing: (1) Some of

the vari ables in the

equations in T

ables B-3- 7, B-3-8, and B- 3-9—including Cs, Cyv, Q, Dydp , and Dywp —are COPC- and site-specific. Uncertainties associated with these variables are site-specific. (2) In the equation in Table B-3-7, uncert ainties a ssociate d with other

variable s include: F w (values for organic c ompounds bas ed on behavior of poly styre ne micr o spheres), Rp (estimated on the basis o f a generalized em

pirical relationship), kp (estim ation proces s does not consider chem ical deg radation) a

nd Yp (estim ated based on national ha rvest y ield and area planted v

alues). A ll of thes e uncerta

inties contr

ibute to the over

all uncert ainty a ssociate d with P i . (3) In the equation in Table B-3-8, COPC-specific Bv values f or nondioxin-lik

e compounds

may be overesti mated by up to one order of

magni tude, based on experim

ental conditions used to dev elop the algorithm to estimate Bv

values. (4) In the equation in Table B-3-9, COPC-specific soil-to-plant biotransfer factors ( Br) may not reflec

t site-specific condi

tions. This

may be espec ially t

rue for inor

ganic COPCs for w

hich estim

ates of Br would be accurately estima ted by using plant uptake response slope factors. 

### Qs Quantity

of soil ing

ested by the animal kg/day 

### 0.37 Thi s var iab le i s sit e-sp ecif ic. We rec ommen d us ing the soi l in gest ion rate of 0. 37 k g/d ay. NC DEHNR

(1997) recom

mended a soil inges

tion rate f or swine of 0.37 kg

/day. T his is est imated by ass

uming a soil inta ke of 8 pe rcent of the total DM

I. NC DEH

NR (1997) does not specif y the tot al DMI use d to estim

ate Qs

. Howeve r, mathe matica lly, Qs appears t

o be based on a

total DMI of

4.7 kg DW

/day (4.7 @ 0.08 = 0.37), w hich is consistent with U.S. EPA (1995). The following uncertainty is associated w ith this variable: The rec omme

nded soil inge stion rate may not accura

tely r epresent site-spec ific or local conditions

. Theref ore, Qs and A porkvalues, may be under- or overestimated to some degree. 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### VariesThis variable is COPC- and site-specific, and calculated using the equation in Table B-3-1. Uncertainties are sitespecific.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 7)

Varia ble Description Units Value



### B-154 Bs Soil bioavailability factor unitless 

### 1.0 The soil bioavailability f

actor, Bs, can be thoug

ht of as t he ratio bet

ween bioc oncentration (or biotransf er) fa ctors for soil and vegetation for a given COPC. The eff iciency of transfer f

rom soil may dif

fer from ef

ficiency or transfer from plant material f

or some COPCs. If the transfer ef ficiency is lower f

or soils, then this ratio would be less than 1.0. If it is equal or greater than that of vegetation, the Bs would be e qual to or gr eater tha n 1.0. Due to lim

ited data r

egarding bioavaila bility f rom soil,we re comm

end a def ault value of 1.0 for Bs, until more COPC-specific data is available for this parameter. Some COPCs may be m uch less bioavailable from soil than from plant tissue s. This unc ertainty may overest imate Bs

. 

### Ba pork Biotransf

er fac tor for pork day/kg FW tissue 

### Varies

This variable is COPC-specific. We discuss this variable in detail in Appendix A-2, and off er COPC-specific values in the HHRA

P companion da

tabase. Ba

porkis defi ned as the ra tio o f the CO PC co ncen trati on in animal tissu e (mg COPC/kg FW

tissue) t o the daily

intake of the COPC (m

g COPC/day

) by the animal. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) We recommend calcul ating Ba porkvalue s for o rgani c COP Cs from Ba beef values, assumi

ng that pork

is 23 percent f

at and beef

is 19 perce

nt fat. Va

lues deriv ed this w ay m ight not acc

urately represe nt the behavior of

organic C OPCs under sit e-specif ic conditions. Ba porkand conseque

nt A porkestim

ates m ay be under- or overestimated to some degree. (2) The sources or method used to support or estimate Ba porkvalues pr

esented in NC DEHNR

(1997) are not known. T

herefore , the degr

ee to which these v

alues repr esent the behavior of

COPCs under s ite-spec ific conditions ca

nnot be determ

ined. 

### MF Metabolism factor unitless 

### 0.01 and 1.0 This variabl e is COPC- specific. Base d on a stu dy by Ikeda et al. (1 980), U.S. EP A (1995a) recommended us ing a metaboli sm f

actor to ac count for m

etabolism in anima ls to off set the a mount of bioaccum

ulation sugg

ested by biotransfe

r factor s. MF applie s only to beef, m ilk, and pork . It does not a pply to direct exposur

es to air,soil, or water,or to inges

tion of produce , chicke

n, or fish. U.S. EPA (1995b) recom mends a n MF of 0.01 f

or bis(2- ethylhexyl)phthalate (BEHP) and 1.0 for all other COPCs.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 7)

B-155 REFERENCES AND DISCUSSION Boone, F.W., Yook C. Ng, and John M. Palms. 1981. “Terrestrial Pathways of Radionuclide Particulates.” Health Physics , Vol. 41, No. 5, pp. 735-747. Novem ber. Thi s do cume nt i s cit ed as the sou rce o f a to tal DMI for h ogs of 3. 4 kg D W/d ay. Ikeda, G.J., P.P. Sapenza, and J.L. Couvillion. 198 0. “Comparative distribution, excretion, and metabolism of di(2-ethylhexyl)phthalate in rats, dogs, and pigs.” Food Cosmet. T oxicology. 18:637-642. NAS. 1987. Predicting F eed Intake

of Food-Producing A nimals . National Research Council, Committee on Animal Nutrition, Washington, D.C. This d ocumen t pres ents a tota l DMI fo r lact atin g sows o f 5.2 k g DW/da y. This d ocumen t is al so cit ed by U. S. EP A (199 5) as t he so urce o f a tota l DMI fo r swine of 4.7 kg DW/d ay. As presented in this document, the value of 4.7 kg DW/day represents the avera ge of specific total DMI values f or gilts (young sows) and for lactating sows. Ng, Y.C., C.S. Colsher

, and S.E. Thom

son. 1982. Transfer Coe fficients for Asses

sing the Dose

from Radionucli

des in Meat

and Eggs . U.S. Nuclear Regulatory C ommis sion. Final R eport. NUREG/C

R-2976. This document is cited as the source of biotransfer factors ( Ba pork ) for se

veral inor ganic COPCs. Howe

ver, U.S. EPA (1995) notes that “a large deg

ree of unc ertainty

” exist s in ma ny of t he exper iments used in th is do cument to de velop the b iotr ansfer factor s. The b iotr ansfer factor s devel oped by Ng, Co lshe r, an d Tho mpson (198 2) are not r ecommen ded fo r use b y U.S. E PA . NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. Grains such as c orn may

be grow n specif ically as sw ine feed. COPC uptake

into these f

eed ma terials m ay occ ur through root upt

ake, w et and dry deposition of

particula te-bound constituents

on plants, and vapor-phas e uptake of COPCs thr ough plant f

oliage. Pla

nts are c lassif

ied as “pr otected” i f they

have an out

er cover ing that ac

ts as a ba rrier to dir

ect deposit

ion and vapor uptake of air contaminants. NC DEHNR (1997) classifies grains as protected, and recomm ends that only root uptake of COPCs be evaluated for grains; because silage m ay consist of forage mater ials that have bee

n stored and f

erment ed, it should be

treated a s forag e (that is , as unprotec

ted). This docu ment also reco mmends the follo wing:

C An F i value of 1, assuming that 100 percent of the plant material eaten by swine have been grown on soil contaminated by com bustion unit emissions.

C Plant type-specific Qp i values for hogs of 3.0 and 1.3 kg DW/day f or grain and silage, respectively. This docume nt cites U.S. EPA (1990) as the source of these ingestion rates.

C A quantity

of soil ing

ested ( Qs ) value of

0.37 kg DW

/day. T his value is calc ulated as 8 percent of

the total DMI (U.S. EPA 1993a). The total DMI of 4.3 kg DW

/day c omes f

rom U.S. EPA (1990).

C A range of Ba porkvalues ( 1.3 x 10 -09 to 5.8 day/ kg we t tissue); howeve

r, the sourc es of or methodolog y used t o estim ate, thes e values

are not ide

ntified. Pennington, J.A .T. 1989. Food Values of Portion s Commonly Used . 15th ed . Harper and Row. New York.

Cited by NC DEHNR (1997)—actually NC DEHNR (1997) cities “Pennington (1993)” but p resents only this document (Pennington 1989 ) in the reference section—for the estimated f at content of pork, 23 perc ent.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 6 of 7)

B-156 U.S. EPA. 1982. “Pesticides Asses sment G

uidelines Subdiv

ision O.” R

esidue Che

mistry. Off

ice of Pes ticides a nd Toxic Substances,

Washing ton, D.C. EPA

/540/9-82-023. This document is cited by U.S. EPA (1990) as the source of the assumption that 70 percent of the total DMI for swine is grain and 30 percent is silage. U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environm ental Crit eria and A

ssessm ent Off ice. Of fice of Rese arch and Deve lop ment . EP A-60 0-9 0-0 03. Janu ary. This docu ment represen ts total d ry matter intake (DM I) rates for h ogs and lact ating sows of 3 .4 and 5 .2 kg DW/day, resp ectively, and recommends the ave rage of these two r ates (4.3 kg DW/day) as the total DMI. U.S. EPA (1990) cites Boone et al. (1981) as the source of the hog ingestion rate and NAS (1987) as the source of the lactating sow ingestion rate. This docu ment then ass umes that 70 percent o f the total DM I for swine is grai n and 30 percent is silage; fractio ns then ar e used to ar rive at the rec ommended grain ingestio n rate of 3.0 kg DW/d ay (4 .3 k g DW/ day @ 0.7 0) a nd t he r eco mmend ed s ila ge in gest ion rate of 1. 3 kg D W/d ay (4 .3 k g DW/ day @ 0.30). U.S. EPA (1990) cites

U.S. EPA (1982)

as the sour

ce of the grain and silage fractions. This docum

ent also recomm

ends an F

i value of 1. This assumes that 100 percent of the plant material eaten by swine is grow n on soil contaminated by combustion unit emissions. U.S. EPA. 1992. Addendum to the M ethodology for As

sessing He

alth Risks Associated w

ith Indirect

Exposure to Combustor Emi ssions . Externa

l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. Novem

ber. This docum

ent recom mends tha

t the quantity

of soil ( Qs ) eaten by swine b e estimated as 8 p ercent of th e total DMI . This docu ment states “Fr ies of USDA not es pigs exhib it ‘root ing’ behavior a

nd assum es a m aximum soil inges

tion intake

of 8 perc ent of dry

matte r based on a

2 to 8 perce

nt range not

ed in his ea

rlier PCB w

ork.” How

ever, thi s docume

nt provides no citations of work performed by Fries or personal communications with Fries. U.S. EPA. 1994a

. Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustio n Facilities . Off ice of Sol id Waste and Eme rgency Response. EPA-530-R-94-021. April. This docum

ent recom mends a n F i value of 1. This a

ssumes that 100 perc ent of the

plant ma terial ing ested by swine ha s been gr own on soil c ontaminat

ed by com

bustion unit em

issions. U.S. EPA. 1994b. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

II: Site-Spe

cific Assessment Procedures

. External Re view Draft

. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docu ment states th at milk is 3.5 percent fat. This documen t also uses exp erimental dat a derived b y McLachlon, et al. (19 90) to cal culate bi otransfer fact ors with un its of (kg feed/kg tissue). U.S. EPA. 1994c

. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docum

ent recom mends a n F i value of 1. This assumes that 100 percent of the plant material eaten by swine has been grow n on soil contaminated by combustion unit emissions.

### TABLE B-3-12 PORK CONC ENTR

ATION DUE T O PLANT AND S OIL ING

ESTION (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 7 of 7)

B-157 U.S. EPA. 1995a

. Further Issues for Modeling the Indirect Exposure Impacts from Combusto r Emissions. Office of Re search a nd Developm

ent. Was hington, D.C. January

20. This document calculates Ba pork val ues for cad mi um,me rcu ry , se leni um,and zinc

by div idin g uptak e slope f act ors ([m g COPC/k

g ti ssue DW

]/[m g COPC/k

g f eed DW ]) f rom U.S . EPA (1993b) - 0.003 (cadmium), 0.0234 (mercury), 2.94 (selenium), and 0.002 (zinc)—by a daily feed ingestion rate f or pork of 4.7 kg DW/day (NAS 1987). This approach is similar to that recomm ended by U .S. EPA (1994b) f or dioxins. T

he calcula

ted biotransf

er fac tors are 6. 0 x 10 -04 (cadm ium); 0.0051 (

mercur y); 6.255 x

10 -01 (selenium

); and 4.0 x 10 -04 (zinc). U.S. EPA. 1995b. “Waste Technolog

ies Industri es Scree

ning Huma

n Health Ri sk As sessm

ent (SHHRA

): Evalua tion of Potentia

l Risk f rom Expos

ure to Routine Operating Emissions.” Volume

V. External Review Draft. U.S. EPA Region 5, Chicago, Illinois. U.S. EPA. 1997. Mercur y Study Repor

t to Congress. Volume III : Fate and Trans

port of Mer

cury in the

Environment. Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-3-13 COPC CONCENTRATION IN EGGS (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 5)

B-158 Description This equa tion calcula

tes the CO

PC concentrat

ion in eggs

due to inges

tion of conta

minated soil and gra

in by hom

e grow n chickens

that have access to soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) This pathw

ay has typica lly bee n applied only

to PCDDs and PCDFs. Howe ver, conc entrations i

n chicken eggs f

or other orga

nics and m

etals ca n be calculated using

biotransf er fac tors in an approach similar to that used to calculate concentrations in animal tissue. (2) Assuming that 10 percent of a chicken’s diet is soil m ay not represent site-specific conditions. Stephens et al. (1995) suggested that the percentage of soil in the diet of chickens raised under field conditions m

ay be g reater t han 10 perce

nt. There fore, the

concentra

tion of COPCs

in eggs , A egg , may

be underest

imated. (3) Estimated COPC-specific soil-to-plant biotransfer factors ( Br) may not reflect site -specific or local con dition s. Therefore, es timates of Pr and A eggmay

be under- or ov

erestim ated to some degree. (4) The rec omme

nded BCFsused in cal culatin g Ba eggmay not accura

tely r epresent t he behavior

of COPCs unde

r site-specific a

nd local condit

ions. For ex

ample, Stephens et

al. (1995) noted that chickens ra

ised under f

ield conditions

showed la

rger appa rent BCFs . Theref

ore, the re comm

ended BCFsmay

underestim

ate the c oncentration of COPCs in e ggs, A egg . (5) The rec omme

nded BCFsare based on incomplete experimental results. Stephens et al. (1995) presented complete experimental results. This study included results from a high-dose group and a low-dose g

roup; results

were based on the full ex posure period. A brief

compar ison of the results f

rom Stephe

ns et al. ( 1992) with thos e from Stephens et

al. (1995) indicates that BCFsfrom the high-dose group are generally highe r than BCFsfrom the low-dos e group. T herefore , using the currently recom mended BCFsmay

underestim

ate the COPC concentr

ation in eggs, A egg . Equation

For mercury modeling, the concentration of COPC in eggs is calculated for divalent m ercury (Hg

2+ ) and methyl merc

ury (MHg) using their respective P i , Cs , and Ba eggs values. Varia ble Description Units Value 

### A egg Concent ration o f COPC in eggs mg COPC/kg FW tissue

### TABLE B-3-13 COPC CONCENTRATION IN EGGS (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 5)

Varia ble Description Units Value



### B-159 F i Fraction of plant type i(grain)

grown on c ontaminat

ed soil and ingested by the animal unitless 

### 1.0 This va riable is site- and plant type -specif ic. F i for chic kens is e stimat

ed for g rain feed only. W

e recom mend using

a defa ult value of 1.0. This is consistent with U.S. EPA (1998), U.S. EPA (1994a), U.S. EPA (1994b) and NC DEHNR (1997), which recommend assuming that 100 percent of the plant materia ls ingested were grown on soil contaminated by f acility emissions. The following uncertainty is associated w ith this variable: Assum ing that 100 pe

rcent of the plant m

aterial eaten by

chickens was g rown on soil contamina

ted by e missions may overestim

ate A egg . 

### Qp i Quantity of plant type i (grain)

ingested by the a

nimal kg DW plant/day 

### 0.2

Qp i for chic

ken is es timated for gra

in feed onl

y, as recomm

ended by N

C DEHNR ( 1997). Uncertain ties associ ated with th is variable i nclude t he followin g:

Actual grain ingestion rates can vary from site to site; this can over- or underestimate Qp i . 

### P i Concentration of COPC in pla nt type I (grain) mg COPC/kg DW 

### Varies

This va riable is COPC-, site- , and plant ty pe-specif ic. Calc ulate va lues for Pifor gra

in using the equation in Table B-3-9. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) Some of the varia bles in th e equatio n in Table B- 3-9—in cludin g Cs, Cyv, Q, Dydp , and Dywp —are COPC- and site-specific. Uncertainties associated with these varia bles are site-specific. (2) In the equation in Table B-3-9, COPC-specific plant-soil bio transfer factors ( Br) may not reflec

t site-specific condi

tions. This

may be espec ially t

rue for inor

ganic COPCs for w

hich Br’swould be m

ore accur ately estimated by using plant uptake response slope factors. 

### Qs Quantity

of soil ing

ested by the animal kg/day 0.022 This va riable is site-specific. W

e recom mend that the soil ingestion rate

of 0.022 kg

/day be used. This

is consist ent with Stephens et

al. (1995). Uncertain ties intr oduced by this variab le includ e the follo wing: (1) The recommended soil ingestion rate ma y not accurately represent site-specif ic or local conditions. (2) Empirica

l data to suppor

t soil inge stion rates

of chick ens are l imited. 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies

This variable is COPC- and site-specific, and calculated using the equation in Table B-3-1. Uncertainties are site-specific.

### TABLE B-3-13 COPC CONCENTRATION IN EGGS (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 5)

Varia ble Description Units Value



### B-160 Bs Soil bioavailability factor unitless 

### 1.0 The soil bioavailability f

actor, Bs, can be thoug

ht of as t he ratio bet

ween bioc oncentration (or biotransf er) fa ctors for soil and vegetation for a given COPC. The eff iciency of transfer f

rom soil may dif

fer from ef

ficiency or transfer f

rom plant material for some COPCs. If the transfer e fficiency is low er for soils, than this ratio would be less than 1.0. If it is equal or greater than that of vegetation, the Bs would be e qual to or gr eater tha n 1.0. Due to lim

ited data r

egarding bioavaila bility f rom soil,we re comm

end a def ault value of 1.0 for Bs, until more COPCspecific data is

availa ble for thi s param

eter. Som

e COPCs m

ay be m uch less bioa

vailable from soil than f

rom plant tissues. This unce rtainty may overest imate Bs

. 

### Ba egg Biotransfer factor for chicken egg s day/kg FW tissue 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP companion database. The following uncertainties are associated with this variable: (1) We recommend calcul ating Ba eggvalues f or organic COPCs other tha n dioxins and f

urans by using the r

egress ion equation dev

eloped on the ba

sis of a study of 29 organic compounds. Va lues calc ulated by using this r

egress ion equation may not accurately represent the behavior of orga nic COPCs under site-specific conditions. Therefore, estimates of Ba eggand, theref ore, A eggmay be under- or overestim ated to some degree. (2) The rec omme

nded BCFsmay not accurately represent the behavior of COPCs under site-specific or local conditions. For example, Stephens et al. (1995) noted that chickens raised under field conditions, and which probably ha

d a more than 10 perce

nt soil in thei

r diet, show

ed large r apparent BCFs . Therefore, the recomm ended BCFsmay

underestim

ate the c oncentration of COPCs in e ggs, A egg . (3) The rec omme

nded BCFsare based on incomple te exper imental results. Stephens et

al. (1995) inc lude results from a high-dose

group and as

a low-dos e group; re sults are based on the

full ex posure period. A brief

compar ison of the results

from Stephens et

al. (1992) and t

hose from

Stephens et

al. (1995) indic ates that BCFsfrom the high-dose group are g

enerally higher tha

n BCFsfrom the low-dos e group. T herefore , using the currently recom mended BCFs may underestim

ate the CO

PC concentrat

ion in eggs , A egg .

### TABLE B-3-13 COPC CONCENTRATION IN EGGS (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 5)

B-161 REFERENCES AND DISCUSSION California Environmental Protection Agency (CEPA). 1993. “ Parameter Values and Ranges for CALT OX.” Draft. Office of

Scientific Affa

irs. California Department of Toxics Substances Control. Sac

rament o, CA. Jul

y. Chang, R.R., D. Hayward, L. G oldman, M. Harnly, J. Flattery, and R.D. Stephens. 1989. “Foraging Farm Animals as Biomonitors for Dioxin Contamination.” Chemosphere. Volume 19: 481-486. This docum

ent appear

s to be cited by Stephe

ns et al. ( 1992) as support for the a ssumption t

hat soil re presents 10 percent of

the diet of

free- range chickens. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is a r efere nce source

for the equation in Ta

ble B-3-13. T

his docume

nt also cit es Stephens

et al. (1992)

as the sour

ce of e stimat

es of the fraction of diet tha

t is soil ( Fd ), and BCF egg for dioxins and furans. Petreas, M.X., L.R. Goldman, D.G. Hayward, R. Chang, J. Flattery , T. Wiesmuller, R.D. Stephens, D.M. Fry, and C. Rappe. 1991. “Biotransfer and Bioaccumulation of PCDD/PCDFs from Soils: Controlled Exposure Studies of Chickens.” Chemosphere. Volume 23: 1731- 1741. This document appears to be cited by Stephens et al. (1992) and Stephens et al. (1995) as support for the assumption that soil represents 10 percent of the diet of free-range chickens. Stephens, R.D ., M.X. Petreas , and D.G. Hayw ard. 1992. “Bi otransfe

r and Bioac cumulation of Dioxi ns and Dibenz

ofurans f rom Soil.”

Hazardous

Material s Labora

tory, Ca lifornia D epartm

ent of Health Services. Berkeley, California. This document is cited as the source of the assumption that free- range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congener-specific BCFs

. However, this document does not clearly refe rence or document the assumption that soil represents 10 percent of a free-range chicken diet. The docume nt appears to cite two other doc umen ts as sup por tin g th is as sump tio n, C han g, Ha yward , Gol dman , Har nly, Fla tte ry, a nd S tep hen s (1 989 ) an d P etr eas, Gold man, Haywar d, C han g, F lat ter y, Wie smul ler , St eph ens , Fr y, and Rappe (1992). Also, this document presents dioxin and furan congener-specific BCFs(egg y olk) for the low-e

xposure g roup after 80 days of a 178-day

exposure period. The

chickens in the low-dose group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 parts per trillion (ppt) I-TEQ. Chickens in the high-dose group were fed a diet containing 10 pe

rcent soil with a PCDD

/PCDF concentr

ation of 458 ppt I-TEQ; BCF results w ere not pre sented f

or this group. Stephens, R.D., M.X. P etreas, and D.G. Hayw ard. 1995. “Biotransfer and Bioaccumulation of Dioxins and furans from Soil: Chickens as a Model for Foraging Anima ls.” The Scienc

e of the Total Environment. Volume 175: 253-273. This document is an expansion of the results originally presented in Stephens et al. (1992). In particular, this document suggests that the percentage of soil in the diet of chickens raised under field conditions is likely to be gre ater than 10 percent, the value tha t was us ed in the ex

perime ntal study presented in this docum

ent. This document also presents dioxin and furan congener-specific BCFs(egg y olk) under tw

o exposure scheme s: low e xposure and high exposur e. The w hite leghor

n (Babcock

D 300) chickens in the low

group we

re fed a diet contai

ning 10 perce

nt soil wi th a PCDD/PCDF c oncentration of 42 ppt I-T EQ. Chick

ens in the hig

h group we

re fed a diet consis

ting of 10 pe

rcent soil with a PCDD/PCDF concentration of 460 pp t I-TEQ (some congeners we re fortified by spiking). The BCFspresented for low- and high-dos e groups both r epresent a verage s of res

ults from D ay-80, D ay-160, a nd Day- 178 (the end of

the exposur

e duration).

### TABLE B-3-13 COPC CONCENTRATION IN EGGS (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 5)

B-162 U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environm ental Crit eria and A

ssessm ent Off ice. Of fice of Researc h and Development. E

PA/600/6-90/003. Ja

nuary. This docum

ent is a r efere nce source

for the equation in Ta

ble B-3-9; a

nd an F

i value of 1.0. U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge. Volumes I and II. EPA 822/R-93-001 a. Office of W ater. Washington, D.C. U.S. EPA (1995) recommends that uptake slope factors for the metals ca dmium, selenium, and zinc cited by this document be used to derive Ba eggvalues. U.S. EPA. 1995. Further Issues for Modeling the Indirect Exposure Impacts from Combusto r Emissions. Office of Re search a nd Developm

ent. Was hington, D.C. January

20. U.S. EPA. 1997a

. Exposure Factors Handbook. “Food Inges tion Factors ”. Volume

II. EPA/600/P-95/002F. August

. U.S. EPA. 1997b. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search and Development. E

PA 452/R-97-005. D ecem ber.

### TABLE B-3-14 CONCENTRATION IN CHICKEN (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 1 of 5)

B-163 Description This equa tion calcula

tes the CO

PC concentrat

ion ( A chicken ) in chick

en mea t due to inge stion of cont aminated soil and gr

ain by hom

e grow n chickens

that have access to soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) This pathw

ay has typica lly bee n applied only

to PCDDs and PCDFs. Howe ver, conc entrations i

n chickens

for other organics and meta ls can be calculat

ed using biotr

ansfer factors using a similar approach as was used to calculate concentrations in other animal tissue. (2) The ass

umption that

10 percent of

a chick en’s diet i s soil m

ay not re present si te-speci fic or loc al conditions of chick ens raised on farm

s. Stephens

et al. (1995)

sugges ts that the percentag e of soil in the diet of

chickens raised unde

r field c onditions ma

y be g reater t han 10 perce

nt. There fore, the

concentra

tion of COPCs

in chicke n, A chicken may

be underest

imated. (3) The rec omme

nded BCFsare based on incomple te exper imental results. Stephens et

al. (1995) pre sents res

ults for a high-dose g

roup and low- dose group (r esults ar e based on t

he full 178-day e xposure per

iod). A c omparison of the re sults fr om Stephe

ns et al. ( 1992) with thos e from Stephens et

al. (1995) show

s that BCF

s from the high dose

group are generally higher than BCFsfrom the low dos e group. T herefore , use of t

he currentl

y rec omme

nded BCFsmay

underestim

ate the CO

PC concentrat

ion in chicke

n, A chicken . Equation

For mercury modeling, the concentration of COPC in chicken is calculated for divalent merc ury (Hg 2+ ) and methyl merc ury (MHg) using their respective P i , Cs , and Ba chicken values. Varia ble Description Units Value 

### A chicken Concentration of COPC in

chicken meat mg COPC/kg FW tissue 

### F i Fraction of plant type i(grain)

grown on c ontaminat

ed soil and ingested by the animal unitless 

### 1.0 This va riable is site- and plant type -specif ic. F i for chickens i s estimated for gra in feed onl y. We recommend using a default value of 1.0. This is consistent with U.S. EPA (1998), U.S. EPA (1994a), U.S. EP A (1994b) and NC DEHNR (1997), whic

h recom mend as suming t

hat 100 perce

nt of the pla

nt mate rials ingested w

ere grow n on soil contam

inated by facility em

issions. The following uncertainty is associated w ith this variable: Assu ming tha t 10 0 pe rcen t of t he p lan t mat eri als eate n by c hic ken s were gro wn on soi l co nta mina ted by fac ili ty emissions may

overestimate A chicken .

### TABLE B-3-14 CONCENTRATION IN CHICKEN (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 2 of 5)

Varia ble Description Units Value



### B-164 Qp i Quantity of plant type i (grain)

ingested by the a

nimal kg DW

plant/day 

### 0.2

Qp i for chic

ken is es timated for gra

in feed onl

y, as recomm

ended by N

C DEHNR ( 1997) and U.S. EPA (1990). Uncertain ties associ ated with th is variable i nclude t he followin g:

Actual grain ingestion rates can vary from site to site; this can over- or underestimate Qp i . 

### P i Concentration of COPC in pla nt type I (grain) mg COPC/kg DW 

### Varies

This va riable is COPC-, site- , and plant ty pe-specif ic. Values

for Piare ca

lculated f or grain us ing the equa

tions in Ta

ble B-3-9. Uncertain ties intr oduced by this variab le includ e the follo wing: (1) Some of the varia bles in th e equatio n in Table B- 3-9—in cludin g Cs, Cyv, Q, Dydp , and Dywp —are COPC- and site-specific. Uncertainties associated with these varia bles are site-specific. (2) In the equation in Table B-3-9, COPC-specific plant-soil bio transfer factors ( Br) may not reflec

t site-specific condi

tions. This

may be espec ially t

rue for inor

ganic COPCs for w

hich Br’swould be m

ore accurately estima

ted by using plant uptake response slope factors. 

### Qs Quantity

of soil ing

ested by the animal kg/day 

### 0.022 This va riable is site-specific. W

e recom mend using

the soil ingestion rate

of 0.022 kg

/day. T his is consi stent wi

th Stephens et

al. (1995). Uncertain ties intr oduced by this variab le includ e the follo wing: (1) The recommended soil ingestion rate ma y not accurately represent site-specif ic or local conditions. (2) Empirica

l data to suppor

t soil inge stion rates

of chick ens are l imited. 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil Varies

This variable is COPC- and site-specific, and calculated using the equation in Table B-3-1. Uncertainties are site-specific. 

### Bs Soil bioavailability factor unitless 

### 1.0 The soil bioavailability f

actor, Bs, can be thoug

ht of as t he ratio bet

ween bioc oncentration (or biotransf er) fa ctors for soil and vege tation for a give

n COPC. The efficiency of transf er from soil ma y diff er from efficiency

or transf er from plant material for some COPCs. If the transfer efficie ncy is lower for soils, then this ratio would be less than 1.0. If it is equal or greater than that of vegetation, the Bs would be e qual to or gr eater tha n 1.0. Due to lim

ited data r

egarding bioavaila bility f rom soil,we re comm

end a def ault value of 1.0 for Bs, until more COPCspecific data is

availa ble for thi s param

eter. Som

e COPCs m

ay be m uch less bioa

vailable from soil than f

rom plant tissues. This unce

rtainty may overest imate Bs

.

### TABLE B-3-14 CONCENTRATION IN CHICKEN (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 3 of 5)

Varia ble Description Units Value



### B-165 Ba chicken Biotransfer factor for chicken day/kg FW tissue 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRA

P companion da

tabase. Ba chicken is defi ned as the ra tio o f the CO PC co ncen trati on in fresh wei ght ti ssue ( mg COPC/kg FW

tissue) t o the daily

intake of the COPC (m

g COPC/day

) from chicken feed. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We recommend calcul ating Ba chicken value s for o rgani c COP Cs ot her th an di oxin s and furan s by from Ba beef values by assum ing that chicken is 15 percent f at and beef

is 19 perce

nt fat. Va

lues calc ulated this way

may not accurately repr

esent the behavior of

organic C OPCs under sit e-specif ic conditions. Theref

ore, estim ates of Ba chicken and, therefore A chicken , may be under- or overestima ted to some degree. (2) The beef-to-chicken fat content ratio method which is used to estimate Ba chicken value s from Ba beef values f or organics (except

PCDDs and PCDFs) assum es that (1) COPCs bioconce

ntrate in the

fat tis sues, and (

2) there a re no differences in metabolism or f eeding characteristics between beef c attle and chicken. Due to uncertainties associat ed with the se assum

ptions, Ba chicken , and A chicken values may be under- or overestimated to some degree. (3) The rec omme

nded BCFsmay not accurately represent the behavior of COPCs under site-specific or local conditions. For example, Stephens et al. (1995) noted that chickens raised under field conditions, and which probably ha

d more tha

n 10 percent s oil in their die t, showed larger a

pparent BCFs . Theref

ore, using t

he recomm ended BCFsmay underestima te A chicken , to some

extent. (4) The rec omme

nded BCFsare based on incomple te exper imental results. Stephens et

al. (1995) pre sented res

ults that are ba

sed on the f

ull 178-day

exposure period. A compari son of the r esults f rom Stephe

ns et al. ( 1992) to those from

Stephens et

al. (1995) show

s that BCFsfrom the high-dose group are generally highe r than BCFs from t he low-dos e group. T

herefore , using the currently recom mended BCFsma

y u nder est imate the COPC concentrat

ion in chicke

n, A chicken .

### TABLE B-3-14 CONCENTRATION IN CHICKEN (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 4 of 5)

B-166 REFERENCES AND DISCUSSION Chang, R.R., D. Hayward, L. G oldman, M. Harnly, J. Flattery, and R.D. Stephens. 1989. “Foraging Farm Animals as Biomonitors for Dioxin Contamination.” Chemosphere . Volume 19; 481-486. This document appears to be cited by Stephens et al. (1992) as support for the assumption that soil represents 10 percent of the diet of free-range chickens. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is the r

efere nce source

for the equation in Ta

ble B-3-14. T

his docume

nt also cit es Stephens

et al. (1992)

as the sour

ce for t he recom mended f raction of diet that is

soil ( Fd ) and BCF

Chicken for dioxins and furan congeners. Petreas, M.X., L. R. Goldman, D. G. Hayw ard, R. Chang, J. Flattery, T. Wiesm uller, R.D. Stephens, D.M. Fry, and C. Rappe. 1991. “Biotransfer and Bioaccumulation of PCDD/P CDFs from Soils: Controlled Exposure Studies of Chickens.” Chemosphere . Volume 23: 1731-1741. This docum

ent appear

s to be cited by Stephe

ns et al. ( 1992) and Stephens et al. (1995)

as support f

or the ass umption that

soil repre sents 10 per

cent of t he diet of free- range chickens. Stephens, R.D ., M.X. Petreas , and D.G. Hayw ard. 1992. “Biotransfe

r and Bioac cumulation of Dioxi ns and Dibenz

ofurans f rom Soil.”

Hazardous

Material s Labora

tory, Ca lifornia D epartm

ent of Health Services. Berkeley, California. Presented at the 12th International Symposium on Dioxins and Related Compounds. August 24 throu gh 28. University of Tam pere, Tampere, Finland. This document is cited as the source of the assumption that free-range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congeners-specific BCFs recomm ended by N

C DEHNR ( 1997). Howe ver this doc

ument does

not clearl

y ref erence or document the assum

ption that soil represent

s 10 percent

of a f ree-rang e chicke n’s diet. T

he document a

ppears to c ite two ot

her docum

ents as s upporting its a

ssumption, (1) Change , Hayw ard, Goldm

an, Harnly

, Flattery and Stephens (1989) and (2) Petr eas, G oldman, Ha

ywa rd, Chang, Fla

ttery,Wiesm

uller, Stephe

ns, Fry, and Rappe (1992)

. This document also presents dioxin and furan congener-specific BCFs(thigh) for the low- exposure group after 80 days of a 178-day total ex posure period. The chickens in the low-dose group we re fed a diet contai

ning 10 perce

nt soil wi th a PCDD/PCDF c oncentration of 42 ppt I-T EQ. Chick

ens in the hig

h-dose group w

ere fed a diet cont

aining 10 per

cent soil w

ith a PCDD/PCDF conce

ntration of 458 ppt I-TEQ; BCF results w ere not pre sented f

rom the high-dose g

roup. Stephens, R.D., M.X. P etreas, and D.G. Hayw ard. 1995. “Biotransfer and Bioaccumulation of Dioxins and Furans from Soil: Chickens as a Model for Foraging Animals.” The Science of the Total Environment. Volume 175: 253- 273. This document is an expansion of the results originally presented in Stephens et al. (1992). In particular, this document suggests that the percentage of soil in the diet of chickens raised under field conditions is likely to be gre ater than 10 percent, the value tha t was us ed in the ex

perime ntal study presented in this docum

ent. This document also presents dioxin and furan congener-specific BCFs(thigh) under two ex posure sche

mes—low expos

ure and high exposure. The w hite leghor

n (Babcock

D 300) chickens in the low

group we

re fed a diet contai

ning 10 perce

nt soil wi th a PCDD/PCDF c oncentrations of 42 ppt I-T

EQ. Chick

ens in the hig

h group we

re fed a diet contai

ning 10 perce

nt soil with a PCDD/PCDF conc entration of 460 ppt I-TEQ

(some congeners

were fortified by spi

king). The BCFspresented for low- and high-dos e groups both r epresent a verage s of res

ults from Day- 80 and Day

-164 of a tot

al 178-day

exposure period.

### TABLE B-3-14 CONCENTRATION IN CHICKEN (CONSUMPTION OF ANIMAL PRODUCTS EQUAT IONS) (Page 5 of 5)

B-167 U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environm ental Crit eria and A

ssessm ent Off ice. Of fice of Researc h and Development. E

PA/600/6-90/003. Ja

nuary. This docum

ent is a r efere nce source

for the equation in Ta

ble B-3-9; a

nd an F

i value of 1.0. U.S. EPA. 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge. Volumes I and II. EPA 822/R-93-001 a. Office of W ater. Washington, D.C. U.S. EPA (1995) recommends that uptake slope factors for the metals ca dmium, selenium, and zinc cited by this document be used to derive Ba chicken values. U.S. EPA. 1995. Further Issues for Modeling the Indirect Exposure Impacts from Combusto r Emissions. Office of Re search a nd Developm

ent. Was hington, D.C. January

20. U.S. EPA. 1997a

. Exposure Factors Handbook. “Food Inges tion Factors ”. Volume

II. EPA/600/P-95/002F. August

. U.S. EPA. 1997b. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search and Development. E

PA 452/R-97-005. D ecem ber.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 8)

B-168 Description Use the equations in this

table to c alculate

an aver age COPC s oil concentr

ation result

ing from wet and dry depos ition of par ticles a nd vapors to s oil over the exposure duration. We

recom mend assumi ng that COPCs are incor

porated only

to a finit e depth (the soil mix

ing zone de

pth, Z

s ). Us e th e COP C so il c onc ent rat ion aver aged over the expo sur e du rat ion , re pre sen ted by Cs , for carcinogenic COPCs, where r isk is a veraged over the lifetim

e of an i ndividual. Because the

hazard quotie

nt associa ted with nonc arcinoge

nic COPCs is

based on a r

efere nce dose ra

ther than a lifetime exposure, we recommend using the highest annual average COPC soil concentration occurring during the exposure duration period for non carcinogenic COPCs. The highest annual aver age C OPC soi l co nce ntr ati on wo uld most like ly oc cur at th e end of th e ti me pe rio d of comb ust ion and is re pre sen ted by Cs tD . The following uncertainties are associated with this variable: (1) We assume that the time period for deposition of COPCs resulting from hazardous waste combustion is a conservative, long-term value. T his assumption may overestim ate Cs and Cs tD . (2) Exposure duration values ( T 2 ) are based o n histo rical mobil ity studies and won’t necessarily remain constant . Specifical ly, mobility stu dies ind icate that mos t recepto rs that move remai n in the vic inity of

the com bustion unit; how

ever, it is impos sible to ac curately predict the

probability

that these

short-dista

nce mov es will influence exposure,based on f

actors such as atmospheric transport of pollutants. (3) Using a v

alue of z ero for T

1 doesn’t account for exposure that may have occurred from historic operations and emissions from hazardous waste combustion. This may underestimate Cs and Cs tD . (4) For soluble COPCs, leaching might lead to movement to below the mixing depth, resulting in lower concentrations within the mixing depth. This uncertainty m ay overestimate Cs and Cs tD . (5) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This m ay underestimate Cs and Cs tD . Equation for Carcinogens Soil Concentra

tion Ave raged Ov er Exposure

Duration

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 8)

B-169 Equation for Noncarcinogens Highest A

nnual Ave

rage Soil Concentrat

ion

where

For merc ury m odeling

Use 0.48Q for total mercur y and F

v = 0.85 in the mercury modeling equation to calculate Ds. Apportion the calculat ed Ds value into the divalent mercury (Hg 2+ ) and methyl mercur y (MHg) forms based on the assumed 98% Hg 2+ and 2% MHg speciation split in soils (see Chapter 2). Elemental mercury (Hg 0 ) occurs in very

small amounts in the vapor

phase and doe s not exis

t in the particle or particle -bound phase. T herefore , assum

e elem ental m ercury deposition onto s oils is neg ligible or zero. Eva

luate ele mental mercur

y for the direct

inhalation pa

thway only (Table B-5-1).
Ds (Hg2+) = 0.98 Ds (Mercu ry) Ds (Mhg) = 0.02 Ds (Mercu ry) Ds (Hg0) = 0.0 Evaluate divalent and methyl me rcury as individual COPCs. Calculate Cs for diva lent and m

ethyl m ercury using the c orresponding ( 1) fate and transport param eters f or merc uric chloride (divalent mercury, Hg 2+ ) and me

thyl m ercury provided in A

ppendix A- 2, and (2) Ds (Hg 2+ ) and Ds (MHg) as calculated above.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 8)

B-170 Varia ble Description Units Value 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Cs tD Soil concentration at time tD mg COPC/kg soil 

### Ds Deposition te rm mg COPC/kg soi l-yr 

### Varies

U.S. EPA (1994a) and NC DEHNR (1991) recommended incorporating a depositio n term into the Cs equation. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Five of the varia bles in the equation for Ds (Q, Cyv, Dywv , Dywp , and Dydp ) are COPC- and site-s pecific

. Values of these variables are estima ted through modeling. The direction and magnitude of any uncertainties shouldn’t be ge

neralize d. (2) Based on the

narrow r ecomm ended range s, we e

xpect unce

rtainties associat

ed with Vdv, F v , and BD to be low. (3) Values for Z s vary by about one

order of m

agnitude. U

ncertainty is grea tly re duced if y

ou know w

hether soils are tilled or untilled. 

### tD Time

period over

which deposition occurs (ti me per iod of com

bustion) yr 

### 30 U.S. EPA (1998) suggests that this period of time can be 

### $ 30 year s. We r ecomm end using 30 y

ears unles s site-s

pecific informa tion is ava

ilable indic ating that

this assum

ption is unreasonable (see Chapter 6 of the HH RAP). 

### ks COPC soil loss constant due

to all processes yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-2. T

he COPC soil loss consta nt is the sum

of all C OPC remov

al process es. Uncertain ty associated wit h this vari able incl udes the fo llowing:

COPC-specif

ic value s for ksg

(one of the variables in the equation in Table B-4-2) are empirically determ ined from f ield studies . No inform

ation is av

ailable r egarding the applica

tion of thes e values

to the site -specif

ic conditions associated with affected facilities.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 8)

Varia ble Description Units Value



### B-171 T 2 Length of

exposure duration yr 

### 6, 30, or 40 We rec omme

nd reasonable

maxi mum e xposure (R

ME) value s for T 2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure dura

tion rates are based on historica l mobility rates a nd may not rema in constant. This ass

umption may overestim

ate or underestimate Cs and Cs tD . (2) Mobility s

tudies indica

te that m ost recept ors that m ove rem ain in the v

icinity of the e mission s ources. How

ever, it is impossible to accurately predict the likelihood that these short-distance moves will influence exposure, based on factors such as atmospheric transport of pollutants. This assumption may overes timate or underestimate Cs and Cs tD . 

### T 1 Time

period at the

beginning of combustion yr 

### 0 Consistent w

ith U.S. EPA ( 1994c), we recom mend a v alue of 0 for T

1 . The following uncertainty is associated w ith this variable: A T 1 of zero doesn’t account for ex posure that m

ay hav e occurre d from historical operation or e missions from the combustion of hazardous waste. This may underestimate Cs and Cs tD . 

### 100 Units conve

rsion fac tor mg-cm 2 /kg-cm

2

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 of 8)

Varia ble Description Units Value



### B-172 Q COPC emis sion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 of the H

HRAP for

guidance calculat

ing this v ariable. Uncertainties associated with this variable are site-specific. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998),which f urther sta tes that l eaching s oluble com pounds might

lead to m

oveme nt below a

1-cm de pth. A default v alue of 2 cm f

or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brzuzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For s olub le COP Cs, le achin g might lead t o movemen t to b elow Z s , resulting in lower concentrat

ions within the Z s . This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, based on a mean value for loam soil obtained from Ca rsel et al. (1988). U.S. EPA (1998) stated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 6 of 8)

Varia ble Description Units Value



### B-173 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP com pani on da taba se. The ran ge i s based

on value s pr

ese nted in A ppen dix A- 2. Va lues are als o pre sen

ted in U .S. E

PA (1994b) and NC DEHNR (1997).
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) st

ates that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) F

v calculat ions assum

e a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urban sources. If a specific site is loc ated in an ur ban area,using the latter ST value m ay be m ore appropria

te. Specifically, the ST

value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local sourc es, and it w

ould result in a

lower c alculate d F v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of v

aporization of the liquid-phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Dytwv Unitized y

early (wate r body or waters hed) aver age tota l deposition from vapor phase s/m 2 -yr 

### Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific. 

### Dytwp Unitized y

early (wate r body or waters hed) aver age tota l (wet a nd dry) deposition from particle phase s/m 2 -yr Varies

This va riable is COPC- and site -specif ic, and is de

termined by air modeling (see Cha pter 3). Unc ertaintie s associ ated wi th this variable are site-specific.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 7 of 8)

B-174 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Brzuzy, L.P. and R.A. Hites. 1995. “Estimating the Atmospheric Deposition of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Soils.” Environmental Science and Technology

. Volume 29. Pag

es 2090-2098. This reference presents soil profiles for dioxin mea surements. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This ref erence i s cited by

U.S. EPA (1994b)

as the sour

ce for a mean s oil bulk densi

ty va lue, BD , of 1.5 g soil/cm 3 soil for loam soil

. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Press, Inc. New York, Ne w York.

Cited by U.S. EPA (1998)

for the s tateme nt that BD is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and c lay c ontent of the soil. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This is one

of the sour

ce docum ents for the equation i

n Table B -4-1. This document a lso recom mends us ing (1) a de

position term

, Ds , and (2) COPC-specific F v values.
Researc h Triang le Institute

(RTI). 1992. Preliminary Soil Action Level for Superfund Sites. Draft Interim Report. Prepa

red for U .S. EPA Haz

ardous Site C ontrol Divis ion, Remedial Opera tions Guidance Branch. A

rlington, Virg

inia. EPA C ontract 68-W 1-0021. Work Assig nment No. B-03, Work

Assig nment Ma

nager Loren Henning . Decem ber. This document is a reference source f or COPC-specific F v values. U.S. EPA. 1992. Estimating Exposure to Dioxin-Like Compo unds. Draft Report. Of

fice of Resear ch and Dev

elopment. Washing

ton, D.C. EPA

/600/6-88/005b. The Exte rnal Rev iew Dr aft of the MPE docum

ent (the f inal is U.S. EPA 1998) cite s this docum ent as the source of values f or soil m ixing zone

depth, Z

s , for tilled and untilled soils. U.S. EPA. 1993. Addendum to the M ethodology for As

sessing He

alth Risks Associated w

ith Indirect

Exposure to Combustor Em issions . Working Group Rec omme

ndations. Of

fice of Solid Was

te. Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This docum

ent is a r efere nce for t he equation in Table B-4-1. It rec omme nds using a deposition ter m, Ds , and COPC-specific F v values in the Cs equation.

### TABLE B-4-1 WATERSHED S OIL CON CENT RATION DUE T O DEPOSI TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 8 of 8)

B-175 U.S. EPA 1994a. Draft Guidanc e for Perf orming Scre

ening Level

Risk Analys is at Combusti on Facilities

Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Was te Combustion Facilities

. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. April. This document is a reference f or the equation in Table B-4-1; it recommends using the following in the Cs equation: (1) a deposition t erm, Ds , and (2) a de fault soil bulk densit y val ue of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil from Carsel e t al. (1988). U.S. EPA. 1994b. Estimating Ex posure to Diox

in-Like Com

pounds

. Volume III: Site-Specific Assessment Procedures. Externa l Review Draft. Off

ice of R esearc h and Development. W

ashington, D.C. June. EPA/600/6-88/0 05Cc. This document recommends T 2 values f or the fa rmer. U.S. EPA. 1994c. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes . Office of Em ergency and Remedial Re sponse. Office of Solid W

aste. Decembe

r. This docu ment recommends th e following:

C Values for

the length of expos

ure duration, T 2
C Value of 0 f

or the tim e period of

the beginning

of com bustion, T

1
C F

v values that range from 0.27 to 1 for organic COPCs

C Default soil bulk density value of 1.5 (g soil/cm 3 soil), based on a me an for loa m soil f rom Car sel et a l. (1988) U.S. EPA. 1997a

. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1997b. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002Fc . August

. This docum

ent is a r efere nce source

for va lues for length of

exposure duration, T 2 . U.S. EPA. 1998. Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions (MPE ) . Update to EPA/600/6-90/003. Of fice of Resear ch and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/ 137. Decem ber. This docum

ent is a r efere nce for r ecomm ended value s for soil

mixing zone depth, Z s , for tilled and untilled soils.

### TABLE B-4-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-176 Description This equation calculates the COPC soil loss constant, which accounts for the loss of COPCs from soil by several m echanisms. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) COPC-specif

ic value s for ksg

are empirically determ

ined from field studies. No information is available rega rding the application of these values to the site-specific conditions associated with affected f

acilities. (2) The sourc e of the equations in T ables B-4- 3 through B-4-5 ha ve not bee

n identified.

Equation

Varia ble Description Units Value 

### ks COPC soil loss constant due

to all processes yr -1



### ksg COPC loss cons tant due to biotic and abiotic degradation yr -1 

### Varies This va riable is COPC-specif

ic. Values

are av ailable in the COPC table s in Appendi x A-2. “Degra dation rate ” values

are als o presented in NC DEHN R (1997), howe

ver, no re ferenc e or source is provided for the v

alues. U. S. EPA (1994a) and U.S. EPA (1994 b) state that ksg values a

re COPC-spe cific; howeve r, all ksg val ues are pre sen ted as z ero (U. S. EPA 1994a) or as “

NA” (U .S. EPA 1994b); the basis of these as sumptions i s not addres sed. The following uncertainty is associated w ith this variable: COPC-specif

ic value s for ksg

are em pirically determ ined from field st udies; no inf

ormation i s available regarding the application of these values to the site-specific conditions associated with affected f acilities.

### TABLE B-4-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-177 kse COPC loss cons tant due to soil erosion yr -1 

### 0 Thi s va ria ble is C OPC-

and sit e-s pec ifi c, a nd is fur ther dis cus sed

in T able B-4 -3. Cons ist

ent wit h U.S . EPA

(199 4a) , U. S. EPA (1994b) and NC DEHNR (1997), w e recom mend a de fault v

alue of 0 for ksebecause contamina ted soil er odes both onto the site and away f rom the site. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The sourc e of the equation in Table B-4-3 ha s not been ide

ntified. (2) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in lower concentrations within the Z s . This uncertainty may overestimate kse

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate kse

. 

### ksr COPC loss constant due to surface

runoff yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-4. N

o refer ence docum

ent is cit ed for this equation; using

this equati on is consist

ent with U .S. EPA (1994b) a nd NC DEHNR

(1997). U.S. EPA

(1994a) ass

umes tha t all ksr values a re zero but

does not ex

plain the bas is of this

assum ption. Uncertain ties associ ated with th is variable ( calculated using Table B-4-4) i nclude t he followin g: (1) The sourc e of Ta ble B-4-4 has

not been ident

ified. (2) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in lower concentrations within the Z s . This uncertainty may overestimate ksr

. (3) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksr

. 

### ksl COPC lo ss constan t due to l eaching yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-5. U sing this equation is consistent w ith U.S. EPA (1998),U.S. EPA(1994b),and NC DEH NR (1997). U.S . EPA (1994a) a ssumes that all ksl values a

re zero but

does not explain the

basis of this assum

ption. Uncertain ties associ ated with th is variable ( calculated using Table B-4-5) i nclude t he followin g: (1) The sourc e of the equation in Table B-4-5 ha s not been ide

ntified. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing with in-situmaterials) compared to other residues. This uncertainty m ay underestimate ksl

.

### TABLE B-4-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-178 ksv COPC loss cons tant due to volatilization yr -1 

### Varies This variable is COPC- and site-specific, and is calculated using the equation in Table B-4-6. This equation calculates the COPC loss constant f rom soil due to volatilization, a nd was obta

ined from U.S. EPA (1998) . The soil loss consta

nt due to vola

tilization (

ksv ) is based on ga

s equilibrium

coeff icients a nd gas phas e mas s transf

er. The first orde

r decay constant, ksv , is obtained by adapt ing the Hwang and Falco e quation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in lower concentrations within the Z s . This uncertainty may overestimate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This uncertainty m ay underestimate ksv

.

REFERENCES AND DISCUSSION Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the reference documents f or Tables B-4-4 and B-4-5. This document is also cited as (1) the source for a range of COPC-specific degradation rates ( ksg), and (2) one of the sour

ces that recomm

end assum

ing that the

loss resul

ting from erosion ( kse ) is zero because of contaminated soil eroding both onto the site and away from the site. U.S. EPA. 1994a

. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous

Waste Com bustion Faciliti es. April. This docum

ent is cit ed as a s ource for

the assum

ptions that los ses res

ulting fr om erosion ( kse ), surface ru noff ( ksr ), degrada tion ( ksg), leachin g ( ksl

), and vola

tilization (

ksv ) are all zero. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This docum

ent is one of

the ref erence doc

uments f or Tables B-4-4 and B-4- 5. This docum ent is als o cited as

one of the

sources t hat recom mend as suming t

hat the loss

resulting from erosion ( kse ) is zero and the loss resulting from degradation ( ksg) is “NA” or zero for all com pounds.

### TABLE B-4-2 COPC SOIL LOSS CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-179 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is one of

the ref erence doc

uments f or the equations for ksr , ksl , and ksv

.

### TABLE B-4-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 5)

B-180 Description This equa tion calcula

tes the c onstant for

COPC loss re sulting f

rom eros ion of soil. Consistent with U.S. EPA (1994), U.S. EPA (1994b), and NC DEHNR (1997), we recomm

end a def ault value of zero for kseis zero because of contaminated soil eroding both onto the site and away from the site. In site-specific cases w here the permitting authority considers it appropriate to calculate a kse , we recommend usin g the equat ion pres ented in this tabl e along with associated uncertai nties. Yo u can find ad dition al discuss ion on determinin g ksein U.S. EPA (1998). Uncertainties associated with this equation include: (1) For soluble COPCs, leaching might lead to movement below 1 centimeter in untilled soils, resulting in a greater m ixing depth. This uncertainty may ove restimate kse

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to other

residues. This unce

rtainty may underestimate kse

. Equation

Varia ble Description Units Value 

### kse COPC loss cons tant due to soil erosion yr -1 

### 0 Consistent w

ith U.S. EPA ( 1994), U.S. EPA ( 1994b), and NC DE HNR (1997), w

e recom mend as suming a

default value of

zero for ksebecause contaminated soil erodes both onto the site and away from the site. Uncerta inty may overestimate kse

. 

### 0.1 Units conve

rsion fac tor g-kg/cm 2

- m 2 

### X e Unit soil loss kg/m 2 -yr 

### Varies This va riable is site-specific and is calculated by using the equation in Ta

ble B-4-13. The following uncertainty is associated w ith this variable: All of the equation v

ariables are site -specif

ic. Using default values r

ather than site-spec ific v

alues f or any or all of these variables will result in unit soil loss ( X e ) estim ates that are under-

or overes timated to some

degree. Based on default v alues, X

e estimates can vary

over a range of less than two orders of magnitude.

### TABLE B-4-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 5)

Varia ble Description Units Value



### B-181 SD Sediment

delivery ratio unitless 

### Varies This va lue is site -specif

ic and is c alculate d using the equation in Ta ble B-4-14. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The rec omme

nded defaul

t values for the e mpirica l interce pt coeff icient, a , are average values that a re based on studies of sedim ent yields from

various w

atersheds . Theref

ore, those de fault v

alues m ay not a ccuratel y repre sent site -specif

ic watershed conditions. As a result, using these default values may under- or overestimate SD

. (2) The rec omme

nded defaul

t value f or the em pirical slope coeff

icient, b , is based on a revie w of s ediment yields

from various watersheds. This single default value m ay not accurately represent site-specif ic watershed conditions. As a result, using the default value may under- or overestim ate SD

. 

### ER Soil enrichm ent ratio unitless 

### Inorga nics: 1 Organic s: 3 COPC enrichm

ent occurs because ( 1) lighter soil partic les erode more quic kly tha n heavier soil particles, and (2)

concentra

tion of organic COPCs—which is a function of organic carbon content of sorbing media—is expected to be higher in eroded mater ial than in in situ soil (U.S. E PA 1998). In the

absence of site- specific data, w e recom mend a de fault v

alue of 3 for organic COPCs and 1 for inorganic COPCs. This is consistent with other Agency guidance (U.S. EPA 1998), which recomm ends a rang

e of 1 to 5 a

nd a value

of 3 as a “reasona ble firs t estim ate.” T his range has been us ed for org

anic ma tter, phosphorus, and othe

r soil-bound COPCs

(U.S. EPA 1998) ; howeve r, no sources

or refe rences w ere provided for this r

ange. ER is gener

ally hig her in sandy

soils than i

n silty or loamy

soils (U.S. EPA 1998). The following uncertainty is associated w ith this variable: The def ault ER value m

ay not a ccuratel y ref lect site -specif

ic conditions; therefor

e, ksemay

be over- or underestimated to an unknown extent. Using county-specific ER values will reduce the extent of any uncertainties. 

### BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

### TABLE B-4-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 5)

Varia ble Description Units Value



### B-182 Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting a greater mixing depth. This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to of othe

r residues

. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient mL w

ater/g soil (or cm 3 water/ g soil) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2. 

### 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This variable is site-specific, and depends on the available water and on soil structure; 2 sw can be es timated as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f a repr

esentativ e wate rshed soil c an be identif

ied. How ever, w e recom mend the use of 0.2 mL/cm 3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soil s) r ecomm ended by U.S . EPA

(199 3) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksemay

be under- or overestimated to a small e xtent, based on the limited range of values.

### TABLE B-4-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 5)

B-183 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agric ultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

for a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics. Academic Press, I nc. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is one of

the source s that rec omme nd assum ing that the

loss resul

ting from erosion ( kse ) is zero because contaminated soil erodes both onto the site and away from the site. U.S. EPA. 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Was te Combustion Facilities

. April. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent is the s ource of v

alues f or soil m ixing zone

depth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This docum

ent recom mends (1)

a defa ult BD value of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988), and (2)

a defa ult 2 sw , valu e of 0. 2 (mL water/cm

3 soil).

### TABLE B-4-3 COPC LOS S CONS TANTDUE T O SOIL E ROSION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 of 5)

B-184 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is the s ource of a

range of COPC enrichm

ent ratio, ER , values. The recomme nded range,

1 to 5, was

used for organic m

atter, phosphor

ous, and other s oul-bound COPCs. This docum

ent recom mends a value of 3 as a “r easonable first e stimat

e,” and st ates that COPC enrichm

ent occurs because l

ighter soil particle s erode m ore quickly

than heav

ier soil pa rticles. Lighter soil particles have

higher ra tios of sur

face a rea to vol ume and a

re higher in organic matter content. T

herefore , concentra

tion of orga

nic COPCs, w

hich is a f unction of the

organic carbon conte

nt of sorbing

media,is expec

ted to be hig

her in erode d mater

ial than in in situ soil. This docu ment is also a so urce of the fol lowing:

C A range of 2 sw values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heavy loam/clay soils). However, no source or reference is provided for this range.

C A range of va

lues for Z

s , for tilled and untilled s oil

C The equat

ions in Tables B-1-3 a

nd B-1-5.

### TABLE B-4-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-185 Description This equat ion calcu lates the CO PC loss constant due to ru noff of soil. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksr

. (2) Deposition to hard surfaces may result in dust residues that have negligible dilution compared to other residues. This uncertainty may underestimate ksr

. Equation

Varia ble Description Units Value 

### ksr COPC lo ss constan t due to r unoff yr -1 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994b), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, s ite-spec ific proc edures f or estim ating the a

mount of surfac e runoff

, such as t hose based on the U.S. Soil Conserva tion Service curve num

ber equation (CNE). U.S. EPA (1985) is cited as a n exam ple of suc h a procedure

. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual surface runoff information is not available, default or estim ated values m ay not a ccuratel y repre sent site -specif

ic or local conditions. A

s a resul t, ksr may be under- or overestim ated to an unknown degree.

### TABLE B-4-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-186 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This va riable is site-specific, a

nd depends on the

availa ble wat er and on soil

structure ; you ca

n estim ate 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a def ault value . This v

alue is the

midpoint of

the range 0.1 (very sandy s oils) to 0.3 (he avy loam/cla y soils), recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range) , and is cons istent w ith U.S. EPA ( 1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, ksr

may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil mix

ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault v

alue of 2 cm for untilled soil mix

ing depth is based on a s

tudy that profiled diox

in meas urement s within s oil (Brzuzy

et al. 1995). A default v alue of 20 cm f

or tilled soil mixing

depth is bas ed on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting lower concentrations within the Z s . This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient mL w

ater/g soil (or cm 3 water/ g soil) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

### TABLE B-4-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-187 BD Soil bulk dens ity g soil/cm3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of

1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology . Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density, BD , value of 1.5 (g soil/cm 3 soil) for loam s oil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docu ment is cited b y U.S. EPA (1 998), U.S. EP A (1994), and NC DEHNR (1997 ) as a reference to calculate aver age annual runoff, RO. This ref erence pr ovides m aps with isolines of annual average surface w ater runoff, which is defined as all flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because these values are to tal contr ibutio ns and no t only surface ru noff, U.S. EPA (199 4) recommends t hat the vo lumes be redu ced by 50 per cent in o rder to est imate surface run off. Hillel, D. 1980. Fundament als of Soil Physics. Acade mic Press, In c. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat dry s oil bulk densi

ty, BD , is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the water and clay

content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is one of

the source

documents

that cite s the use of

Table B -4-4; howev

er, this doc

ument is not the origi

nal source of this equa

tion (this sour

ce is unknow

n). This doc

ument also recommend s the follo wing:

C Estima

ting annual c

urrent runof

f, RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as using the U.S. Soil Conservation Service curve number equation (CNE); U.S. EPA (1985) is cited as an example of such a procedure.

C Default value of 0.2 (mL w ater/cm3 soil) for

soil volum

etric w ater conte nt ( 2 sw )

### TABLE B-4-4 COPC LOSS

CON STA

NT D UE T O RUNOFF (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-188 U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edure for Tox

ic and Conventi

onal Pollutants in Sur

face and Ground W

ater—Part I (Revised. 1985) . Environmental Research Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This docum

ent is cit ed by NC DEHNR (1997)

as an ex ample of the use of

the U.S. Soil Conserva

tion Servic e CNE to e stimat e site-s pecific surfac e runoff

. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s a range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes . Attachment C, Draft Ex posure Assessment Guidance for RCRA

Hazardous

Waste Combustion Facilitie s. Off ices of Emerg ency a nd Reme dial Respons e. Off ice of Sol id Waste . Decem

ber 14. This docu ment recommends th e following:

C Estima

tion of av erage a nnual runoff

, RO , by using the Water Atlas of the United States (Gera ghty e t al. 1973)

C Default

soil dry bulk density

, BD , value of 1.5 (g soil/cm 3 soil), based on the me an for loa m soil tha t is take n from Carsel e

t al. (1988)

C Default

soil volum

etric w ater conte nt, 2 s w , value of 0.2 (mL wa ter/cm 3 soil) U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of soil volumet ric wa ter content, 2 sw , values of 0.1 (ve ry sa ndy soils) to 0.3 (heav

y loam /clay soils) (the

original s ource of, or refe rence f or, these v

alues is not

identified)

C A range of va

lues for soil mix

ing depth, Z

s , for tilled and untilled s oil (the orig inal source

of, or re ferenc e for, the se value s is not ident ified)

C Using the Water Atlas of the United States (Gera ghty, Miller, Van der

Leeden,and Troise

1973) to calc

ulate av erage a nnual runoff

, RO

### TABLE B-4-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 5)

B-189 Description This equat ion calcu lates the CO PC loss constant resultin g from leaching o f soil. Uncer tainties associated with this eq uation includ e the follo wing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksl

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ithin situmater

ials) com pared to other

residues. This unce

rtainty may underestimate ksl

. (3) The original source of this equation has not been identified. U.S. EPA (1998 ) presents the equation as shown here. U.S. EPA (1994a) and NC DEHNR (1997) replaced the nu merator as

shown w ith “ q ”, defined as ave

rage annua

l recharg e (cm /yr). Equation

Varia ble Description Units Value 

### ksl COPC loss cons tant due to le aching yr -1 

### P Avera

ge annual precipitat

ion cm/yr 

### 18.06 to 164.19 This va riable is site-specific. T

his range is based on informa

tion presented in U.S. EPA ( 1998), repres enting data for 69 selected cities (

U.S. Burea

u of Census

1987; Baes e

t al. 1984). T

he 69 selec

ted cities are not ide

ntified; how

ever, the y appea r to be located throughout the contin ental United States. We recomme nd using site-specific data. The following uncertainty is associated w ith this variable: To the ex tent that a site is not

located ne ar an est

ablished m

eteorologic al data s

tation, and si

te-speci fic data

are not available, defa

ult avera ge annual precipitat

ion data m

ay not a ccuratel y ref lect site -specif

ic conditions. As a r

esult, ksl may be un der- or ove resti mated. However , avera ge ann ual p recip itati on d ata are reaso nabl y availab le; th erefor e, we expect unc ertainty

introduced by

this variable to be m

inimal.

### TABLE B-4-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 5)

Varia ble Description Units Value



### B-190 I Avera

ge annual irrigation cm/yr 

### 0 to 100 This variable is site-specific. T his range is based on information presented in U.S. EPA (1998), representing data for 69 selected cities (Baes et al. 1984). The 69 selected cities are not identified; however, they a ppear to be located throughout the cont inental United States. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l irrigat ion inform

ation is not a

vailable , default

values ( generally based on the closest c omparable location) may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be under- or overestimated to an unknown degree. 

### RO Avera

ge annual surfac e runoff

from pervious areas cm/yr 

### Varies This variable is site-specific. A ccording to U.S. EPA (1998), U.S. EP A (1994a), and NC DEHNR (1997), you can estimate RO by using the Water Atlas of the United States (Gera ghty e t al. 1973). A

ccording to NC DEHNR

(1997), you c an also use more detailed, site-specific procedures, such as those based on the U.S. Soil Conservation Service CNE. U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual surface runoff information is not available, default or estim ated values m ay not a ccuratel y repre sent site -specif

ic or local conditions. A

s a resul t, ksl may be under- or overestim ated to an unknown degree. 

### E v Avera

ge annual evapotra

nspiration cm/yr 

### 35 to 100 This va riable is site-specific. T

his range is based on informa

tion presented in U. S. EPA ( 1998), repres enting data from 69 selected cities. The 69 selected cities are not identified; however, they appear to be located throughout the contin ental United States. The following uncertainty is associated w ith this variable: To the extent that site-specific or local average annual evapotranspiration information is not available, default values may not accura

tely r eflec t site-specific c onditions. As a result, ksl

may be un der- or ove resti mated t o an u nkno wn degree.

### TABLE B-4-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 5)

Varia ble Description Units Value



### B-191 2 sw Soil volum

etric w ater conte nt mL

water/cm

3 soil 

### 0.2

This va riable is site-specific, a

nd depends on the

availa ble wat er and on soil

structure . You can e stimat e 2 sw as the m

idpoint betwee n a soil’s f

ield capacity and w

ilting point, i f you c an identif y a re presentat ive wa tershed soil. We recomm end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range of 0.1 (very sandy soils) to 0.3 (heavy loam/clay soils) recomm ended by U .S. EPA (1998) (no source or r efere nce is prov

ided for thi s range)

and is consi stent wi

th U.S. EPA (1994b) and NC DEHN

R (1997). The following uncertainty is associated w ith this variable: The def ault 2 sw value may not accurately reflect site-specif ic or local conditions; therefore, ksl may be under- or overestimated to a small e xtent, based on the limited range of values. 

### Z s Soil depth m

ixing zone cm 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998), w

hich furthe

r states that leac hing soluble c ompounds m ight lead t

o movem ent below a 1-cm depth. A de fault value of 2 cm f or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brz

uzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in lower concentrations within the Z s . This uncertainty may overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. T

his uncertainty may underestim ate Cs and Cs tD . 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5

This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of

1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions.

### TABLE B-4-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 5)

Varia ble Description Units Value



### B-192 Kd s Soil-wat

er partiti on coeff

icient cm 3 water

/g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A-2.

REFERENCES AND DISCUSSION Baes, C.F., R.D. Sharp, A.L. Sjoreen and R.W. Shor. 1984. “A Review and Analysis of Parameters for Asse ssing Transport of Environmentally Released Radionuclides through Agriculture.” Prepared f

or the U.S. D epartm

ent of Ene

rgy unde r Contract No. DEAC 05-840R21400. For the contine

ntal United S tates, as cited in U .S. EPA (1998), t his docume

nt is the sour

ce of a series of ma

ps showing : (1) ave

rage annua

l precipita

tion ( P ), (2) ave

rage annua

l irrigat ion ( I ), and (3) average annual evapotranspiration isolines. Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994a) a s the sourc e for a mean s oil bulk densi ty va lue, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Gerag hty, J.J ., D.W. Mil

ler, F. Van de

r Leede n, and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r, Por t Washingto n, New York. This docu ment is cited b y U.S. EPA (1 998), U.S. EP A (1994a) , and NC DEH NR (1997 ) as a reference for cal culatin g RO . This docu ment provid es maps with isol ines of ann ual average surface runoff, which is defined as a ll flow contributions to surface water bodies, including direct runoff, shallow interflow, and ground water recharge. Because these volumes are total contrib ution s and not only surface ru noff, U.S. EPA (199 4a) recommends that the vo lumes be redu ced by 50 per cent in o rder to est imate average annu al surface run off. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat BD is aff

ected by the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and c lay c ontent of the soil.

### TABLE B-4-5 COPC LOSS CONSTANT DUE TO LEACHING (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 of 5)

B-193 NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the source documents that cites the use of the equation in Table B-4-5. However, the document is not the original source of this equation. This document also recommends the following:

C Estima

tion of av erage a nnual surfa

ce runoff , RO (cm/yr), by

using either the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as the U. S. Soil Conservation Service CNE; U.S. EPA 1985 is cited as an example of such a procedure.

C A default value of 0.2 (mL water/cm

3 soil) for soil volum

etric w ater conte nt, 2 sw U.S. Burea

u of the Ce

nsus. 1987. Statistical Abstract of t he United State

s: 1987. 107th editi on. Washington, D.C. This docum

ent is a s ource of a

verage annual prec ipitation (

P ) inform ation for 69 selected cities, a s cited in U .S. EPA (1998); t hese 69 cit

ies are not identifi ed. U.S. EPA. 1985. Water Quality Assessment: A Screening Procedure for Toxic and Conventiona l Pollutants in Surface an d Groundwater . Part I (Revised 1985). Environmental Research

Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. This document is cited by NC DEHNR (1997) as an exam ple of the use of the U.S. Soil Conservation Service CNE to estimate RO

. U.S. EPA. 1990. Interim Final Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor Emissions. Environm ental Crit eria and A

ssessm ent Off ice. Of fice of Rese arch and Deve lop ment . EP A 600 -90 -00 3. J anu ary. This docum

ent present

s ranges of (1) av erage a nnual precipi

tation, (2) a

verage annual irrig

ation, and (3) averag

e annual ev

apotranspira

tion. This doc

ument ci tes Bae s et al. ( 1984) and U.S. Bureau of the Census

(1987) as the

original s ources of

this infor mation. U.S. EPA. 1994a

. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. U.S. EPA. 1994b. Estimating Exposure to Dioxin-Like Compou nds. Volume III: Site-specific Assessment Procedures. Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s values for soil m

ixing depth, Z s , for tilled and untilled s oil, as cit ed in U.S. EPA

(1993). This docum

ent recom mends (1)

a defa ult soil volum

etric w ater conte nt, 2 sw , value of 0.2 (mL wa ter/cm 3 soil), based on U.S. EPA (1993) , and (2) a de fault soil bulk densit y, BD , value of

1.5 (g soil/cm 3 soil), based on a me an value for loam soil from Carsel e t al. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This document is one of the reference source documents f or the equation in Table B-1-5. The original source of this equation is not ident ified. This document also presents a range of va lues for soil m ixing depth, Z, for tilled and untilled s oil; the orig inal source

of these values i s not identif

ied.

### TABLE B-4-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 5)

B-194 Description This eq uati on cal culat es the COPC loss c onst ant fro m soil d ue to volat iliza tion , and was obt ained from Methodology for Assessi ng Health Risk

s Associate

d with Multiple

Exposure Pat

hways to Combustor Emi

ssions(U.S. EPA 1998) . The soil loss consta

nt due to vola

tilization (

ksv ) is base d on gas equilibrium c oefficients and gas phase mass transfe r. The f irst order decay c onstant, ksv , is obtained by

adapting the

Hwang and Falco equation for s oil vapor phase diff usion (Hwa

ng and Falc o 1986). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) For soluble COPCs, leaching might lead to movement to below 2 centimeters in untilled soils, resulting in a greater mix ing depth. This uncertainty may overe stimate ksv

. (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ mater

ials) com pared to other

residues. This unce

rtainty may underestimate ksv

. Equation

Varia ble Definition Units Value 

### ksv Constant f or COPC loss due

to volatiliz ation yr 1

3.1536 x 10 +07 Units conve rsion fac tor s/yr 

### H Henry’ s Law constant atm-m 3 /mol 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRA

P companion da

tabase. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated by using

the param

eters and algorithm

s in Appendi

x A-2, m ay under - or overesti mate t he actual COPC-specif

ic value s. As a

result, ksv

may be under- or ov

erestim ated.

### TABLE B-4-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 5)

Varia ble Definition Units Value



### B-195 Z s Soil mix ing zone de

pth cm 

### 2 to 20 We rec omme

nd the follow

ing value s for Z s : Soil Dept h (cm) Reference Untilled 2 Brzuzy et al. (1995) Tilled 20 U.S. EPA (1998) U.S. EPA (1992) recomm ended value s of 1 cm

(for untilled) and 20cm

(for tilled soil). T

hese va lues are consistent with U.S. EPA (1998),which f urther sta tes that l eaching s oluble com pounds might

lead to m

oveme nt below a

1-cm de pth. A default v alue of 2 cm f

or untilled soil mixing

depth is bas ed on a study that profiled dioxin m

easurem ents wit hin soil (Brzuzy et al. 1995). A def

ault value of 20 cm for tilled soil mix

ing depth is based on U.S. EPA (1998). The following uncertainties are associated with this variable: (1) For solu ble COP Cs, leachi ng might lead t o movement to b elow 2 centi meters in un tilled so ils, resu lting a greater mixing depth. This uncertainty m ay overestimate Cs and Cs tD . (2) Deposition to ha rd surfac es ma

y res ult in dust residues that ha ve negligible dilution compar ed to other re sidues. This uncertainty may

underestimate Cs and Cs tD . 

### Kd s Soil-wat

er partiti on coeff

icient cm 3 water

/g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A

-2. 

### R Universa l gas cons tant atmm 3 /mol-K 8.205 x 10 -5

There a re no uncert

ainties a ssociate d with this

param eter.

### TABLE B-4-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 5)

Varia ble Definition Units Value



### B-196 T a Ambie

nt air tem perature K 

### 298 This variable is site-specific. U.S. EPA (1998) also recomme nds an ambient air temperature of 298 K. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for t he varia ble are not available, defa ult values may not accurately repr

esent sit e-specif ic conditions. We ex

pect the unc ertainty

associa ted with t he selec tion of a s ingle value f rom w ithin the tem

perature r ange at a single

location to be

more s ignific ant than the uncertainty associat ed with c hoosing a si

ngle am bient tem perature t o represe nt all loca lities. In other words , the range of average ambient tem

peratures across the country is generally less than the temperature range at an individual site. 

### BD Soil bulk density g soil/cm 3 soil 

### 1.5

This va riable is affected by

the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) stated tha t a value of 1.5 would suffi ce for m ost uses, i f site- specific inform ation was unavailable. The following uncertainty is associated w ith this variable: The recommended soil bulk density value m ay not accurately represent site-specif ic soil conditions. 

### D soil Solids particle density g/cm3 2.7 We rec omme

nd the use of

this value , based on Bla

ke and Ha

rtage (1996)

and Hillel (1980). The solids particle density will vary with location and soil type. 

### D a Diffusivity of COPC in a ir cm 2 /s 

### Varies This va lue is COPC-s

pecific . We dis cuss this v ariable i n detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The def ault D a values m

ay not a ccuratel y repre sent the be

havior of COPCs under s ite-spec ific condi tions. Howeve r, we e xpect the degree of uncerta

inty to be minim al.

### TABLE B-4-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 5)

Varia ble Definition Units Value



### B-197 2 sw Soil volum etric w ater conte nt mL/cm 3 soil 

### 0.2 This variable depends on the available water and on soil structure. You can estimate 2 sw as the m idpoint between a soil’s field ca pacity and wilti ng point, if

you can identify

a repres entative

water shed soil. Howeve

r, we recomm

end using 0.2 ml/cm

3 as a default value. This value is the midpoint of the range 0.1 (very sandy soils) to 0.3 (heavy loam /clay soils) rec omm ended by U.S . EPA

(199 8) ( no so urc e or ref ere nce is p rov ided for this ran ge) and is c onsi ste

nt w ith U .S. E PA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 sw values may

not accurately reflect site-specif ic or local conditions; therefore, ksv maybe underor overestimated to a small ex tent, based on the limited range of values.

REFERENCES AND DISCUSSION
Blake, G R. and K.H. H

artge. 1996. Particle D

ensity. M ethods of Soil Anal

ysis, Part 1: Physical

and Mineralogic

al Methods . Se con d Ed iti on. Arno ld K lut e, E d. Ame ric an S oci ety o f Agro nomy, Inc. Madison,WI., p. 381. Carsel, R.F., R.S, Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Vol. 2. Pages 11-24. This docum

ent is cit ed by U. S. EPA (1994b) as the source

of a m ean soil bulk

density value, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Ph ysics. Academic Press, I nc. New York, New Yo rk. Hwang S. T. and Fa

lco, J. W. 1986. “Estim

ation of m

ultimedia exposures

related t o hazardous w

aste f acilities ”, In: Pollutants in a M ultimedia Env

ironment . Yoram

Cohen, Ed. Plenum

Publishing Corp. New Yo rk. Miller, R.W . and D.T. Gardiner . 1998. In: Soils in Our Env ironment . J.U. Mille

r, Ed. Prentice

Hall. Uppe

r Saddle Riv

er, NJ. pp. 80-123. U.S. EPA. 1994a. Estimating Exposure to Dioxin-Like Compou nds. Volume III: Site-specific Assessment Procedures . Externa l Review Draft. Office of Re search a nd Developm

ent. Was hington, D.C. EPA/600/6-88/00 5Cc. June. This docum

ent present

s value f or soil, m ixing depth, Z s , for tilled and untilled s oil. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Waste. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14.

### TABLE B-4-6 COPC LOS S CONS TANTDUE T O VOLAT ILIZ ATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 of 5)

B-198 This docum

ent recom mends a default soil density

, BD , value of 1.5 (g soil/cm 3 soil), based on a me an value for loam soil that is

taken f rom Car sel et a l. (1988). U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment recommends th e following:

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled soil; however, the source or basis for these values is not identified

C A def

ault am bient air te

mperat ure of 298 K

C A range of soil volumet ric wa ter content, 2 sw

### TABLE B-4-7 TOTAL WATER BODY LOAD (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 2)

B-199 Description This equa tion calcula

tes the tot al aver age w ater body load from

wet and dry va

por and partic le deposition,runoff, and erosion loa ds. The li mitations and uncerta

inties as sociated w

ith this equa

tion includ e the follo wing: (1) Uncertainties associated with variables in equations presented in Tables B-4-8, B-4-9, B-4-10, B-4-11, and B-4-12 that are site-specific. These variables include Q, Dytwv , Dytwp, A w , Cywv, A I , A L , Cs , and X e . Values f

or many of these variable s are es

timated through the us e of m athema tical m odels and the

uncertaint

ies ass ociated w

ith values for thes e varia

bles ma y be signifi cant in som

e cases (Bidlem an 1988). (2) We expect the unce rtainties associat

ed with the

rema ining var iables in equations pres ented in Ta bles B-4-8, B -4-9, B-4-10, B-4-11, and B-4-12 to be less s ignific ant, prim arily because of the narrow ranges of probable values for these variables or because values for these variables (such as Kd s ) were estimated using well-established methods. Equation

Varia ble Description Units Value 

### L T Tot al CO PC loa d to the water bod y g/yr 

### L DEP Total (wet and dry) particle phase

and vapor phase COPC direct deposition load to wate

r body g/yr 

### Varies This va riable is COPC- and site -specif ic, and ca lculated us ing the equa

tion presented in Table B-4-8. Uncertain ty associated wit h this vari able incl ude the fol lowing:

Most of the

uncertaint

y ass ociated w

ith the var

iables in t he equation in Table B-4-8, specif ically those ass ociated w

ith Q, Dytwv, Dytwp , and A w , are sit e-specif ic and m ay be signific ant in som

e cases . 

### L dif Vapor phase COPC diffusion load

to wa ter bod y g/yr 

### Varies This va riable is calculat

ed using equa

tion presented in Table B-4-12. Uncertain ty associated wit h this vari able incl ude the fol lowing:

Most of the

uncertaint

y ass ociated w

ith the var

iables in t he equation in Table B-4-12, specif ically those ass ociated w

ith Q, Cywv , and A w , are site-specific.

### TABLE B-4-7 TOTAL WATER BODY LOAD (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 2)

Varia ble Description Units Value



### B-200 L RI Runoff loa

d from imperv

ious surfaces g/yr 

### Varies This va riable is calculat

ed using the

equation pres ented in Ta ble B-4-9. Uncertain ty associated wit h this vari able incl ude the fol lowing:

Most of the

uncertaint

y ass ociated w

ith the var

iables in t his equation, s

pecific ally thos e associ ated wi th Q, Dytwv, Dytwp , and A I , are site-specific. 

### L R Runoff load from pervious surfaces g/yr 

### Varies This va riable is calculat

ed using equa

tion presented in Table B-4-10. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Most of the

uncertaint

ies ass ociated w

ith the var

iables in t he equation in Table B-4-10, specif ically those for A L , A I , and Cs , are site-specific. (2) Uncertai

nties ass ociated w

ith the rem

aining va riable in the

equation in Table B-4-10 a re not expected to be s ignific ant, primarily because of the narrow ranges of probable values for these variables or the use of w ell-established estimation procedures (

Kd s ). 

### L E Soil erosion load g/yr 

### Varies This va riable is calculat

ed using equa

tion presented in Table B-4-11. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Most of the

uncertaint

ies ass ociated w

ith the var

iables in t he equation in Table B-4-11, specif ically those for X

e ,, A L , A I , and Cs, are site-specific. (2) Uncertai

nties ass ociated w

ith the rem

aining va riables in the equation i

n Table B -4-11 are not e

xpected t o be signif

icant, primarily because of the narrow range of probable values for these variables or the use of w ell-established estimation procedures (

Kd s ).

REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion in Table B-1-1.

### TABLE B-4-8 DEPOSITION TO WATER B ODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-201 Description This equa tion calcula

tes the a verage load to the w

ater body from direct depos ition of w et and dry particle s and we

t vapors onto the surfa

ce of the water body. Unc ertaintie s associ ated wi th this equatio n inclu de the foll owing: (1) Most of the

uncertaint

ies ass ociated w

ith the var

iables in t his equation, s

pecific ally thos e associ ated wi th Q , Dytwv , Dytwp , and A w , are site-specific. (2) It is calculated as suming a default ST

value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, using the latter ST value may be m

ore appropriate. Specifically, the ST value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local source s and would result in a lower c alculate d F v value. H

oweve r, F v would lik

ely to be only a f ew perc ent lowe

r. Equation

For merc ury m odeling

Use 0.48Q for total mercur y (to account for los s to the global cy cle) and F

v = 0.85 in the m

ercury modeling

equation. Varia ble Description Units Value 

### L DEP Total (wet and dry) particle phase

and vapor pha

se direct deposition load to wa

ter body g/yr


### Q COPC-specif ic emi ssion rate g/s 

### Varies This va riable is COPC- and site -specif ic. See C hapters 2 a

nd 3 for guida

nce on calc

ulating this

variable

. Uncertainties associated with this variable are site-specific.

### TABLE B-4-8 DEPOSITION TO WATER B ODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

Varia ble Description Units Value



### B-202 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRAP companion database. This range is based on values presented in Appendix A-2. Values are also presented in U.S. EPA (1994b)

and NC DEH

NR (1997).
F v was c alculate d using an e quation prese nted in Junge

(1977) for a

ll organic COPCs, includi

ng PCDDs and PCDFs. U.S. EPA (1994c) states

that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If a specif ic site i s located in an urban ar ea, using the latter ST

valu e may be more app rop ria te. Spe cifi call y, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources. It would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge constan t) is const ant for all ch emicals; however, the value of c depends on the chemical (sorbate) molecular weight, the surf ace conc entration f

or monolay

er cover age, and t he diff erence be tween t he heat of desorption from t he particl e surfa

ce and the heat of v

aporization of the liquid-phase sorba te. To the

extent tha

t site- or COPC-sp ecific cond itions may cause the value of c to vary , uncertaint

y is int roduced if a constant value of c is used to calculate F v . 

### Dytwv Unitized y

early (wate r body or waters hed) aver age tota l (wet a nd dry) deposition from vapor phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### Dytwp Unitized y

early (wate r body or waters hed) aver age tota l (wet a nd dry) deposition from vapor phase s/m 2 -yr 

### Varies

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### A w Water body surface area m 2 

### Varies

This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific.

### TABLE B-4-8 DEPOSITION TO WATER B ODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

B-203 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technol ogy. Volume 22. N umber 4. Pag

es 361-367. For discussion, see Re ferenc es and Dis cussion in Table B-1-1. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is a reference source f or the equation in Table B-4-8. This document also recommends by using the equations in Bidleman (1988) to calculate F v values for all organics other than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. Finally, this document states that metals are generally entirely in the particulate phase ( F v = 0 ) except

for m ercury, which is

assum ed to be enti

rely i n the vapor phase. T

he docume

nt does not sta

te whet her F v for mercury s

hould be calculated by using the equations in Bidleman (1988). U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber 14. This docum

ent is a r efere nce source

for Equation B-4-8. This document also prese

nts value s for org

anic COPCs t

hat range from 0.27 to 1. F v values f or organics

other than PCDD

/PCDFs are calculated by using the equations presented in Bidleman (1988). The F v value for PCDD/PCDFs is assumed to be 0.27, based on U.S. EPA (no date). Finally, this document presents F v values for inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatile and assumed to be 100 percent in th e particulate phase and 0 percent in the vapor phase. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-4-9 IMPERVIOUS RUNOF F LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-204 Description Thi s eq uat ion calc ula tes the aver age r uno ff lo ad t o th e wate r bo dy fro m impe rvi ous sur faces in t he wa ter she d fro m whic h ru nof f is c onv eyed dir ectl y to t he wa ter bod y. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Most of the

uncertaint

ies ass ociated w

ith the var

iables in t his equation, s

pecific ally thos e associ ated wi th Q , Dytwv , Dytwp , and A I , are site-specific. (2) The equat

ion assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, using the latter ST

value may be m ore appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources and would result in a lower calculat ed F v value; however, the F v value is likely to be only

a few percent low

er. Equation

For Mercury

modeling

Use 0.48Q for total mercur y (to account for los s to the global cy cle) and F

v = 0.85 in the m

ercury modeling

equation. Varia ble Description Units Value 

### L RI Runoff loa d from imperv

ious surfaces g/yr 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This variable is COPC- and site-specific (see Chapters 2 and 3). Uncertainties associated with this variable are site-specific.

### TABLE B-4-9 IMPERVIOUS RUNOF F LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

Varia ble Description Units Value



### B-205 F v Fraction of

COPC air concentration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion da

tabase. This rang

e is based on values presented i n Appendix A-2. Value s are al so presented in U.S. EPA ( 1994b) and NC DEHN

R (1997).
F v wa s ca lculate d usi

ng a n equ ati on pr ese nted in J unge (197 7) f or a ll or gan ic C OPCs , includi

ng PCDDs

and PCDF s. U .S. E

PA (1994c) stat

es that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) Calculations assum e a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urb an source s. If a specific site is

located in an urban are a, using the latter ST value may be more appropriate. Specifically, the ST value f or urban source s is about one order of m

agnitude g

reater t han that f or backg round plus local

sources, and it would result in a lower calculat ed F v value; however, the F v value is likely to be only

a few percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constant for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr ation for monolayer coverag

e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfa

ce and the heat of vaporizat ion of th e liquid -phase so rbate. To th e extent tha t site- or C OPC-sp ecific cond itions may cause the value of c to vary, uncer tainty is in trodu ced if a const ant value o f c is used to calculate F v . 

### Dytwv Unitized y early (wate r body or waters hed) aver age tota l (wet a nd dry) deposition from vapor phase s/m 2 -yr 

### Varies This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties ass ociated with this variable are site-specific. 

### Dytwp Unitized y early (wate r body or waters hed) aver age tota l (wet a nd dry) depos ition from

particle phase s/m 2 -yr 

### Varies This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties ass ociated with this variable are site-specific.


### A I Impervious watershed area

receiv ing COPC depos ition m 2 

### Varies This variable is site-specific. Uncertainties associated with this variable are site-specific.

### TABLE B-4-9 IMPERVIOUS RUNOF F LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

B-206 REFERENCES AND DISCUSSION Bidlema n, T.F. 1988. “ Atmospheric Processes. ” Environmental Science and Technol ogy. Volume 22. N umber 4. Pag

es 361-367. For discussion see Ref

erences and Discus sion in Table B-1-1. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is a reference source f or the equation in Table B-4-9. This document also recommends using the equations in Bidleman (1988) to calculate F v values for all organics other than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. Finally, this document states that generally metals are entirely in the particulate phase ( F v = 0 ) except

for m ercury, which is

assum ed to be enti

rely i n the vapor phase. T

he docume

nt does not sta

te whet her F v for mercury s

hould be calculated using the equations in Bid leman (1988). U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This document is a reference source f or the equation in Table B-4-9. This document also presents F v values f or organic COPCs that ra nge form 0.27 to 1. F

v values for organics other than PCDD/PCDFs are calculated using the equations presented in Bidleman (1988 ). The F v value f or PCDD/PCDFs is

assum ed to be 0.27, based on Lorbe r (no date). Finally , this docum ent presents F

v values f or inorganic

COPCs equal to 0, based on t he assum ption that thes e COPCs are nonvolatile

and 100 perce

nt in the part

icle phase (and 0 perce

nt in the va

por phase). U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-4-10 PERVIOUS RUNOFF LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-207 Description This equat ion calcu lates the aver age runoff loa d to the water body from pervio us soil su rfaces in the water shed. Unc ertainty asso ciated with this equ ation in cludes th e following:

To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estim ated val ues ma y not ac curately

represe nt site-specific or

local condit

ions. As a re sult, L R may be under- or overestim ated to an unknown degree. Equation

Varia ble Description Units Value 

### L R Runoff load from pervious surfaces g COP C/yr 

### RO Avera

ge annual surfac e runoff

from pervious areas cm wat er/ yr 

### Varies This variabl e is site-sp ecific. Accordi ng to U.S. EPA (199 8), U.S. EPA (199 4), and NC DEHNR (19 97), average annual surf

ace runof f, RO , can be estimated by using the Water Atlas of the United States (Gera ghty e t al. 1973). According t o NC DEHNR (1 997), more detailed , site-sp ecific proced ures for esti mating the amou nt of surface ru noff, such as those based on the U.S. Soil Conservation Service CNE may also be used. U.S. EPA (1985) is cited as an example of such a procedure. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local ave rage annua

l surfac e runoff

inform ation is not a

vailable , default

or estima ted value s may

not accura

tely r epresent site-spec ific or local conditions . As a result, RO may be under- or overestimated to an unknown degree. 

### A L Total w

atershed a rea rec eiving COPC deposition m 2 

### Varies

This va riable is site-specific. Se e Chapter 4 for procedures to ca lculate thi s varia

ble. Uncer

tainties a ssociate d with this variable are site-specific. 

### A I Impervious watershed area

receiv ing COPC depos ition m 2 

### Varies

This va riable is site-specific. Se e Chapter 4 for procedures to ca lculate thi s varia

ble. Uncer

tainties a ssociate d with this variable are site-specific.

### TABLE B-4-10 PERVIOUS RUNOFF LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-208 Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies This variable is COPC- and site-specific, and is calculated using the equation presented in Table B-4-1. Uncertainties associated with this variable are site-specific. 

### BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This va riable is affected by

the soil st

ructure, suc

h as loosene ss or com

paction of the soil, depe

nding on the w

ater and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soi l, ba sed on a me an v alue for loa m s oil o btai ned f rom Car sel et a l. ( 1988) . U. S. EPA (1998) state d that a va

lue of 1.5 w

ould suff ice for most use s, if si

te-speci fic inf

ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The rec omme

nded range of soil bulk

density values m ay not a ccuratel y repre sent site -specif

ic soil conditions. 

### 2 sw Soil volum

etric w ater conte nt mL water/cm 3 soil 

### 0.2 This variable depends on the available water and on soil structure; you can estimate 2 sw as the m idpoint between a soil’s f ield capacity and w

ilting point, i f a repr

esentativ e wate rshed soil c an be identif

ied. How ever, w e recom mend using a default value of 0.2 mL/cm 3 ; this valu e is the midpo int of the r ange 0.1 (ve ry sandy soils) t o 0.3 (h eavy loam/clay soil s) recom

mended by

U.S. EPA (1998)

(no source or

refer ence is pr ovided for

this range

) and is cons istent with other U.S. EPA (1994b) and NC DEHNR (1997 ) guidance. The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, K

R maybe underor overes timated to a lim

ited exte nt. 

### Kd s Soil-wat

er partiti on coeff

icient cm 3 water /g soil 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A

-2. 

### 0.01 Units conve

rsion fac tor cm 2 water -kg soil- g COPC/m

2 -gsoilmg COPC

### TABLE B-4-10 PERVIOUS RUNOFF LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

B-209 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contamina nt Hydrology. Volume 2: pa

ges 11-24. Gerag hty, J.J ., D.W Miller, F. Van der Leeden,and F.L. T

roise. 1973. Water Atlas of the United States . Water Informati on Cente r. Port Washingto n, New York. This docum

ent is cit ed by U. S. EPA (1993), U .S. EPA (1994c), and NC DEH

NR (1997) as a refe

rence f or calcula ting ave rage annua

l runoff, RO . Specif

ically, this ref

erence pr ovides m aps with isoli nes of a nnual aver

age surf ace w ater runof f, whic h is defined as all f

low contri

butions to surf

ace w ater bodies , including dir ect runoff , shallow interflow , and ground w

ater rec harge. Because these volumes are total contributions and not only surface runoff, U.S. EPA (1994c) notes that they need to be reduced to estimate surface runoff. U .S. EPA (1994c) recommends a reduction of

50 percent. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Pres, Inc. New York.

This docum

ent is cit ed by U. S. EPA (1990) f

or the stat ement t hat soil bulk

density, BD , is aff

ected by soil struc ture, such a

s loosenes s or com

paction of the soil, depe

nding on the w

ater and clay content of the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is one of the source documented that cites the use of the equation in Table B-4-10; however, the document is not the original source of this equation. This document also recommends the following:

C Estima

tion of av erage a nnual runoff

, RO (cm/yr), by

using the Water Atlas of the United States (Gera ghty e t al. 1973) or s ite-spec ific proc edures, suc h as the U. S. Soil Conservation Service CNE; U.S. EPA (1985) is cited as an example of the use of the CNE

C A default value of 0.2 (mL water/cm

3 soil) for soil volum

etric cont ent ( 2 sw ) U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edures for

Toxic and Conv

entional Pollutants

in Surface and G

round Water -

Part I (R evised - 1985) . Environmental Research Laborator y. A thens, Georgia. EPA

/600/6-85/002a. Sept

ember. U.S. EPA. 1994. Revised Draft Guidance of Performing Screening Level Risk Analysis at Combu stion Facilities Burning Hazard ous Wastes . Attac hment C, Draft E

xposure Assessm

ent Guida nce for RCRA Ha

zardous W

aste Com bustion Facili

ties. Of fice of Emerg ency a nd Reme dial Respons e. Off ice of Sol id Waste . Decem

ber 14. This document recommends (1) a def ault soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil f rom Carsel et al. (1988), and (2) a default soil volumetric water content, 2 sw , value of 0.2 (mL wa ter/cm 3 soil), based on U.S. EPA (1993)

. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-4-10 PERVIOUS RUNOFF LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-210 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent cites Hillel (1980)

for the s tateme nt that only

soil bulk de

nsity, BD , is aff

ected by the soil st

ructure, suc

h as loosened or compa

ction of the

soil, depending

on the wa

ter and clay content of the soil. This docu ment is also a so urce of the fol lowing:

C A range of soil volumet ric wa ter content

( 2 sw ) values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heav

y loam /clay soils). How

ever, no s ource or re ferenc e is provided for this range.

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil

### TABLE B-4-11 EROSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-211 Description This equat ion calcu lates the lo ad to the water body from soil erosion . Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Uncertainties associated with the variables X e , A S , A I , and Cs , are sit

e-specif ic and m ay be signific ant in som

e cases . (2) Uncertai

nties ass ociated w

ith the rem

aining va riables a ren’t expected to be s ignific ant, prim arily because of

the narrow

ranges of probable values f or these v ariables or the use of well-established estimation procedures (Kd s ). Equation

For mercury modeling, the erosion load to water body is calculated f or divalent mercury (Hg 2+ ) and methyl merc

ury (MHg) using their respective Cs values a nd Kd

s values.
Varia ble Description Units Value 

### L E Soil erosion load g COP C/yr 

### X e Unit soil loss kg soil/m 2 -yr 

### Varies This va riable is site-specific, a

nd calculat

ed using the

equation pres ented in Ta ble B-4-13. The following uncertainty is associated w ith this variable: All of the equation v

ariables are site -specif

ic. Using default values r

ather than site-spec ific v

alues, f or any or all or these v ariables , will re sult in esti mates of unit soil

loss, X

e , that are under- or ove

restim ated to som

e degree

. The range of X e calculat ed on the bas is of def

ault value s spans sl

ightly more tha

n one order of

magni tude (0.6 to 36.3 kg/m

2 -yr). 

### A L Total w

atershed a rea rec eiving deposition m 2 

### Varies

This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific. 

### A I Area of imperv ious watershed receiv ing deposition m 2 

### Varies

This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific.

### TABLE B-4-11 EROSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-212 SD Waters

hed sedim

ent delive ry rat io unitless 

### Varies This va lue is site -specif

ic and calculated usi

ng equation in Table B-4-14. The following uncertainty is associated w ith this variable: The recommended default va lues for the variables a and b (empir ical inter cept coef ficient and empir

ical slope coefficient, respectively) are average values, based on a rev iew of sediment y

ields from various watersheds. T hese default v alues m ay not a ccuratel y repre sent site -specif

ic wat ershed condit

ions and, ther

efore, m ay cont ribute to under- or ove

r estim ating L E . 

### ER Soil enrichm ent ratio unitless 

### 1 or 3 COPC enrichm

ent occurs because ( 1) lighter soil partic les erode more quic kly tha n heavier soil particles and (2) concentrat

ions of organic COPCs— a function of organic carbon c ontent of sor bing me dia—are e

xpected t o be higher in eroded m aterial than in situ soil (U.S. E PA 1998). In the

absence of site- specific data, w e recom mend a de fault v

alue of 3 for organic COPCs and 1 for inorganic COPCs. This is consistent with other Agency guidance (U.S. EPA 1998), which recomm ends a rang

e of 1 to 5 a

nd a value

of 3 as a “reasona ble firs t estim ate”. T his range has been us ed for org

anic ma tter, phosphorus, and othe

r soil-bound COPCs

(U.S. EPA 1998) ; howeve r, no sources

or refe rences w ere provided for this r

ange. ER is gener

ally hig her in sandy

soils than i

n silty or loamy

soils (U.S. EPA 1998). The following uncertainty is associated w ith this variable: The def ault ER value m

ay not a ccuratel y ref lect site -specif

ic conditions; therefor

e, L E may be over- or underestimated to an unknown, but relatively small, extent. Using county-specif ic ER values w

ill reduce the exte nt of any uncertainties. 

### Cs Average soil concentration over

exposure dur

ation mg COPC/kg soil 

### Varies

This variable is COPC- and site-specific, and calculated using the equation in Table B-4-1. Uncertainties are site-specific. 

### Kd s Soil-wat

er partiti on coeff

icient mL w

ater/g soil (or cm 3 water/ g soil) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail a

nd offer COPC-speci fic va

lues in A ppendix A- 2. The following uncertainty is associated w ith this variable: Uncertain ties associ ated with th is parameter will be limited if Kd s values a re calc ulated as described i

n Appendix A

-2.

### TABLE B-4-11 EROSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-213 BD Soil bulk dens ity g soil/cm 3 soil 

### 1.5 This variable is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of the soil (Hillel 1980), as summ arized in U .S. EPA (1998). U .S. EPA (1994c) recomm ended a def

ault BD value of 1.5 g soil/cm 3 soil, base d on a me an value for loam soil obtaine d from Carsel e t al. (1988). U .S. EPA (1998) s tated that a value of 1.5 would suf

fice f or most us es, if site-spec ific inf ormation w

as unava ilable. The following uncertainty is associated w ith this variable: The rec omme

nded BD value m

ay not a ccuratel y repre sent site -specif

ic soil condi

tions; and m

ay under - or overestimate site-specific s oil conditions to an unkno wn degree. 

### 2 sw Soil volum

etric w ater conte nt mL water/cm 3 soil 

### 0.2

This va riable is site-specific, a

nd depends on the

availa ble wat er and on soil

structure ; you ca

n estim ate 2 sw as the m

idpoint betwee n a soi l’s fie ld cap acity an d wilt ing p oint , if you can id enti fy a repre sent ative watersh ed so il. Ho wever, we recommend using 0.2 ml/cm 3 as a default valu e. This value i s the midpo int of the r ange 0.1 ( very sandy soils) to 0.3 ( heavy loam/clay soil s) recom

mended by

U.S. EPA (1998)

(no source or

refer ence is pr ovided for

this range

) and is cons istent w

ith U.S. EPA (1994b). The following uncertainty is associated w ith this variable: The def ault 2 sw value m

ay not a ccuratel y ref lect site -specif

ic or local conditions; the

refore, L E may

be under- or overestimated to a small e xtent, based on the limited range of values. 

### 0.001 Units conve

rsion fac tor mgCOPC/

g COPC

### TABLE B-4-11 EROSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-214 REFERENCES AND DISCUSSION Carsel, R.F., R.S. Parrish, R.L. Jones, J.L. Hansen, and R.L. Lamb. 1988. “Characterizing the Uncertainty of Pesticide Leaching in Agricultural Soils.” Journal of Contam inant Hydrology

. Volume 2. Pag

es 11-24. This docum

ent is the s ource for

a mea n soil bulk de

nsity, BD , of 1.5 (g soil/cm 3 soil) for loam s oil. Hillel, D. 1980. Fundamentals of Soil Physics . Academic Press, Inc. New York.

This docum

ent is cit ed by U. S. EPA (1998) f

or the stat ement t hat soil bulk

density, BD , is affected by the soil structure, such as looseness or compaction of the soil, depending on the water and clay content of

the soil. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docu ment is cited as one of the so urces for th e range of BD values, a nd the defa

ult value f

or the volum

etric soil water content. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attac hment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This document recommends (1) a def ault soil bulk density value of 1.5 (g soil/cm3 soil), based on a mean value for loam soil f rom Carsel et al. (1988), and (2) a default soil volumetric water content, 2 sw , value of 0.2 (mL wa ter/cm 3 soil). U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is the s ource of a

range of COPC enrichm

ent ratio, ER , values. The recomme nded range,

1 to 5, was

used for organic m

atter, phosphor

ous, and other s oul-bound COPCs. This docum

ent recom mends a value of 3 as a “r easonable first e stimat

e,” and st ates that COPC enrichm

ent occurs because l

ighter soil particle s erode m ore quickly

than heav

ier soil pa rticles. Lighter soil particles have

higher ra tios of sur

face a rea to vol ume and a

re higher in organic matter content. T

herefore , concentra

tion of orga

nic COPCs, w

hich is a f unction of the

organic carbon conte

nt of sorbing

media,is expec

ted to be hig

her in erode d mater

ial than in in situ soil. This docu ment is also a so urce of the fol lowing:

C A range of soil volumet ric wa ter content

( 2 sw ) values of 0.1 ml water/cm 3 soil (very sandy soils) to 0.3 ml w ater/cm3 soil (heav

y loam /clay soils). How

ever, no s ource or re ferenc e is provided for this range.

C A range of va

lues for soil mix

ing zone de

pth, Z

s , for tilled and untilled s oil

### TABLE B-4-12 DIFFUSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-215 Description This equat ion calcu lates the lo ad to the water body due to vapor p hase diffusio n. Uncerta inties asso ciated with this equ ation in clude th e following: (1) Most of the uncertainties associated with the variables K v , Q, Cywv , and A w , are site-specific. (2) This equa

tion assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, using the latter ST

value may be m ore appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than that for background plus local sources and would result in a lower calculat ed F v value; however, the F v value is likely to be only

a few percent low

er. Equation

For Mercury

modeling

Use 0.48Q for total mercur y (to account for los s to the global cy cle) and F

v = 0.85 in the m

ercury modeling

equation. Varia ble Description Units Value 

### L dif Vapor phase diffusion load to water

bod y g COP C/yr


### K v Overall

transfe r rate c oefficient m/yr 

### Varies This va riable is COPC- and site -specif ic, and ca lculated us ing the equa

tion in Table

B-4-19. Unce

rtainties associat

ed with this variable are site-specific.

### TABLE B-4-12 DIFFUSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-216 Q COPC-specif ic emi ssion rate g COPC/s 

### Varies This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance on calculating this variable. Uncertainties associated with this variable are site-specific. 

### F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion database. Values are also presented in U.S. EPA (1994), RTI (1992), and NC DEHNR (1997). Values are based on the work

of Bidlem

an (1988), as cited in U.S . EPA (1994) and NC DEHNR (1997). U.S. EPA

(1994) prese

nts value s for organic C OPCs that ra

nge from 0.27 to 1. All

values pr esented by

U.S. EPA (1994)

for inorganic COPCs a

re give n as 0. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) This equa

tion assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value for urban sources. If a specific site is loc ated in an ur ban area,using the latter ST value m ay be m ore appropria

te. Specifically, the ST

value f or urban sourc es is about one order of magni tude grea ter than tha

t for bac kground plus local sourc es and w

ould result in a

lower c alculate d F v value; however, the F v value is likely to be only a f ew percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c is constan t for all chemical s; however, th e value of c depends on the chemical (sorbate) molecular weight, the surface concentration for monolayer coverage, and the differe nce between the heat of desorption from the particle surface and the heat of vaporization of the liquid phase sorbate. To the extent that site- or COPC-specific conditions may cause the valu e of c to vary, uncer tainty is in trodu ced if a const ant value o f c issued to calculate F v . 

### Cywv Unitized y

early averag e air concentration from vapor phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific, and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable are site-specific. 

### A w Water body surface area m 2 

### Varies

This va riab le is si te-sp ecific (see Ch apter 4). Un certa inti es asso ciate d with this variab le are s ite-s pecifi c. Howe ver, we expect that the uncertainty associated with this variable will be lim ited, because maps, aerial photographs, and other resources from which w

ater body surface areas c an be measured, are readily av ailable. 

### 10 -6 Units conve

rsion fac tor g/μg

### TABLE B-4-12 DIFFUSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-217 H Henry’ s Law constant atm-m 3 /mol 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated by using

the param

eters and algorithm

s in Appendi

x A-2, m ay under - or overesti mate t he actual COPC-specif

ic value s. As a

result, L Dif

may be under- or overestim ated to a limited degree. 

### R Universa

l gas cons tant atm-m 3 /mol-K 

### 8.205 x 10 -5 

### T wk Water body

temper ature K 

### 298 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic inform ation, consis

tent with U.S. EPA (1998) and U .S. EPA (1994). The following uncertainty is associated w ith this variable: To the extent that the default water body tem perature value does not accurately represent site-specific or local conditions, L dif

will be under- or ove

restim ated.

REFERENCES AND DISCUSSION Bidlema n, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technol ogy. Volume 22. N umber 4. Pag

es 361-367. For discussion, see Re ferenc es and Dis cussion in Table B-1-1. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This document is a reference source f or the equation in Table B-4-12. This document also recommends using the equations in Bidleman (1988) to calculate F v values for all organics other than dioxins (PCDD/PCDFs). However, the document does not present a recommendation for dioxins. This document also states that metals are generally entirely in the particulate phase ( F v = 0), exc ept for m

ercury, which is

assum ed to be enti

rely i n the vapor phase. T

he docume

nt does not sta

te whet her F v for m ercury should be ca

lculated by

using the equations in Bidleman (1988); We assume that this is the case. U.S. EPA 1994. Revised Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous Waste Combustion Facili ties. Office of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. This docum

ent is cit ed as the refere

nce source

for T wk, water body temperature (298 K); however, no ref erences or sources are identified for this value. This document is a reference source for the e quation in Ta

ble B-4-8. T

his docume

nt also pres ents val

ues for or ganic COPCs that rang

e from 0.27 to 1. F

v values f or organics

other than PCDD

/PCDFs are calculat

ed by usi ng

### TABLE B-4-12 DIFFUSION LOAD TO WATER BODY (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-218 the equations presented in Bidleman (1988). The F v value for PCDD/PCDFs is assumed to be 0.27, based on Lorber (no date). Finally, this document presents F v values f or inorganic COPCs equal to 0, based on the assumption that these COPCs are nonvolatil e and 100 percent in the particulate phase and 0 percent in the vapor phase. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This d ocumen t reco mmends a range (10°C to 20 °C ; 283 K to 303 K) f or wate r body tem

perature, T

wk . No source

was ide ntified f or this range.

### TABLE B-4-13 UNIVERSAL SOIL LOSS EQUATION (USLE) (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-219 Description This equat ion calcu lates the so il loss rat e from the watershed by using the Un iversal Soi l Loss Equa tion (US LE); the resu lt is used in the soi l erosion load equ ation in Table B-4-1 1. Estimates o f unit soil loss , X e , shoul d be deter mined specifi c to each watersh ed evaluated . Informatio n on det ermining sit e- and watersh ed-specifi c values for vari ables used in calcula ting X e is provided in U.S. Department o f Agriculture ( U.S. Depar tment of Agricult ure 199 7) and U. S. EPA gui dance (U.S . EPA 198 5). Uncert ainties ass ociated wit h this eq uation includ e the follo wing: (1) All of the equation v ariables are site -specif

ic. Use of defa

ult values will re sult in esti

mates of unit soil

loss, X

e , that are under- or ove

restim ated to som

e unknown de

gree. Equation

Varia ble Description Units Value 

### X e Unit soil loss kg/m 2 -yr 

### RF USLE rai

nfall (or erosivit y) f actor yr -1 

### 50 to 300 This value is site-specific and is derived on a storm-by -storm basis. As cited in U.S. EPA (1998), average annual values were compiled regionally by Wischmeier and Smith (1978); the recommended range ref lects these compiled values. The following uncertainty is associated w ith this variable: The rang e of av erage a nnual rainf

all fac tors (50 to 300) f

rom Wi schmeier and Sm

ith (1978) ma

y not ac curately reflec t site-specific c onditions. The refore,unit soil loss , X e , may be under- or ov

erestim ated. 

### K USLE erodi bility f actor ton/acre 

### Varies This va lue is site -specif

ic. We recomm

end using cur

rent guidanc e (U.S. De

partme nt of Ag riculture 1997; U.S. EPA 1985) i n determ ining wa tershed-s pecific values f or this var

iable based on site-specific i nforma tion. A def

ault value of 0.39, as

cited in NC DEHNR

(1997) and U.S. E

PA (1994), w

as based on a soil organic ma tter conte nt of 1 perc ent (Droppo et al. 1989), and chosen to be represent

ative of a whole waters

hed, not just a

n agricult ural field. The following uncertainty is associated w ith this variable: Using a s ite-spec ific USL E soil erodibility f

actor, K , may cause unit

soil loss, X

e , to be under- or

overest imated to some unknown degree.

### TABLE B-4-13 UNIVERSAL SOIL LOSS EQUATION (USLE) (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-220 LS USLE leng

th-slope f actor unitless 

### Varies This va lue is site -specif

ic. We recomm

end using cur

rent guidanc e (U.S. De

partme nt of Ag riculture 1997; U.S. EPA 1985) i n determining watershed-specific values f or this variable based on site-specific information. A value of 1.5 as cited in NC DEHNR (1997) and U.S. EPA (1994 ), reflects a variety of possible distance and slope conditions (U.S. EP A 1988), and was chosen to be represent

ative of a whole waters

hed, not just a

n agricult ural field. The following uncertainty is associated w ith this variable: A site- specific USLE le

ngth-slope f

actor, LS , may

not accura

tely r epresent site-spec ific condi tions. The

refore,unit soil loss, X

e , may be under- or overestima ted to some unknown degree. 

### C USLE cov

er ma nagem ent fac tor unitless 

### Varies This va lue is site -specif

ic. We recomm

end using cur

rent guidanc e (U.S. De

partme nt of Ag riculture 1997; U.S. EPA 1985) i n determ ining wa tershed-s pecific values f or this var

iable based on site-specific i nforma tion. The r

ange of values up to 0.1 reflec t dense ve

getativ e cover, such as pa

sture gra ss; value s from

0.1 to 0.7 ref

lect ag ricultural row crops ; and a va lue of 1.0 reflec ts bare s oil (U.S. EPA

1998). U.S. EPA

(1993) recom

mended a value of 0.1 for both g

rass and a gricultura l crops. T

his range of values w as also cited in NC DEHNR (1997). H oweve r, U.S. EPA ( 1994) and NC DE HNR (1997) both recomm ended a def

ault value of 0.1 to be r

epresenta tive of a whole waters

hed, not just a

n agricult ural field. The following uncertainty is associated w ith this variable: The USL E cover m

anagem ent fac tor, C , value de

termined may

not accura

tely r epresent site-spec ific condi tions. Theref ore, the v alue for C may result in the

under- or ove

restim ation of unit

soil loss, X

e . 

### PF USLE support ing practice fac

tor unitless 

### Varies This va lue is site -specif

ic. We recomm

end using cur

rent guidanc e (U.S. De

partme nt of Ag riculture 1997; U.S. EPA 1985) i n determining watershed-specific values f or this variable based on site-specific information. A default va lue of 1.0, which conserva tively represe nts the abse

nce of a ny eros ion or runoff

control m

easures , was cited in NC DEHNR (1997) a nd U.S. EPA (1998; 1994). The following uncertainty is associated w ith this variable: Using a s ite-spec ific USL E supporting pra

ctice f actor, PF , may result in un der- or o verestimatin g X e depending on the actual extent tha

t there ar e erosion or runoff c ontrol mea sures in the

vicinity of the w atershed e valuated. 

### 907.18 Units conve

rsion fac tor kg/ton 

### 4047 Units conve

rsion fac tor m 2 /acre

### TABLE B-4-13 UNIVERSAL SOIL LOSS EQUATION (USLE) (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

B-221 REFERENCES AND DISCUSSION Droppo, J.G . Jr., D.L . Strenge, J.W. Buc k, B.L. H oopes, R.D. B rockhaus, M.B. Walt er, and G . Whelan. 1989. Multimedia E nvironmental Pollutant Asse ssment Sy stem ( MEPAS) Applic

ation Guidance: Volume 2-Guidelines for Evalu ating MEPAS Input Para meters . Pacific Northwe st Labora

tory. Ri chland, Wa

shington. Decembe

r. This docum

ent is cit ed by U. S. EPA 1994 and NC DEHNR 1997 a

s the ref erence s ource for

a USLE e

rodibility factor value of

0.36, based on a

soil organic matt

er content of

1 percent. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment recommended the followin g:

C A USLE

erodibility

factor, K , value of 0.36 ton/acre

C A USLE

length-slope fact

or, LS , value of 1.5 (unitless)

C A range of USL E cover m

anagem ent fac tor, C , values of 0.1 to 1.0; it also rec omme

nded a val

ue of 0.1 to be

represe ntative of a whole waters

hed, not just a

n agricult ural field.

C A USLE

supporting pra

ctice f actor, PF , value of 1.0 U.S. Depar

tment of Agric ulture. 1997. Predicting Soi l Erosion by W

ater: A Guide

to Conserv

ation Planning With t

he Revise d Universal Soil Loss Equati on (RUSLE) . Agricultural Research Service, Agri cul tur e Han dbo ok Nu mber 703 . Jan uar y. U.S. EPA. 1985. Water Quali ty Asses sment: A Sc

reening Proc

edure for Tox

ic and Conventi

onal Pollutants in Sur

face and Ground W

ater—Part I (Revised). ORD. A thens, Georgia. EPA/600/6-85/0 02a. U.S. EPA. 1988. Superfund Exposur e Asses sment Manual. Offi ce of Solid Waste . Washing ton, D.C. A

pril. This docum

ent is cit ed by U. S. EPA 1994 and NC DEHNR 1997 a

s the ref erence s ource for

the USLE length-slope

factor, LS , value of 1.5. This value reflects a variety of possible distance and slope condi

tions and w

as chosen to be repre sentativ e of a w hole wat ershed, not j ust an agr

icultural f ield. U.S. EPA. 1993. Addendum: Methodolog y for Assessing Health Risks Associated with Indirect Exposure to Combustor Emission s. Working Group Recommendations. Office of Solid Waste and Offic e of Res earch and Developm ent. Was hington, D.C. S eptembe

r. This docu ment recommends th e following:

C A USLE

cover m anagem ent fac tor, C , of 0.1 f

or both gras s and agr

icultural c

rops

C A USLE

supporting pra

ctice f actor, PF , of 1.0, based on the assumed absence of any erosion or runoff control measures

### TABLE B-4-13 UNIVERSAL SOIL LOSS EQUATION (USLE) (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-222 U.S. EPA. 1994. Guidance for P erforming Sc

reening Lev

el Risk Anal

ysis at Com bustion Faciliti es Burning Haz

ardous Waste

s. Offic e of Em

ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Decem ber. This docu ment recommends th e following:

C A USLE

erodibility

factor, K , value of 0.36 ton/acre

C A USLE

length-slope fact

or, LS , value of 1.5 (unitless)

C A range of USL E cover m

anagem ent fac tor, C , values of 0.1 to 1.0; it recom mends a default value of

0.1 to be repre sentativ

e of a w hole wat ershed, not j ust an agr

icultural f ield.

C A USLE

supporting pra

ctice f actor, PF , value of 1.0 U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent cites Wischm eier and Sm

ith (1978) as t

he source of

averag e annual USL

E rainfa ll fact ors, RF , and state s that annua

l values range f rom les s than 50 for

the arid w

estern United State s to grea

ter than 300 f

or the southea

st. This docum

ent discuss es the USL

E cover m

anagem ent fac tor. This factor, C , primarily reflects how erosion is influenced by vegetative cover a nd cropping practices, such as planting across slope rat her than up and d own slope . This docu ment discus ses a range of C values f or 0.1 to 1.0; va

lues gre ater than 0. 1 but less tha n 0.2 are appr

opriate f or agricul tural row crops, and a value of 1.0 is appropria

te for s ites m

ostly de void of v egetation. Wischm eier, W .H., and D.D . Smith. 1978. Predicting Rainfall Erosion Los ses—A Guide

to Conserv

ation Planning. Agric

ultural Handbook

No. 537. U.S. D epartm

ent of A griculture Washing ton, D.C. This docum

ent is cit ed by U. S. EPA (1998) as the source

of ave rage annua

l USLE ra

infall f actors, RF

, compiled regionally. According to U.S. EPA (1998), annual values range from less than 50 for t

he arid w estern Uni

ted States to great er than 300 f

or the southea

st.

### TABLE B-4-14 SEDIMENT DE LIVERY RATIO (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-223 Description This equa tion calcula

tes the sediment delivery

ratio for the wat ershed; the

result is used in the s oil erosion loa d equation in Table B-4-11. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The rec omme

nded defaul

t empirical inter

cept coef ficient ( a ) values

are av erage v alues bas ed on various

studies of

sedime nt yields from various w

atersheds . Theref

ore, these default values m ay not a ccuratel y repre sent site -specif

ic wat ershed condit

ions. As a result, using these default values m

ay under - or overe stimat

e the wa tershed sediment delivery ratio, SD

. (2) The rec omme

nded defaul

t empirical slope coeff

icient ( b ) value i s based on a review of sedim ent yields from

various w

atersheds . This si

ngle def ault value may not accura

tely r epresent site-specific w

atershed conditions. As

a result,using this default v alue ma y under- or overes

timate the wat ershed sediment delivery

ratio, SD

. Equation

Varia ble Description Units Value SD Waters

hed sedim

ent delive ry rat io unitless



### a Empirica

l interce pt coeff icient unitless 

### 0.6 to 2.1 This va riable is site-specific and is determ ined on the bas is of the waters hed area (Vanoni 1975), as cited in U.S . EPA (1998): Watershed “ a ” Coeff icient Area (sq. miles) (unitless) # 0.1 2.1 1 (>0.1 but # 1.0) 1.9 10 (>1.0 but # 10) 1.4 100 (>10 but # 100) 1.2 1,000 (>100) 0.6 Note: 1 sq. m ile = 2.59 x

10 6 m

2 Using thes e values

is consist ent with U .S. EPA (1994a), U.S. EPA (1994b) , and NC DEH NR (1997). The following uncertainty is associated w ith this variable: The rec omme

nded defaul

t empirical inter

cept coef ficient, a , values are ave

rage v alues bas ed on various

studies of sedime nt yields from various w

atersheds . Theref

ore, these default values m

ay not a ccuratel y repre sent site -specif

ic waters hed conditions. As a re sult, using t hese def ault value s may

under- or ove

restim ate the w atershed s ediment delivery ratio, SD

.

### TABLE B-4-14 SEDIMENT DE LIVERY RATIO (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

Varia ble Description Units Value



### B-224 A L Total w

atershed a rea rec eiving deposition m 2 

### Varies This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific. 

### b Empirica

l slope coe ffici ent unitless 0.125 As cited in U.S. EPA (1998), this variable is an empirical constant based on the research of Vanoni (1975), which concludes that sedim

ent delive ry rat ios vary approxim

ately with neg ative one -eighth (

G 1/8) power of the dra inage ar ea. The use of thi s value is consistent

with U.S. EPA (1994a), U .S. EPA (1994b), a nd NC DEHNR

(1997). The following uncertainty is associated w ith this variable: The rec omme

nded defaul

t empirical slope coeff

icient, b , value is

based on a r

eview of sedim ent yields from

various waters heds. This

single de fault v

alue ma y not ac curately

represe nt site-specific w

atershed conditions. As

a result, use of this

default value m

ay under - or overe stimat

e the wa tershed sediment delivery ratio, SD

.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the empi

rical inte rcept coe ffici ent, a , and em pirical slope coeff

icient, b , values. This document cites U.S. EPA (1993) as the source of its inf

ormation. U.S. EPA. 1994a

. Draft Guidance for Performing Screening Level Risk Analysis at Combu stor Facilities Burning Hazardou s Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the empi

rical inte rcept coe ffici ent, a , and em pirical slope coeff

icient, b , values. This docum ent does not ide

ntify Vanoni (1975) as the source of

its infor mation. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the empi

rical inte rcept coe ffici ent, a , and the em pirical slope coeff

icient, b , va

lues . Th is d ocum ent cit es U .S. E PA (1993) as the source of

its infor mation.

### TABLE B-4-14 SEDIMENT DE LIVERY RATIO (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

B-225 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the empi

rical inte rcept coe ffici ent, a , and em pirical slope coeff

icient, b , values. This docum ent cites Vanoni (1975) as its source of inform ation. Vanoni, V.A. 1975. Sedimentation E ngineering . Am

erican Soc iety of

Civil Eng

ineers. N ew York , New Y ork. Pages

460-463. This docum

ent is cit ed by U. S. EPA (1998) as the source

of the e quation in Ta

ble B-4-14 and the empi

rical inte rcept coe ffici ent, a , and em pirical slope coeff

icient, b , values. Based on various s tudies of s ediment yields

from waters

heds, this doc

ument conc

ludes that t

he sedim ent delive ry rat ios vary approxim

ately with neg ative one -eighth (

G 1/8) po wer of the drain age ratio. U.S. EPA has not c ompleted a revie w of thi s docume

nt.

### TABLE B-4-15 TOTAL WATER

BODY CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-226 Description This equa tion calcula

tes the tot al wat er body c oncentration,including the water column a nd the bed se diment. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The default variable values recom mended for use in the equation in Table B-4-15 may not accurately re present site-specific water body conditions. The degree of uncertainty associated with the variables Vf x , A w , d

wc , and d

bs is expec

ted to be lim

ited either

because the probable r

anges f or these v ariables are narr ow or inf ormation a

llowing a ccurate estima

tes is g enerally available. (2) Uncertai

nty ass ociated w

ith f wc is largely the result of uncertainty associated with default organic carbon (OC) content values and may be significant in specific instances. Uncertainties asso ciat ed wi th t he t ota l co re lo ad i nto water bod y ( L T ) and overa

ll total w ater body core diss ipation rate

constant (

k wt ) may also be significa

nt in some

instances because of the sum

mation of many va

riable-specific uncertainties. Equation

Varia ble Description Units Value 

### C wtot Tot

al w ate r bod y C OPC concentration, including water column and bed sedim

ent g COPC/m 3 water body (equivale nt to mg COPC/L wate r bo dy) 

### L T Tot al CO PC loa d to the water bod y,

including depos ition, runoff , and erosion g/yr 

### Varies This va riable is COPC- and site -specif ic, and ca lculated us ing the equa

tion in Table

B-4-7. Unce

rtainties associat

ed with L DEP

, L Dif , L RI , L R , and L E , as pres ented in the equation in Table B-4-7, are also associat ed with L T .

### TABLE B-4-15 TOTAL WATER

BODY CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-227 Vf x Avera

ge volum etric f low rate through wa

ter body m 3 /yr 

### Varies This variable is site-specific. T he following uncertainty is associated with this variable: Default average volum

etric flow rate ( Vf x ) information may not accurately represent site-specific conditions, especia lly f or those w

ater bodies

for which flow

rate inf ormation i s not readil

y ava ilable. T herefore , using def

ault Vf

x values m ay cont ribute to under-

or overes timating total wa ter body C OPC concentra tion, C

wtot . 

### f wc Fra

cti on of tota l w ate r bod y C OPC conc entr atio n in t he wate r colu mn unitless 

### 0 to 1 This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-16. The following uncertainty is associated w ith this variable: The default values for the variables in the equation in Table B-4-16 may not accurately represent site- and water body - speci fic condit ions. Ho wever, the range of several variab les—incl uding d bs , C BS , and 2 bs —is rela

tively narrow. Other variables, such as d wc and d

z , can be re asonably

estim ated on the ba

sis of g enerally availa ble informa tion. The largest degree of uncertaint

y ma y be intr oduced by t

he defaul t medium -specif ic organic carbon ( OC ) content values. Because OC cont ent va lues may vary widel y in di fferent locat ions in th e same medi um, using default values may

result in insignificant uncertainty in specific cases. 

### k wt Overall

total wa ter body di ssipation rate const ant yr -1 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-17. The following uncertainty is associated w ith this variable: All of the varia

bles in the equation in Ta ble B-4-17 ar

e site-s pecific ; theref

ore, using de fault v

alues f or any or all of these variab les will cont ribute t o under - or overest imating C wtot . The deg

ree of unc ertainty

associa ted with t he variable K

b is expec ted to be under

one order of

magni tude and is a

ssociate d largely

with the estima

tion of the uni

t soil loss, X

e , values for the variables f wc , K v , and f

bs are depe

ndent on me dium-specific es timate s of OC content. Because OC content can vary widely for different locations in the same m edium, uncertainty associated with these three may be signif

icant in specific instances. 

### A w Water body surface area m 2 

### Varies This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . See Chapt

er 4 for procedures to determine this variable. Uncertai nties ass ociated w

ith this va riable ar e site-s pecific . Howev

er, we expect that the unce

rtainty associa ted with t his variable will be limited because m aps, aerial photographs , and other re sources f rom w hich wat er body s urface areas c an be measured, are readily av

ailable.

### TABLE B-4-15 TOTAL WATER

BODY CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-228 d wc Depth of w

ater colum

n m 

### Varies This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . The following uncertainty is associated w ith this variable: Depth of w

ater colum

n, d wc , values may not accurately reflect site-specif ic conditions, especially for those water bodies for which dep th of water col umn informati on is un available o r outdat ed. Therefore , using d wc values may contribute to unde

r-or overe stimat

ing total w

ater body COPC concentr

ation, C

wtot . 

### d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . We re comm

end a def ault upper benthic s ediment depth of 0.03 m eter, w hich is consi stent wi

th U.S. EPA (1994)

and NC DEH

NR (1997) guida

nce. This value was cited by

U.S. EPA (1993); however, no reference was presented. U.S. EPA (1998) suggests a range of values, from 0.01 to 0.05 meters. The following uncertainty is associated w ith this variable: Default d

bs values m

ay not a ccuratel y repre sent site -specif

ic wat er body c onditions. How ever, ba sed on the na

rrow recomm ended range , we ex

pect any uncertaint

y introduc ed to be lim

ited.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is als o cited as

one of the

refer ence sourc e docume

nts for the

default depth of upper

benthic lay

er value . The def

ault value is the m idpoint of an a

cceptable range. T his document cites U.S. E

PA (1993) as i

ts source of inform

ation for t he range of value s for the depth of the

upper benthic layer

. U.S. EPA. 1993. Addendum: Methodology for Assessing He alth Risks Associated w

ith Indirect

Exposure to Combustor Emi ssions. Working Group Rec omme ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. S eptembe

r 24. This docum

ent is cit ed by NC DEHNR (1997)

and U.S. EPA (1994) as the source of the range and defa ult value f

or the depth of

the upper bent

hic lay er ( d bs ). U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combu stor Facilities Burning Hazardou s Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April 15. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the defa

ult depth of t

he upper benthic

laye r value. The def

ault value is the m idpoint of an a

cceptable range. T his document cites U.S. E

PA (1993) as i

ts source of inform

ation for t he range of value s for the depth of the

upper benthic layer

.

### TABLE B-4-15 TOTAL WATER

BODY CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-229 U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent is cit ed as the source of

a range of value s for the

depth of the

upper benthic layer

( d bs ).

### TABLE B-4-16 FRACTION IN WATER COLUMN AND BENTHIC SEDIM ENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 o f 5)

B-230 Description This equa tion calcula

tes the f raction of total wa ter body concentration occurring i n the wat er colum n and the bed s ediments

. Uncertain ties associ ated with th is equati on incl ude the fol lowing:

The default var iable valu es may not accuratel y represent sit e-specific water b ody condi tions. However, the ran ge of several variab les—incl uding d bs , C BS , and 2 bs —is rela

tively narrow. Other variables, such as d wc and d

z , can be re asonably

estim ated on the ba

sis of g enerally availa ble inform

ation. The

larges t degree of uncert ainty m ay be i ntroduced by

the defa ult medium -specif ic OC conte

nt values

. OC content values can vary widely for different locations in the same m edium. Therefore, the use of defa ult values may introduce significant uncertainty in some cases. Equations

Varia ble Description Units Value 

### f wc Fra

cti on of tota l w ate r bod y C OPC conc entr atio n in t he wate r colu mn unitless 

### f bs Fra

cti on of tota l w ate r bod y C OPC concentrat

ion in benthic s ediment unitless

### TABLE B-4-16 FRACTION IN WATER COLUMN AND BENTHIC SEDIM ENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 o f 5)

Varia ble Description Units Value



### B-231 Kd sw Suspended sediments/surface water partition coe ffici ent L water/kg suspended sedime nt (or cm 3 water/kg suspended sedime nt) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: Kd sw values i n the HHRA

P companion da

tabase a re based on default OC

contents f

or surfac e wate

r and soil. Kd sw values ba sed on def

ault value s may

not accura

tely r eflec t site- a nd water body-spe cific c onditions and m ay under

or overes timate actual Kd

sw values. You can re duce uncert ainty a ssociate d with Kd sw by using

site-spe cific a

nd medium-specific OC

estimates to calculate Kd sw . 

### TSS Total sus

pended solids concentrat

ion mg/L 

### 2 to 300 This va riable is site-specific. W

e recom mend using

site- and waterbody

specif ic mea sured val ues, repre sentativ

e of long- term averag e annual v

alues f or the wa ter body of

concern (s ee Chapte

r 5). A v alue of 10 mg/L

was c ited by N

C DEHNR ( 1997) and U.S. EPA (1993) in the absence of site-specific measured data. The following uncertainty is associated w ith this variable: Limitation on measured data used for determining a w ater body specific total suspended solids ( TSS ) value m ay not accurately ref

lect site - and wa

ter body- specific conditions long term . Theref ore, the TSS value m

ay cont ribute to under- or overesti mating f wc . 

### 1 × 10
- 6 Units conve

rsion fac tor kg/mg


### d wc Depth of w

ater colum

n m 

### Varies This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . The following uncertainty is associated w ith this variable: Depth of w

ater colum

n, d wc , values may not accurately reflect site-specif ic conditions, especially for those water bodies for which dep th of water col umn informati on is un available o r outdat ed. Therefore , using d wc values may contribute to unde

r- or over estima ting total w

ater body COPC concentr

ation, C

wtot .

### TABLE B-4-16 FRACTION IN WATER COLUMN AND BENTHIC SEDIM ENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 o f 5)

Varia ble Description Units Value



### B-232 d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . We re comm

end a def ault upper benthic s ediment depth of 0.03 m eter, w hich is consi stent wi

th U.S. EPA (1994)

and NC DEH

NR (1997) guida

nce. This value was cited by

U.S. EPA (1993); however, no reference was presented. U.S. EPA (1998) suggests a range of values, from 0. 01 to 0.05 met

er. The following uncertainty is associated w ith this variable: A def ault d

bs value m ay not a ccuratel y repre sent site -specif

ic wat er body c onditions. How ever, w e expec t any uncertainty introduced to be limited on the basis of the narrow recommended range. 

### d z Total w

ater body depth m 

### Varies This va riable is site-specific. W

e recom mend using

the follow

ing equation t

o calculat e total w ater body depth, consis

tent with NC DEHNR (1997): d z = d

wc + d

b s The following uncertainty is associated w ith this variable: Calculating this variable sums the concentrations associated with the two variables d wc and d

bs . Becaus e most of the total wa ter body de

pth ( d

z ) is ma de up of the

depth of the

water column ( d wc ), and we don’t expect the uncertainties associat ed with d

wc to be signi ficant, we lik ewise don’t expec

t the total unc ertaintie s associ ated wi th d z to be signifi cant. 

### C BS Bed sediment concentration (or bed

sed imen t bu lk d ens ity) g/cm3 (equivale nt to kg/L) 

### 1.0

This va riable is site-specific. W

e recom mend a de fault v

alue of 1. 0, consistent

with U.S. EPA (1998), w hich state s that this val ue s houl d be reasona

ble for mos t ap plic ati ons. The

rec omm ended def ault val ue i s al so c onsi ste

nt w ith o ther U.S . EPA (1994), and NC DEHNR (1997) guidan ce. The following uncertainty is associated w ith this variable: The recommended default va lue may not accurately

represent site- and water body-specific conditions. Therefore, the variable f

wc may be under- or ov

erestim ated. Bas ed on th narrow recom mended r ange, w e expec t the under- or overesti mation w ill be lim ited.

### TABLE B-4-16 FRACTION IN WATER COLUMN AND BENTHIC SEDIM ENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 o f 5)

Varia ble Description Units Value



### B-233 2 bs Bed sedim

ent porosity L water /L sediment 

### 0.6 This variable is site-specific. We recommend a defa

ult bed sediment porosity of 0.6 (by using a C BSvalue of 1 g/cm 3 and a sol id d ens ity ( D s ) value of 2.65 kg/L

) calcula ted by us ing the f

ollowing equation (U.S. EPA 1998):
2 bs = 1 - C

BS/ D s This is consistent with other U.S. EPA (1994), and NC DEHNR (1997) guid ance. The following uncertainty is associated w ith this variable: Calculation of this v

ariable c ombines t

he uncerta

inties as sociated w

ith the tw o variable s, C

BSand D s , used in the calculati on. To th e extent tha t the recommend ed default val ues of C BSand D s don’t accur

ately represe nt site- a nd water body-specific conditions, 2 bs will be under- or ove restim ated. 

### Kd bs Bed sediment/sediment pore water partition coe ffici ent L water/kg bottom sedime nt (or cm 3 water/ g bottom sedime nt) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The Kd

bs values i n the HHRA

P companion da

tabase a re based on default

OC contents f

or sedim ent and soil. Kd bs values ba sed on def

ault OC values may not accurately represent site- and water body-specif ic conditions and may under- or ove

restim ate actua l Kd bs values. Uncertai

nty ass ociated w

ith this va riable w ill be reduc ed if sit

e- and water body-specificOC estimates are used to calculate Kd bs .

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment is cited as one of the so urces of the range o f Kd s values TSS values. This docum

ent cites U.S. EPA (1993b)

as its s ource of i

nforma tion. the equation f

or calcula ting total w

ater body depth. No sour

ce of thi s equation w

as identif ied. the defa ult value f

or bed sedim

ent porosity . This docum ent cites U.S. EPA (1993b)

as its s ource of i

nforma tion. the defa ult value f

or depth of t

he upper benthic

laye r. The de fault v

alue is the

midpoint of

an acce ptable rang

e. This doc

ument ci tes U.S. EPA

(1993b) as its

source of inform ation for the ra nge of v alues f or the depth of

the upper bent

hic lay er. the defa ult bed sedim

ent concentr

ation. This

document cites U.S . EPA (1993b) as its source

of infor mation.

### TABLE B-4-16 FRACTION IN WATER COLUMN AND BENTHIC SEDIM ENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 o f 5)

B-234 U.S. EPA. 1993. Addendum: Methodology for Assessing He alth Risks Associated w

ith Indirect

Exposure to Combustor Emi ssions. Working Group Rec omme ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. S eptembe

r. This document is cited by NC DEHNR (1997) as the source of the TSS value. This document is also cited by NC DEHNR (1997) and U.S. EPA (1994) as the source of the default bed sediment porosity value and the equation used to calculate C BS , and the ra

nge for the depth of

the upper bent

hic lay er value s. U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combu stor Facilities Burning Hazardou s Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the defa ult value f

or bed sedim

ent porosity . This docum ent cites U.S. EPA (1993b)

as its s ource of i

nforma tion. the defa ult value f

or depth of t

he upper benthic

laye r. The de fault v

alue is the

midpoint of

an acce ptable rang

e. This doc

ument ci tes U.S. EPA

(1993b) as its

source of inform ation for the ra nge of v alues f or the depth of

the upper bent

hic lay er. the defa ult bed sedim

ent concentr

ation. This

document cites U.S . EPA (1993b) as its source

of infor mation. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docu ment is cited as one of the so urces of the equ ati on f

or c alcu lat ing bed sed imen t po ros ity ( 2 bs ); no source of this equa tion was identified. the range of the be d sedime

nt concentra

tion ( C

BS ); no origina

l source of

this range was

identified.

### TABLE B-4-17 OVERALL TOTAL WATER BODY DISSIP ATION RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 2)

B-235 Description This equa tion calcula

tes the ov erall COPC dissipation r

ate in surf

ace w ater due to volatilization and benthic burial. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) All of the variab les in the eq uation in Table B-4 -17 are sit e-specific. Therefore, usi ng default val ues for any or all of these variab les will cont ribute t o under - or overest imating k wt . We expect the uncertainty associated with the variable k b to be one orde

r of m agnitude a

t most. This unce

rtainty is assoc iated w

ith the est imation of

the unit soil loss, X e (a componen t of k b ). Values for the variables f wc , k v , and f

bs are dependent on medium-specific estimates of medium-specific OC content. Because OC content can vary widely for dif ferent locations in t

he same medium, uncertainty associated with these three variables m ay be significant in specific instances.

Equation

Varia ble Description Units Value 

### k wt Overall

total wa ter body di ssipation rate const ant yr -1 

### f wc Fra

cti on of tota l w ate r bod y C OPC conc entr atio n in t he wate r colu mn unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-16. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The def

ault vari able val

ues we recom mend y ou use in the equation in Ta ble B-4-16 m

ay not a ccuratel y repre sent site-speci fic water body con dition s. However, th e ranges of several componen t variables— includ ing d bs , C BS , and 2 sw —are moderate (factors of 5, 3, and 2, respectively). We therefore expect the degree of uncertainty associated with these variables to be moderate. You can reasonably es timate other variables, such as d wc and d

z , using generally av

ailable inf

ormation. We ther

efore e xpect the degree of uncerta

inty as sociated w

ith these v

ariables to be relati vely small. (2) The larg

est degr ee of unc ertainty

may be introduced by the de fault m edium-specific

OC content va

lues. OC content va

lues are often not readily a vailable and can va

ry w idely f or diffe rent locat ions in the sa

me m edium. Therefore, the degree of uncertainty m ay be significant in specific instances.

### TABLE B-4-17 OVERALL TOTAL WATER BODY DISSIP ATION RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 2)

Varia ble Description Units Value



### B-236 k v Water c olumn vola tilization r

ate constant yr -1 Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-18. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) All of the varia bles in the equation in Ta ble B-4-18 ar

e site-s pecific . Theref

ore, using de fault v

alues f or any or all of these variab les could contrib ute to un der- or o verestimatin g k v . (2) We expect the deg ree of unc ertainty

associa ted with k

v components d z and TSS to be minimal, either because informa tion needed to estima

te these variable s is gene

rally available or beca

use the ra nge of li kely values i s narr ow. (3) Values for the variable k v and Kd

sw are depe

ndent on me dium-specific es timate s of OC content. Because OC content can vary widely for different locations in the same m edium, uncertainty associated with these two va riables may be signif icant in specific i

nstances. 

### f bs Fra

cti on of tota l w ate r bod y C OPC concentrat

ion in benthic s ediment unitless Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-16. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The def

ault vari able val

ues we recom mend y ou use in the equation in Ta ble B-4-16 m

ay not a ccuratel y repre sent site-speci fic water body con dition s. However, th e ranges of several componen ts—inclu ding d bs , C BS , and 2 sw —are relative ly narr ow. We therefor e expec t the degr ee of unc ertainty

associa ted with t hese va riables to be relati

vely small. You can reasonably estim ate other components, such as d wc and d

z , using ge

nerally availa ble inform

ation. (2) The larg

est degr ee of unc ertainty

may be introduced by the de fault m edium-specific

OC contact v

alues. OC content va

lues are often not readily a vailable and can va

ry w idely f or diffe rent locat ions in the sa

me m edium. Therefore, the degree of uncertainty m ay be significant in specific instances. 

### k b Benthic buria l rate cons

tant yr -1 Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-22. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) All of the variables in the equation in Table B-4-22 are site-specific. Theref ore, using default values rather than site-speci fic values, for an y or all of these var iables, will contrib ute to un der- or o verestimatin g K b . (2) The deg

ree of unc ertainty

associa ted with each of the se vari ables is a s follows: (1) X e —about one orde

r of magnit ude at m ost, (2) C

BS , d bs , Vf x , TSS, and A w —limited because of the narrow recomm ended ranges for these variable s or becaus e resourc es to esti mate v ariable v alues are general ly av ailable, a nd (3) A L and SD—very site-specific, degree of

uncertaint

y unknow n.

### TABLE B-4-18 WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-237 Description This equat ion calcu lates the water column COP C loss rate co nstant d ue to vola tilizati on. Uncer tainty associ ated with th is equati on incl udes the fo llowing: All of the variab les in the eq uation in Table B-4 -18 are sit e-specific. Therefore, usi ng default val ues for any or all of these variab les will cont ribute t o under - or over est imating k v . We expect the uncertainty associated with the variables d wc , d bs , and d

z to be mini

mal, either beca

use inform

ation neces sary to estim

ate these variable s is gene

rally available or beca

use the range of probable values is narrow. Values for the variables K v and Kd

sw are depend ent on medi um-specific est imates of OC content. Because OC

content ca

n vary widely for dif ferent locations in the same medium, uncertainty associated with these two variables may be significant in specific instances. Equation

Varia ble Description Units Value 

### k v Water c olumn vola tilization r

ate constant yr -1



### K v Overall

COPC transf

er rate coeff icient m/yr 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-19. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) All of the varia bles in the equation in Ta ble B-4-19—e

xcept R , the univer

sal gas constant, w

hich is well-e stablished—

are site -specif

ic. Ther efore, using defa

ult values , for any

or all thes e varia

bles, could c ontribute to under- or overesti mating K v . (2) We expect the degree of uncertainty associated with the variables H and T

wk to be mini

mal. Va lues for H are well-e stablished,and T wk will lik ely v ary le ss than 10 per

cent of t he defaul t value. (3) The uncertainty associated with the variables K L and K

G is attribut

able larg ely to m edium-specific e stimat

es of org anic carbon , OC , content. Because OC content va

lues can v

ary w idely f or diffe rent locat ions in the sa

me m edium, us ing default v alues m ay ge nerate significa

nt uncertai

nty in specific i

nstances. Finally, the origin of the recomm ended tem

perature c orrection f

actor, 2 , value is

unknown. T

he degree of associated uncer

tainty i s theref

ore also unknow

n.

### TABLE B-4-18 WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-238 d z Total w

ater body depth m 

### Varies This variable is site-specific. We recommend using the following equation to calculate d z , consistent

with NC DEHNR (1997): d z = d

wc + d

bs The following uncertainty is associated w ith this variable: Calculating this variable sums the concentrations associated with the two variables d wc and d

bs . Becaus e most of the total wa ter body de

pth ( d

z ) is ma de up of the

depth of the

water column ( d wc ), and we don’t expect the uncertainties associat ed with d

wc to be signi ficant, we lik ewise don’t expec

t the total unc ertaintie s associ ated wi th d z , to be signifi cant. 

### d wc Depth of w

ater colum

n m 

### Varies This variable is site-specific. The following uncertainty is associated w ith this variable: Default values f or depth of w

ater colum

n, d wc , may not accurately

reflect site-specific conditions, especially f or water bodies for which dept

h of wa ter colum n inform ation is unav

ailable or outdated. T

herefore , using def

ault d

wc values may contribute to under- or ove restim ating tota l wate r body COPC concentration, C wtot . Howev

er, we don’t expec

t the degree of under- or ove

restim ating to be signifi cant. 

### d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. T

he value you select repres ents an av erage v alue for the entire

year . We re comm

end a def ault upper benthic s ediment depth of 0.03 m eter, w hich is consi stent wi

th U.S. EPA (1994)

and NC DEH

NR (1997) guida

nce. T his value w as cited by U.S. E

PA (1993); how

ever, no r efere nce was presented. U.S. EPA ( 1998) sugge sts a ra nge of v alues, f rom 0.01 to 0.05 me

ter. The following uncertainty is associated w ith this variable: A def ault d

bs value m ay not a ccuratel y repre sent site -specif

ic wat er body c onditions. How ever, w e expec t any uncertainty introduced to be limited on the basis of the narrow recommended range.

### TABLE B-4-18 WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-239 Kd sw Suspended sediments/surface water partition coe ffici ent L water/kg suspended sedime nts 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The Kd

sw values pr

esented in the HHRA

P companion da

tabase w ere calculated on the

basis of default OC

contents f

or surfac e wate

r and soil. Kd sw values ba

sed on def

ault value s may

not accura

tely r eflec t site-and water body-specific conditions and m

ay under - or overe stimat

e actual Kd

sw values. You can re duce uncert ainty a ssociate d with this variable by using site-specific and m edium-specific OC

estimates to calculate Kd sw . 

### TSS Total sus

pended solids concentrat

ion mg/L 

### 2 to 300 This va riable is site-specific. W

e recom mend using

site- and waterbody

specif ic mea sured val ues, repre sentativ

e of long- term averag e annual v

alues f or the wa ter body of

concern (s ee Chapte

r 5). A v alue of 10 mg/L

was c ited by N

C DEHNR ( 1997) and U.S. EPA (1993) in the abse nce of s ite-spec ific m

easured da

ta. The following uncertainty is associated w ith this variable: Limitation on measured data used to determine a w ater body specific total suspended solids ( TSS ) value m ay not accurately reflect site- and water body-specific conditions long term. Theref ore, the TSS value m

ay cont ribute to under- or overesti mating f wc . 1 × 10 -6 Units conve

rsion fac tor kg/mg

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docum

ent is cit ed as the source of

the equation for calc

ulating tota

l wate r body depth. No source of this equa tion was identified. This docum ent is als o cited as

one of the

sources of

the range of Kd s values a nd an assum

ed OC value of 0.075 for surf

ace w ater. T his docume

nt is also cited as one

of the sour

ces of TSS . This docum

ent cites U.S. EPA (1993b)

as its s ource of informa tion. U.S. EPA. 1993. Addendum: Methodolog y for Assessing Health Risks Associated with Indirect Exposure to Combustor Emission s. Working Group Rec omme

ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. S eptembe

r. This docum

ent is cit ed by U. S. EPA (1994) and NC DEHNR (1997) as the

source of the range and defa ult value f

or the depth of

the upper bent

hic lay er ( d bs ). This doc

ument is also cited by NC DEHNR (1997) as the source of the TSS value.

### TABLE B-4-18 WATER COLUMN VOLATILIZATION LOSS RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-240 U.S. EPA. 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facility Bur ning Hazardous W

astes. Att achment C, D

raft Exposure

Assessm ent Guidance for RCRA Hazardous Was te Combustion Facility . April 15. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the defa

ult value of

the depth of

the upper bent

hic lay er. The default v

alue is the

midpoint of

an acce ptable rang

e. This document cites U.S. E

PA (1993b) as i

ts source of inform

ation. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber.

### TABLE B-4-19 OVERALL COPC TRANSFER RATE COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-241 Description This equa tion calcula

tes the ov erall tra nsfer ra te of cont aminants from the liquid and g

as phases in surfa ce wa ter. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) All of the varia bles in the equation in Ta ble B-4-19—e

xcept R , the univer

sal gas constant, w

hich is w ell-esta blished—are

site-spe cific. Theref

ore, using de fault v

alues f or any or all of these variab les will cont ribute t o under - or overest imating K v . (2) We believe the degree of uncertainty associated with the variables H and T

wk to be mini

mal. Va lues for H are w ell-esta blished, and T wk will lik ely v ary le ss than 10 per

cent of t he defaul t value. (3) The uncertainty associated with the variables K v and K

G is attribu table largel y to medium-speci fic estimates of OC content. Because OC

content va

lues can v

ary w idely f or diffe rent locations in the sam

e medium , using def

ault value s may

generat e signif icant uncer

tainty i n specif ic instanc es. Finall

y, the or igin of the

recom mended v alue is unk

nown; there fore, the degree of associa ted uncerta

inty is also unknow

n. Equation

Varia ble Description Units Value 

### K v Overall

COPC transf

er rate coeff icient m/yr

### TABLE B-4-19 OVERALL COPC TRANSFER RATE COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

Varia ble Description Units Value



### B-242 K L Liquid phase

transfe r coeff icient m/yr 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-20. Uncertain ties associ ated with th is variable i nclude t he followin g:

All of the variables in the equation in Table B-4-20 are site-specific. Theref ore, using default values rather than site-speci fic values, for an y or all of these var iables, will contrib ute to un der- or o verestimatin g K v . The deg

ree of uncertainty associated with these variables is as f ollows: a) We assume the uncertainty a ssociated with six variables— D w , u , d

z , D a , D w , and μ w —is mini

mal or insignif icant, eit her becaus e of narr

ow recom mended r anges f or these v ariables or because

inform ation to estimate variable values is generally available. b) No original

sources w

ere identi fied f

or the equations used to der ive rec omme

nded values

or specif ic recommended values for v ariables C

d , k , and 8 z . Therefore, the degree and direction of any uncertainties associat ed with the se vari ables are unknown. c) Uncertainties associated with the variable W are site -specif

ic. 

### K G Gas phase transf er coef ficient m/yr 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-21. Uncertain ties associ ated with th is variable i nclude t he followin g:

All of the variab les in the eq uation in Table B-4 -21, with the excepti on of k, are sit e-specif ic. Ther efore, using default v alues rat her than sit

e-specif ic value s, for a

ny or all of these variable s, will contribute to under - or overestimati ng K G . The degree of uncertainty ass ociated with each of these variables is as follows: a) We assume the uncertainty a ssociated with the variables D a , μ a , and D a , is minimal or insignificant, because these va riables ha ve been e xtensiv ely st udied, and equa

tion procedure s are w

ell-esta blished. b) No original

sources w

ere identi fied f

or equations us ed to deriv e recom mended v alues or s pecific recommended values for v ariables C

d , k , and d

z . Therefore, the degree and direction of any uncertainties are unknow

n. c) Uncertainties associated with the variable W are site -specif

ic and cannot

be readily

estim ated. 

### H Henry’ s Law constant atm-m 3 /mol 

### Varies

This variable is COPC-specific. We discuss this variable in detail in detail in Appendix A-2, and offe r COPC-specific values in the HHRAP companion database. The following uncertainty is associated w ith this variable: Values for

this variable, est

imated using the pa

ramet ers and al gorithms in Appendix

A-2, m ay under - or overe stimat

e the actual COPC-speci fic va

lues. A s a resul

t, K v may be under- or overestima ted to a limited degree.

### TABLE B-4-19 OVERALL COPC TRANSFER RATE COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

Varia ble Description Units Value



### B-243 R Universa

l gas cons tant atm-m 3 /mol-K 

### 8.205 x 10 G 5

There a re no uncert

ainties a ssociate d with this

constant. 

### T wk Water body

temper ature K 

### 298 This va riable is site-specific. W

e recom mend using

this defa ult value w

hen site-s pecific inform ation is not a

vailable ; this is consistent with U.S. EPA (1994) and U .S. EPA (1998). The following uncertainty is associated w ith this variable: To the extent that the default water body tem perature value does not accurately represent site- and water body-specific condi

tions, K

v , will be under- or ove

restim ated. 

### 2 Tempe

rature cor rection f actor unitless 

### 1.026 This va riable is site-specific. W

e recom mend using

this defa ult value w

hen site-s pecific inform ation is not a

vailable . This is consistent with U.S. EPA (1994) and U .S. EPA (1998). The following uncertainty is associated w ith this variable: The purpose

and sources

of this v ariable a nd the recom

mended v alue are unknown.

REFERENCES AND DISCUSSION U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes

. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This document is cited as the reference source f or water body temperature ( T wk ) and tem

perature c orrection f

actor ( 2 ). This doc

ument appa

rently cites U.S . EPA (1993a) a s its sourc e of informa tion. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This document is the reference source for the equation in Table B-4-19. This document also recomm ends the T

wk value of 298 K (298 K = 25°C) and the 2 value of 1.026. No source was identified for these values.

### TABLE B-4-20 LIQUID PHASE TRANSFER COEF FICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 5)

B-244 Description This equa tion calcula

tes the ra te of COPC transfe

r from the liquid phas e for a flowing or quiesce

nt wate r body. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) We ass

ume unce rtainly associa ted with t he follow ing six v ariables is minim al or insig nificant: D w , u, d z , D a , D w , and μ w . (2) No original

sources w

ere identi fied f

or equations us ed to deriv e recom mended v alues or s pecific recom mended v alues f or the following three varia bles: C

d , k , and d

z . Theref ore, the degree a nd duration of any unce

rtainties associat

ed with the se vari ables is unk nown. (3) Uncertainties associated with the variable W are site-specific. Equation For flow ing strea ms or ri vers

For quiesce

nt lakes or ponds

Varia ble Description Units Value 

### K L Liquid phase transfer

coeff icient m/yr

### TABLE B-4-20 LIQUID PHASE TRANSFER COEF FICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 5)

Varia ble Description Units Value



### B-245 D w Diffusivity of C OPC in water cm 2 /s 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The def ault D w values m

ay not a ccuratel y repre sent the be

havior of COPCs under w

ater body -specif ic conditions. Howeve r, we e xpect the degree of uncerta

inty to be minim al.



### u Current velocity m/s 

### Varies This va riable is site-specific, a

nd relates to the volum

etric f low rate of the w aterbody evaluat ed. The following uncertainty is associated w ith this variable: Sources of values for this variable are reasonably available for most large surface water bodies. Estimated values for this vari able may be necessary for small er water bodi es; uncert ainty will be asso ciated with these estimates . We don’t expec

t the degr ee of unc ertainty

associa ted with t his varia ble to be sig

nificant. 

### d z Total w

ater body depth m 

### Varies This va riable is site-specific, a

nd, in most cases, represent s the ave rage m ean acros s the wa

terbody e valuated. We recomme

nd that you c alculate

this value

using the f

ollowing equation, consis tent with U.S. EPA (1994) and NC DEHN R (1997): d z = d wc + d

bs No refe rence w as cited for this r

ecomm endation. The following uncertainty is associated w ith this variable: Calculating this variable sums the concentrations associated with the two variables d wc and d

bs . Becaus e most of the total wa ter body de

pth ( d

z ) is ma de up of the

depth of the

water column ( d wc ), and the unc ertaintie s associ ated wi th d wc are not ex

pected to be

significant, we

likew ise don’t ex

pect the tot

al uncerta inties as sociated w

ith d z to be signifi cant. 

### 3.1536 x 10 7 Units conve rsion fac tor s/yr

### TABLE B-4-20 LIQUID PHASE TRANSFER COEF FICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 5)

Varia ble Description Units Value



### B-246 C d Drag coe ffici ent unitless 

### 0.0011 This va riable is site-specific. W

e recom mend a de fault v

alue of 0. 0011, consistent with U.S. EPA (1994), NC DEHNR (1997) , and U.S. EPA ( 1998). The following uncertainty is associated w ith this variable: The original source of this variable value is unknown. Therefore, any uncertainties associated with its use are also unknown. 

### W Average annual wind speed m/s 

### 3.9 Consistent w

ith U.S. EPA ( 1998), we recomm end a def ault value of 3.9 m /s. See C hapter 3 f or guidance

regarding

the references and methods use d to dete rmine a site-sp ecific value th at is consi stent with air disper sion model ing. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for t his varia ble are not available, defa ult values may not accura

tely represent site-spe cific c onditions. The uncertaint

y ass ociated w

ith the sel ection of a single value f rom w ithin the range of winds peeds at a sin gle locatio n may be more significan t than th e uncertai nty associated with choo sing a single w indspeed to re

present al l locations. 

### D a Density of air g/cm3 

### 0.0012 We rec omme

nd this defa

ult value w

hen site-s pecific inform ation is not a

vailable . This is

consistent

with U.S. EPA (1994) and NC DEHNR

(1997), both of w

hich cite W

east (1979) a

s the sourc e of this value. T his value applies a t standard c onditions (25°C or 298 K

and 1 atm

or 750 mm

Hg). The density of air will v

ary with tempera

ture. 

### D w Density of water g/cm3 

### 1 We rec omme

nd this defa

ult value, consistent with U.S. EPA (1994) and N C DEHNR ( 1997), both of w hich cite W

east (1979) as the sour

ce of thi s value. This va

lue applies

at standa rd conditions (25° C or 298 K and 1 a tm or 750 m

m Hg) . There is no significant uncertainty associated with this variable. 

### k von Karm an’s consta

nt unitless 

### 0.4 This va lue is a c onstant. W

e recom mend using

this value , consistent

with U.S. EPA (1994) and N C DEHNR ( 1997). The following uncertainty is associated w ith this variable: The original source of this variable value is unknown. Therefore, any uncertainties associated with its use are also unknown.

### TABLE B-4-20 LIQUID PHASE TRANSFER COEF FICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 5)

Varia ble Description Units Value



### B-247 8 z Dimensionless viscous sublayer

thickness unitless 

### 4 This va lue is site -specif

ic. We recomm

end using this

default value w

hen site-s pecific inform ation is not a

vailable ; consiste

nt with U.S. EPA (1994) and N C DEHNR ( 1997). The following uncertainty is associated w ith this variable: The sourc e of the value f

or this var

iable is unk

nown. The

refore,any unce

rtainties associat

ed with it s use ca nnot be quantified. 

### : w Viscosity of water

corresponding to water temper ature g/cm- s 

### 1.69 x 10 G 02 We recomme

nd this default value, consistent with U.S. EPA (1994) and NC DEHNR (1997), which both cite Weast (1979) as the source of this v

alue. This value a pplies at s

tandard condit

ions (25°C or

298 K and 1 atm

or 760 mm

Hg). T here is no significant uncertainty associated with this variable.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment is cited as one of the so urces of the r ange of D w values a nd assum ed C d , D a , D w , k, " 8 , and : w values of 0.0011, 1.2 x 10 -3 , 1, 0.4, 4, and 1.69 x 10 -2 , respect

ively . This document cites (1) Weast (1979 ) as its sou rce of informati on regard ing D a , D w , and μ w ; and (2) U.S. EP A (1993a) as its sour ce of informatio n regardin g C d, k, and d

z . U.S. EPA. 1993a

. Addendum: Methodology for Assessi ng Health Risk

s Associate

d with Indirect Exposure t o Combustor Em issions . Working Group Rec omme

ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r 24. This docum

ent is cit ed by U. S. EPA (1994) and NC DEHNR (1997) as the

source of the recom

mended dr

ag coef ficient ( C

d ) value of

0.0011 and the re comm

ended von Ka

rman’s constant (

k ) value of 0.4. The original sourc es of v ariable v alues are not identif

ied. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes

. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docu ment is cited as one of the so urces of the r ange of D w values a nd assum ed C d , D a , D w , k, 8 z , and : w values of 0.0011, 1.2 x 10 -3 , 1, 0.4, 4, and 1.69 x 10 -2 , respect

ively . This document cites (1) Weast (1979 ) as its sou rce of informati on regard ing D a , D w , and μ w ; and (2) U.S. EP A (1993a) as its sour ce of informatio n regardin g C d, k, and d

z . U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-4-20 LIQUID PHASE TRANSFER COEF FICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 5 of 5)

B-248 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent recom mends a value of 0.0011 for the drag coef

ficient ( C

d ) variable and a va

lue of 0.4 f

or von Karm

an’s consta

nt ( k ). No sources are cited for these values. Weast,R. C. 1979. CRC Handbook of Chemistry and Physics . 60th ed. CRC Press, Inc. Clevela

nd, Ohio. This docu ment is cited as the sour ce of D a , D w , and μ w variable s of 1.2 x 10 -3 , 1, and 1.69 x 10 -2 , re spe cti vely.

### TABLE B-4-21 GAS PHASE TRANSFER COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-249 Description This equat ion calcu lates the rat e of COPC tr ansfer from the gas p hase for a flowin g or quies cent water bo dy. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Minimal or insignificant uncertainty is assumed to be associated w ith the variables D a , μ a , and D a . (2) No original sources were identified for equations used to derive recommended values or specif ic recommended values f

or variables C d , k, and 8 z . Theref

ore, the deg

ree and dir

ection of any unce rtainties associat

ed with the se vari ables are unknown. (3) Uncertainties associated with the remaining variables are site-specific. Equation Flowing s treams or rive

rs

Quiescent lakes or ponds

Varia ble Description Units Value 

### K G Gas phase transf er coef ficient m/yr 

### C d Drag coe ffici ent unitless 

### 0.0011 This va riable is site-specific. W

e recom mend using

this defa ult value w

hen site-s pecific inform ation is not a

vailable , consistent with U.S. EPA (1994), NC DEHNR (1997),and U.S. EPA (1998). The following uncertainty is associated w ith this variable: The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also unknown.

### TABLE B-4-21 GAS PHASE TRANSFER COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-250 W Average annual wind speed m/s 

### 3.9 Consistent with U.S. EPA (1998), we recommend a default value of 3.9 m/s. See Chapter 3 of the HHRAP for guidance regarding t he references an d methods u sed to det ermine a site-sp ecific value th at is consi stent with air disper sion model ing. The following uncertainty is associated w ith this variable: To the ex tent that s ite-spec ific or local val ues for t his varia ble are not available, defa ult values may not accura

tely represent site-spe cific c onditions. The uncertaint

y ass ociated w

ith the sel ection of a single value f rom w ithin the range of winds peeds at a sin gle locatio n may be more significan t than th e uncertai nty associated with choo sing a single w indspeed to re

present al l locations. 

### k von Karm an’s consta

nt unitless 

### 0.4 This va lue is a c onstant. W

e recom mend using

this value , consistent

with U.S. EPA (1994) and N C DEHNR ( 1997). The following uncertainty is associated w ith this variable: The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also unknown. 

### 8 z Dimens ionless vi scous

sublayer thickness unitless 

### 4 This va lue is site -specif

ic. We recomm

end using this

default value w

hen site-s pecific inform ation is not a

vailable , consistent with U.S. EPA (1994) and N C DEHNR ( 1997). The following uncertainty is associated w ith this variable: The original source of this variable is unknown. Therefore, any uncertainties associated with its use are also unknown. 

### : a Viscosity of air g/cm- s 

### 1.81 x 10 G 04 We rec omme

nd using this default v

alue whe n site-spe cific i

nforma tion is not av

ailable, c onsistent w

ith U.S. EPA ( 1994) and NC DEHNR

(1997), both of w

hich cite W

east (1979) a

s the sourc e of thei

r inform ation. The

re is no sig

nificant uncertainty associated with this variable. 

### D a Density of air g/cm3 

### 0.0012 We rec omme

nd using this default v

alue whe n site-spe cific i

nforma tion is not av

ailable, c onsistent w

ith U.S. EPA ( 1994) and NC DEHNR

(1997), both of w

hich cite W

east (1979) a

s the sourc e of this value. T his value applies a t standard c onditions (25°C or 298 K and 1 atm or 760 mm Hg )

. The density of air will v

ary with tempera

ture.

### TABLE B-4-21 GAS PHASE TRANSFER COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-251 D a Diffus ivity of COPC in a ir cm 2 /s 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in detail in A

ppendix A- 2, and off

er COPC-spe cific v

alues in the HHRA

P companion da

tabase. The following uncertainty is associated w ith this variable: The rec omme

nded D a values m

ay not a ccuratel y repre sent the be

havior of COPCs under w

ater body -specif ic conditions. How

ever, w e expec t the degr ee of unc ertainty

to be mini

mal. 3.1536 x 10 7 Units conve rsion fac tor s/yr

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is cited as one of the sources of the variables D a , k, 8 z , and μ a values of 1.2 x 10 -3 , 0.4, 4, and 1.81 x 10 G 04 , respect

ively . This docum

ent cites (1) Wea st (1979) as its source

of informa tion for D a and μ a , and (2) U.S. EPA (1993a) as its sourc e of inf ormation f

or k and 8 z . U.S. EPA. 1993a

. Addendum: Methodology for Assessing He alth Risks Associated w

ith Indirect

Exposure to Combustion Emis sions . Working

Group Rec omme

ndations. Of

fice of Solid Was

te, and Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This docum

ent is cit ed by U. S. EPA (1994) and NC DEHNR (1997) as the

source of (1) the recomme

nded drag c oefficient ( C d ) value of

0.0011, (2) the recomm

ended von Ka

rman’s constant ( k ) value of 0.4, and (3) the recommended dimensionless viscous sublayer thickness ( 8 z ) value of

4. The original sourc es of the se vari able val ues are not

identified. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes

. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This document is cited as one of the sources of the variables D a , k, 8 z , and μ a values of 1.2 x 10 -3 , 0.4, 4, and 1.81 x 10 G 04 , respect

ively . This docum

ent cites (1) Wea st (1979) as its source

of informa tion for D a and μ a , and (2) U.S. EPA (1993a) as its sourc e of inf ormation f

or k and 8 z . U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-4-21 GAS PHASE TRANSFER COEFF ICIENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-252 U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. This docum

ent recom mends (1)

a value of 0.0011 for

the drag coeff

icient ( C

d ) variable, (2) a v

alue of 0. 4 for von K

arman’ s constant (

K ), and (3) a value of

4 for the di

mensionle ss visc ous sublayer thickness ( 8 z ) variable. The or iginal sour

ces of the varia

ble value s are not identified. Weast,R.C. 1979. CRC Handbook of Chemistry and Physics. 60th ed. CRC Pres, Inc. C leveland,

Ohio. This docu ment is cited as the sour ce of D a , D w , and : a variable s of 1.2 x 10 -3 , 1, and 1.69 x 10 -2 , re spe cti vely.

### TABLE B-4-22 BENTHIC BURIAL RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-253 Description This equa tion calcula

tes the w ater colum

n loss consta

nt due to burial

in benthic sediment. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) All of the varia bles in the equation in Ta ble B-4-22 ar

e site-s pecific . Theref

ore, using de fault v

alues rat her than sit

e-specif ic value s, for a

ny or all of these variable s, will contribute to under- or ove

restim ating k b . The deg

ree of unc ertainty

associa ted with each of the se vari ables is a s follows: (a) X e —about one orde

r of m agnitude a

t the mos t, (b) C

BS , d bs , V fx , TSS , and A w —limited because of the nar row rec omme

nded ranges

for thes e varia

bles or bec ause res ources to e stimat e varia ble value s are generally

availa ble, (c) A L and SD—very site-specific, degree of uncertaint

y unknow n. Based on t he possi ble ranges for the inpu t variables t o this eq uation , values of k b can range over about one order of magnitude.

Equation

Varia ble Description Units Value 

### k b Benthic buria l rate cons

tant yr -1 

### X e Unit soil loss kg/m 2 -yr 

### Varies This va riable is site-specific and is calculated using the equation in Table B -4-13. The following uncertainty is associated w ith this variable: All of the varia

bles in the equation used to c alculate unit soil loss , X e , are site-specific. Using default va lues rather than sit e-specific valu es, for any or all of the equat ion variab les, will resu lt in esti mates of X e that under- or overesti mate t he actual value. W

e expec t the degr ee or m agnitude of

any under

- or overe stimat

ion to be about one order of magnitude or less. 

### A L Total w

atershed a rea rec eiving deposition m 2 

### Varies This variable is site-specific (see Chapter 4). Uncertainties associated with this variable are site-specific.

### TABLE B-4-22 BENTHIC BURIAL RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-254 SD Waters

hed sedim

ent delive ry rat io unitless 

### Varies

This va lue is site -specif

ic and is c alculate d using the equation in Ta ble B-4-14. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The def

ault value s for em

pirical inte

rcept coe ffici ent ( a ) that we recom mend f or use in the

equation in Table B-4-14, are ave rage v alues bas ed on various

studies of

sedime nt yields from various w

atersheds . Theref

ore, these default values may not accurately represent site-specific w atershed conditions. As a result, using these default values may contribute to unde

r- or over estima ting the bent

hic burial ra

te constant, k

b . (2) The def

ault value for em pirical slope coeff

icient ( b ) that we

recom mend f or use in the

equation in Table B-4-14 i s based on a r

eview of sedim ent yields from

various w

atersheds . This si

ngle def ault value may not accura

tely represent site-spe cific w

atershed conditions. As

a result,using this default v alue ma y contri bute to under-or overestimati ng k b . 

### 1 x 10 3 Units conve

rsion fac tor g/kg 

### Vf x Avera

ge volum etric f low rate through wa

ter body m 3 /yr 

### Varies This va riable is site-specific. W

e recom mend using

site- and waterbody

-specif ic mea sured val ues, repre sentativ

e of long- term averag e annual v

alues f or the wa ter body of

concern. The following uncertainty is associated w ith this variable: Default average volum

etric flow rate ( Vf x ) values may not accura

tely r epresent site-spec ific w

ater body conditions. Therefore, u sing such default valu es may contribu te to und er- or overe stimating k b . Howev er, we expect that the uncertainty

associa ted with t his varia ble to be lim

ited, beca use resourc es such as maps , aerial photographs, a nd gauging station m

easurem ents—fr om whic h Vf x can be estimated—are generally available. 

### TSS Total sus

pended solids concentrat

ion mg/L 

### 2 to 300 This va riable is site-specific. W

e recom mend using

site- and waterbody

specif ic mea sured val ues, repre sentativ

e of long- term averag e annual v

alues f or the wa ter body of

concern (s ee Chapte

r 5). A v alue of 10 mg/L

was c ited by N

C DEHNR ( 1997), and U.S. EPA ( 1993) in the abs ence of site-specific m easured da

ta. The following uncertainty is associated w ith this variable: Limitation on measured data used for determining a w ater body specific total suspended solids ( TSS ) value m ay not accurately reflect site- and water body-specific conditions long term. Theref ore, the TSS value m

ay cont ribute to under- or overesti mating f wc .

### TABLE B-4-22 BENTHIC BURIAL RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-255 A w Water body surface area m 2 

### Varies This variable is site-specific. T he value selected represents an average value for the entire year. See Chapter 4 for guidance regarding the ref erences and met hods used to det

ermine this value . Uncerta

inties as sociated w

ith this va riable ar e site-s pecific

. Howeve r, we e xpect tha t the uncert

ainty a ssociate d with this

variable will be limited,because maps, a erial photog

raphs—and other resour

ces fr om whic h water body surf

ace area, A w , can be measured—are readily a vailable. 1 x 10 G 6 Units conve

rsion fac tor kg/mg 

### C BS Bed sedim

ent concentr

ation g/cm3 

### 1.0 This va riable is site-specific. W

e recom mend a de fault v

alue of 1. 0, consistent

with U.S. EPA (1998), w hich state s that this value should be reasona

ble for m ost applica

tions. No re ferenc e is cited for this r ecomm endation. T

he recom mended de fault value is also consis

tent with U.S. EPA (1994),and NC DEH NR (1997). The following uncertainty is associated w ith this variable: The rec omme

nded value may

not accura

tely r epresent site-spec ific w

ater body conditions. 

### d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. T

he value selected represe

nts an ave

rage v alue for the entire

year . We re comm

end a def ault upper-benthic sedime

nt depth of 0.03 meter

s, which is based on t

he center of the ra nge cite d by U.S. EPA (1993). T his value is also consistent w

ith U.S. EPA (1994) and NC DEHNR (1997). The following uncertainty is associated w ith this variable: The rec omme

nded defaul

t value f or depth of uppe

r benthic sediment la

yer, d

bs , may not accura

tely r epresent site-specific w

ater body conditions. T

herefore , use of t

his defa ult value m

ay cont ribute to the under- or overestimati on of k b . However, the degree of uncertainty associated with this variable is expected to be limited because of the narrow recomm ended range.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document is cited as one of the sources of the range of all recommended specific C BSand d

bs values. This document cites U.S. EPA (1993a) as its source.

### TABLE B-4-22 BENTHIC BURIAL RATE CONSTANT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-256 U.S. EPA. 1993. Addendum: Methodology for Assessing He alth Risks Associated w

ith Indirect

Exposure to Combustion Emis sions . Working

Group Rec omme

ndations. Of

fice of Solid Was

te, and Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This docum

ent is cit ed by U. S. EPA (1994) and NC DEHNR (1997) as the

source of (1) the recomme

nded drag c oefficient ( C d ) value of

0.0011, (2) the recomm

ended von Ka

rman’s constant ( k ) value of 0.4, and (3) the recommended dimensionless viscous sublayer thickness ( 8 z ) value of

4. The original sourc es of the se vari able val ues are not

identified. U.S. EPA 1994. Draft Guidance for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustor

Facilities

Burning Hazardous

Waste

. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April 15. This document is cited as one of the reference s ources for the d bs value. The recomm

ended value is the midpoint of an acceptable range. This document is also cited as one of the ref erence source docum

ents for the defa

ult C BSvalue. This document cites U.S. EPA (1993a) as its source. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber.

### TABLE B-4-23 TOTAL WATER

COLUMN

CONCE NTRA TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-257 Description This equa tion calcula

tes the tot al wat er colum n concentra

tion of COPCs

including (1)

both dissolved COPCs and (2) COPCs sorbed t o suspended sol

ids. Uncer

tainties a ssociate d with this equatio n inclu de the foll owing: (1) All of the varia bles in the equation in Ta ble B-4-23 ar

e COPC- and s ite-spec ific. T herefore , using def

ault value s rather t

han site-s pecific values, for any

or all of these va riables, w ill contrib ute to un der- or o verestimatin g C wctot . We expect the degree of uncertainty associated with the variables d wc and d

bs to be minimal either because informa tion for estimating a variable (d wc ) is gene

rally available or beca

use the proba

ble range for a variable (d bs ) is narrow. The uncertainty associated w ith the variables f wc and C

wtot is associate d with estimates of OC content. Because OC

content va

lues can v

ary w idely f or diffe rent locations in the sam

e medium , the uncert

ainty a ssociate d with using

default OC

values may

be significant in specific cases. Equation

Varia ble Description Units Value 

### C wct ot Total COPC concentration in water colu mn mg COPC/L water colu mn 

### f wc Fra

cti on of tota l w ate r bod y C OPC concentrat

ion in the w

ater colum

n unitless 

### 0 to 1

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-16. The following uncertainty is associated w ith this variable: The def ault vari able val

ues we recom mend y ou use in the equation in Ta ble B-4-16 m

ay not a ccuratel y repre sent site-speci fic water body con dition s. However, the ranges of several var iables—i ncludi ng d bs , C BS , and 2 sw —are relatively narrow. Theref ore, we expect the uncertainty to be relatively small. You can reasonably estim ate other variables, such as d wc and d

z , using ge

nerally availa ble inform

ation. The

larges t degree of uncert ainty m ay be introduced by the default medium-specific OC content va

lues. OC content va

lues are often not readily a vailable and can vary widely for dif ferent locations in t

he sam e medium. Theref

ore, defa ult values may not adequately repr

esent site-specific conditions.

### TABLE B-4-23 TOTAL WATER

COLUMN

CONCE NTRA TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

Varia ble Description Units Value



### B-258 C wtot Tot

al w ate rbod y C OPC concentration including water column and bed sedim

ent mg

COPC/L water body (or g COPC/m

3 wate r bo dy) 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-15. The following uncertainty is associated w ith this variable: The default variable values w e recommend y

ou use in the equation in Table B-4-15 may not accurately represent site- -specific water body conditions. We expect the degree of uncertainty associated with variables Vf x , A w , d

w , and d

bs to be limit ed either because the

probable ra

nges f or variables are na

rrow or inf

ormation a

llowing a ccurate estima

tes is generally av

ailable. Uncertai

nty ass ociated w

ith f wc is large ly the r esult of w ater body -associa ted defa ult OC content values, and may be signif icant in specific instances. Uncertainties associated with the total COPC load into water bod y ( L t ) and overa

ll total w ater body COPC dissipa

tion rate c onstant (k wt ) may also be sig

nificant in some instances because of the combination of many v ariable-specific uncertainties. 

### d wc Depth of w

ater colum

n m 

### Varies This variable is site-specific. T he following uncertainty is associated with this variable: Default values f or depth of w

ater colum

n, d wc , may not accura

tely r eflec t site-specific w

ater body conditions. Therefore, u sing defaul t values may contri bute to under- o r overestimati ng C wctot . Howev

er, we expect the degre e of uncertainty

associa ted with t his varia ble to be lim

ited, beca use inform

ation rega rding this v

ariable i s genera

lly available. 

### d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. W

e recom mend a de fault upper

-benthic sediment de

pth of 0.03 m

eters, w hich is based on the center of a range cited by U.S. EPA (1993)

This va lue is consi stent wi

th U.S. EPA ( 1994) and NC DE HNR (1997). The following uncertainty is associated w ith this variable: The rec omme

nded defaul

t value f or depth of uppe

r benthic sediment la

yer, d

bs , may not accura

tely r epresent site-specific w

ater body conditions. T

herefore , using this default v alue ma y contri bute to under- or

overest imating C wctot . Howev

er, we expect the degre e of unce rtainty associa ted with t his varia ble to be lim

ited becaus e of the narrow recommended range.

### TABLE B-4-23 TOTAL WATER

COLUMN

CONCE NTRA TION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

B-259 REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment is cited as one of the so urces of the r ange of d bs values. This document cites U.S. EPA (1993a) as its source. U.S. EPA. 1993. Addendum: Methodology for Assessing He alth Risks Associated w

ith Indirect

Exposure to Combustor Emi ssions. Working Group Rec omme ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This docu ment is cited b y U.S. EPA (1 994) an d NC DEHNR (1 997) as o ne of the sou rces of the ran ges of d bs values. No original

source of this range

was ide ntified. U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combu stor Facilities Burning Hazardou s Waste. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Was te Combustion Facility . April. This docum

ent is cit ed as one of

the ref erence s ources f

or the def ault value for depth of

upper benthic layer

( d bs ). The recomm

ended value

is the m idpoint of an a

cceptable range. T his document cites U.S. EPA (1993) as the source of its information. The degree of uncertainty as sociated with the variables d wc and d

bs is expec

ted to be m

inimal either beca

use inform

ation for estimating these variables is ge nerally available (d wc ) or the probable range for a variable ( d bs ) is narrow. Uncertainty associated with the va riables f

wc and C

wtot is large ly ass ociated w

ith the use of de fault OC

content values. Because OC content is k

nown to va

ry w idely in differ

ent locations

in the sam

e medium , use of de fault m

edium-specific v

alues ca n result in s ignific ant uncertainty in some instances.

### TABLE B-4-24 DISSOLVED PHA SE WAT ER CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 3)

B-260 Description This equat ion calcu lates the co ncentrat ion of COP C dissol ved in the water column. Un certainti es associated with this eq uation includ e the follo wing: (1) The va

riables in the equation i

n Table B -4-24 are s ite-spec ific. T herefore , using def

ault value s rather t

han site-s pecific values, for any

or all of these va riables, w ill contribute

to under- or overestimati ng C dw . We ex

pect the degree of

uncertaint

y ass ociated w

ith TSS to be rela tively small , because

inform ation rega rding reas onable site -specif ic value s for this

variable are generally available or it can be eas ily measured. On the other hand, the uncertainty associated with the variables C wctot and Kd

sw is associate d with estimates of OC content. Because OC content va

lues can v

ary w idely f or diffe rent locat ions in the sa

me m edium, us ing defa

ult OC values may

result in significant uncertainty in specific cases. Equation

For mercury model ing,

Use the equation above to calculate the C dw mercury va

lue. Apportion into the divalent mercury (Hg 2+ ) and methyl merc ury (MHg) forms based on the assumed 85% Hg 2+ and 15% MHg speciation split in the water body (see Chapter 2) using the correlations below. Elemental merc ury (Hg 0 ) occurs in very

small amounts in the vapor

phase and doe s not exis

t in the part

icle or par

ticle-bound phase. T herefore , assum

e elem ental m ercury in the wa ter body i s neglig

ible or zer

o, and eval

uate it f or the direc

t inhalation pa

thway only (Table B-5-1). C dw (Hg2+) = 0.85 C dw (Mercu ry) C dw (Mhg) = 0.15 C dw (Mercu ry) C dw (Hg0) = 0.0 Evaluate divalent and methyl me rcury as individual COPCs to determine C fish (Tables B-4- 26 and B -4-27) for calculat ing COPC intake from fish in Table C-1-4 , and in eva luating C OPC int ake from drinking water (Ta

ble C-1-5). Calculate C dw (Mercury) as above using the corresponding fate and transport parameters for merc uric chloride (Hg 2+ ) provided in Appendix A-2, and determine C dw (Hg2+) and C

dw (Mhg) as calculated above.

### TABLE B-4-24 DISSOLVED PHA SE WAT ER CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 3)

B-261 Varia ble Description Units Value 

### C dw Dissolved phase water

concentrat

ion mg COPC/L water 

### C wct ot Total COPC concentration in water colu mn mg COPC/L water colu mn 

### Varies

This va riable is COPC- and site -specif ic, and is calculat

ed using the

equation in Table B-4-23. The following uncertainty is associated w ith this variable: All of the variables in the equation in Table B-4-23 are COPC- and site-specific. Therefore, using default values ra ther than sit e-specific valu es, for any or all of these variab les, will con tribut e to und er- or overe stimating C wctot . We expect the degree of uncertainty associated with the variables d wc and d

bs to be mini

mal ei ther beca use inform

ation for estimating a variable ( d wc ) is generally available or because the probable range for a variable ( d bs ) is narrow . The uncertainty associated with the variables f wc and C

wtot is assoc iated w

ith estim ates of Organic Carbon, OC , content. Because OC

content va

lues can v

ary w idely f or diffe rent locat ions in the sa

me m edium, us ing defa

ult OC values may result in significant uncertainty in specific cases. 

### Kd sw Suspended sediments/surface water partition coe ffici ent L water/kg suspended sedime nt 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: Values conta

ined in Appe

ndix A-2 f

or Kd

sw are based on default OC content values for surface wate r and soil. Because OC content ca

n vary widely for dif ferent locations in t

he sam e medium , the uncert

ainty a ssociate d with es

timated Kd

sw values ba sed on def

ault OC content values may be signif icant in specific cases. 

### TSS Total sus

pended solids concentrat

ion mg/L 

### 2 to 300 This va riable is site-specific. W

e recom mend using

site- and waterbody

specif ic mea sured val ues, repre sentativ

e of long- term averag e annual v

alues f or the wa ter body of

concern (s ee Chapte

r 5). A v alue of 10 mg/L

was c ited by N

C DEHNR ( 1997) and U.S. EPA (1993b) in the abse nce of s ite-spec ific m

easured da

ta. The following uncertainty is associated w ith this variable: Limitation on measured data used for determining a w ater body specific total suspended solids ( TSS ) value m ay not accurately reflect site- and water body-specific conditions long term. Theref ore, the TSS value m

ay cont ribute to under- or overesti mating f wc . 1 x 10 -6 Units conve

rsion fac tor kg/mg

### TABLE B-4-24 DISSOLVED PHA SE WAT ER CON CENT RATION (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 3)

B-262 REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment is cited as one of the so urces of the r ange of Kd s values and the TSS

value of 10. This doc

ument ci tes U.S. EPA

(1993) as its

sources of

inform ation rega rdingTSS , and (2) RTI (1992 ) as its sou rce regardin g Kd s . U.S. EPA. 1993. Addendum to the Methodolo gy for Assessing Health Risks Associated with Indirect Exposure to Combusto r Emissions. Working Group Rec omme

ndations. Of

fice of Solid Was

te and Off ice of R esearc h and Development. W

ashington, D .C. Septem

ber. This docu ment is cited b y U.S. EPA (1 994) an d NC DEHNR (1 997) as o ne of the sou rces of the ran ge of Kd s value a nd the assum

ed OC value of 0.075 for surf

ace w ater. T he generic equation for

calculat ing partition coeff

icients (s oil, surfa

ce wa ter, and bed sedime

nts) is as follows : Kd

ij = K

ocj * OC

i . K oc is a che mical- specific value; howeve r, OC is me dium-specific. The range of Kd s values w

as based on an assum

ed OC value of 0.01 for soil. Therefore, the Kd sw values were estim

ated by multiplying the Kd s values by 7.5, because the OC value f or surfac e wate

r is 7.5 tim

es grea ter than the

OC value f or soil. T his docume

nt is also cited by U .S. EPA (1994) a nd NC DEHNR

(1997) as the

source of the recom

mended TSS

value. U.S. EPA. 1994. Draft Guidanc e for Perf orming Scre

ening Level

Risk Analys is at Combusti on Facilities

Burning Hazardous

Waste

. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April 15. This docu ment is cited as one of the so urces of the r ange of Kd s values, citing RT

I (1992) as it

s source of

inform ation.

### TABLE B-4-25 COPC CONCENTRATION SORB ED TO BED SEDIMENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 1 of 4)

B-263 Description This equation calculates the concentration of COPCs sorbed to bed sediments. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The def

ault vari able val

ues recom

mended f or use in the

equation in Table B-4-25 m ay not a ccuratel y repre sent site -specif

ic wat er body c onditions. We

expect the degre e of unce rtainty associated with variables 2 bs , C BS , d wc , and d

bs to be lim

ited either

because the probable r

anges f or these v ariables are narr ow or bec ause inf

ormation a

llowing r easonable estim ates is generally available. (2) Uncertainties associated with variables f bs , C wtot and Kd

bs are lar gely associat

ed with the

use of de fault OC

content va

lues in thei

r calcula tion. The unc ertainty

may be signif icant in specific instances, because OC cont ent i s known to var y widely in differ ent l ocati ons i n the same medi um. Equation

Varia ble Description Units Value 

### C sb Concentration sorbed to bed

sedime nt mg COPC/kg sedime nt 

### f bs Fra

cti on of tota l w ate r bod y C OPC concentrat

ion that occur

s in the benthic sedi

ment unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-16. The following uncertainty is associated w ith this variable: The default values for the variables in the equation in Table B-4-16 may not accurately represent site- and water body-spec ific condi tions. However, the ran ge of several variab les—incl uding d bs , C BS , and 2 bs —is rela

tively narrow. You can reasonably estimate other variables, such as d wc and d

z , using generally available inform ation. The largest degree of uncertainty ma

y be introduced by the default medium-specif ic OC content values. Because OC content values m ay va ry w idely in differ

ent locations

in the sam

e medium , using def

ault value s may

result in s ignific ant uncertainty in specific cases.

### TABLE B-4-25 COPC CONCENTRATION SORB ED TO BED SEDIMENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 2 of 4)

Varia ble Description Units Value



### B-264 C wtot Total w

ater body concentra

tion including water column and bed sedime nt mg COPC/L water body (or g COPC/cm 3 wate r bo dy) 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-15. The following uncertainty is associated w ith this variable: (1) The default variable values m ay not accurately represent site-specif ic water body conditions. We expect the degree of uncertainty associated with variables Vf x , A w , d

wc , and d

bs to be limited either because the probable ranges for these variables are narrow or information allowing reasonable estim ates is generally av

ailable. (2) Uncertai

nty ass ociated w

ith f wc is large ly the r esult of unc ertainty

associa ted with de fault OC

content values and may be significant in specific instances. Uncertainties associated with the va riable L T and K wtmay also be significa

nt because of the combination of many v ariable-specific uncertainties. 

### Kd bs Bed sediment/sediment pore water partition coe ffici ent L water/kg bed sedim

ent (or cm 3 water/g bed sedime nt) 

### Varies This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. The following uncertainty is associated w ith this variable: The def ault Kd

bs values i n Appendix A-2 are

based on def

ault OC content values for sediment and soil. Because medium-specific OC

content may vary

widely at diff

erent locations in the same medium, the uncertainty ass ociated with Kd

bs values c alculate d by using default OC

content values may be signif icant in specific instances. 

### 2 bs Bed sedim

ent porosity unitless (L pore volume /L sediment) 

### 0.6

This variable is site-specific. We recommend a defa

ult bed sediment porosity of 0.6 (using a C BSvalue of 1 g/cm 3 and a solids den sit y ( D s ) value of

2.65 kg/L

), calcula ted using the

followi ng equation (

U.S. EPA 1998):
2 bs = 1 - C

BS / D s This als o is consist

ent with U .S. EPA (1993), U .S. EPA (1994), a nd NC DEHNR

(1997). The following uncertainty is associated w ith this variable: To the extent that the re commended defau lt values of C BSand D s don’t accurately represent site- and water body-specific condi

tions, 2 bs will be under- or ove restim ated to som

e degree . Howev

er, we expect the degre e of uncertainty to be minimal, based on the narrow range of rec ommended values.

### TABLE B-4-25 COPC CONCENTRATION SORB ED TO BED SEDIMENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 3 of 4)

Varia ble Description Units Value



### B-265 C BS Bed sediment concentration (or bed

sed imen t bu lk d ens ity) g/cm3 

### 1.0 This va riable is site-specific. W

e recom mend a de fault v

alue of 1. 0, consistent

with U.S. EPA (1998), w hich state s that this value should be reasona

ble for m ost applica

tions. No re ferenc e is cited for this r ecomm endation. T

his is als o consistent

with U.S. EPA (1993),U.S. EPA (1994) , and NC DEH NR (1997). The following uncertainty is associated w ith this variable: The rec omme

nded defaul

t value f or 2 bs may

not accura

tely r epresent site- and w

ater body -specif ic conditions. Therefore, the variable C sb may be under- or ov

erestim ated to a limited degree, a s indicate d by the na

rrow rang e of recommended values. 

### d wc Depth of w

ater colum

n m 

### Varies This va riable is site-specific. The following uncertainty is associated w ith this variable: Default d

wc values m

ay not a ccuratel y ref lect site -specif

ic conditions. Theref

ore, using t

hese va lues ma y contri bute to under- or overestimating the variable C sb . However, we ex

pect the degree of uncertainty to be minim al, because resources allowing reas onable wate r body-spe cific estimates of d wc are generally av

ailable. 

### d bs Depth of uppe r benthic sediment layer m 

### 0.03 This va riable is site-specific. W

e recom mend a de fault upper

-benthic sediment de

pth of 0.03 m

eters, w hich is based on the center of a range cited by U.S. EPA (1998) . This v alue is c onsistent w

ith U.S. EPA (1994) and NC DEHNR (1997). The following uncertainty is associated w ith this variable: Default d

bs values m

ay not a ccuratel y ref lect site -specif

ic conditions. Theref

ore, using t

hese va lues ma y contri bute to under- or overesti mating C sb . Howev

er, we expect the degre e of unce rtainty to be sm all, base d on the narrow recommended range of def ault values.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment is cited as one of the so urces of the r ange of Kd s values a nd an assum

ed OC value of 0.04 for sediment. T

his docume

nt cites R TI (1992) as

its source

of infor mation regarding Kd

s valu es. This doc umen t is also cit ed as one of th e ref eren ce so urc e do cume nts for t he d efau lt va lue for b ed s edi ment por osi ty( 2 sw ). This document cites U.S. EPA (1993a; 1993b) as its s ource of i

nforma tion. This doc

ument is also cited as one of

the ref erence s ource docum

ents for the defa

ult value f

or depth of t

he upper benthic

laye r. The de fault v

alue is the

### TABLE B-4-25 COPC CONCENTRATION SORB ED TO BED SEDIMENT (CONSUMPTION OF DRINKING WATER AND

FISH EQUATIONS) (Page 4 of 4)

B-266 midpoint of

an acce ptable rang

e. This doc

ument ci tes U.S. EPA

(1993a) and U. S. EPA (1993b) as its source

of infor mation f or the range of va

lues for the depth of

the upper bent

hic lay er. This docum

ent is als o cited as

one of the

refer ence sourc e docume

nts for the

default bed sedim

ent concentr

ation ( C

BS ). This document cites U.S. EPA (1993a; 1993b) as its source. U.S. EPA. 1993b. Addendum: Methodolog y for Assessing Health Risks Associated with Indirect Exposure to Combustor Emission s. Working Group Rec omme

ndations. Of

fice of Solid Was

te and Offic e of Res earch and Developm ent. Was hington, D.C. Septembe

r. This document is cited by NC DEHNR (1997) and U.S. EPA (1994) as the source of the default bed sediment porosity value ( 2 sw ), the default bed sediment concentration value ( C BS ), and the range f or depth of uppe

r benthic la

yer ( d bs ) values

. U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analysis at Combu stor Facilities Burning Hazardou s Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCR

A Hazardous Waste Combustion Facilit ies . April. This docu ment is cited as one of the so urces of the r ange of Kd s values a nd an assum

ed OC value of 0.04 for se diment. T

his docume

nt cites R TI (1992) as its sourc e of inf ormation regarding Kd

s valu es. This doc umen t is cit ed as one of th e ref eren ce so urc e do cume nts for t he d efau lt va lue for b ed s edi ment por osi ty ( 2 sw ). This doc ument ci tes U.S. EPA

(1993a; 1993b) as its sour

ce. This document is also ci

ted as one of the re ferenc e source doc uments f or the def ault value for depth of

upper benthic layer

( d bs ). The default value is the midpoint of an accepta ble range . This docum

ent cites U.S. EPA (1993a

) and U.S. EPA

(1993b) as its

source of inform ation for t he range of value s for the depth of the

upper benthic layer . This docum ent is also ci ted as one of the re ferenc e source doc uments f or the def ault bed se diment c oncentration ( C BS ). This doc

ument ci tes U.S. EPA

(1993b) as its

source. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. Thi s do cume nt i s als o ci ted as th e so urc e of t he eq uat ion for c alcu lat ing bed sed imen t po ros ity ( 2 sw ). No source of this equation was identified. This document was also cited as the source for the ra nge of the bed sedim

ent concentr

ation ( C

BS ). No source

of this ra nge wa s identif ied.

### TABLE B-4-26

FISH CON CENT RATION FROM BIOCO NCEN TRAT ION FAC TORS U SING D ISSOLV ED PHAS E WATE R CONC ENTR ATION (CONSUMPTION OF FISH EQUATIONS )

(Page 1 of 3)

B-267 Description This equat ion calcu lates fish co ncentrat ion, fro m dissolved C OPCs, b y using a bioc oncentr ation facto r. Uncertai nty associated with this eq uation includ e the follo wing:

Calculati ng C

dw is dependent on default values for two variables C wctot and Kd

sw . Values for these two variables are, in turn, dependent on default medium-specific OC content va

lues. Because OC

content ca

n vary widely at diff erent loca tions in the s ame m

edium, s ignific ant uncerta inty m ay be a ssociate d with C wctot and Kd

sw and, in turn, C dw in specific instances. Equation

Varia ble Description Units Value 

### C fish Concentration of COPC in fish mg COPC/kg FW tissue 

### C dw Dissolved phase water

concentrat

ion mg COPC/L 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-24. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The va

riables in the equation i

n Table B -4-24 are s ite-spec ific. T herefore , using def

ault value s rather t

han site-s pecific values, for an y or all of these var iables, will contrib ute to th e under- or overesti mating C dw . We ex

pect the degree of uncertainty

associa ted with TSS

to be relatively sma

ll, because information regarding reasonable site-specific values for this v ariable i s genera

lly av ailable or can be ea

sily m easured. (2) The uncertainty associated with the variables C wctot and Kd

sw is depend ent on est imates of OC content. Because OC content va

lues can v

ary w idely f or diffe rent locat ions in the sa

me m edium, the

uncertaint

y ass ociated w

ith using differ ent OC content values may be signif icant in specific cases.

### TABLE B-4-26

FISH CON CENT RATION FROM BIOCO NCEN TRAT ION FAC TORS U SING D ISSOLV ED PHAS E WATE R CONC ENTR ATION (CONSUMPTION OF FISH EQUATIONS )

(Page 2 of 3)

Varia ble Description Units Value



### B-268 BCF fish Bioc once

ntra tion fa ctor for COPC in fish unitless ([mg COPC/kg FW tissu e]/[ mg COPC/kg fe ed]) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP companion database. As explained in Append ix A-2, we recommend u sing BCFsfor organic C OPCs with log K ow less than 4.0 and

BAFs(rather than BCFs ) for organi c COPCs with log K ow of 4.0 or gr eater. For organics with a log K ow value of

less than 4.0 and all m

etals (except lead and mercury), w e obtained values from U.S. EPA (1998) or, when measured values were not available, derived from t he correla tion equation pre sented by Lym an et al. ( 1982). The following uncertainty is associated w ith this variable: The COPC-s

pecific BCF values m ay not a ccuratel y repre sent site -specif

ic wat er body c onditions, beca

use estim ates of BCFs and BAFs can vary, based on experime ntal conditions.

REFERENCES AND DISCUSSION
Ellgenhausen, H. J., A. Guth, and H.O. Esser. 1980. “Factors Determining the Bioaccumulation Potential of Pesticides in the Individu al Compartments of A quatic Food Chains.” Ecotoxicology Environmental

Safety . Vol. 4. P. 134. BCF s for pestici des and p olycyclic aromatic h ydrocarbo ns (PAHs) wit h log K ow less than 5.5 were

apparently

calculat ed by usi ng the fol lowing e quation deriv

ed for pes ticides f rom this document: log BCF = 0.83
A log K ow - 1.71 where BCF = Bioconcentration factor for COPC in fish(unitless) K ow = Octanol-water partition coefficient (unitless) Lym an, W.J., W.F. Ree

hl, and D.H. R

osenblatt. 1982. Handbook of Chemical Property Estimatio n Methods: Environmental Behavior of Orga nic Compounds. McGraw-Hill Book Company . New York, New York. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document cites Ogata et al. (1984), U.S. EPA (1994, 1995) as its sources of the equations used to calculate BCF s fish:

### TABLE B-4-26

FISH CON CENT RATION FROM BIOCO NCEN TRAT ION FAC TORS U SING D ISSOLV ED PHAS E WATE R CONC ENTR ATION (CONSUMPTION OF FISH EQUATIONS )

(Page 3 of 3)

B-269 Ogata, M.K., Y. Ogino Fijusaw, and E. Mano. 1984. “Partition Coefficients as a Measure of Bioconcentration Potent ial of Crude Oil Compounds in Fish and Shellfish.” Bulletin of Env ironmental Contaminant Toxic

ology . Vol. 33. P. 561. BCF s for com pounds with

log K

ow less than 5.5 were

calculat ed by usi ng the fol lowing e quation deriv

ed for ar omatic compounds f

rom this document: log BCF = 0.71
A log K ow - 0.92 where BCF = Bioconcentration factor for COPC in fish (unitless) K ow = Octanol-water partition coefficient (unitless) U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offic e of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber. U.S. EPA. 1995. Review D raft Deve lopment of Hum an-Health Base d and Ecologically

- Based Exi

t Criteri a for the Haz

ardous Waste

Identificati

on Project. Volumes I and I I. Offic e of Solid Waste. March. This docum

ent recom mends tha

t the following re ferenc es be use d:

C BCFsfor organic C OPCs with log K ow less than 4. 0 should be based on equations pr esented in Thomann,R.V. 1989. “Bioa ccumula tion Model of Organic Chemic al Distri bution in Aquatic Food Chains.” Environmental Science and Technology -23(b): 699-707.

C BAFs for organic C OPCs with log K ow greate r than or equa

l to 4.0 and les s than 6.5 are estim ated on the ba

sis of m odels prese

nted in Thom

ann (1989) - se e above -

for the limnetic ecosystem, or for the littoral ec osyste m, based on the follow

ing docum

ent:

- Thomann,R.V., J.P. Connolly , and T.F. Par

kerton. 1992. “

An Equilibrium

Model of O

rganic C hemica l Accum ulation in A

quatic Food W

ebs with Sediment Interaction.” Environmental Toxicology and Chemistry . 11:615-629.

C For organ ics with log K ow greate r than or equa

l to 6.5, a def

ault BAF of 1,000 wa

s assum ed on the bas is of an a

nalysi s of av

ailable da ta on polyc

yclic aroma tic hydr ocarbons (PAH), and t

he follow ing docum

ent:

- Stephan, C.E. et al. 1993. “ Derivation of Proposed Human Health and Wildlife Bioaccumulatio n Factors for the Great Lake Initiative. ” Off ice of R esearc h and Development. U.S. EPA Research Laboratory. PB93-154672. Springfield, Virginia.

C BCFsfor inorganics were obtained from various literature sources and the AQ UIRE electronic database. All BCFsand BAFs were corrected to 5 percent lipid, ref lecting a typica l value f or a fis h fillet. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. Envir

onmental Criteria and Ass essme nt Off ice. ORD . Cincinnati , Ohio. U.S. EPA. 1999. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combu stion Facilities. Peer Rev iew Dr aft. Of fice of Solid Was

te. Aug ust.

### TABLE B-4-27

FISH CON CENT RATION FROM BIOAC CUMULATION FACTORS USIN G DISS OLVEDPHASE W ATER CONCE NTRA TION (CONSUMPTION OF FISH EQUATIONS )

(Page 1 of 3)

B-270 Description This equat ion calcu lates fish co ncentrat ion from dis solved COP C concent ration b y using a bioa ccumulatio n factor. Un certainty asso ciated with this equ ation in clude th e following:

Calculati ng C

dw uses on default values for variables F water and C

wtot . Values for these two variables, in turn, depend on default medium-specific OC content values. Because OC content can vary widely at diff erent loca tions in the s ame m

edium, s ignific ant uncerta inty m ay be a ssociate d with F water and C

wtot , and, in turn, C wtin specific instances. Equation

For mercury model ing, the co ncentrat ion of COP C in fish is cal culated fo r divalent mercury (Hg 2+ ) and me thyl m ercury (MHg) as

shown in the

followi ng equations :

Varia ble Description Units Value 

### C fish Concentration of COPC in fish mg COPC/kg FW tissue

### TABLE B-4-27

FISH CON CENT RATION FROM BIOAC CUMULATION FACTORS USIN G DISS OLVEDPHASE W ATER CONCE NTRA TION (CONSUMPTION OF FISH EQUATIONS )

(Page 2 of 3)

Varia ble Description Units Value



### B-271 C dw Dissolved phase water

concentrat

ion mg COPC/L 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-24. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The va

riables in the equation i

n Table B -4-24 are s ite-spec ific. T herefore , using def

ault value s rather t

han site-s pecific values, for an y or all of these var iables, will contrib ute to un der- or o verestimatin g C dw . We ex

pect the degree of uncertainty

associa ted with TSS

to be relatively sma

ll, because information regarding reasonable site-specific values for this v ariable i s genera

lly av ailable or can be ea

sily m easured. (2) The uncertainty associated with the variables C wctot and Kd

sw depends on estimates o f OC content. Because OC

content values c an vary

widely for dif ferent locations in t

he sam e medium , the uncert

ainty a ssociate d with using

diffe rent OC content values may be signif icant in specific cases. 

### BAF fish Bioa

ccu mulati on f

act or f or C OPC in fish L/kg FW tissue 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. As di scussed i n Appendix A-2, BAF fish values were adjusted for dissolved wate r concentrations. We obtaine d BAFs for all o rganics with a log K ow gre ate r tha n or equal

to 4. 0 fr om U .S. E

PA ( 1998) , wh

ich cit es U .S. E PA (1995a), U.S. EPA (1995 b), and U.S. EPA (1994b). We calculated the BAF fish value f

or lead as a geom etric m ean of da ta from various li terature sources de scribed in U .S. EPA (1998). W e don’t expect Elem

ental m ercury to deposit significa

ntly onto s oils and surfa ce wa ter; there fore, as sume no t ransfe r of ele mental mercur

y to f ish. Ass ume that all me rcury i n fish ex ists or is converted to the methyl mercury (organic) form after uptake into the fish tissue. For this HHRAP, we use the BAF fish value f

or methy l merc ury list ed in U.S. EPA

(1997) for a

trophic lev

el 4 fish. The following uncertainty is associated w ith this variable: The COPC-specific BAF

values m ay not a ccuratel y repre sent site -specif

ic wat er body conditions, beca

use estim ates of BAFs can var

y, based on experim

ental conditions.

REFERENCES AND DISCUSSION NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This docu ment cites the following d ocuments as i ts sources of informatio n regardin g BAF s:

### TABLE B-4-27

FISH CON CENT RATION FROM BIOAC CUMULATION FACTORS USIN G DISS OLVEDPHASE W ATER CONCE NTRA TION (CONSUMPTION OF FISH EQUATIONS )

(Page 3 of 3)

B-272 U.S. EPA. 1993. “

Derivation of Proposed Human Health and Wildlife Bioaccumulatio n Factors for the Great Lakes Initiative .” Office of Re search and Development, U.S. Environmental Research Laborator y. Dulut h, Minnesota. March. This study

presents three m

ethods for estima

tingBAFs , in the following orde r of pref erence ( first to last): (1)

meas ured BAF; (2) measured BCF multiplied by a food-chain multiplier estimated from lo g K ow ; and (3) BAF estimated from lo g K ow. U.S. EPA 57 Fe deral Reg ister 20802. 1993. “Proposed Wa ter Qualit y Guidance for

the Gre at Lak

es Sys tem.” April. This docu ment recommends u sing BAF s for compou nds with a lo g K ow greate r than 5.5. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analysis at Combusti on Facilities Burning Hazardo us Wastes Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Facilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber. U.S. EPA. 1995a. Review Draft Dev elopment of H

uman Health-Based and Ecological ly-Based Ex

it Criter ia for the Haz

ardous Waste

Identificati

on Project. Volumes I and I I. Offic e of Solid W

aste. March 3. This docum

ent recom mends tha

t the following re ferenc es be use d.

C BAFs for organic C OPCs with log K ow greate r than 4.0 b ut le ss tha n 6.5 shou ld be calcu lated from th e foll owing referen ces for the li metic ec osyste m and th e lite ral eco system, resp ecti vely.

- Thomann, R.V. 1989. “Bioaccumulation Model of Organic Chemical Distribution in Aquatic Food Chains.” Environmental Science and Technology

. 23(6):699-707.

- Thomann,R.V., J.P. Connolly , and T.F. Par

kerton. 1992. “

An Equilibrium

Model of O

rganic C hemica l Accum ulation in A

quatic Food W

ebs with Sediment Interaction.” Environmental Toxicology an d Chemistry . 11:6115-629.

C BAFs for com

pounds with log K ow greate r than 6.5 w

ere allow ed to equal 1,000,

based on an a

nalysi s of av

ailable da ta on PAHs a

nd the follow

ing docum

ent:

- Stephan, C.E. et al. 1993. “ Derivat ion of Proposed H

uman He alth and Wildlife Bioaccum ulation Fact

ors for the

Great Lake s Initiativ

e.” Of fice of Resear ch and Development, U.S. Environmental Research Laboratory. PB93-154672. Springfield, Virigina. All BAFs were corrected to 5 percent lipid, ref lecting a typica l value f or a fis h fillet. U.S. EPA. 1995b. Great Lakes Water Quality Initiative. Technical Support Do cument for the Procedure to Determine Bioaccumulation Fa ctors. Office of W ater. EPA-820-B-95-005. Mar ch. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber. U.S. EPA. 1998. “

Methodology for

Assessi ng Health Risk

s Associate

d with Multiple

Pathways of Ex

posure to Com bustor Emiss ions .” Update to EPA/600/6-90/003. O ffice of Research and Developm

ent, Nationa

l Center f or Environm

ental A ssessm

ent, U.S. EPA . EPA/600/R-98/137. Decem ber. U.S. EPA. 1999. Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combu stion Facilities. Peer Rev iew Dr aft. Of fice of Solid Was

te. Aug ust.

### TABLE B-4-28

FISH CONCENTRATION F ROM BIOTA-TO -SEDIMENT ACCUMULATION FACTORS USING COP C SORBED TO BED SEDIMENT (CONSUMPTION OF FISH EQUATIONS )

(Page 1 of 3)

B-273 Description This equa tion calcula

tes fis h concentra

tion from bed sedim

ent concentr

ation, by using a biota

-to-sedim ent accum

ulation fa ctor ( BSAF ). Uncert ainties a ssociate d with this

equation incl

ude the following: (1) Calculati on of C sb is largely dependent on default medium-specif ic OC content values. Because OC content can vary widely

within a medium, significant uncertainty may be associated with estimates o f C sb in specific instances. (2) Lipid conte

nt varies betwee n diffe rent species of f

ish. Ther efore, us e of a de fault f lipid valu e res ult s in a mod erat e deg ree o f un cert ain ty. (3) Some species o f fish have limited , if any, contac t with water bo dy sediments. The refore, use o f BSAFs to estim ate the a ccumula tion of COPCs

in these s pecies m ay be signific antly uncertain. Equation

Varia ble Description Units Value 

### C fish Concentration of COPC in fish mg COPC/kg FW tissue 

### C sb Concentration of COPC sor bed to bed sedim

ent mg COPC/kg bed sedime nt 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-4-25. Uncertai nties ass ociated w

ith this va riable inc lude the f

ollowing: (1) The default variable values recom mended for use in the equation in Table B-4-25 may not accurately represent sitespecific water body conditions. We expect the degre e of uncertainty associated with variables 2 bs , TSS, d wc , and d

bs to be limit ed either because the

probable ra

nges f or these v ariables are narr ow or inf ormation a

llowing r easonable estimates is generally

available. (2) Uncertainty associated with variables f bs , C wtot , and Kd

bs is large ly ass ociated w

ith the use of

default OC

content va

lues. Because OC

content is k

nown to va

ry w idely in differ

ent locations

in the sam

e medium , use of de fault m

edium-specific values can result in significant uncertainty in some instances.

### TABLE B-4-28

FISH CONCENTRATION F ROM BIOTA-TO -SEDIMENT ACCUMULATION FACTORS USING COP C SORBED TO BED SEDIMENT (CONSUMPTION OF FISH EQUATIONS )

(Page 2 of 3)

Varia ble Description Units Value



### B-274 f lipid Fish lipid conte nt unitless 

### 0.03 to 0.07 We rec omme

nd this defa

ult range of value s to be repr esentativ e of w arm w ater non-sa

lmonoid f ish (3 perce

nt lipid content

) at the low end and cold water salmonoid game f ish at the high end (7 percent lipid content). Examples of non-salmonoid fish that may have li pid p erc enta

ges in t he e dibl e por

tion at t he l owe r en d of the ran ge w ould be c atf ish,nort her n pik e, a nd w all ey e. U .S. E PA (1994a) and U.S. EPA (1994b) recomme nded values

of 7 perc ent, whic

h was originally

cited by Cook et a

l. (1991). A

value of 3 percent li

pid content f

or the edible

portion is prov

ided by U .S. EPA (2000). The following uncertainty is associated w ith this variable: (1) Lipid conte

nt may vary betwee n diffe rent species of f

ish. Ther efore, using a def

ault f lis value m

ay re sult in under- or overestimati ng C fish . 

### BSAF Biota-to-sediment a ccumula tion factor unitless ([mg COPC/kg lipid tis sue ]/[m g COPC/kg sed iment] ) 

### Varies

This va riable is COPC-specif

ic. We discuss this

variable in detail in Appendix A

-2, and off

er COPC-spe cific v

alues in the HHRAP com

panion databas e. These f actors ar e applied only

to PCDDs, PCDFs , and polyc hlorinated biphe

nyls (PCBs), consiste

nt with NC

DEHNR (1997) , U.S. EPA (1992),U.S. EPA (1994) , and U.S. EPA (1995). Uncertai nty is a ssociate d with this

variable : The gre atest unce

rtainty associa ted with us ingBSAFsis that som e specie s of fi sh have li

mited, i f any, contact w

ith water body sedim

ents. A ny acc umulation of

compounds i

nto the tissue

of these fishes is alm ost entirel y the re sult of contact wit h surface water. Th erefore, usi ng BSAFs to estim ate COPC accumulation in these s pecies m ay be unc ertain. 

### OC sed Fraction of

organic c arbon in bottom se diment unitless 

### 0.04 This va riable is site-specific. W

e recom mend a de fault v

alue of 0.04, the midpoint of the r ange (0.03 t

o 0.05), if s ite-spec ific informa tion is not av

ailable. This is c onsistent w ith other U.S. EPA (1994b) and N C DEHNR ( 1997) guidance

. The following unc ertainty is assoc iated w

ith this va riable:: The rec omme

nded OC

sed value may not accurately represent site-specific w ater body conditions. However, as indicated by the probable range of values for this parame ter, we expect any uncertainty to be limited in most cases.

### TABLE B-4-28

FISH CONCENTRATION F ROM BIOTA-TO -SEDIMENT ACCUMULATION FACTORS USING COP C SORBED TO BED SEDIMENT (CONSUMPTION OF FISH EQUATIONS )

(Page 3 of 3)

B-275 REFERENCES AND DISCUSSION Cook, P.M., D.W . Duehl, M.K. Walke r, and R.E. Pete

rson. 1991. Bioaccumulation an d Toxicity of TCDD and Related Compou nds in Aquatic Ecosystems . In Gal lo, M .A., R .J. S cheu plei n, an d K.A. Van Der Heijden (eds)

. Banbury Report 35: Biological Bas is for Risk Assessm ent of Dioxins

and Related Com

pounds . Cold Spring H

arbor Labor

atory Pre ss. 0-87969-235-9/91. This docum

ent is cit ed by U. S. EPA (1992) and U.S. EPA (1994) as the sour ce of the fish lipid content va

lue. NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for biota-to-se diment f actors f or PCBs and diox

ins. This document cites U.S. E PA (1992) as i

ts source. This docum

ent is also cite d as one of

the ref erence doc

uments f or the def ault value for fr action OC

in bottom sediment. The default value is the m idpoint of the range obtained from U.S. EPA (1993). No source of this recom

mendation was ide

ntified. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the fish l

ipid content v

alue. The document cites Cook

, Duehl, Wa

lker, and Peterson (1991) a s its orig inal source

of information. This document is also cited by U.S. EPA (1994) and NC DEHNR (1997) as the source of the BSAF s. BSAF values f rom this document w

ere eithe r mea sured val ues or est imat es b ased on a whol e fis h li pid con ten t of 7 per cen t. S pec ific all y, BSAF values from this document must be evaluated because of th e difficult exp erimental metho ds used to derive them. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-Like Compo unds. Volume III: Site-specific Assessment Procedures . Externa l Review Draft. Offi ce of Re search a nd Developm

ent. Was hington. D.C. EPA/600/6-88/00 5Cc. June. U.S. EPA. 1994b. Draft Guidance for Performing Screening Level Risk Analysis at Combu stion Facilities Burning Hazard ous Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous Waste Combustion Facili ties . April. This docum

ent is cit ed as one of

the ref erence s ource docum

ents for the fish l

ipid content v

alue. The document cites Cook

, Duehl, Wa

lker, and Peterson (1991) a s its orig inal source

of informa tion. This doc

ument is also cited as one of

the ref erence s ource docum

ents for biota-to-se diment f actors f or PCBs and diox

ins. This document cites U.S. E PA (1992) as i

ts source of informa tion. This doc

ument is also cited as one of

the ref erence doc

uments f or the def ault fra ction OC in bottom sediment value. The default value is the m idpoint of the range obtained from U .S. EPA (1993). N o source of

this recom

mendation was ide

ntified. U.S. EPA. 1995. Review D raft Deve lopment of Hum an Health-Base d and Ecologically

-Based Exit

Criteria for the Hazar

dous Waste I

dentification P

roject. Vol

umes I and II

. Offic e of Solid W

aste. March. U.S. EPA. 2000. Draft Met hodology for Der

iving Ambient

Water Qual

ity Crite ria for Prote

ction of Human H

ealth. Techni

cal Support Docum ent Volume I II: Bioaccum ulation Part 1 - D evelopme nt of National Bioacc

umulation Factors

. Offic e of Scie nce and T echnology

in the Of fice of Water. This document is cited as one of the reference s ource documents for the fish lipid content value.

### TABLE B-5-1 AIR CO NCEN TRAT ION (DIRECT INHALATION EQUATION)

(Page 1 of 3)

B-276 Description This equation calculates the air concentration of a COPC based on the fraction in vapor phase and the fraction in particle phase. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Most of the uncertainties associated with the variables in this equation—specifically, those associated with variables Q, Cyv , and Cyp —are site-specific. (2) In calcul ation o f F v , the equati on assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, the use of the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than the ST value for background plus local sources and would re sult in a low er calc ulated F

v value; however, the F v value is likely to be only

a few percent low

er. Equation For all COP Cs (e xcep t mer cur y)

Air conc entration is

calculat ed using (1)

0.002 Qand F v = 1.0 for elemental merc ury (Hg 0 ) and (2) 0.48Q

and F

v = 0.85 for divalent mercury (Hg 2+ ). Elem ental m ercury is eval uated only

for the inhalation ex

posure pathw

ay (s ee discus sion in Chapte r 2).

Varia ble Description Units Value 

### C a Air conc entration : g/m 3 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This variable is COPC- and site-specific. See Chapters 2 and 3 for guidance on calculating this variable. Uncertainties associat ed with thi s varia

ble are C OPC- and site -specif ic.

### TABLE B-5-1 AIR CO NCEN TRAT ION (DIRECT INHALATION EQUATION)

(Page 2 of 3)

Varia ble Description Units Value



### B-277 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion da

tabase. This rang

e is based on values presented i n Appendix A-2. Value s are al so presented in U.S. EPA ( 1994b) and NC DEHN

R (1997).
F v wa s ca lculate d usi

ng a n equ ati on pr ese nted in J unge (197 7) f or a ll or gan ic C OPCs , includi

ng PC DDs and PCDF s. U .S. E

PA (1994c) stat

es that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It uses a

default S T value f

or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site is locate d in an urban a

rea, using the latte r ST value may be more appropriate. Specifically, the ST value for urban sources is about one order

of ma gnitude gr

eater tha n that for background plus local s ources, and it would re sult in a lower c alculate d F v value; however, the F v value is likely to be only

a few percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfac e and the he at of va porization of

the liquid-phas e sorbate. To the e xtent that site- or C OPC-specif

ic conditions may cause the value of c to vary, uncer tainty is in trodu ced if a const ant value o f c is used to calculate F v . 

### Cyv Unitized y early air conce ntration from vapor phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable

are COPC- and site-s

pecific

. 

### Cyp Unitized y early air conce ntration from particle phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable

are COPC- and site-s

pecific

.

### TABLE B-5-1 AIR CO NCEN TRAT ION (DIRECT INHALATION EQUATION)

(Page 3 of 3)

B-278 REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26. NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document recommends using the equations in Bidleman (1988) to calculate F v values f or all orga

nics other t

han dioxins (PCDD/PCDFs). How ever, thi s docume

nt does not pre sent a recommendation for dioxins. This document also states that me tals are generally entirely in the particulate phase (F v = 0), exc ept for m

ercury, which is

assum ed to be enti

rely i n the vapor phase. T he docume

nt does not sta

te whet her F v for m ercury should be ca

lculated by

using the equations in Bidleman ( 1988). U.S. EPA. 1994. Revised D raft Guidance

for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous Waste Combustion Facili ties . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This document presents F v values f or organic COPCs that ra nge from 0.27 to 1. F

v values for organics other than PCDD/PCDFs are calculated by using the equations presented in Bidleman (1988). The F v value f or PCDD/PCDFs is

assum ed to be 0.27. T

his value represe nts dioxin T

EQs by w eighting da

ta for a ll dioxin and f

uran congene

rs with nonz

ero TEFs. This docum

ent presents F

v values f or most i norganic C OPCs equal to 0, based on the

assum ption that thes e COPCs are nonvolatile

and assum

ed to be 100 per

cent in the particulat

e phase a nd 0 percent i

n the vapor phase. U.S. EPA. 1997. Mercury Study Report t

o Congress. Volume III: Fate and Transpor t of Merc ury in the Env

ironment . Off

ice of A ir Quality and Planning and Standards a nd Offi ce of Re search a

nd Developm

ent. EPA 452/R

-97-005. Dece

mber.

### TABLE B-6-1 ACUT E AIR CONCE NTRA TION E QUATION

(ACUTE EQUATION) (Page 1 of 3)

B-279 Description This equation calculates the total air concentration of a COPC (hourly) based on the fraction in vapor phase and the fraction in particle phase. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Most of the uncertainties associated with the variables in this equation—specifically, those associated with variables Q, Chv , and Chp —are site-specific. (2) In calcul ating F v , the equati on assum

es a def ault ST value f or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site i s located in an urban ar ea, using the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than the ST value f or backg round plus local

sources a nd would result in a lower c alculate d F v value; however, the F v value is likely to be only

a few percent low

er. Equation For all COP Cs (e xcep t mer cur y)

Consistent w

ith Table B-5-1, air c oncentration is calculated using (1) 0.002 Qand F v = 1.0 for elemental merc ury (Hg 0 ) and (2) 0.48Q

and F

v = 0.85 for divalent mercury (Hg 2+ ). Although calculated as separ ate spec ies, acut

e toxicit y benchm arks ar e not ava ilable f or merc ury and the

refore,acute ai

r concentra

tion for ea

ch specie s should be sum med f or compa rison to the a

cute toxicity benc

hmark for me rcu ry.

Varia ble Description Units Value 

### C acute Acute a

ir concentr

ation : g/m 3 

### Q COPC-specif ic emi ssion rate g/s 

### Varies This va riable is COPC- and site-specif ic. See C hapters 2 a

nd 3 for guida

nce rega rding the c alculation of

this variable. Uncertai nties ass ociated w

ith this va riable ar e COPC- and s ite-spec ific.

### TABLE B-6-1 ACUT E AIR CONCE NTRA TION E QUATION

(ACUTE EQUATION) (Page 2 of 3)

Varia ble Description Units Value



### B-280 F v Fraction of

COPC air conc entration in vapor phase unitless 

### 0 to 1 This variable is COPC-specific. We discuss F v in de tail i n Appe ndix A-2, an d offer COPC -spec ific val ues in the HH RAP companion da

tabase. This rang

e is based on values presented i n Appendix A-2. Value s are al so presented in U.S. EPA ( 1994b) and NC DEHN

R (1997).
F v wa s ca lculate d usi

ng a n equ ati on pr ese nted in J unge (197 7) f or a ll or gan ic C OPCs , includi

ng PC DDs and PCDF s. U .S. E

PA (1994c) stat

es that F

v = 0 for a ll meta ls (exc ept mer

cury). The following uncertainties are associated with this variable: (1) It assum

es a def ault S T value f

or backg round plus local

sources, rather tha

n an ST value f or urban sourc es. If

a specif ic site is loc ated in an ur

ban area,using the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order

of ma gnitude gr

eater tha n that for background plus local s ources, and it would re sult in a lower c alculate d F v value; however, the F v value is likely to be only

a few percent low

er. (2) According to Bidleman (1988), the equation used to calculate F v assumes that the variable c (Junge c onstant) is constan t for all chemical s; however, th e value of c depends on the chemic al (sorbat

e) mole cular w

eight, the surfac e concentr

ation for m

onolayer coverag e, and the dif

ferenc e betwe en the heat

of desorpt

ion from the partic le surfac e and the he at of va porization of

the liquid-phas e sorbate. To the e xtent that site- or C OPC-specif

ic conditions may cause the value of c to vary, uncer tainty is in trodu ced if a const ant value o f c is used to calculate F v . 

### Chv Unitized hourl y air concentration from vapor phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable

are COPC- and site-s

pecific

. 

### Chp Unitized hourl y air concentration from particle phase : g-s/g-m 3 

### Varies This variable is COPC- and site-specific and is determined by air dispersion modeling (see Chapter 3). Uncertainties associated with this variable

are COPC- and site-s

pecific

.

REFERENCES AND DISCUSSION Bidleman, T.F. 1988. “Atmospheric Processes.” Environmental Science and Technology . Volume 22. Number 4. Pages 361-367. For discussion, see Re ferenc es and Dis cussion, T able B-1-1. Junge, C.E. 1977. Fate of Pollutants in Air and Wate

r Environme

nts, Part I

. Suffe t, I.H., Ed. W

iley. New Yor

k. Pages 7-26.

### TABLE B-6-1 ACUT E AIR CONCE NTRA TION E QUATION

(ACUTE EQUATION) (Page 3 of 3)

B-281 NC DEHNR . 1997. Final NC DEH NR Protocol f

or Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Combust

ion Units . Jan uar y. This document recommends using the equations in Bidleman (1988) to calculate F v values f or all orga

nics other t

han dioxins (PCDD/PCDFs). How ever, thi s docume

nt does not pre sent a recommendation for dioxins. This document also states that me tals are generally entirely in the particulate phase (F v = 0), exc ept for m

ercury, which is

assum ed to be enti

rely i n the vapor phase. T he docume

nt does not sta

te whet her F v for m ercury should be ca

lculated by

using the equations in Bidleman ( 1988). U.S. EPA. 1994. Revised D raft Guidance

for Perfor

ming Scree

ning Level Ri

sk Analysi

s at Combustion Facilities Burning Hazardous

Wastes. Attachment C

, Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous Waste Combustion Facili ties . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This document presents F v values f or organic COPCs that ra nge from 0.27 to 1. F

v values for organics other than PCDD/PCDFs are calculated by using the equations presented in Bidleman (1988). The F v value f or PCDD/PCDFs is

assum ed to be 0.27. T

his value represe nts dioxin T

EQs by w eighting da

ta for a ll dioxin and f

uran congene

rs with nonz

ero TEFs. This docum

ent presents F

v values f or most i norganic C OPCs equal to 0, based on the

assum ption that thes e COPCs are nonvolatile

and assum

ed to be 100 per

cent in the particulat

e phase a nd 0 percent i

n the vapor phase. U.S. EPA. 1997. “Mercury Study Re port to Congre ss.” Volum e III. Dr aft. Of fice of Air Qua lity and Planning and Sta ndards and Of

fice of Resear ch and Dev

elopment. Decem

ber.

# APPENDIX C RISK CHARACTERIZATION EQUATIONS 

# Table Equation C-1-1 COPC INT AKE F ROM S OIL C-1-2 COPC INTAKE FROM PRODUCE C-1-3 COPC INTAKE FROM BEEF, MILK, PORK, POULTRY, AND EGGS C-1-4 COPC I

NTAKE FROM FI SH C-1-5 COPC I

NTAKE FROM DRI

NKING WATER C-1-6 TOTAL D AIL Y INTAKE C-1-7 INDIVIDUAL CANCER RISK C-1-8 HAZARD QUOTIENT C-1-9 TOTAL CANCER RISK C-1-10 TOTAL HAZARD INDEX C-1-11 SEGREGATED HAZARD INDEX FOR SPECIFIC ORGAN EFFECTS C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS C-2-2 INHALATION HAZARD QUOTIENT FOR COPCS C-2-3 TOTAL INHALATION CANCER RISK C-2-4 HAZARD INDEX FOR INHALATION C-3-1 CONCENTRATION OF DIOXINS AND DIOXIN-LIKE PCBs IN BREAST MILK C-3-2 AVERAGE DAILY DOSE TO THE EXPOSED INFANT C-4-1 ACUTE HAZARD QUOTIENT

## TABLE C-1-1 COPC IN TAKE FR

OM SOIL (Page 1 of 4)

C-1 Description This equa tion calcula

tes the da ily inta ke of C OPC from

soil consum

ption. The s oil concentr

ation will vary with ea ch scenar io location, a

nd the soil cons

umption rat

e varie s for children and adults. Uncertainties associated with this equation include: (1) Assume that the am ount of soil intake is constant and representative of the exposed population. This assumption may under- or overestimate I soi l . (2) The standard assumptions regarding period exposed might not be representative of an actual exposure situation. This assumption may under- or overestimate I soil . Equation

Varia ble Description Units Value 

### I soil Daily intake of COPC from

soil mg/kgday 

### Cs Average soil concentration over

exposure dur

ation mg/kg Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-1-1. Cs varies

based on w

hether the COPC is carcinogenic or noncarcinogenic. For carcinog

enic COPCs, this value

is equal to the soil conc entration a veraged over the exposure dur ation (Ta ble B-1-1) (U .S. EPA 1994 and NC DEHNR 1997). For noncarcinogenic COPCs, this value is equal to the highes

t annual soil

concentra

tion occu rrin g withi n the expos ure d urat ion. The hi ghest annu al soi l con centr atio n woul d most likel y occur at the end o f the ti me period of c ombustion (T

able B-1-1) (U.S. EPA 1994 a nd NC DEHNR

1997). The following uncertainties are associated with this variable: (1) We assume that the time period for deposition of COPCs resulting from hazardous waste combustion is a conservative, long-term value. This assumption may overestimate Cs and Cs tD . (2) Exposure duration values ( T 2 ) are bas ed o n hi sto ric al mo bil ity s tud ies and won’ t ne cess ari ly rem ain con sta nt. Spe cifi call y, mobility studies indic ate that m

ost recept ors that m ove rem ain in the v

icinity of the c ombustion unit ; howeve r, it is impossible to accur

ately predict the

probability

that these

short-dista

nce mov es will influence exposure,based on f

actors such as atmospheric transport of pollutants. (3) Using a v

alue of z ero for T

1 doesn’t ac count for e

xposure tha

t may have occ urred from

historic ope

rations and e

missions from hazardous waste com bustion. This may underestimate Cs and Cs tD . (4) For soluble COPCs, leaching might lead to m

oveme nt to below the mix

ing depth, re sulting in low er concent

rations w ithin the mixing depth. This uncertainty may overestimate Cs and Cs tD . (5) Deposition to ha

rd surfac es ma

y res ult in dust residues that ha ve negligible dilution (as a re sult of pote ntial mi xing w ith in situ materials) compared to other residues. This m ay underestimate Cs and Cs tD .

## TABLE C-1-1 COPC IN TAKE FR

OM SOIL (Page 2 of 4)

Varia ble Description Units Value



## C-2 CR soil Consumption r ate of s oil kg/day 

### 0.0001 to 0.0002 The soil c onsumption ra

te varie s for the

adult and child receptor

s (U.S. EPA

1997). Receptor Int ake R ate ( kg/d ay) Adult 0.0001 Child 0.0002 U.S. EPA (1997) recomm ends using a

child intak

e rate of 0.0002 kg/day

for a c hild recept

or as a c onservati

ve esti mate of exposure. These v

alues are consistent

with U.S. EPA (1991). U. S. EPA (1997) re ferenc es studies done by Hawley

(1985) and Calabres e (1990) as t

he sources

used to deri

ve soil c onsumption ra

tes. Uncertainties associated with this variable include: (1) Trace

r studies ha

ve resul ted in wide

ranging e stimat

es of the amount of

soil and dust ingested by y oung children,maki

ng it diff icult to ident

ify a single v alue to use . It is al so extre mely diffic ult to separ

ate the c ontribution of e

xposure re sulting from e xterior s oil vs. inte

rior dust. As a resul

t, the intak

e rate is reported as the com

bined rate f

or soils and dus

ts. This uncertainty may under- or overestim ate CR soil . (2) Our recom

mended int

ake rat es ma y not ac curately

represe nt behaviora

l charac teristics since the y are upper estim

ates. T his uncertainty may ove

restimate CR soi l . (3) The intak

e rates represent

normal m

outhing tendencies. Som e children e

xhibit abnorm

al mouthing

(i.e. “pic a” ) beha

vior and would have much higher intake rates. This uncertainty m ay considerably underestimate CR soil . 

### F soil Fraction of

soil that is

contami nated unitless 

### 1.0

We rec omm

end a ssu mi ng t hat all cons umed soil is

cont am inat ed. Thi s is

consist ent wit h NC DEH NR ( 1997)

and U.S. EPA (1994), whic

h assum e the fr action of consumed soil contam inated is 1.0 for all e

xposure sc enarios. Uncertainty associated with this variable include: U.S. EPA guidance rec omme nds the fr action of consumed soil contam inated is equal to 1.0. How ever, due to varia tions in the proxim

ity of the rece ptor to the cont

aminated source, s ize of t he contam

inated sourc e, rece

ptors of c oncern, mobility of receptors, and nature of exposure, this assumption may underestimate or overestimate F soil .

## TABLE C-1-1 COPC IN TAKE FR

OM SOIL (Page 3 of 4)

Varia ble Description Units Value



## C-3 BW Body w

eight kg 

### 15 or 70 We rec omme

nd using def

ault value s of 70 (a

dults) and 15 (c

hildren). T

hese def ault value s are consistent w ith U.S. EPA ( 1991; 1994). Uncertainty associated with this variable include: These body

weight s represe nt the ave rage w eight of an adult and c

hild. Howe

ver, depe nding on the ac

tual rece ptor, body weights may be higher or lower. These default v alues m ay ove restim ate or under

estima te actual body we ights. How

ever, the degre e of under-

or overes timation is not expe cted to be s ignific ant.

REFERENCES AND DISCUSSION Calabres e, E.J., Sta

nek, E.J., Gilbert,C.E., and Ba rnes, R.M. 1990. Prelimina ry adult soil inges

tion estim ates; re sults of a

pilot study

. Regul. Toxicol . Pharmacol . 12:88-95. This document is cited by U.S. EPA (1997) as a source of information used to derive soil consumption rates. Hawle y, J.K. 1985. Ass essme

nt of heal th risk f rom ex posure to conta

minated soil. Risk Analys is 5:289-302. This document is cited by U.S. EPA (1997) as a source of information used to derive soil consumption rates. NC DEHNR . 1997. North Carolina Protocol fo r Performing Indirect Exposure Risk Assessments for Hazardous Waste Combustion Units. Jan uary. This docum

ent is one of

the source s for the

equation in Table C-1-1. This docum ent also st

ates that (1) for c arcinoge

nic COPCs, Cs is equal to the soil conc entration a veraged over the exposure duration; however, no reference document is cited and (2) for noncarcinogenic COPCs, Cs is equal to the highes t annual soil

concentra

tion occurring

within the

exposure duration; the highest annual soil concentration would occur at the end of the time period of emissions. U.S. EPA. 1991. Human Health E valuation Manual, Suppl emental Gui

dance: Standard D

efault Exposur

e Factors. Office of Solid Waste and Emergen cy Response. OSWER Directi ve 9285.6-03. Was

hington, D.C. March 21. This docum

ent is cit ed as the refere

nce source

document of soil ing

estion rate s, and the e

xposure f requency and body w

eight va riables. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Haz

ardous Waste

Combustion Fac ilities. Offi ce of Em ergency and Rem edial Res ponse. Of

fice of Solid Was

te. Dece mber 14. This docum

ent is one of

the source s for the

equation in Table C-1-1. This docum ent also st

ates that (1) for c arcinoge

nic COPCs, Cs is equal to the soil conc entration a veraged over the exposure dur

ation; howe

ver, no re ferenc e docume nt is cite d and (2) for

noncarcinogenic COPCs, Cs is equal to the highes t annual soil

concentra

tion occurring

within the

exposure duration; the highest annual soil concentration would occur at the end of the time period of emissions.

## TABLE C-1-1 COPC IN TAKE FR

OM SOIL (Page 4 of 4)

C-4 U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This document is the source for soil consumption rates.

## TABLE C-1-2 COPC INTAKE FROM PRODUCE

(Page 1 of 4 )

C-6 Description This equa tion calcula

tes the da ily inta ke of C OPC from

ingestion of

exposed a

boveground, pr

otected abov

eground, and belowground pr oduce. The

consumption rate va

ries for children and adults, and f

or the ty pe of produce . The conc entration in e xposed abov

eground, prote cted aboveground, and belowground produc e will a lso vary with ea ch scenar io location. Consumption rates were derived from the Exposure Factors Handbook (U.S. EPA 1997) . U.S. EPA ( 1997) presents consumption rates ba

sed on body weight; therefor e, body w eight is not includ ed as a variabl e in the calc ulation of I ag . Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The amount of produce intake is assumed to be constant and representative of the exposed population. This assumption may under- or overestim ate I ag . (2) The standard assumptions regarding period exposed may not be representative of a ny actual exposure situation. This assumption may under- or overestimate I ag . Equation

Varia ble Description Units Value 

### I ag Daily intake of COPC from produce mg/kg-day DW 

### Pd Aboveground exposed

produce conce

ntration due to d ire ct (w et an d dr y) deposition onto pla

nt surfaces mg/kg 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d by using the equation in Table B -2-7. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The recommended equatio n for calcul ating kp does not consider chem ical deg radation proc esses. Adding che mical degradat

ion processes would decrease half-lifes and thereby increase kp values; plant concentration decreases as kp increases. Using a kp value that does not consider chemical degradation processes is protective. (2) Estima

ting other pa

ramet er value s (for e

xample , Fwand Rp ) is based directly or indirectly on studies of vegetation other than aboveground produce (prim arily grasse s). Uncer

tainty i s introduced t

o the exte nt that the c alculate d param eter va lues do not accurately represent aboveground produce-specific values.

## TABLE C-1-2 COPC INTAKE FROM PRODUCE

(Page 2 of 4 )

Varia ble Description Units Value



## C-7 Pv Aboveground exposed

produce conce

ntration due to air-to-plant transfer mg/kg 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d by using the equation in Table B -2-8. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) The range of values f or the variable Bv

(air-to-pla

nt biotransf

er fac tor) is about 19 orders of

magni tude for org

anic COPCs. (2) The algorithm used to calculate values for the va riable F

v assum es a def ault value for the pa

ramet er ST (Whitby’s average s

urface area of particula tes [aeros ols]) of bac

kground plus local source s rather t han an ST value f or urban sourc es. If

a specif ic site i s located in a

n urban area, the use of

the latte r ST value may be more appropriate. The ST value for urban sources is about one order of ma gnitude gr

eater tha n that for background plus local s ources and w ould result in a

lower F

v value; however, the F v value is likely to be only

a few percent low

er. 

### Pr Aboveg

round exposed and protected produce concentrat

ion due to root uptake mg/kg 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d by using the equation in Table B -2-9. Uncertain ty associated wit h this vari able incl ude the fol lowing: Estimated COPC-specific soil-to-plant bioconcentration factors ( Br) may not be repre sentativ

e of site -specif

ic conditions. 

### Pr bg Belowground produce

concentrat

ion due to root uptake mg/kg 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d by using the equation in Table B -2-10. Uncertain ty associated wit h this vari able incl ude the fol lowing: Estimated COPC-specific soil-to-plant bioconcentration factors ( Br) may not be representative of site-specific conditions.

## TABLE C-1-2 COPC INTAKE FROM PRODUCE

(Page 3 of 4 )

Varia ble Description Units Value



## C-8 CR ag 

### ; CR pp 

### ; CR bg Consumption r ate of aboveground, protected aboveground,and belowground produce, respecti vely kg/kg-day DW This variable is site-specific. T he recommended default values represent the total of the f ollowing produce-specific ingestion rates: Ingestio n Rate (kg/kg-d ay DW) Plant Ty pe Farme r Farmer

Child Resident Res. Child Fisher Fisher Child Exposed Aboveground Produce (Cr ag ) 0.00047 0.00113 0.00032 0.00077 0.00032 0.00077 Protected Aboveground Produ ce (Cr pp ) 0.00064 0.00157 0.00061 0.00150 0.00061 0.00150 Belowground Produce (Cr bg ) 0.00017 0.00028 0.00014 0.00023 0.00014 0.00023 We deriv ed ingest ion rates f rom U.S. EPA (1997), T ables 13-61, 13- 62, 13-63, 13-64, and 13-65. The ingestion rate s listed in U.S. EPA (1997) are

derived f rom the 1987- 1988 USDA N ational Food Cons

umption Surv

ey and m ay be us ed to asse ss exposur e to contamina

nts in foods grown a

t a speci fic sit

e. The i ngestion ra

tes we re adjusted for cook

ing and prepa

ration loss as recom

mended by U.S. EPA (1997). The am ount of prepa

ration and cook

ing loss v aried depe

nding on ty

pe of f ood consume d. We as sumed tha t no preparation and cooking

loss occur

s with e xposed f ruits beca use we further a ssumed this type

of frui t is eate n in the raw

form. In addition, ingestion rates for the child receptor represent a time-weighted mean from the respective tables. Uncertain ty associated wit h this vari able incl ude the fol lowing: The recommended ingestion rates are based on national average home produced consumption rates. Site-specific ingestion rates may be higher or lower than those recomm ended. The

refore,using the r

ecomm ended inges

tion rates may

under- or ove

restim ate I ag . 

### F ag Fraction of

produce that

is contaminated unitless 1.0 This va riable is site-specific. W

e recom mend using

the defa ult value i

n the absenc e of site -specif ic inform ation, consis

tent with U.S. EPA (1997). Only tha t portion of the

diet produced at home (and theref ore exposed to facility em issions) is of conse quence in the

risk as sessm

ent. As deta iled above

(in Section 6. 2.2.2), the cons umption rat

es we recom mend re present only

the home -produced portion of the die t. Therefore, by using consumption rates specific to home produced foods, it is reasonable to assume that 100% of those home produced foods are contami nated. The following uncertainty is associated w ith this variable: Using default values may overestimate F ag .

## TABLE C-1-2 COPC INTAKE FROM PRODUCE

(Page 4 of 4 )

C-9 REFERENCES AND DISCUSSION Baes, C.F ., R.D. Sharp,

A.L. S joreen, and R .W. Shor. 1984. Review and Analysis of Parameters and Assessing Transpo rt of Environmentally Released Radion uclides through Agriculture . Oak Ridge National Laboratory. Oak Ridge, Tennessee

. This docum

ent is cit ed as a s ource for Br

values. U.S. EPA 1990. Exposure Factors Handbook . Off ice of Health and Env

ironmenta

l Asse ssment, Exposure A ssessm ent Group. Washingt

on, D.C. Marc

h. This is t he docume

nt cited as

the source

of the f raction of produce that is contam

inated ( F ag ) the adult r

esident, c hild resident, and fishe

r. U.S. EPA assume s that F ag for the f

isher child is the same as for t

he fishe r. U.S. EPA 1992. Technical Suppor t Document f

or Land Application of

Sewage Sludge . Volumes I and II. Office of W ater. Washington, D.C. EPA 822/R-93-001 a. This document is cited as a source for plant uptake response slope factors. U.S. EPA. 1994. Guidance for P erforming Sc

reening Lev

el Risk Anal

yses at C ombustion Facili

ties Burning H

azardous Wast

e . Office of Em

ergency and Remedial Re sponse. Office of Solid Waste. This docum

ent is cit ed as the source of

the fra ction of produc e that is c ontaminat ed ( F ag ) for the farm

er (U.S. EPA

assum es that F

ag for the f

armer child is the

same as for the farm

er). U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This document is the source for produce consumption rates.

## TABLE C-1-3 COPC INTAKE FROM B EEF, MILK, PORK, POU LTRY, AND E GGS (Page 1 of 4)

C-10 Description This equation calculates the daily intake of COPCs from the ingestion of anim al tissue (where the iin the equat ion refer s to beef , milk,pork, poultry

, or eggs). The c onsumption ra te varie s for children and adults and for the type of animal tissue ( j ). The c oncentration in the anim al tissue will al so vary

with ea ch scenar io location. Consumption rates were derived from the Exposure Factors Handbook (U.S. EPA 1997) . U.S. EPA ( 1997) presents consumption rates ba

sed on body weight; therefor e, body w eight is not includ ed as a variabl e in the calc ulation of I i . Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The am

ount of anim

al tissue intake is assum ed to be cons

tant and repr

esentativ e of the exposed popula

tion. This a

ssumption m

ay under - or overe stimat

e I i

. (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may

under- or ove

restim ate I i . Equation

Varia ble Description Units Value 

### I i Daily intake of COPC i

from a nimal jtissue mg/kg-day


### A j Concentration of COPC i

in animal tissue j mg/k g FW 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using output f rom the equations in T ables B-3- 10, B-3-11, B-3-12,B-3-13, and B-3-14. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Based on the

inform ation provide d, A beef

and Aporkdepend on est

imated concentrat

ions of COPCs in plant f

eeds and s oil, and the biotransfe

r factor s estim ated for each const

ituent. To the exte

nt the esti mated c oncentrations

and biotransf

er fac tors do not reflec t site-specific or

local condit

ions, A beef may be under- or ov

erestim ated. (2) Uptake of

COPCs into chi cken and eggs has typica lly bee n applied only

to PCDDs and PCDFs but could poss ibly be us ed to calculat e A chick and A egg resulting

from other COPCs. (3) The assumption that 10 percent of a chicken’s diet is soil may not represent site-specific or local conditions of chickens raised on farm s. Stephens , Petreas, a

nd Hayw ard (1992) and St

ephens, Petre as, and Ha

ywa rd (1995) sugg

est the pe rcentage of soil in the diet of

chickens raised unde

r field c onditions ma

y be g reater t han 10 perce

nt. There fore, the

concentra

tion of COPCs

in eggs, A egg , and the conc entration of COPCs in chic

ken, A chick , may

be underest

imated.

## TABLE C-1-3 COPC INTAKE FROM B EEF, MILK, PORK, POU LTRY, AND E GGS (Page 2 of 4)

Varia ble Description Units Value



## C-11 CR j Consumption r ate of animal tissue

j kg/k g-d ay

FW 

### Varies

This variable is site-specific. We derived our recommended ingestion rates of animal tissues (see the equation in Table C-1-4 for fish ingestion) from U .S. EPA (1997): Animal Tissue In gestion Ra tes (kg/kg-day FW)

Farme r Farmer

Child Homegrown Beef 0.00122 0.00075 Homeg rown Milk 0.01367 0.02268 Homeg rown Poultry 0.00066 0.00045 Homegrown Eggs 0.00075 0.00054 Homeg rown Pork 0.00055 0.00042 Ingestion r

ates w ere based on data f

rom U.S. EPA (1997) Ta bles 13-28, 13-36, 13-43, 43-54, and 13-55. T he ingest ion rates l isted in U.S. EPA (1997) were de rived f rom the 1987- 1988 USDA N ational Food Cons

umption Surv

ey and m ay be us ed to asse ss exposur e to contaminants in foods raised at a specific site. Prior to the adjustment for cooking and preparation loss, the mean individual meat consumption rates were weighted by a ge group. The ingestion rates were then adjusted for cooking and preparation loss as recomm ended in U.S. E

PA (1997). The

total prepa

ration and cook

ing loss w

as in the r ange of 45 to 54 perce

nt for bee f, pork, a

nd pou ltr y. In addition, ingestion rate s for the child rece

ptor repres ent a tim

e-weig hted mea n from the respec

tive tables. Whe

re data f or a speci fic age gro up w as i ncom plet e, t he i ntak e was e xtr apol ate d usi

ng d ata fr om t he gene ral popu lat ion (Tab les

11-1 1 and

11-1 3 of U.S . EPA 1997). See HH

RAP Section 6.2.2.2 for a more de tailed ex planation of

our recom

mended m

ethod for e stimat

ing age -appropriate consumption rates. U.S. EPA (1997) provides inf ormation f

or total hom

e produced da

iry (Table 13-28 of

U.S. EPA 1997), but does not specify intake f or fluid milk.
For t he metal s mercur y, selen ium, an d cadmi um, th e conc entr atio n in b eef, mil k, and pork , and the co nsump tion rate ar e in ki logr ams dry w eight per day. W

et-weight to dry

-weig ht convers ion inform

ation for be ef, m

ilk, and pork

is prese nted in U.S. EPA

(1997) The following uncertainty is associated w ith this variable: The recommended tissue-specific consumption rates may not accuratelyreflect site-specific local conditions. As a result, tissuespecific intake s may

be under- or ov

erestim ated.

## TABLE C-1-3 COPC INTAKE FROM B EEF, MILK, PORK, POU LTRY, AND E GGS (Page 3 of 4)

Varia ble Description Units Value



## C-12 F j Fraction of animal tissue j

that is cont

aminated unitless 

### 1.0 This va riable is site-specific. W e recom mend an F

j of 1.0 for

all anim al tissue s consum

ed. This r

ecomm endation is c onsistent w

ith NC DEHNR

(1997). The following uncertainty is associated w ith this variable: The fr action of animal tissue tha t is contam

inated is s ite-spec ific; the refore,any of

the follow

ing ma y be under

- or overesti mated: variations in the prox imity of the receptor to the

contami nated source , size of

the contam

inated sourc e, rece

ptors of concern, mobility of receptors, and nature of exposure.

REFERENCE AND DISCUSSIONS Stephens, R.D ., M.X. Petreas , and D.G. Hayw ard. 1992. “Biotransfe

r and Bioac cumulation of Dioxi ns and Dibenz

ofurans f rom Soil.”

Hazardous

Material s Labora

tory, Ca lifornia D epartm

ent of Health Se rvices. Berkeley, Ca

lifornia. Presented a

t the 12th Inte

rnational Sy

mposium on Dioxins a

nd Related C ompounds. A ugust 24 throug

h 28. Univer

sity of Tam pere, Ta mpere,Finland. This document is cited as the source of the assumption that free-range chickens ingest soil as 10 percent of their diet and as the source of the dioxin and furan congeners-specific BCF s recomm ended by N

C DEHNR ( 1997). Howe ver this doc

ument does

not clearl

y ref erence or document the assum

ption that soil represent

s 10 percent

of a f ree-rang e chicke n’s diet. T

he document appears to cite two oth er document s as suppo rting its assumption : (1) Chan g, Hayward, Goldman, Harnly, Flat tery and Step hens (19 89) and (2) Pet reas, Goldman, Hayward, Chang, Flattery , Wiesm uller, Stephe

ns, Fry, and Rappe (1992)

. Also, this document presents dioxin and furan congener-specific BCF s (thigh) f or the low-

exposure group aft

er 80 days of a 178- day tota l exposure

period. The

chickens in the low-dose group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 42 ppt I-TEQ. Chickens in the high-dose group were fed a diet containing 10 percent soil with a PCDD/PCDF concentration of 458 ppt I-TEQ; BCF results w ere not pre sented f

rom the high-dose g

roup. Stephens, R.D., M.X. P etreas, and D.G. Hayw ard. 1995. “Biotransfer and Bioaccumulation of Dioxins and Furans from Soil: Chickens as a Model for Foraging Animals.” The Science of the Total Environment. Volume 175: 253- 273. This docum

ent is an e

xpansion of

the result

s originally pres ented in Stephe ns, Petreas , and Hay

ward (1992). In particular, this doc ument sug

gests tha t the perce

ntage of soil in the di et of chickens raised unde

r field c onditions is lik

ely to be greate r than 10 perc ent, the va

lue that w as used in t

he experi mental study pre sented in thi s docume nt. Also, this document presents dioxin and furan congener-specific BCF s (thigh) unde

r two ex posure sche

mes; low expos

ure and high exposure. The w hite leghor

n (Babcock

D 300) chick

ens in the low g roup were

fed a di et containing

10 percent s oil with a

PCDD/PCDF conce

ntrations of

42 ppt I-TEQ . Chicke

ns in the hig

h group we

re fed a diet contai

ning 10 perce

nt soil wi th a PCDD/PCDF conce

ntration of 460 ppt I-TEQ (some c ongeners w ere for tified by spiking). The BCF s presented for low

- and high-dos e groups both r epresent a verage s of res

ults from Day- 80 and Day

-164 of a tot

al 178-day

exposure period.

## TABLE C-1-3 COPC INTAKE FROM B EEF, MILK, PORK, POU LTRY, AND E GGS (Page 4 of 4)

C-13 U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This document is the source for home produced beef, milk, pork, poultry, and egg consumption rates.

## TABLE C-1-4 COPC IN TAKE FR

OM FISH (Page 1 of 4)

C-14 Description This equation calculates the daily intake of COPCs from the ingestion of f ish. Consumption rates were derived from the Exposure Factors Handbook (U.S. EPA 1997) . U.S. EPA ( 1997) presents consumpt ion rates based on body weight; t herefore, b ody weight is no t includ ed as a variabl e in the calc ulation of I fish . The limitatio ns and un certainty in trodu ced in calcu lating th is value inc lude th e following: (1) The am

ount of fis

h intake is

assum ed to be cons

tant and repr

esentativ e of the exposed popula

tion. This a

ssumption m

ay under - or overe stimat

e I fish . (2) The standard assumptions regarding period exposed may not be representative of a ny actual exposure situation. This assumption may under- or overestimate I fish . Equation

Varia ble Description Units Value 

### I fish Daily intake of COPC from fish mg/kg-day


### C fish Concentration in fish mg/kg 

### Varies This variable is COPC- and site-specific, and is calculated using output from the equations in Tables B-4-26 through B-4-28; the fish con cen tra tio n wil l var y for e ach water bod y. The following uncertainty is associated w ith this variable: The m ethodology

does not ac count for c oncentration variations across f ish specie s. Diff

erent species ma

y acc umulate COPCs to different extents depending, for example, on their feeding habits and fat content. This ma y cause C

fish to be underor overes timated.

## TABLE C-1-4 COPC IN TAKE FR

OM FISH (Page 2 of 4)

Varia ble Description Units Value



## C-15 CR fish Consumption rate of fish kg/kg-day FW 

### Varies

The consumption rate varies for the receptor considered. The following home produced or caught ingestion rates for fish w ere derived from U .S. EPA (1997): Receptor Ingestio n Rate (kg/kg-d ay FW) Fisher 0.00125 Fisher Child 0.00088 We derived ingestion rates using data from U.S. EPA (1997) Table 13-23. The ingestion rates listed in U.S. EPA (1997) were derived from t he 1987-1988 USDA

National Food Consumption Survey and may be used to a

ssess e xposure to c ontaminant

s in foods g

rown, raised, or caught at a specific site. Prior to the adjustment for cooking and preparation loss, the mean individual fish consumption rates we re w eig hted by age gro up. T he i nge sti on ra

tes we re t hen a djus ted for cook ing and pre par ati on lo ss a

s re com me nded in U .S. E PA (1997). The t

otal prepar

ation and cook

ing loss f or fish w as 41 perce

nt. In addition, the ingestion rates for the child receptor represents a time-weighted mean. Where data f or a specific age group was incomplet

e, the inta ke wa s extra polated using

data fr om the general popula

tion (Table

10-46 of U.S. EPA 1997). See HHRAP Se ction 6.2.2.2 for a more detailed explanation of our recommended method for estimating ag e-appropriate consumption rates. Uncertain ties intr oduced by assumption s made to calcul ate this valu e includ e the follo wing: (1) Our recom

mended int

ake rat es don’t nec essarily

take into account the types of fish that will be present in t

he wate r body. Separate intake rates are needed for fre shwater and estuarine fish and shellfish, depending on the nature of the local surface water body. This assum

ption can overestimate or underestimate CR fish . (2) These i

ntake ra tes do not re

present long

behavior pa

tterns, w hich is the f

ocus of the

exposure assess

ments us ed to support chronic health effects. This introduces uncertainty into the estimates of m edians and other percentiles. This assumption can overestimate or underestimate CR fish . (3) The intak

e rates represent

total intak

e rates of home -caught f

ish. Wher

e use of site-spe cific i

nforma tion would re

veal the amount of

fish cons umed f rom w aters w ithin the study

area, thi s inform

ation should be us ed. This a ssumption c an overes

timate or underestimate CR fish . 

### F fish Fraction of

fish that is contaminated unitless 

### 1.0 We recomme

nd using this default value if site-specific information is not available. T he contaminated fraction will vary with each exposure s cenario; how

ever, NC DEHNR ( 1997) and U.S. EPA (1994) assum

e that this value e quals 1.0 for

the fis her. The following uncertainty is associated w ith this variable: Using 1.0 as a def

ault value for fr action of fish that

is contam

inated ass umes tha t receptor s consum e only c ontaminat

ed fish; this assumption may overestim ate F fish .

## TABLE C-1-4 COPC IN TAKE FR

OM FISH (Page 3 of 4)

C-16 REFERENCES AND DISCUSSION NC DEHNR . 1997. NC DEHNR P rotocol for Pe

rforming Indir

ect Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. This docum

ent is one of

the ref erence s ource docum

ents for the equation i

n Table C -1-4. U.S. EPA. 1994. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docum

ent is one of

the ref erence s ource docum

ents for the equation i

n Table C -1-4. U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This document is the source for home-caught fish consumption rates.

## TABLE C-1-5 COPC IN TAKE FR

OM DRINK

ING WATER (Page 1 of 3)

C-17 Description This equation calculates the daily intake of COPC from drinking w ater. COPC intake from drinking water is c alculated from the concentration of COPC dissolved in the water column of each surface water body or w

atershed identified as a drinking water source. The dissolved concentration is used to estimate COPC intake from drinking water because it is assumed the w ater is filtered prior to huma

n consumption. The COPC concentrat ion will v ary f or each w ater body . The cons

umption rat

e varie s for children and adult s. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The amount of drinking water intake is a ssumed to be constant and representative of the exposed population. This assumption may under- or overestimate I dw . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of any ac tual expos

ure situation. This as sumption m ay under - or overe stimat

e I dw . Equation

Varia ble Description Units Value 

### I dw Daily intake of COPC from drinking w

ater mg/kg-day


### C dw Dissolved phase water

concentrat

ion mg/L 

### Varies This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble B-4-24. Uncertain ties associ ated with th is variable i nclude t he followin g: All of the variables in the equation in Table B-4-24 are COPC- and site-specific. Therefore, using default values ra ther than site-speci fic values, for an y or all of these var iables, will contrib ute to th e under- or overesti mating C wt . We expect the degree of uncertainty associated with the variables d w and d

b to be minimal b ecause infor mation for est imating d w is gener ally a vailable and the probable range for d b is narrow. The uncertainty associated w ith the variables F water and C

wtot is associated with estimates o f OC content. Because OC

cont ent va lues can var y widely fo r diffe rent locat ions in th e same medium , using def

ault OC values may

result in significant uncertainty in specific cases.

## TABLE C-1-5 COPC IN TAKE FR

OM DRINK

ING WATER (Page 2 of 3)

Varia ble Description Units Value



## C-18 CR dw Rate of

consumption of drinking w

ater L/day 

### 0.67 or 1.4 This variable is site-specific. We recommend using default values of 0.67 (child) and 1.4 (adu lt) in the absence of site-specific data. Our recom

mended a verage adult consum

ption rate of

drinking w

ater is ba sed on infor

mation c ited in U.S. E

PA (1997). For the

child receptor, U.S. EPA (1997) provides recomm ended drinking

water intake r ates f or various age gr

oups in Table

3-30. The c

hild defaul

t drinking water intake was derived using a time-weighted averag e for the age groups 0 to 6 years of age. The following uncertainty is associated w ith this variable: The av erage consumption ra

te of drink

ing wat er is bas ed on the av

erage i ntake obse

rved fr om fiv e studies. The num

ber of studies conduct may underestimate or underestimate CR dw . 

### F dw Fraction of drinking water

that is cont

aminated unitless 

### 1.0 This va riable is site-spec

ific. C onsistent w

ith U.S. EPA ( 1994), we recomm end assum

ing 1.0 for the frac

tion of drink

ing wat er that is contamina

ted. The following uncertainty is associated w ith this variable: Some re ceptors m

ay cons ume a f raction of their drink

ing wat er from sources uni

mpacted by fa

cility emiss ions. Ther

efore, t his assumption will likely overestim ate F dw . 

### BW Body w

eight kg 

### 15 or 70 This va riable is site-spec

ific. W e recom mend using

default values of

15 (children)

or 70 (adults)

in the abse

nce of s ite-spec ific informa tion. Thes e defaul

t values are consi stent wi

th U.S. EPA (1991; 1994). Uncertainties associated with this variable include: These body

weight s represe nt the ave rage w eight of an adult and c

hild. Howe

ver, depe nding on the re ceptor, the body weights may be higher or lower. These default v alues m ay ove restim ate or under

estima te actual body we ights. How

ever, the degree of under- or ove

restim ation is not e

xpected t o be signif

icant.

## TABLE C-1-5 COPC IN TAKE FR

OM DRINK

ING WATER (Page 3 of 3)

C-19 REFERENCES AND DISCUSSION U.S. EPA. 1991. Human Health E valuation Manual, Suppl emental Gui

dance: Standard D

efault Exposur

e Factors. Offic e of Solid W aste and E

merge ncy Re sponse. OSW

ER Direc tive 9285.6-03. Washingt on, D.C. Marc

h 21. This docum

ent is cit ed as the refere

nce source

document of the ex

posure frequency a

nd body we

ight var iables. U.S. EPA. 1994. Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste. This docum

ent was cited as the source

of the f raction of drinking w

ater that is contam

inated. U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This document is the source for the drinking water consumption rates.

## TABLE C-1-6 TOTAL DAI LY INTAKE (Page 1 of 3)

C-20 Description This equa tion calcula

tes the da ily inta ke of C OPC via all indirect e xposure pat

hways. As di scussed i

n Chapter 4 a

nd Table 4- 1, the indirec

t exposure

pathway s considered in the calculation of the total daily

intake of COPCs are specific to the re comm ended expos

ure scena rio evalua ted and the r

epresenta tive ex posure sett

ing. Dail y intak e values from exposure pa

thway s which a re not evaluated in a respective exposure scenario may be assumed to be zero when calculating the total daily intake of COPC ( I). Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The uncer

tainties a ssociate d with es

timate s of total

intake a re those a ssociate d with ea

ch of the medium

- or tissue -specif

ic intake s. (2) To the extent that medium- or tissue-specific intake s do not accurately represent site-specific local conditions, I may be under- or ov

erestim ated. Equation

Varia ble Description Units Value 

### I Tot

al d ail y i ntak e of COPC mg/kg-day 

### I soil Daily intake of COPC from soil mg/kg-day 

### Varies This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble C-1-1. T

he value for this v

ariable w ill vary for each rec eptor and ea

ch exposure

scenario location. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We ass

ume the amount of

soil intak e is consta

nt and repre sentativ

e of the exposed popula

tion. This a

ssumption m

ay under - or overesti mate I soil . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may under- or ove

restim ate I soil .

## TABLE C-1-6 TOTAL DAI LY INTAKE (Page 2 of 3)

Varia ble Description Units Value



## C-21 I ag Daily intake of COPC from aboveground produce mg/kg-day DW 

### Varies

This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble C-1-2. T

he value for this v

ariable w ill vary for each rec eptor and ea

ch exposure

scenario location. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We assume the am ount of produce intake is constant and representative of the exposed population. This assumption may under- or ove

restim ate I ag . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may under- or ove

restim ate I ag . 

### I beef 

### ; I milk 

### ; I pork 

### ; I poultry 

### ; I eggs Daily intake of COPC from bee f, mil k, p ork , po ult ry, and eggs mg/kg-day FW 

### Varies

This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble C-1-3. T

he value for this v

ariable w ill vary for each rec eptor and ea

ch exposure

scenario location. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We assume the am ount of animal tissue intake is constant and representative of the exposed population. This assumption may under- or overestimate I beef , I milk , I pork , I poultry , and I

eggs . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may under- or overestima te I beef , I milk , I pork , I poultry , and I

eggs . 

### I fish Daily intake of COPC from fish mg/kg-day FW 

### Varies

This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble C-1-4. T

he value for this v

ariable w ill vary for each w ater body evaluat ed. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We ass

ume the amount of

fish inta ke is cons tant and repr

esentativ e of the exposed popula

tion. This a

ssumption m

ay under - or overestimate I fish . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may under- or overestima te I fish .

## TABLE C-1-6 TOTAL DAI LY INTAKE (Page 3 of 3)

Varia ble Description Units Value



## C-22 I dw Daily intake of COPC from drinking water mg/kg-day 

### Varies This va riable is COPC- and site-specif ic, and is c alculate d using the equation in Ta ble C-1-5. T

he value for this v

ariable w ill vary for each w ater body evaluat ed. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We assume the am ount of drinking water intake is constant and representative of the exposed population. This assumption may under- or overestimate I dw . (2) The sta

ndard assum

ptions rega

rding period e

xposed m ay not be represe ntative of an actual exposure situation. T

his assum ption may under- or overestima te I dw .

## TABLE C-1-7 INDIVIDUAL CANCER RISK: CARCINOGENS

(Page 1 of 3)

C-23 Description This equa tion calcula

tes the indi

vidual ca ncer risk from indirect e

xposure to c arcinoge

nic COPCs. T

he exposure

duration va

ries for diffe rent scena

rios. Unce

rtainties associat

ed with thi s equatio n inclu de the foll owing: (1) Default

factors for ex posure frequency a

nd exposure duration are

assum ed to repre sent the hig

hest expos

ure that is reasonably

expected to occur at

a site a nd, in practic e, is est

imated by combining upper-bound (90 th to 95th percentile) values for these exposure parameters, but not all parameters. This assum ption may over- or underestimate the Cancer Risk i . (2) Slope fac

tors are us ed to estim

ate an upper

-bound lifeti

me proba bility of an individual

developing

cancer as a res

ult of ex posure to a pa

rticular l evel of

a COPC, and a

re accom panied by the weight of evidence classif ication to indicate the strength of the evidence that the agent is a human carcinogen. This classifica tion potentially over- or underestimates Cancer Risk i . (3) Risk at low expos ure levels is dif

ficult to measur

e directl y, eithe r by anim al exper iments or by epide

miologic al studies . The dev elopment of a ca

ncer slope factor g

enerally entails applying a model to the ava

ilable data

set and usi

ng the m odel to extr

apolate f rom the r elatively high doses adm

inistered t o experim

ental anim

als (or the exposures

noted in epidemiological studies) to lower exposure levels expected for human c ontact in the environment. This approach may under- or overestimate Oral CSF

. Equation

Varia ble Description Units Value 

### Cancer Risk i Individual lifetime cancer risk through indirect exp osur e to COPC carcinogen i unitless



### I i Daily intake of COPC ifrom

animal tissue

j mg COPC/kg

BW-day 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-1-6. T

he value for this v

ariable w ill vary for eac h exposure pathway

and each e

xposure sc enario loca

tion. The following uncertainty is associated w ith this variable: This variable is COPC- and site-specific. See the equation in Table C-1-6 regarding the calculation of and uncertainties associated with this variable.

## TABLE C-1-7 INDIVIDUAL CANCER RISK: CARCINOGENS

(Page 2 of 3)

Varia ble Description Units Value



## C-24 ED Exposure dura tion yr 

### 6, 30, or 40 This variable is exposure scenario-specific: Exposure Sc enario ED Farmer 40 (U.S. EPA 1994) Farmer Child 6 (U.S. EPA 1989) Adult Res ident 30 (U.S. EPA 1989) Child Reside

nt 6 (U.S. EPA 1989) Fisher 30 (U.S. EPA 1994) Fisher Child 6 (U.S. EPA 1989) The following uncertainty is associated w ith this variable: This ex posure durati on is a sing

le value that repre sents the highest ex posure that i s reasona

bly ex pected to oc cur at a s ite. This assumption may ove restimate ED

. 

### EF Exposure frequency days /yr 

### 350 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic inform ation, consis

tent with U.S. EPA (1991). The following uncertainty is associated w ith this variable: This ex posure frequency i s a single value that repre sents the m ost freque nt exposure

that is re asonably

expected to occur at

a site, ass uming 2 w

eeks of vacation or travel. This a ssumption m

ay ove restim ate EF

. 

### AT Averagi ng time yr 

### 70 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic inform ation, consis

tent with U.S. EPA (1989). The following uncertainty is associated w ith this variable: The recommendation for avera ging time may

not accurately represent site-specific tim e; specifically, this single value m ay under- or overestimate the length of time of e xposure. 

### 365 Units conve

rsion fac tor day/ yr

## TABLE C-1-7 INDIVIDUAL CANCER RISK: CARCINOGENS

(Page 3 of 3)

Varia ble Description Units Value



## C-25 Oral CSF Oral Canc er Slope Fac tor (mg/ kg-d ay) -1 

### Varies This va riable is COPC-specif

ic. We recomm

end using the

companion database

to the HHRA

P as an initia

l source f or this parame ter. We also rec omme

nd checking

the recom

mended hie

rarchy of source s of hea

lth benchm

ark va lues (disc ussed in Appendix A

-2) to ma ke sure the databas e values are still valid, e specially

if using database values r esult in ris

k estim ates of concern. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Slope fac

tors are us ed to estim

ate an upper

-bound lifeti

me proba bility of an individual

developing

cancer as a res

ult of exposure t

o a particular level of a COPC; and are a ccompa nied by the

weight of evide nce clas sifica

tion to indicat

e the strength of

the evide nce that the

agent is a human carcinogen. (2) Risk at low expos

ure levels is dif

ficult to measur

e directl y eithe r by anim al exper iments or by epide

miologic al studies

. Developing

a cance r slope f actor ge nerally entails a pplying a model to t

he available data set and using the model to extrapolate from the relatively high doses administered to experimental animals (or the exposures noted in epidemiological studies) to the lowe

r exposure

levels expected for hum

an contact in the envir

onment. T

his approach may

under- or overesti mate Oral CSF

.

REFERENCES AND DISCUSSION U.S. EPA. 1989. Risk Asse ssment Gui

dance for Super

fund, Volume I, Human Health E valuation Manual (

Part A). Interim

Final. Of

fice of Emerg ency a nd Reme dial Respons e. EPA/540/1-89/ 002. Decem ber. This docum

ent is cit ed as the refere

nce source

document of the ex

posure durati on for adult and child residents. T his docume

nt is also cited as the

refer ence sourc e docume

nt for the averag

ing time f or carcinog

ens. U.S. EPA. 1991. Human Health E valuation Manual, Suppl emental Gui

dance: Standard D

efault Exposur

e Factors. Offic e of Solid W aste and E

merge ncy Re sponse. OSW

ER Direc tive 9285.6-03. Washington, D.C. This docum

ent is cit ed as the refere

nce source

document of the ex

posure frequency. U.S. EPA. 1994. Draft Guidance for Performing Screening Level Risk Analyses at Combusti on Facilities Burning Hazardo us Wastes. Attachment C , Draft Exposure Asse

ssment Gui

dance for RCRA Hazardous Waste Combustion Facili ties . April 15. This docum

ent is cit ed as the refere

nce source

document of the ex

posure durati on for the f

isher and f

armer .

## TABLE C-1-8 HAZARD QUOTIENT: NONCARCINOGENS

(Page 1 of 3)

C-26 Description This equa tion calcula

tes the ha zard quotient

for indire ct exposur

e to noncarc inogenic CO

PCs. The f

ollowing unc ertainty

is assoc iated w

ith this equa

tion. A chronic RfDis an est

imate of a dail

y expos ure level for the human populat ion, including s ensitive

subpopulations, t

hat is lik ely to be without an appreciable risk of deleteri ous eff

ects during a lifetime. Chronic RfDs are specifically dev eloped to be protective for long-term exposure (from 7 years to a lifetime) to a com pound. COPC-specific reference doses ( RfD ) are unlikely to underestimate a chemical potential for causing adverse effects. Equation

Varia ble Description Units Value 

### HQ Hazard quotient unitless 

### I i Daily intake of COPC i

from a nimal ti ssuej mg COPC/ kg-day 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-1-6. T

he value for this v

ariable w ill vary for each exposure pathway and each exposure scenario location. Uncertainties associated with this variable a re site-specific. 

### ED Exposure dura tion yr 

### 6, 30, or 40 Consistent with U.S. EPA (1994b) and NC DEHNR (199 7), we recomme nd using the following default values: Exposure Sc enario ED Farmer 40 (U.S. EPA 1994a) Farmer Child 6 (U.S. EPA 1989) Adult Res ident 30 (U.S. EPA 1989) Child Reside

nt 6 (U.S. EPA 1989) Fisher 30 (U.S. EPA 1994a) Fisher Child 6 (U.S. EPA 1989) Uncertainty associated with this variable includes: These e xposure dura

tions are s ingle va

lues that r epresent t he highest

exposure that is re asonably expected to occur at

a site. These values may

overestimate ED for some individuals.

## TABLE C-1-8 HAZARD QUOTIENT: NONCARCINOGENS

(Page 2 of 3)

Varia ble Description Units Value



## C-27 EF Exposure frequency days /yr 

### 350 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic data. T his value is based on U.S. EPA (1991) and is

consistent

with U.S. EPA (1994b). Uncertainty associated with this variable includes: This ex posure frequency i s a single value that repre sents the m ost freque nt exposure

that is re asonably

expected to occur at

a site with two weeks of

vacation or travel. This recomm ended value may overes

timate EF for individuals who a

re awa y fr om their home f or more t han two w

eeks e ach ye ar. On the other hand, som e individual s (such as

farm ers) m ay re main at their hom

e (or farm ) for m ore than 350 day

s per y ear. In either cas e, the deg ree of ov er- or undere stimat

ion is not ex

pected to be

significant in most ca ses. 

### RfD Reference Dose mg/kg-day 

### Varies This va riable is COPC-specif

ic. We recomm

end using the

companion database

to the HHRA

P as an initia

l source f or this para

meter

. We als o recom

mend che cking the

recom mended hie

rarchy of source s of hea

lth benchm

ark va lues (disc ussed in A

ppendix A- 2) to make sure the da

tabase v alues are still va lid, espec ially i f using da tabase v alues res ult in risk estima

tes of c oncern. The following uncertainty is associated w ith this variable: A chronic RfDis an est

imate of a dail

y expos ure level for the human populat ion, including s ensitive

subpopulations, t

hat is likely to be without an appreciable risk of deleterious eff ects during a lifetime. Chronic RfDs are specificall y developed to be protective for long-term exposure (from 7 y ears to a lifetime) to a com pound. COPC-specific RfDs are unlik ely to unde

restim ate a COPC’s pote

ntial for causing a

dverse health eff

ects. 

### 365 Units conve

rsion fac tor day/ yr 

### AT Averagi ng time yr 

### 6, 30, or 40 This va riable is site-specific and related t o ED . Specifically, the AT for noncar

cinogens i s numerically

the sam e as ED. This def

ault value is consistent

with U.S. EPA (1989), U.S . EPA (1991), a nd U.S. EPA (1994a

). Uncertainty associated with this variable includes: Our recom

mended a veragi ng time may not accura

tely r epresent site-spec ific tim

e; specif ically this single value may

under- or overesti mate t he length of

an aver age adult lifetim e.

## TABLE C-1-8 HAZARD QUOTIENT: NONCARCINOGENS

(Page 3 of 3)

C-28 REFERENCES AND DISCUSSION NC DEHNR

(1997). Draft North C

arolina Protocol for Perform ing Indirect Exposure Ri sk Asse ssments f or Hazardous W

aste Exposur

e Risk As sessme nts for Hazar

dous Waste C

ombustion Units . Jan uar y. U.S. EPA. 1989. Risk Asse ssment Gui

dance for Super

fund, Volume I, Human Health E valuation Manual (

Part A). Interim Final. Of

fice of Emerg ency a nd Reme dial Respons e. EPA/540/1-89/ 002. Decem

ber. This docum

ent is cit ed as the refere

nce source

document of the ex

posure durati on for adult and child residents. U.S. EPA OSW a ssumes that the recomm

ended expos

ure duration f

or the child resident m

ay al so reasona

bly be a pplied to the f

armer child and to the

fisher child. U.S. EPA. 1991. Human Health E valuation Manual, Suppl emental Gui

dance: Standard D

efault Exposur

e Factors. Offic e of Solid W aste and E

merge ncy Re sponse. OSW

ER Direc tive 9285.6-03. Washington, D.C. This document is cited as a source document for exposure frequency and averaging time. U.S. EPA. 1994a

. Estimating Exposure to Dioxin-like Compo nents - Volume III: Site-Specific Assessment Procedure . Revie w Draf t. Off ice of R esearc h and Development. W

ashington D. C. EPA/600/6-88/0 05Cc. June. This docum

ent is cit ed by U. S. EPA (1994b) as the sam e docume nt for the recomm

ended defa

ult exposure

duration (

ED ) values for the farm

er and fisher. The ED value of 40 year s recommended for both the farme r and the fisher is based on the assumption that “farmers live in one location longer than the general populatio n”. U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustio n Facilities Burning Hazardou s Wastes. Attachment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docu ment recommends th e following:

C An exposure frequency of 350 days per year

C Receptor- specific exposure duration va

lues as pr esented in U.S. EPA (1994a )— fishe r (40 ye ars) and f

armer (40 yea rs) and U.S. EPA (1989)—adul t resident (30 yea

rs) and child resident (6 years)

C Adult and c

hild body w

eights of 70 kg and 15 k

g, respe ctively

## TABLE C-1-9 TOTAL CANCER RISK: CARCINOGENS

(Page 1 of 1)

C-29 Description For carcin ogens, can cer risks are add ed across all carcinogen ic COPCs. See Appendi x A for identifica tion of car cinogens . Uncertain ty associated wit h this eq uation includ es the follo wing: Total Cancer Risk

assum es that dif ferent c arcinoge

ns aff ect the s ame ta

rget organ to produce a

cancer response, ignoring pote ntial antag

onistic or s

ynerg istic ef fects or disparat

e eff ects on differ ent targe t organs. Equation

Varia ble Description Units Value 

### Total Cancer Risk Individual lifetime cancer

risk through indirect exp osur e to all COPC carcinogens unitless



### Cancer Risk i Individual lifetime cancer risk through indirect exp osur e to COPC carcinogen i unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-1-7. T

he value for this v

ariable w ill vary for each expo sur e pat hway. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) We ass

ume that the defa ult values for ex posure frequency a

nd exposure duration repre sent the hig hest expos

ure that is reasonably expected to occur at a site. In practice, intakes are estim ated by combining upper-bound (90th to 9 5th percentile) values for these exposure variables, but not for other parameters. This assumption is likely to overestimate intakes and the Cancer Risk i . (2) Slope fac

tors are us ed to estim

ate an upper

-bound lifeti

me proba bility of an individual

developing

cancer as a res

ult of ex posure to a partic

ular level of a pote

ntial car cinogen; a

nd are ac companied by the w eight of evidence classif ication to indi cate the strength of the eviden ce that the agent is a hu man carcinogen . This classific ation p otentia lly over- or u nderesti mates risk. (3) Risk at low expos

ure levels is dif

ficult to measur

e directl y eithe r by anim al exper iments or by epide

miologic al studies

. Developing

a cance r slope f actor ge nerally entails a pplying a model to t

he available data set and using the model to extra

polate from the relatively

high doses administered to experimental animals (or the exposures noted in epidemiological studies) to lower exposure levels expected for human contact in the environment. This approach is likely to overestimate CSF

.

## TABLE C-1-10 TOTAL HAZARD INDEX: NONCARCINOGENS

(Page 1 of 1)

C-30 Description For non-cance

r health ef

fects, hazard quotie

nt for all COPCs, reg

ardless of target organs, a

re summ ed to calc ulate a tot al hazard index . Uncerta inties as sociated w

ith this equa

tion include the following: (1) Assum

ing that dif

ferent C OPCs aff

ect the s ame ta

rget organ to produce a

n adverse health ef fect, w hile ignoring

potential a

ntagonistic

or syne rgistic effects or dispa

rate ef fects on diffe

rent target organ s, may overestimate the total haza rd index. (2) Total haz

ard index a

ssumes that a sing

le individua

l in the ex posure sce

nario is ex

posed to site -related contamina nts at est imated exposure c oncentrations by all pathway

s that m ake up the scenario. It is unli kely, however, th at a single in dividu al will be expo sed by each pat hway in the expo sure media. Thi s assumptio n may overestimate the total haza rd index. Equation

Varia ble Description Units Value 

### Total Hazard Index Total indiv

idual hazar

d index for

all COPCs acros s all ex

posure pat hways unitless



### HI j Hazard I

ndex for exposure pat hway j unitless 

### Varies This variable is COPC- and site-specific. The value f or this variable will vary f or each exposure pathway. Uncertainties associated with this variable are site-specific. 

### HQ i Hazard Quotient for COPC i unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-1-8. T

he value for this v

ariable w ill vary for each e

xposure pathway. Uncertainties associated with this variable are site-specific.

## TABLE C-1-11 SEGREGATED HAZARD INDEX FOR SPECIFIC ORGAN EFFECTS: NONCARCINOG ENS (Page 1 of 1)

C-31 Description For non-cance

r health ef

fects, hazard quotie

nts are a dded across

COPCs whe

n they ta rget the same organ to ca lculate a segreg ated hazard index . See A ppendix A- 2 for identi fication of noncarcinogens and thei

r associa ted targe t organ. Si

nce seg regation by

critica l eff ect requir es the ide ntificat ion of all m

ajor eff ects, inf ormation i

n Appendix A-2 m

ay not a lway s represe nt the most current and complete information on COPC-specific major eff ects. Therefore, Appendix A-2 m ay require supplemental information about COPC-specific major eff ects. Uncertainties associated with this eq uation includ e the follo wing: (1) Targe

t organ segregat

ion is depende

nt upon the crit

ical ef fect. Segregation by c

ritical e ffec

t requires the identif

ication of all ma jor eff ects, not jus

t those see

n at higher

doses. T he segregation process may

over- or underestimate the hazard index

. Equation

Varia ble Description Units Value HI j Hazard inde

x for e xposure pathway j unitless
HQ i Hazard quotient for COPC i unitless Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-1-8. T

he value for this v

ariable w ill vary for e ach expo sur e pat hway. The following uncertainty is associated w ith this variable: (1) We ass

ume that the defa ult values for ex posure frequency a

nd exposure duration repre sent the hig hest expos

ure that is reasonably expected to occur as a site. In practice, intakes a re estimated by com

bining upper-boun d (90th to 95th percentile) values f or these e xposure v ariables , but not for ot

her param

eters. T his equation i s likely

to overes timate intakes and HI j . (2) Adverse health effects at low exposure levels are diff icult to either directly either by animal experim ents or by epidemiological studies. T

he developm

ent of RfD s genera

lly enta ils apply ing uncerta

inty f actors to e

xtrapolate from the results

of studies

using high exposur

e doses to lower ex

posure doses

expected for hum

an contact in the envir

onment. T

his approach is unlikely

to underestimate and likely overestim ate HI

j . The u nce rta int ies asso ciat ed wi th t his vari abl e are COP C- an d si te- spe cifi c and will vary fo r eac h exp osu re p ath way.

## TABLE C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS (Page 1 of 4)

C-32 Description This equation calculates the excess lifetime individual cancer risk from the averag e daily intake via inhalation of a COPC carcinogen. Uncertainties associated with this equation include: (1) COPC-specific URF values a re unlikel y to undere stimat

e, and m ay ove restim ate, the c arcinoge

nic potential

of a COPC because of

the choice

of ma thematical models and the us e of uncertainty factors in the estimation of these va lues. (2) The uncertai nty a ssociated wit h the variabl e C a are largely sit e-speci fic. Equation

Varia ble Description Units Value 

### Cancer Risk inh(i) Individual lifetime cancer risk through direc

t inhalation of COPC carci

nogen i unitless



### EC Exposure c oncentration : g/m 3

## TABLE C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS (Page 2 of 4)

Varia ble Description Units Value



## C-33 URF Inhalation Uni t Risk Fa ctor (μg/m 3 ) -1 

### Varies This va riable is COPC-specif

ic. We recomm

end using the

companion database

to the HHRA

P as an initia

l source f or this parame ter. We also rec omme

nd checking

the recom

mended hie

rarchy of source s of hea

lth benchm

ark va lues (disc ussed in Appendix A

-2) if usi ng databas e values

results i n risk es timate s of conc ern. The following general uncertainty is as sociated with this variable: COPC-specific inhalation unit risk factors ( URF s) are g enerally estim ated by fitting the results

of studies

conducted on laborat ory animals with a math ematical model. The model general ly recommended by U.S . EPA is th e linearize d multistage (LMS) m odel. U.S. EPA ’s position on a ssessing carcinogenic potentia

l was upda

ted (U.S. EPA

1996b) and should be considered along with recommended toxicological benchmarks and informa tion (U.S. EPA 1995; 19 96a). The LMS model assumes that there is no “safe dose” or threshold below which a COPC causing cancer at higher doses will no longer cause cancer i n expected individuals. In other w ords, any exposure to a carc inogen m ay, throug

h a serie s of sta

ges, ca use cance r in an expose d individual. Also, a series of

uncertaint

y fa ctors are applied to the

results be fore the results a re fitted with the LMS model. Apply ing uncertainty

factors follows the underly

ing assum ption that hum

ans are, or may

be, as se nsitive or more s ensitive

to the carcinogenic ef

fects of COPCs tha

n the laborat

ory anim als that w ere test ed. As a result of the choice

of models and the us e of uncertainty factors, COPC-specific URF s are unlik

ely to unde

restim ate a COPC’s potential for caus ing cance r. 

### C a Total COPC air conce ntration : g/m 3 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-5-1. Uncertainty associated with this variable includes: Calculated assum

ing a def ault ST value for background plus local sources, rather than a ST value for urb an source s. If a specific site is

located in an urban are a, using the latter ST value may be more appropriate. Specifically, the ST value for urban sources is about one order of magnitude greater than the ST value f or backg round plus local

sources a nd would res

ult in a lower c alculate d F v value; however, the F v value is likely to be only

a few percent low

er.

## TABLE C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS (Page 3 of 4)

Varia ble Description Units Value



## C-34 EF Exposure frequency days /yr 

### 350 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic data. T his value is based on U.S. EPA (1991) and is consis tent with U.S. EPA (1994b). Uncertainties associated with this variable include: This ex posure frequency i s a single value that repre sents the m ost freque nt exposure

that is re asonably

expected to occur at

a site, w ith two w eeks of vacation. This re comm

ended value

may overest imate EF for indiv

iduals who are aw

ay f rom their home f or more t han two w

eeks e ach ye ar. On the ot her hand, indiv

iduals such a

s subsiste nce far mers m ay re main at their home (or f

arm) f or more t han 350 days

per ye ar. In eithe

r case, we don’t e

xpect a signifi cant degr

ee of ov er- or underestimation in most cases. 

### ED Exposure dura tion yr 

### 6, 30, or 40 We rec omme

nd reasonable

maxi mum e xposure (R

ME) value s for T 2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure duration rates are based on historical mobility rates and may not rema in constant. This assumption may overestimate or underestimate Cs and Cs tD . (2) Mobility s

tudies indica

te that m ost recept ors that m ove rem ain in the v

icinity of the e mission s ources. How

ever, it is impossible to accurately predict the likelihood that these short-distance moves will influence exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestim ate or underestimate Cs and Cs tD .

## TABLE C-2-1 INHALATION CANCER RISK FOR INDIVIDUAL CHEMICALS: CARCINOGENS (Page 4 of 4)

Varia ble Description Units Value



## C-35 AT Averagi ng time yr 

### 70 This variable is site-specific. We recommend using this default value in the absence of site-specific data. This def ault value is consist ent with U .S. EPA (1989), U .S. EPA (1991), a nd U.S. EPA (1994b)

. Uncertainties associated with this variable include: The recommendation for avera ging time may

not accurately represent site-specific tim e; specifically this single va lue may under- or overestimate the length of an average a dult lifetime.

REFERENCES AND DISCUSSION

U.S. EPA. 1995. Health Effe cts Asse ssment Summ ary Tables. Annual Update . OHEA-ECAO-CI N-909. Environm

ental Crit eria and A

ssessm ent Off ice, Of fice of Resear ch and Dev

elopment Cincinnati, O

hio. This docu ment represen t U.S. EP A’s secondar y source of Inhalation CSF values. U.S. EPA. 1996a . “Integ rated Ris k Inform ation Sys tem (I RIS)”. Database on Toxi city Inform ation Network (TOXNET)

. This reference r epresents U.S. EP A’s primary source o f Inhalation CSF values and other toxicity factors. This ref erence is updated periodically and should be reviewed prior to preparing a risk assess ment. U.S. EPA. 1996b. “Pro posed Guidelines for Carcinogenic Risk Assessm ent.” Federal Register. 61 FR 31667. Volum e 61. Num

ber 120. June 20. This document proposes new guidelines for assessing the carcinogenicity of COPCs.

## TABLE C-2-2 INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS (Page 1 of 3)

C-36 Description This equation calculates the HQfor inhala tion exp osures to COPCs th at have non cancer healt h effects. Uncert ainties ass ociated wit h this eq uation includ e the follo wing: (1) COPC-specific reference concentrations ( RfC ) are unlikely to underestimate a COPC’s potential for causing adverse health ef fects. (2) Most of the uncertainties associated with the variables in the equation in Table B-5-1 (used to calculate C a ), specifically those associated w ith the variables Q, Cyv , and Cyp , are sitespecific. Equation

Varia ble Description Units Value 

### HQ inh(i) Hazard quotient for direct

inha lat ion o f C OPC noncarcinogen i unitless



### EC Exposure c oncentration : g/m 3 

### 0.001 Units conve rsion fac tor mg/ : g

## TABLE C-2-2 INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS (Page 2 of 3)

Varia ble Description Units Value



## C-37 RfC Refere

nce conce ntration mg/m 3 

### Varies This va riable is COPC-specif

ic, and va lues can be

found in the H

HRAP com

panion databas e. The following uncertainty is associated w ith this variable: COPC RfCs are generally estim ated by applying a serie s of unce

rtainty factors to the res ults of st udies conducted on laboratory animals . The appl

ication of uncertaint

y fa ctors fol lows the underlying

assum ption that hum

ans are, or may

be, as se nsitive or more se nsitive to the harm

ful ef fects of COPCs tha

n the laborat

ory anim als that w ere test ed. RfCs are designed to ensure that the gener al public, inc luding sensi tive subpopula

tions, will not exper

ience adv erse hea lth eff ects as a result of expos

ure to a COPC at its RfC . As a result, COPC-specific RfCs are unlik ely to unde

restim ate a COPC’s potential for caus ing adve rse healt h effects. 

### C a Total COPC air

concentrat

ion : g/m 3 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-5-1. 

### EF Exposure frequency days /yr 

### 350 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic data. T his value is based on U.S. EPA (1991) and is

consistent

with U.S. EPA (1994b). Uncertainties associated with this variable include: This ex posure frequency i s a single value that repre sents the m ost freque nt exposure

that is re asonably

expected to occur at

a site, with t wo weeks o f vacati on. This r ecommen ded va lue may o verest imate E F for i ndiv idua ls who are away fro m their home for mor e than tw o week s each y ear. On the

other had, indiv

iduals such a

s subsiste nce far mers m ay re main at their hom

e (or farm) for m

ore than 350 days per year. In either case, we don’t expect a significant degree of over- or underestimation in most cases.

## TABLE C-2-2 INHALATION HAZARD QUOTIENT FOR COPCS: NONCARCINOGENS (Page 3 of 3)

Varia ble Description Units Value



## C-38 ED Exposure dura tion yr 

### 6, 30, or 40 We rec omme

nd reasonable

maxi mum e xposure (R

ME) value s for T 2 : Exposure D

uration RME Reference Child Reside

nt 6 year

s U.S. EPA (1997b) Farmer Child Fisher Child Adult Res ident and 30 year s U.S. EPA (1997b) Fisher
Farmer 40 year s U.S. EPA (1994b) U.S. EPA (1994c) recommended the following unreferenced values: Exposure D

uration Years Subsistence Farmer 40 Adult Res ident 30 Subsistence Fisher 30 Child Reside

nt 9 Uncertain ties associ ated with th is variable i nclude t he followin g: (1) Exposure dura

tion rates are based on historica l mobility rates a nd may not rema in constant. This ass

umption m

ay ove restim ate or underestimate Cs and Cs tD . (2) Mobility s

tudies indica

te that m ost recept ors that m ove rem ain in the v

icinity of the e mission s ources. How

ever, it is impos sible to accurately predict the likelihood that these short-distance moves will influence exposure, based on factors such as atmospheric transport of pollutants. This assumption may overestim ate or underestimate Cs and Cs tD . 

### AT Averagi ng time yr 

### 6, 30, or 40 This va riable is site-specific and related t o ED . Specifically, the AT for noncar

cinogens i s numerically

the sam e as ED. This def

ault value is consistent

with U.S. EPA (1989; 1991; 1994a)

. Uncertainty associated with this variable includes: Our recom

mended a veragi ng time may not accura

tely r epresent site-spec ific tim

e; specif ically this single value may

under- or overesti mate t he length of

an aver age adult lifetim e.

## TABLE C-2-3 TOTAL INHALATION CANCER RISK: CARCINOGENS (Page 1 of 1)

C-39 Description Cancer ri sk to the i

ndividual via inhalation are added across a ll COPCs that

are ca rcinogenic

via the di rect inhalation route of

exposure. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) Total Cancer Risk

assum es that dif ferent c arcinoge

ns aff ect the s ame ta

rget organ to produce a

cancer response, ignoring pote ntial antag

onistic or s

ynerg istic ef fects or disparat

e effects on differe

nt target organs. This assumption may overestimate Total Cancer Risk

. (2) The summation of cancer risk s across multiple COPCs means that the uncertainties associated with estim ating cancer risk for each COPC are also sum med. This means Total Cancer Risk, as def

ined below , is unlikely to be overesti mated. Equation

Varia ble Description Units Value 

### Total Cancer Risk inh Total individual lifetime cancer risk through direc

t inhalation of

all COPC carci

nogens unitless



### Cancer Risk inh(i) Individual lifetime cancer risk thro ugh direct i

nhal ati on f

or C OPC carcinogen i unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-2-1. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) COPC-specific URF values are unlikely to underestimate, and m ay overestimate , the carcinogenic potential of COPCs because of the mathema

tical models and the use of uncertainty factors in the estim ation of these values. (2) Most of the uncertainties associated with the variables used to calculate C a , sp ecif ical ly Q, Cyv , and Cyp , are site-specific.

## TABLE C-2-4 HAZARD INDEX FOR INHALATION: NONCARCINOG ENS (Page 1 of 1)

C-40 Description For non-cance

r health ef

fects, HQs for inhala

tion exposure s are added across C OPCs when t hey ta rget the same organ to obta in an HI for the t arget org an. See A

ppendix A- 2 for targ

et organs and Appendix A

-3 for COPC- specific inhalation RfC s and for identific ation of CO PCs that caus e noncarci

nogenic ef

fects via the inha

lation route of

exposure and their as sociated t arget org ans. Uncertain ties associ ated with th is equati on incl ude the fol lowing: (1) The summation of noncarcinogenic hazards across m ultiple COPCs means that the uncertainties associated with estimating hazards for each COPC (see HQbelow) a re also s ummed. This means that the tota

l noncarcinog

enic haza rd, as def ined below , is unlikely to be overesti mated. (2) As defined below, the HI sums the HQ s for all COPCs to w hich a rec eptor is pote

ntially exposed. Ideally, HQs should be sum med only for COPCs that aff

ect the s ame ta

rget organs and syste ms. To the exte

nt that COPCs affect diff erent tar get orga ns, summ ing their a

ssociate d HQs will ov

erestim ate the a ctual HI

. Equation

Varia ble Description Units Value 

### HI inh ( j ) Hazard index for target organ eff ect jthrough direc

t inhalation of

all COPCs unitless


### HQ inh(i) Hazard quotient for direct

inhalation of COPC i unitless 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-2-2. Uncertain ties associ ated with th is variable i nclude t he followin g: (1) COPC-specific RfCs are unlikely to underestimate a COPC’s potential for causing adverse health ef fects. (2) Most of the uncertainties associated with the variables used to calculate C a , sp ecif ical ly Q, Cyv , and Cyp , are site-specific.

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 1 of 7)

C-41 Description This equat ion calcu lates the co ncentrat ion of di oxins and dioxin- like PCBs in milkfat of breas t milk. Uncerta inties asso ciated with this equ ation in clude th e following: (1) The most significant uncertainties associated with this equation are those associated with the variable m . Because m is calculat ed as the sum of n umerous po tential i ntakes, esti mates of m incorporate uncertainti es associated w ith each e xposure pat

hway . Theref

ore, m may be under- or overestim ated. Every eff

ort should be made to limit and characterize the uncertainties associated with this variable. (2) This equa

tion assum

es that the

concentra

tion of dioxi

nand dioxin-lik

e PCBs in brea

st milk fat is t he sam e as in m aternal f at. To the

extent tha

t this is not t

he case, uncertaint

y is int roduced. Equation

The av erage m aternal i ntake of dioxin for each adult exposure s cenario ( m ) is equal to the total daily intake of dioxin and dioxin-like PCBs (I ) from inhalation [ca

lculated a s the ave rage daily COPC intake

via inhala

tion ( ADI ) using th e equatio n provid ed below] and all in direct pa thways [which i s calculated using the equatio n in Table C- 1-6 and based on the highe st annual average soil concentration (Cs td )] for eac h adult expos

ure scena rio concentr

ation.

Varia ble Description Units Value 

### C milkf at Concentration of dioxin and dioxinlike PCBs i

n milk f at of bre ast milk for a specific e

xposure sc enario pg COPC/ kg milk fat

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 2 of 7)

Varia ble Description Units Value



## C-42 m Avera

ge ma ternal inta

ke of diox

in and dioxin-lik

e PCBs for

each adult exposure s cenario mg COPC/kg BW-day 

### Varies

This variable is COPC- and site-specific and is equal to the total daily intake of dioxin and dioxin-like PCBs ( I ) from inhalation [ca

lculated a s the ave rage daily COPC int

ake vi a inhalation (ADI) us ing the equa tion provided a

bove] and all indirect pa

thway s [which is

calculat ed using the

equation in Table C-1-6 a nd based on the

highest a nnual aver

age soil concentration (Cs td )] for eac h adult expos

ure scena rio concentr

ation. The following uncertainty is associated w ith this variable: (1) The uncer

tainty a ssociate d with this

variable may be signif icant, bec ause this unc ertainty represe nts the sum

of all uncertainti es associated w ith each of

the potentia

l exposure

pathway s. To ga uge the pote

ntial ma gnitude of

the uncertainty

associa ted with t his varia ble, com pare esti mated m values to values reported in the literature. 

### 1 × 10 9 Units conve

rsion fac tor pg/mg 

### h Half-life of dioxin in adults days 

### 2,555 This va riable is COPC- and site -specif ic. We recomm

end using this

default value, c onsistent w ith U.S. EPA ( 1994a) and U.S. EPA (1994b). The following uncertainty is associated w ith this variable: As discussed in U.S. EPA (1994a), the half-life may v ary from a

bout 5 to 7 years for 2,3,7,8-TCDD. Using the upper end o f th e ra nge is c onse rva tive. B ase d on t

he w ork of S che cte

r (1 991) , an

d Schlat ter (199 1), a s di scu sse d in U .S. E

PA (1994 a), the valu e of h may vary by alm ost one order of ma

gnitude (1.1 to 50) for dif ferent dioxin and fur

an congene

rs around the va

lue of 7 propos ed for 2,3,7,8- TCDD. T he diff erences are lar gely the result of diff

erences in absorption. However, if the aver age material int ake of dioxin is calculat ed in terms of TEQ s, we assume using a single h value based on 2,3,7,8-TCDD is reasonable. 

### f 1 Fraction of

ingeste d dioxin and dioxin-like

PCBs that is

stored in fat unitless 

### 0.9 This va riable is COPC- and site -specif ic. We recomm

end using this

default value, c onsistent w ith U.S. EPA ( 1994b). The source of this value

is U.S. EPA

(1994a). 

### f 2 Fraction of

mother’ s weig

ht that is fat unitless 

### 0.3 Thi s va ria ble is C OPC- spe cif

ic. We rec omm end using this def ault val ue, cons ist

ent wit h U.S . EPA

(199 4a)and U.S. EPA (1994b). The s ource of t

his value is U.S. EPA

(1994a). The following uncertainty is associated w ith this variable: Altho ugh t his si ngle va lue cl early d oes n ot ad equa tely rep resen t all p oten tiall y expos ed women of chi ldbe arin g age, we assume the ave rage unce rtainty associa ted with t his value to be mini

mal.

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 3 of 7)

Varia ble Description Units Value



## C-43 ADI Avera

ge daily COPC intake

via inhalation mg COPC/ kg-day 

### C a Total COPC air conce ntration : g/m 3 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble B-5-1. Uncertainty associated with this variable includes: Calculated assum

ing a def ault ST value for background plus local sources, rather than a ST value for urb an source s. If a specific site is

located in an urban are a, using the latter ST value may be more appropriate. Specifically, the ST value f or urban sources is about one order of magnitude greater than the ST value f or backg round plus local

sources a nd would result in a lower c alculate d F v value; however, the F v value is likely to be only

a few percent low

er. 

### IR Inhalation ra te m 3 /hr 

### adult: 0.83 We rec omme

nd using def

ault value s of 0.83 in the

absence of site- specific inform ation. The

recom mended a dult value i s cons ist ent wit h va lues use d in U .S. E

PA ( 1991; 1994

b; 19 96a) , an

d consistent

wi th a ver age of v alue s pr ovi ded i n U.S . EPA (1997) when c onsidering a dult age br

ackets for both m

ale and f emale inhalation ra

tes for indoor and outdoor ac tivities in a residentia l setting. Uncertainty associated with this variable includes: The rec omme

nded inhalation rates do not consider indiv idual respir

atory or activit y diff erences . Theref

ore, based on the individua

l and the ac

tivities that individua

l is enga ged in, the recomm

ended inhalat

ion rates m

ay under -or overesti mate t he actual rates. Howeve

r, we don’t

expect the degre e of under- or overes timation to be signif

icant. 

### ET Expo sure t ime hrs/day 

### 24 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic data. Uncertainty associated with this variable includes: The rec omme

nded ET value assumes

that an indiv

idual rem ains at a specif ic location 24 hours per day. In reali ty this is likely to be true only

for a m inority of the population including young children, their careg

ivers, a nd elderly

or individuals w

ho are sic k. Ther efore, t he recom mended v alue contri

butes to a degree of

overest imation f or much of

the population. However, it must be noted that though an individu al may not alw ays be at a single location, that individual may continue to be

exposed to emiss ions at an a lternate location.

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 4 of 7)

Varia ble Description Units Value



## C-44 EF Exposure frequency days /yr 

### 350 This variable is site-specific. We recommend using this default value in the absence of site-specific data. This value is based on U.S. EPA (1991)

and is consi stent wi

th U.S. EPA (1994b)

. Uncertainties associated with this variable include: This ex posure frequency i s a single value that repre sents the m ost freque nt exposure

that is re asonably

expected to occur at a site with two wee ks of vacation. This recomm ended value may overes

timate EF for individuals who a

re away f rom their home for more than tw o weeks each y

ear. On the other hand, some individuals (such as farmers) ma y remai n at their hom

e (or fa rm) f or more t han 350 days

per ye ar. In eit

her case , we don’t expect t he degree of over - or underestim

ation to be significa

nt in most cases. 

### ED Exposure dura tion yr 

### 30, or 40 This variable is site-specific. Consistent with U.S. EPA (1994b), we recomm end using the following default values: Exposure Sc enario ED Farmer 40 (U.S. EPA 1994a) Adult Res ident 30 (U.S. EPA 1989) Fisher 30 (U.S. EPA 1994a) Uncertainties associated with this variable include: These e xposure dura

tions are s ingle va

lues that r epresent t he highest

exposure that is re asonably expected to occur at

a site. These values ma

y overestimate ED for some individuals. 

### BW Body w

eight kg 

### 70 This va riable is site-specific. W

e recom mend using

default value of

70 (adults) i

n the absenc e of site -specif ic inform ation. These de fault v

alues are consistent

with U.S. EPA (1991; 1994b). Uncertainties associated with this variable include: This body weight represe nts the av erage w eight of an adult. Howeve

r, depending on the site, the body w eights m ay be higher or lower. This default value may overestimate or underestimate actual body w eights. However, we don’t expect the degre e of under-

or overes timation to be signif

icant.

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 5 of 7)

Varia ble Description Units Value



## C-45 AT Averagi ng time yr 

### 70 This va riable is site-specific. W

e recom mend using

this defa ult value i

n the absenc e of site -specif ic data. T his defa ult value is consiste

nt with U.S . EPA (1989), U. S. EPA (1991), a nd U.S. EPA (1994b)

. Uncertainties associated with this variable include: The recommended avera

ging time may

not accurately represent site-specific tim e; specifically this single va lue may under- or ove

restim ate the le ngth of an averag

e adult lif etime. 

### 0.001 Units conve

rsion fac tor mg/ : g 

### 365 Units conve

rsion fac tor days /yr

REFERENCES AND DISCUSSION Schecter , A. 1991. “

Dioxins and Related C

hemica ls in Hum ans and in the

Environm

ent.” In: Biological Basis for Risk Assessme

nt of Dioxins and Related Com pounds : Gallo, M.; Schenplein, R; Van Der Heijden, K. Eds; Banbury Report 35, Cold Sprin g Harbor Laboratory Press. This docum

ent is cit ed by U. S. EPA (1994a) a s the sourc e of inf

ormation r

elated to t he meta bolism of dioxin and related com

pounds, in addition t

o concentra

tions of v arious congeners in adipose tissue. Schlatter, C., 1991. “Da

ta on Kinetic s of PCDDs

and PCDFs as

a Prerequisi

te for H uman Ris k Ass essme

nt.” In: Biological Basis for Risk Assessme

nt of Dioxins and Related Com pounds ; Gallo, M; Schenplein, R; Van Der Heijder, K., eds. Banbury Report 35, Cold Sp ring Harbor Laboratory press. This document is cited by U.S. EPA (1994a) as a source of a me thod of estimating the half-life of dioxin-related compounds, based on uptake data relative to 2,3,7,8-TCDD. U.S. EPA (1994a) proposed the f

ollowing equation, base d on this docum ent:

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 6 of 7)

C-46 where CTCDD = Concentration of TCDD in body D TCDD = Daily intake of TCD D t 1/2 , TCDD = Half-li fe of TCDD in body V = Volume of body com

partme nt Smith, A.H. 1987. “Infant Exposure Assessment f or Breast Milk Dioxins and Furans Derived from Waste Incineration Emissions.” Risk Analysis. 7(3) 347-353. This docum

ent is cit ed by U. S. EPA (1994a) a s the sourc e of the equation in Table C-3-1 a nd the recom

mended v alues f or h (2,555 days), f 1 (0.9), and f

2 (0.3). This

document assume s that the concentrat

ion of dioxins

in breast milkf

at is the s ame a

s in ma ternal f at. U.S. EPA. 1989. Risk Asse ssment Gui

dance for Super

fund, Volume I, Human Health E valuation Manual (

Part A). Interim

Final. Of

fice of Emerg ency a nd Reme dial Respons e. EPA/540/1-89/ 002. Decem ber. This docum

ent is cit ed as the refere

nce source

document of the ex

posure durati on for adult residents. This docum ent is als o cited as

refer ence sourc e docume

nt for the averag

ing time for carcinogens. U.S. EPA. 1991. Human Health E valuation Manual, Suppl emental Gui

dance: Standard D

efault Exposur

e Factors. Offic e of Solid W aste and E

merge ncy Re sponse. OSW

ER Direc tive 9285.6-03. Washingt on, D.C. Marc

h 21. This docum

ent is cit ed as the refere

nce source

document of the ex

posure frequency, body

weight, and adult inha

lation rate

variable s. U.S. EPA. 1994a

. Estimating Ex posure to Diox

in-Like Com

pounds. Volume I

I: Properti

es, Source

s, Occurr ence, and Bac

kground Exposur

es. Revi ew Draft. Office of Re search a nd Developm

ent. EPA/600/6-88/0 055Cb. Washington, D.C. June. This document cites Smith (1987) as the source for half of the recom mended values for the life of dioxin for adults ( h) , proportion of i

ngested di oxin that is

stored in f

at ( f 1 ), and proportion of mother’s milk t hat is fa t ( f 2 ). This docum

ent is cit ed by U. S. EPA (1994b) as the sam e docume nt for the recomm

ended defa

ult exposure

duration (

ED ) values for the farm

er and fisher. The ED value of 40 year s recommended for both the farme r and the fisher is based on the assumption that “farmers live in one location longer than the general populatio n”.

## TABLE C-3-1 CONCENTR

ATION OF

DIOXINS AN

D DIOXIN-LIKE PC Bs IN BREAST M ILK (Page 7 of 7)

C-47 U.S. EPA. 1994b. Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Waste. Attach ment C, Draft Exposure Assessment Guidance for RCRA Hazardous Waste Combustion Fa cilities . Off ice of E merge ncy and R

emedia l Response. Office of Solid Waste . Decem ber 14. This docum

ent recom mends us ing the equa

tion in Table

C-3-1 and va

lues for the varia

bles in this equation: h (2,555 days), f 1 (0.9), and f

2 (0.3). This docu ment also reco mmends the follo wing:

C An adult inha

lation rate

of 20 m

3 /day (0.83 m 3 /hr)

C An exposure frequency of 350 days per year

C Receptor-specific exposure duration values as presented in U.S. EPA (1994a)—fisher (40 years) and farmer (40 y ears) and U.S. EPA (1989)—adult resident (30 years)

C Adult bo dy weight of 70 kg

C An ave

raging t ime, AT , of 70 y ears U.S. EPA. 1997. Exposure Factors Handbook. Offi ce of Re search a nd Developm

ent. EPA/600/P-95/002F. August. This docum

ent recom mends a n adult inhala

tion rate v

alue of 20. 5 m 3 /day (0.85 m 3 /hr) if considering indoor and outd oor activities.

## TABLE C-3-2 AVERAGE DAILY DOSE TO THE EXPOSED INFANT

(Page 1 of 3)

C-48 Description This equat ion calcu lates the aver age daily dose fo r an infant exposed to contaminat ed breast milk. Uncertain ty associated wit h this eq uation includ es the follo wing: The most significant uncertainty ass ociated with this equation is the selection of a value for averaging tim e ( AT ). As s tated in U.S . EPA (1994a), “Little agreem ent exis ts rega rding the appropriate choice of

an aver aging tim e for le ss than lif

etime exposures . This is

especia lly true for cas es whe

re exposur

e is occur ring in a pa

rticularly sensitiv e developm

ental peri od.” An averaging time

( AT ) of 1 y ear is a ppropriate f

or asses sing noncar

cinogenic effects. How

ever, us ing this v

alue ma y over estima te a lif etime averag

e appropriat

e for as sessing

carcinogenic risk by almost two order

s of m agnitude (70/ 1). Equation

Varia ble Description Units Value 

### ADD infant Avera

ge daily dose for infant exposed to contaminated breast milk pg COPC/kg BW-day 

### C milkf at Concentration of COPC in milk f at of bre ast milk for a specific exposure

scenario pg

COPC/kg milkfat 

### Varies

This va riable is COPC- and site -specif ic, and is c alculate d using the equation in Ta ble C-3-1. The following uncertainty is associated w ith this variable: The most significant uncertainties associated with the calculation of this variable a re those associated with the variable m and the estimate o f C milkf at . Uncerta

inties as sociated w

ithm represe

nt a sum of the v arious uncer

tainties a ssociate d with ea

ch of the potential

exposure pathway

s (see t he equation in Table C- 1-6). 

### f 3 Fraction of mother’s breast

milk that is fat unitless 

### 0.04 This va riable is COPC- and site -specif ic. We recomm

end using this

default value, c onsistent w ith U.S. EPA ( 1994a ; 1994b; 2002 ). As cited in U.S. EPA (1994a), the source of this variable value is Smith (1987).
We ass ume the uncertainty

associa ted with t his value is minim al.TABLE C-3-2AVERAGE DAILY DOSE TO THE EXPOSED INFANT(Page 2 of 3)Variable Description Units ValueC-49f4Fraction of ingested COPC thatis absorbedunitless0.9This variable is COPC- and site-specific. We recommend using this defaultvalue, as do U.S. EPA (1994a; 1994b). As cited inU.S. EPA (1994a), the source of thisvariable value is Smith (1987).We assume the uncertainty associated with this value is minimal.IRmilkIngestion rate of breast milk bythe infantkg/day0.688This variable is COPC- and site-specific. We recommend using this default value, from Table 2-10 in U.S. EPA (2002).The following uncertainty is associated with this variable:U.S. EPA (2002) reports a 12-month time weighted average of 688 mL/day. Assuminga density of breastmilk of slightlymore than 1.0, the recommended value is converted from milliliters per day to kilograms per day. We don’t anticipatesignificant site-specific variation from this value.EDExposure duration yr1.0This variable is COPC- and site-specific. We recommend using this default value, as do U.S. EPA (1994a; 1994b).The following uncertainty is associated with this variable:Some infants may nurse for more or less than the recommended 1 year. However, we don’t expect the average uncertaintyassociated with this variable value to be large.BWinfantBody weight of infant kg9.4As cited in U.S. EPA (2002), this value is estimated using using data fromNHANES III, which was conducted from 1988 to 1994.The following uncertainty is associated with this variable:As reported in U.S. EPA (2002), NHANES III collected body weight data for approximately 15,000 children between theages of 2 months and 17 years. U.S. EPA (2002) reported a range of body weights for 7-12 month-old infants of 9.1 to 9.7kilograms, with a mean body weightof 9.4 kilograms. Based on thisinformation and an assumed 1-yearED, we expect theuncertainty associated with thisvariable value to be minimal.TABLE C-3-2AVERAGE DAILY DOSE TO THE EXPOSED INFANT(Page 3 of 3)Variable Description Units ValueC-50ATAveraging time yr1This variable is COPC- and site-specific. We recommend using this default value, as do U.S. EPA (1994a; 1994b).The following uncertainty is associated with this variable:The uncertainty associated with this variable value is significant, as stated inU.S. EPA (1994a): “Little agreement existsregarding the appropriate choice of an averaging time for lessthan lifetime exposures. This is especially true for caseswhere exposure is occurring in a particularlysensitive developmental period.” An averaging time of 1 year is appropriate forassessing noncarcinogenic effects. However,using this value may overestimate a lifetime average, appropriate for assessingcarcinogenic risk, by almost two orders of magnitude (70/1).REFERENCES AND DISCUSSIONNational Center for Health Statistics. 1987.Cited in U.S. EPA (1994a) as the source of the recommendedBWinfantvalue of 10 kilograms. However, that document does not provide a complete reference for this document.Smith., A.H. 1987. “Infant Exposure Assessment for Breast Milk Dioxins and FuransDerived from Waste Incineration Emissions.”Risk Analysis. 7(3) 347-353.This document is cited by U.S. EPA (1994a)as the source of the recommended values forthe variables in the equation in Table C-3-2.U.S. EPA. 1994a.Estimating Exposure to Dioxin-Like Compounds. Review Draft.Office of Research and Development.EPA/600/6-88/0055Cc. Washington ,D.C. June.This document is cited as the original source of the fraction of fat in breast milk, fraction of ingested COPC that is absorbed, and exposure duration.U.S. EPA. 1994b.Revised Draft Guidance for Performing Screening Level Risk Analyses at Combustion Facilities Burning Hazardous Wastes. Attachment C, Draft Exposure Assessment Guidancefor RCRA Hazardous Waste Combustion Facilities.Office of Emergency and Remedial Response. Office of Solid Waste. December 14.This document recommends using the equation in Table C-3-2 and values for the variables in this equation:f3(0.04),f4(0.9),ED(1 year), andAT(1 year).U.S. EPA. 2002.Child-Specific Exposure Factors Handbook. EPA-600-P-00-002B. National Center for Environmental Assessment (Washington Office) andU.S. EPA ORD. September.This document recommends values for the variablesf3(0.04),IRmilk(0.688 kg/day), andBWinfant(9.4 kg).

## TABLE C-4-1 ACUTE HAZARD QUOTIENT

(Page 1 of 1)

C-51 Description This equa tion calcula

tes the a cute haza rd quotient AHQfor short t erm inhalati on expos ures to COP Cs. Uncertai nties asso ciated with this equ ation in clude th e following: (1) Uncertai

nties m ay be a ssociate d with dev

elopment components

of COPC-specific a

cute inhala

tion exposure

criteria (AIECs), including e

xposure g roup protecte d, exposure

duration, and toxicity endpoint. Uncertainties are specific to each COPC’s AIEC, and may under or overestimate the potential for causing adverse health eff ects. (2) Most of the uncertainties associated with the variables in the equation in Table B-6-1 (used to calculate C acute ), specifically those associated w ith the variables Q, Chv , and Chp , are site-specific. Equation

Varia ble Description Units Value 

### AHQ inh(i) Acute ha

zard quotient

for inhalation of COPCs unitless


### C acute Acute a

ir concentr

ation : g/m 3 

### Varies This va riable is COPC- and site -specif ic, and is c alculate d by using the equation in Table B -6-1. 

### AIEC COPC acute i nhalation ex

posure criteria mg/m 3 

### Varies This variable is COPC-specific (see the companion database to the HHRAP) and determined following a hierarchal approach as discus sed in Chapte

r 7 of the H

HRAP. The following uncertainty is associated w ith this variable: Uncertai nties m ay be a ssociate d with dev

elopment components

of COPC-specific a

cute inhala

tion exposure

criteria (AIECs) , including e

xposure g roup protecte d, exposure

duration, and tox

icity e ndpoint. Uncer

tainties a re specif ic to each COPC’s AIEC, and may under or overestim ate the potential for causing adverse health effects. 

### 0.001 Conversion f actor mg/ : g