Consultation on the Two-dim

Exposure Rainfall-Runoff As

(TERRA) Watershed Model a

in the FIFRA Ecological Risk A

for Antimicrobial Uses of C

FIFRA SCIENTIFIC ADVISORY PANEL

Consultation

October 25-26, 2011

U.S. Environmental Protection Agency

Office of Pesticide Programs

Washington, DC
Presentations to the 

Introduction of OPP Aquatic Exposure Assessment Procz Part 1: Dr. James Hetrick, EPA

 Ecological Risk Assessment Framework Exposure Modeling Approaches Other Modeling Approaches Exposure for Conventional Uses of Copper

z Part 2: Dr. Siroos Mostaghimi, EPA

 Exposure for Antimicrobial Uses of Copper

Overview of the Two-dimensional Exposure Rainfall-Ru

(TERRA) Model: Dr. Mark Velluex, ACC/HydroQual

Application of TERRA in Antimicrobial Exposure Assess

Velluex, ACC/HydroQual

EPA Review of the TERRA Model: Dr. Stephen Wente, 
Introduction to the Office of 

Program’s Environmental E

Modeling and Assessm

Part 1: Dr. James Hetrick, USE

FIFRA SCIENTIFIC ADVISORY PANEL

Consultation

October 25-26, 2011

U.S. Environmental Protection Agency

Office of Pesticide Programs

Washington, DC
Ecological Risk Asse

Framework
Risk Assessment Frame
Terminology for Cop

z Ionic copper = Cu2+z Dissolved Copper= Ionic 

copper + Inorganic Complexes + Organic Complexes

z Sorbed Copper= copper 

sorbed to sediment/soil 

z Copper Minerals

Sorbed copper 

on 

soil/sediment

Copper 

Minerals 

Bound Copper 
Problem Formulation St

Use Characterizatio

Stressor Components

Antimicrobial Uses Conventio

Use Pattern Algaecide

Micro-biocide

AlgaecideFungicideHerbicideMollusicide

Distribution Urban

ResidentialMarinas

UrbanResidentiaAgricultura

Rates Wood:0.06-0.13 lbs/ft

3 Crops:0.6-

Shingles:2 – 20% by weight

Surface Wa
Problem Formulation 

Environmental Chemistry for 

z Soil/Sediment Partitioning 

 pH Cation exchange capacity  Organic carbon 

z Chemical Speciation

 Different valence states (Cu

0, Cu

+,Cu2+

)

 Inorganic complexes (CuOH

+, Cu(OH)2 , Cu(OH

etc.)

 Organic complexes (DTPA, ETDA, humic acids, 

etc.)

z Soil and Aquatic Chemistry

 Mineral equilibria Soil solution and water chemistry
Problem Formulation 

Conceptual Model

Transport Processes

Overland Flow

Erosion

Infiltration

Deposition/Resuspension

Surface Water

Terrestrial

Use Site

Application Rate

Leaching Rate

Aquatic

Use Site

Application Rat

Leaching Rate

Chemical Proce

Sorption/Desorpt

Precipitation/Disso

Complexation

Sediment

ETransport Processes

Dispersion

Deposition/Resuspension

Flow

CChemical P

Sorption/Des

Precipitation/D

Complexa
Exposure Model

Approaches
Aquatic Exposure Assessm

Conventional Pesticide

z Tiered Surface Water Modeling Proc

National Exposure Assessment

 Systematic, rapid screening approach for asse

risk 

• Tier 1 modeling- High End Exposure Estimati

– Pass-Low probability of risk for adverse effects

– Fail-Risk for adverse effects cannot be preclude

• Tier 2 modeling-Refined Exposure Modeling 

– Considers representative meteorology, soil, app

application timing for pesticide use sites 
Exposure Assessment Pro

Conventional Pesticide

z Field-scale model scenario

 10 hectare field

• Uniform soil properties• Runoff, eroded sediment, 

spray drift moves into pond

• 100% treated with 

pesticide

 1 hectare pond

• 20E6 liter volume• No outflow (static)

1 ha Static 

Pond
Aquatic Exposure Assessment Co

Pesticides

GENEEC

z Metamodel PRZM/EXAMSz Yazoo, MS sitez Single runoff eventz Application rate and methodz Spray driftz Koc/Kd, aerobic soil half-life, 

hydrolysis half-life, photolysis half-life, aquatic metabolism half-life

z Daily peak, 4-day average, 21-

day average, 60-day average, 90-day average EEC 

PRZM/

z Representative 

 Meteorology

• 30 years 

 Soils

z Application Rate, z Spray Driftz Koc/Kd, aerobic so

half-life, photolysimetabolism half-limetabolism half

z 1 in 10 year daily 

21-day average, 6day average, annuyear annual avera

Tier 1 Modeling Tier 2 M
Schematic of PRZM/EXAMS 

14

Pesticide Applied

PRZM

Runoff/Erosion

/Leaching 

Model

Spray Drift•Default•Models

-AgDRIFT-AGDISP

EXAMS

Surface Water Quality Model

Estimated Environmental

Concentration (EEC)

Pesticide PropertiesSoil PropertiesSoil/crop ManagementMeteorological Data

Pesticide PropertiesDaily Temperature
PRZM/EXAMS Modeling O

0.00

10.0020.0030.0040.0050.0060.0070.0080.00

1

355

709

1063

1417

1771

2125

2479

2833

3187

3541

3895

4249

4603

4957

5311

5665

6019

6373

6727

7081

7435

7789

8143

8497

8851

9205

Dissolved Copper (μg/L)

Time (Days)

0.001.002.003.004.005.006.007.008.009.00

1

344

687

1030

1373

1716

2059

2402

2745

3088

3431

3774

4117

4460

4803

5146

5489

5832

6175

6518

6861

7204

7547

7890

8233

8576

8919

9262

Pesticide (μg/L)

Time (Days)
Concentration (μg/L)

10 100 

Exceedance Frequency

0

102030405060708090

100

Yearly 

Yearly Avg.:

chronic
Other Modeling Appro
Reviews of Watershed/Basin Sca

z USEPA, 1998- FIFRA SAP

 Basin scale models require calibration No subroutines for addressing plant growth, pest

and agronomic practices.

z OW Review, 1997

 Found major difference in spatial resolution, phys

processes, and CPU requirements

z HydroQual, 2010

 Few models had the capabilities to simulate chem
Watershed Modeling in OPP an

Programs

z Office of Pesticide Programs 

(OPP)

 PRZM/EXAMS Index Reservoir

• Drinking water assessments

z Office of Water (OW)

 Total Maximum Daily 

Load (TMDL)

 Water Quality Criteria

z Office of Solid Waste and 

Emergency Response (OSWER)

 Superfund Sites
Exposure Model

Approaches:

Conventional Uses of 
Risk Assessment Process fo

z Estimate environmental concentra

dissolved copper

z Calculate the cupric ion (Cu2+) con

using the Biotic Ligand Model 

z Derive site specific toxicity values 

using the Biotic Ligand Model 

z Calculate risk quotients
OPP Risk Assessment Strategy f

Biotic Ligand 

Model

(Speciation Mode)

Exposure:Developing Activity-basedSite Specific EECs

EffectsDevelobasedSite Sp

Site Specific 

LC50 (

Site Specific

USGS Water Quality

Monitoring Data

Site Specific RQs

Daphnia magna

(unitless)

Site specific EECs 

(mol Cu2+/L)

Site 

Daphnia ma

Bio

(Tox

MODEL

SIMULATIONS

(Site Specific 

Scenarios)

EECs (ppb)

[Cu] total dissolved
Water Quality Statistics for 811 USGS Mon

Parameter Units Data Range for BLM Missing Data Low Value High Val

Temperature

0C 10 to 25

0 10 24.5 

pH 4.9 to 9.2

0 5.05 9.2 

Cu ug/L 363 1.0 51.4 

DOC mg/L 0.05 to 29.65

0 0.2 29.2 

Humic Acid2 % 10 to 60

0 10 29.15 

Ca2+ mg/L 0.204 to 120.24

0 0.95 114 

Mg2+ mg/L 0.024 to 51.9

0 0.18 51.8 

Na+ mg/L 0.16 to 236.9

0 0.88 190 

K+ mg/L 0.039 to 278.4

0 0.09 18 

SO42- mg/L 0.096 to 278.4

0 0.10 270 

Cl- mg/L 0.32 to 279.72

0 0.32 266 

Alkalinity mg/L 1.99 to 360

0 2.0 311 

S2- mg/L ND 811 ND ND 
PRZM/EXAMS Modelin

Conventional Uses of Cop

PRZM/EXAMS Inputs•

K

d

 400 L/kg (Sand) 3600 L/kg (Clay) 

• 12 crops modeled• CA, MN, NC, TX, PA, FL, IL, OH,GA, ID,ME• Application Rate

 0.59 to 35.62 kg Cu/ha

• First-year Peak Concentration

 1.8 μg/L - 350 μg/L

Relationship oand Peak Cu 

Cu Applica

0 5 10 15 

Peak Cu

2+ Conc (ug/L)

0

20406080

100
Risk Description of

Conventional Uses of Co

Toxicity Profile for 

Daphnia magna

z Threshold for 5% of 

USGS sites exceeding OPP level of concern of 0.5

 3.4 μg Cu/L 1.68 kg Cu/ha

Acute S

Cu Con

0 100 

Percent Site Exceeding LOC

0

102030405060708090

100

Daphnia magny=105.53(1-e-
Uncertainties, Limitations, Ass

Conventional Copper Exposure A

z Assume chemical equilibria controls ionic copper 

 No reaction kinetics

z PRZM/EXAMS modeling with the static pond pred

year accumulation of copper concentration in the 

 No mineral precipitation/dissolution No sediment burial

z Median water quality data at each site were used
Introduction to the Office of 

Program’s Environmental E

Modeling and Assessm

Part 2: Dr. Siroos Mostaghimi, E

FIFRA SCIENTIFIC ADVISORY PANEL

Consultation

October 25-26, 2011

U.S. Environmental Protection Agency

Office of Pesticide Programs

Washington, DC 
EXPOSURE ASSESSME

ANTIMICROBIAL USE

COPPER
Outline

z Major Use Patterns

 Wood Preservatives

 Roof Shingles Antifoulant Paints

z Exposure Assessments for Major Uses

 Residential Uses – Treated Wood

 Residential Uses – Roof Shingles Marinas/Harbors – Antifoulant Paint
Major Usage Patterns 

Wood Preservatives

z Applied to wood by pressure treatment to 

decay
Major Usage Pattern

Roof Shingles

z Mixed into component materials of shingles to prev

formation
Major Usage Patterns – An

z Mixed into paints and then applied to boat hu

prevent biofouling

z Used Marine Antifoulant Model to Predict Env

Concentrations (MAMPEC)
Exposure Assessment for Antimicrob

Biotic Ligand 

Model

(Speciation Mode)

Exposure:Developing Activity-basedSite Specific EECs

EffectsDevelobasedSite Sp

Site Specific 

LC50 (

Site Specific

USGS Water Quality

Monitoring Data

Site Specific RQs

Daphnia magna

(unitless)

Site specific EECs 

(mol Cu2+/L)

Site 

Daphnia ma

Bio

(Tox

Using emission rates, and specific scenarios based on use patterns to estimate the dissolved Cu concentration in a standard pond

EECs (ppb)

[Cu] total dissolved
Conceptual Model for Antim

Uses of Copper

Treated Wood Decking, Fencing, Utility Po

Aquatic Plants

Invertebrates, Vertebrates

Individual Organisms

Reduced survival

Growth reduction

Reduced reproduction

Food Chain

Reduced production

Shift in community competition

R

Stressor

Source

Receptor

Attribute 

Change

Leaching from Wood and Shing

Exposure 

Media

Water/Sediment

Rain

Runoff
Antimicrobial Residential Scenari

Used on Shingles and W

Assumptions:z Deck, fencing ,utility 

poles and shingles on residential property have all been treated

z Residential properties 

are adjacent and share fencing

z Runoff from the 

watershed and properties flows into the same pond through impervious surfaces.
Residential Uses – Treated 

Variable Values

Parameter Value 

Housing Density 9.88 h

Total Number House in Watershed 98.8 hRainfall event (upper 10 percentile in Jackson, Mississippi)

0.125

m

Pond Volume 20E6 liPole exposed surface area 4.38

m

Deck exposed surface area 17.84

m

Wood fence exposed surface area 146.32

m

Exposed surface area for decks in 10 Ha 1762.59 m Exposed surface area for wood fences in 10 Ha 14456.42 m Exposed surface area for poles in 10 Ha 432.74 m Total exposed surface area for decks, fences and poles

16651.75 m 

Copper emission rate for treated wood 3.2 m
Tier 1 Modeling: Impervious 

Surfaces

z Dissolved Cu concentration=333 μg/L

 Assumes direct runoff into pond Assumes runoff over impervious 

surface (driveway, etc.)

z 97 % of USGS sites exceeded 

the LOC of 0.5

Refined Modeling: Pervious Surfacesz Using PRZM/EXAM derived regression 

equations

 Assumed runoff over soil Single event conc.= 2.29 μg Cu/L

z 3.3% of USGS sites exceed the 

LOC of 0.5

30 year daily time 

Cu Concentration (ug/L)

01234

Concentration for 5%of Si

Exposure Assessment for Antimic

of Copper on Wood
Residential Uses – Roof Sh

Variable Values

Parameter Value 

Housing density 9.88 houseTotal number house in watershed 98.8 house

Rainfall event (upper 10th percentile in 

Jackson, Mississippi)

0.125

m

Pond volume 20E6 liters

Roof area per house 232.36

m

2

Copper emission rate (Maximum) 0.38 mg C

Copper emission rate (Minimum) 0.05 mg CCopper emission rate (Average) 0.16 mg C
Exposure Assessment for Antimicro

Copper on Roof Shingle

Tier 1 Modeling: Impervious Surfacesz Estimated Dissolved Cu Concentration = 22

 Assumed direct runoff into pond Assumed runoff over impervious surface (drivew Assumed average emission rate from shingles (0 Assumed 4 houses per acre

z Using BLM , 18 % of USGS sites excee

0.5
Exposure Assessment for Antimicro

Copper on Roof Shingle

Refined Modeling: Pervious Surfacesz Using PRZM/EXAM derived regression eq

 Assumed runoff over soil Used Jackson, Mississippi weather data Application rates for single events ranged from 

0.0711 lb/A Cu

z No USGS site exceed the LOC of 0.5
Uncertainties, Limitations, Assum

Antimicrobial Copper Exposure A

z Lack of reliable information

 Number of houses per acre Percentages of roof shingle and wood structure

copper

• Assumed 100% of roofs and wood structures were tre

 Size of wood structures and roof surface area Ratio of pervious and impervious areas in a wa

z Variation

 Copper emission rates from wood and shingles

• Used average rates for shingles

 Environmental factors 

• Assumed a one rainfall event of 0.125 meters
Questions