EPA/540/1-89/002

December 1989

Risk Assessment 

Guidance for Superfund

Volume I

Human Health Evaluation Manual

(Part A)

Interim Final

Office of Emergency and Remedial Response

U.S. Environmental Protection Agency

Washington, D.C. 20450
Page ii

NOTICE

The policies and procedures set forth here are intended solely as guidance to EPA and other government

employees and contractors. This guidance does not constitute rulemaking by the Agency, and cannot be relied on to

create a substantive or procedural right enforceable by any party in litigation with the United States. EPA may take

action that is at variance with the policies and procedures in this manual and may change them at any time without

public notice.

This interim final guidance is based on policies in the proposed revisions to the National Oil and Hazardous

Substances Pollution Contingency Plan (NCP), which were published on December 21, 1988 (53 Federal Register

51394). The final NCP may adopt policies different than those in this manual and should, when promulgated, be

considered the authoritative source. A final version of this manual will be published after the revised NCP is

promulgated.

Following the date of its publication, this manual is intended to be used as guidance for all human health risk

assessments conducted as part of Superfund remedial investigations and feasibility studies. Issuance of this manual

does not invalidate human health risk assessments completed before (or in progress at) the publication date and based

on previously released Agency guidance.
Page iii

ABOUT THE REVISION . . .

WHAT IT EPA's Human Health Evaluation Manual is a revision of the Superfund Public

IS Health Evaluation Manual (SPHEM; October 1986); it is Volume I of the two-volume set called

Risk Assessment Guidance for Superfund. This manual has three main parts: the baseline risk

assessment (Part A); refinement of preliminary remediation goals (Part B); and evaluation of

remedial alternatives (Part C). (Only Part A is included in the first distribution; see below.)

WHO IT'S Risk assessors, risk assessment reviewers, remedial project managers (RPMs), and risk

FOR managers involved in Superfund site cleanup activities will benefit from this revision.

WHAT'S This revision builds upon the process established in SPHEM and provides more detailed

NEW guidance on many of the procedures used to assess health risk. New information and techniques are

presented that reflect the extensive Superfund program experience conducting health risk

assessments at Superfund sites. Policies established and refined over the years

-- especially those resulting from the proposed National Oil and Hazardous Substances Pollution

Contingency Plan (NCP) -- have been updated and clarified. Additionally, the links between the

human health evaluation, the environmental evaluation, and the remedial investigation/feasibility

study (RI/FS) have been strengthened.

In Part A you will find:

For the risk assessor -- Updated procedures and policies, specific equations and variable

values for estimating exposure, and a hierarchy of toxicity data sources.

For the risk assessment reviewer -- A baseline risk assessment outline for consistent

presentation of risk information and format, and a reviewer's checklist to ensure

appropriate quality and content of the risk assessment.

For the RPM -- A comprehensive overview of the risk assessment process in the RI/FS,

a checklist for RPM involvement throughout the process, and a complete index for quick

reference.

For the risk manager -- An expanded chapter on risk characterization (Chapter 8) to help

summarize and present risk information for the decision-maker, and more detailed

descriptions of uncertainties in the assessment.

DISTRIBU- This manual is being distributed as an interim final document while the proposed NCP is

TION PLAN being finalized. After the final NCP is published, the manual will be updated and finalized. Parts

B and C -- which were not distributed as interim final because they are highly dependent on possible

revisions to the NCP -- will be added. Periodically, updates of portions of the manual will be

distributed.

WHERE Toxics Integration Branch

TO SEND Office of Emergency and Remedial Response

COMMENTS 401 M Street, SW (OS-230)

Washington, DC 20460

Phone: 202-475-9486
Page iv

WORKGROUP

EPA HEADQUARTERS

Office of Emergency and Remedial Response: Marlene Berg

David Cooper

Linda Cullen

Carla Dempsey

Steve Golian

Bruce Means

Pat Mundy

Sandra Panetta

Office of Solid Waste: Stephanie Irene

Office of Waste Programs Enforcement: Georgia Valaoras

Office of Solid Waste and Emergency Response: Larry Zaragoza

Office of Policy, Planning, and Evaluation: Charlotte White

Craig Zamuda

Office of General Counsel: Joe Freedman

Office of Research and Development: Rebecca Madison

Sue Norton

Office of Water: Frank Gostomski

Robert Zeller

EPA REGIONAL OFFICES

Region I: Sarah Levinson

Region V: Dan Bicknell

Pamela Blakley

Region VI: Fred Reitman

Region X: Dana Davoli

David Tetta

OTHER EPA OFFICES

Great Lakes National Program Office, IL: Cynthia Fuller

Office of Health and Environmental

 Assessment, OH: Chris DeRosa

Office of Air Quality Planning and

 Standards, NC: Fred Hauchman
Page v

TABLE OF CONTENTS

Page

INTRODUCTION

CHAPTER 1 INTRODUCTION ....................................................... 1-1

1.1 OVERVIEW OF THE HUMAN HEALTH EVALUATION PROCESS

IN THE RI/FS ........................................................ 1-3

1.1.1 Project Scoping ....................................................... 1-4

1.1.2 Site Characterization (RI) ............................................... 1-4

1.1.3 Feasibility Study ...................................................... 1-8

1.2 OVERALL ORGANIZATION OF THE MANUAL ................................ 1-10

CHAPTER 2 STATUTES, REGULATIONS, GUIDANCE, AND STUDIES RELEVANT

 TO THE HUMAN HEALTH EVALUATION ................................. 2-1

2.1 STATUTES, REGULATIONS, AND GUIDANCE GOVERNING HUMAN

HEALTH EVALUATION ................................................... 2-1

2.1.1 CERCLA and SARA .................................................. 2-1

2.1.2 National Contingency Plan (NCP) ........................................ 2-4

2.1.3 Remedial Investigation/Feasibility Study Guidiance .......................... 2-5

2.1.4 ARARs Guidance .................................................... 2-7

2.1.5 Superfund Exposure Assessment Manual .............................. 2-8

2.2 RELATED SUPERFUND STUDIES ........................................... 2-8

2.2.1 Endangerment Assessments ............................................. 2-8

2.2.2 ATSDR Health Assessments ............................................ 2-9

2.2.3 ATSDR Health Studies ................................................ 2-10

CHAPTER 3 GETTING STARTED: PLANNING FOR THE HUMAN HEALTH

 EVALUATION IN THE RI/FS ............................................ 3-1

3.1 Goal of the RI/FS .......................................................... 3-1

3.2 Goal of the RI/FS Human Health Evaluation ..................................... 3-1

3.3 Operable Units ............................................................ 3-2

3.4 RI/FS Scoping ....................................................... 3-2

3.5 Level of Effort/Level of Detail of the Human Health Evaluation ...................... 3-3

PART A -- BASELINE RISK ASSESSMENT

CHAPTER 4 DATA COLLECTION ................................................... 4-1

4.1 BACKGROUND INFORMATION USEFUL FOR DATA COLLECTION ................ 4-1

4.1.1 Types of Data ........................................................ 4-1
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4.1.2 Data Needs and the RI/FS ............................................... 4-2

4.1.3 Early Identification of Data Needs ......................................... 4-3

4.1.4 Use of the Data Quality Objectives (DQO) Guidance ........................... 4-4

4.1.5 Other Data Concerns .................................................... 4-4

4.2 REVIEW OF AVAILABLE SITE INFORMATION .................................. 4-4

4.3 ADDRESSING MODELING PARAMETER NEEDS ................................ 4-5

4.4 DEFINING BACKGROUND SAMPLING NEEDS .................................. 4-5

4.4.1 Types of Background ................................................... 4-5

4.4.2 Background Sampling Locations ........................................... 4-8

4.4.3 Background Sample Size ................................................. 4-8

4.4.4 Comparing Background Samples to Site-Related Contamination ................... 4-9

4.5 PRELIMINARY IDENTIFICATION OF POTENTIAL HUMAN EXPOSURE ............ 4-10

4.5.1 General Information ......................................................... 4-10

4.5.2 Soil ................................................................ 4-11

4.5.3 Ground Water ........................................................ 4-12

4.5.4 Surface Water and Sediment ............................................. 4-13

4.5.5 Air ................................................................. 4-14

4.5.6 Biota ............................................................... 4-15

4.6 DEVELOPING AN OVERALL STRATEGY FOR SAMPLE COLLECTION ............. 4-16

4.6.1 Determine Sample Size ................................................. 4-17

4.6.2 Establish Sampling Locations ............................................ 4-18

4.6.3 Determine Types of Samples ............................................. 4-19

4.6.4 Consider Temporal and Meteorological Factors ............................... 4-19

4.6.5 Use Field Screening Analyses ............................................ 4-20

4.6.6 Consider Time and Cost of Sampling ....................................... 4-21

4.7 QA/QC MEASURES ........................................................ 4-21

4.7.1 Sampling Protocol ..................................................... 4-21

4.7.2 Sampling Devices ..................................................... 4-21

4.7.3 QC Samples .......................................................... 4-22

4.7.4 Collection Procedures .................................................. 4-22

4.7.5 Sample Preservation ................................................... 4-22

4.8 SPECIAL ANALYTICAL SERVICES ........................................... 4-22

4.9 TAKING AN ACTIVE ROLE DURING WORKPLAN DEVELOPMENT AND DATA

COLLECTION ............................................................. 4-22

4.9.1 Present Risk Assessment Sampling Needs at Scoping Meeting ................... 4-22

4.9.2 Contribute to Workplan and Review Sampling and Analysis Plan ................. 4-23

4.9.3 Conduct Interim Reviews of Field Investigation Outputs ........................ 4-24
Page vii

CHAPTER 5 DATA EVALUATION ..................................................... 5-1

5.1 COMBINING DATA AVAILABLE FROM SITE INVESTIGATIONS ................... 5-2

5.2 EVALUATION OF ANALYTICAL METHODS .................................... 5-5

5.3 EVALUATION OF QUANTITATION LIMITS ..................................... 5-7

5.3.1 Sample Quantitation Limits (SQLs) That Are Greater Than Reference

Concentrations ......................................................... 5-7

5.3.2 Unusually High SQLs .................................................. 5-10

5.3.3 When Only Some Samples in a Medium Test Positive for a Chemical .............. 5-10

5.3.4 When SQLs Are Not Available ........................................... 5-11

5.3.5 When Chemicals Are Not Detected in Any Samples in a Medium ................. 5-11

5.4 EVALUATION OF QUALIFIED AND CODED DATA ............................. 5-11

5.4.1 Types of Qualifiers .................................................... 5-11

5.4.2 Using the Appropriate Qualifiers .......................................... 5-16

5.5 COMPARISON OF CONCENTRATIONS DETECTED IN BLANKS WITH CONCENTRATIONS

DETECTED IN SAMPLES ................................................... 5-16

5.6 EVALUATION OF TENTATIVELY IDENTIFIED COMPOUNDS .................... 5-17

5.6.1 When Few TICs Are Present ............................................. 5-18

5.6.2 When Many TICs Are Present ............................................ 5-18

5.7 COMPARISON OF SAMPLES WITH BACKGROUND ............................. 5-18

5.7.1 Use Appropriate Background Data ......................................... 5-19

5.7.2 Identify Statistical Methods .............................................. 5-19

5.7.3 Compare Chemical Concentrations with Naturally Occurring Levels ............... 5-19

5.7.4 Compare Chemical Concentrations with Anthropogenic Levels ................... 5-19

5.8 DEVELOPMENT OF A SET OF CHEMICAL DATA AND INFORMATION

FOR USE IN THE RISK ASSESSMENT ......................................... 5-20

5.9 FURTHER REDUCTION IN THE NUMBER OF CHEMICALS (OPTIONAL) ............ 5-20

5.9.1 Conduct Initial Activities ................................................ 5-20

5.9.2 Group Chemicals by Class ............................................... 5-22

5.9.3 Evaluate Frequency of Detection .......................................... 5-22

5.9.4 Evaluate Essential Nutrients ............................................. 5-23

5.9.5 Use a Concentration-Toxicity Screen ....................................... 5-23

5.10 SUMMARY AND PRESENTATION OF DATA ................................... 5-24

5.10.1 Summarize Data Collection and Evaluation Results in Text ..................... 5-27

5.10.2 Summarize Data Collection and Evaluation Results in Tables and Graphics ......... 5-27
Page viii

CHAPTER 6 EXPOSURE ASSESSMENT ................................................ 6-1

6.1 BACKGROUND ............................................................ 6-1

6.1.1 Components of an Exposure Assessment ..................................... 6-1

6.1.2 Reasonable Maximum Exposure ........................................... 6-4

6.2 STEP 1: CHARACTERIZATION OF EXPOSURE SETTING ......................... 6-5

6.2.1 Characterize Physical Setting ............................................. 6-5

6.2.2 Characterize Potentially Exposed Populations ................................. 6-6

6.3 STEP 2: IDENTIFICATION OF EXPOSURE PATHWAYS ........................... 6-8

6.3.1 Identify Sources and Receiving Media ....................................... 6-8

6.3.2 Evaluate Fate and Transport in Release Media ................................ 6-11

6.3.3 Identify Exposure Points and Exposure Routes ............................... 6-11

6.3.4 Integrate Information on Sources, Releases, Fate and Transport, Exposure Points,

and Exposure Routes Into Exposure Pathways ................................ 6-17

6.3.5 Summarize Information on All Complete Exposure Pathways .................... 6-17

6.4 STEP 3: QUANTIFICATION OF EXPOSURE: GENERAL CONSIDERATIONS ......... 6-19

6.4.1 Quantifying the Reasonable Maximum Exposure .............................. 6-19

6.4.2 Timing Considerations .................................................. 6-23

6.5 QUANTIFICATION OF EXPOSURE: DETERMINATION OF EXPOSURE

 CONCENTRATIONS ........................................................ 6-24

6.5.1 General Considerations for Estimating Exposure Concentrations .................. 6-24

6.5.2 Estimate Exposure Concentrations in Ground Water ........................... 6-26

6.5.3 Estimate Exposure Concentrations in Soil ................................... 6-27

6.5.4 Estimate Exposure Concentrations in Air .................................... 6-28

6.5.5 Estimate Exposure Concentrations in Surface Water ........................... 6-29

6.5.6 Estimate Exposure Concentrations in Sediments .............................. 6-30

6.5.7 Estimate Chemical Concentrations in Food .................................. 6-31

6.5.8 Summarize Exposure Concentrations for Each Pathway ........................ 6-32

6.6 QUANTIFICATION OF EXPOSURE: ESTIMATION OF CHEMICAL INTAKE ......... 6-32

6.6.1 Calculate Ground-water and Surface Water Intakes ............................ 6-34

6.6.2 Calculate Soil, Sediment, or Dust Intakes ................................... 6-39

6.6.3 Calculate Air Intakes ................................................... 6-43

6.6.4 Calculate Food Intakes ................................................. 6-43

6.7 COMBINING CHEMICAL INTAKES ACROSS PATHWAYS ........................ 6-47

6.8 EVALUATING UNCERTAINTY .............................................. 6-47

6.9 SUMMARIZING AND PRESENTING THE EXPOSURE ASSESSMENT RESULTS ....... 6-50
CHAPTER 7 TOXICITY ASSESSMENT ................................................. 7-1

7.1 TYPES OF TOXICOLOGICAL INFORMATION CONSIDERED IN

TOXICITY ASSESSMENT .................................................... 7-3

7.1.1 Human Data .......................................................... 7-3

7.1.2 Animal Data .......................................................... 7-5

7.1.3 Supporting Data ........................................................ 7-5

7.2 TOXICITY ASSESSMENT FOR NONCARCINOGENIC EFFECTS ..................... 7-5

7.2.1 Concept of Threshold ................................................... 7-6

7.2.2 Derivation of an Oral RfD (RfDo) .......................................... 7-6

7.2.3 Derivation of an Inhalation RfD (RfDi) ...................................... 7-8

7.2.4 Derivation of a Subchronic RfD (RfDs) ...................................... 7-8

7.2.5 Derivation of a Developmental Toxicant RfD (RfDdt) ........................... 7-9

7.2.6 One-day and Ten-day Health Advisories ..................................... 7-9

7.2.7 Verification of RfDs ................................................... 7-10

7.3 TOXICITY ASSESSMENT FOR CARCINOGENIC EFFECTS ........................ 7-10

7.3.1 Concept of Nonthreshold Effects .......................................... 7-10

7.3.2 Assigning a Weight of Evidence .......................................... 7-11

7.3.3 Generating a Slope Factor ............................................... 7-11

7.3.4 Verification of Slope Factors ............................................. 7-13

7.4 IDENTIFYING APPROPRIATE TOXICITY VALUES FOR

SITE RISK ASSESSMENT ................................................... 7-13

7.4.1 Gather Toxicity Information for Chemicals Being Evaluated ..................... 7-13

7.4.2 Determine Toxicity Values for Noncarcinogenic Effects (RfDs) .................. 7-15

7.4.3 Determine Toxicity Values for Carcinogenic Effects (Slope Factors) ............... 7-16

7.5 EVALUATING CHEMICALS FOR WHICH NO TOXICITY VALUES ARE AVAILABLE . 7-16

7.5.1 Route-to-Route Extrapolation ............................................ 7-16

7.5.2 Dermal Exposure ...................................................... 7-16

7.5.3 Generation of Toxicity Values ............................................ 7-17

7.6 UNCERTAINTIES RELATED TO TOXICITY INFORMATION ...................... 7-17

7.7 SUMMARIZATION AND PRESENTATION OF THE TOXICITY INFORMATION ....... 7-20

7.7.1 Toxicity Information for the Main Body of the Text ........................... 7-20

7.7.2 Toxicity Information for Inclusion in an Appendix ............................ 7-20
Page x

CHAPTER 8 RISK CHARACTERIZATION .............................................. 8-1

8.1 REVIEW OF OUTPUTS FROM THE TOXICITY AND EXPOSURE

ASSESSMENTS ............................................................. 8-1

8.1.1 Gather and Organize Information ........................................... 8-4

8.1.2 Make Final Consistency and Validity Check .................................. 8-4

8.2 QUANTIFYING RISKS ....................................................... 8-6

8.2.1 Calculate Risks for Individual Substances .................................... 8-6

8.2.2 Aggregate Risks for Multiple Substances ................................... 8-11

8.3 COMBINING RISKS ACROSS EXPOSURE PATHWAYS ........................... 8-15

8.3.1 Identify Reasonable Exposure Pathway Combinations ......................... 8-15

8.3.2 Sum Cancer Risks ..................................................... 8-16

8.3.3 Sum Noncancer Hazard Indices .......................................... 8-16

8.4 ASSESSMENT AND PRESENTATION OF UNCERTAINTY ........................ 8-17

8.4.1 Identify and Evaluate Important Site-Specific Uncertainty Factors ................ 8-17

8.4.2 Identify/Evaluate Toxicity Assessment Uncertainty Factors ..................... 8-22

8.5 CONSIDERATION OF SITE-SPECIFIC HUMAN STUDIES ......................... 8-22

8.5.1 Compare with ATSDR Health Assessment ................................. 8-24

8.5.2 Compare with Other Available Site-Specific Epidemiological or Health Studies ..... 8-24

8.6 SUMMARIZATION AND PRESENTATION OF THE BASELINE RISK

CHARACTERIZATION RESULTS ............................................. 8-25

8.6.1 Summarize Risk Information in Text ...................................... 8-25

8.6.2 Summarize Risk Information in Tables ..................................... 8-26

CHAPTER 9 DOCUMENTATION, REVIEW, AND MANAGEMENT TOOLS FOR THE RISK

 ASSESSOR, REVIEWER, AND MANAGER .................................... 9-1

9.1 DOCUMENTATION TOOLS .................................................... 9-1

9.1.1 Basic Principles ........................................................ 9-1

9.1.2 Baseline Risk Assessment Report ........................................... 9-2

9.1.3 Other Key Reports ...................................................... 9-3

9.2 REVIEW TOOLS ............................................................. 9-3

9.3 MANAGEMENT TOOLS ...................................................... 9-14
Page xi

CHAPTER 10 RADIATION RISK ASSESSMENT GUIDANCE ............................. 10-1

10.1 RADIATION PROTECTION PRINCIPLES AND CONCEPTS ....................... 10-3

10.2 REGULATION OF RADIOACTIVELY CONTAMINATED SITES ................... 10-8

10.3 DATA COLLECTION ...................................................... 10-10

10.3.1 Radiation Detection Methods ........................................... 10-10

10.3.2 Reviewing Available Site Information .................................... 10-14

10.3.3 Addressing Modeling Parameter Needs .................................... 10-14

10.3.4 Defining Background Radiation Sampling Needs ............................ 10-14

10.3.5 Preliminary Identification of Potential Exposure ............................. 10-15

10.3.6 Developing a Strategy for Sample Collection ............................... 10-15

10.3.7 Quality Assurance and Quality Control (QA/QC) Measures .................... 10-16

10.4 DATA EVALUATION ...................................................... 10-16

10.4.1 Combining Data from Available Site Investigations .......................... 10-17

10.4.2 Evaluating Analytical Methods .......................................... 10-17

10.4.3 Evaluating Quantitation Limits .......................................... 10-17

10.4.4 Evaluating Qualified and Coded Data ..................................... 10-20

10.4.5 Comparing Concentrations Detected in Blanks with Concentrations 

 Detected in Samples .................................................. 10-20

10.4.6 Evaluating Tentatively Identified Radionuclides ............................. 10-21

10.4.7 Comparing Samples with Background ..................................... 10-21

10.4.8 Developing a Set of Radionuclide Data and Information for 

 Use in a Risk Assessment .............................................. 10-21

10.4.9 Grouping Radionuclides by Class ........................................ 10-21

10.4.10 Further Reduction in the Number of Radionuclides .......................... 10-21

10.4.11 Summarizing and Presenting Data ....................................... 10-22

10.5 EXPOSURE AND DOSE ASSESSMENT ....................................... 10-22

10.5.1 Characterizing the Exposure Setting ...................................... 10-23

10.5.2 Identifying Exposure Pathways .......................................... 10-23

10.5.3 Quantifying Exposure: General Considerations ............................. 10-24

10.5.4 Quantifying Exposure: Determining Exposure Point Concentrations ............. 10-25

10.5.5 Quantifying Exposure: Estimating Intake and Dose Equivalent ................. 10-26

10.5.6 Combining Intakes and Doses Across Pathways ............................. 10-27

10.5.7 Evaluating Uncertainty ................................................ 10-27

10.5.8 Summarizing and Presenting Exposure Assessment Results .................... 10-27

10.6 TOXICITY ASSESSMENT .................................................. 10-27

10.6.1 Hazard Identification .................................................. 10-28

10.6.2 Dose-Response Relationships ........................................... 10-30
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10.7 RISK CHARACTERIZATION ................................................ 10-32

10.7.1 Reviewing Outputs from the Toxicity and Exposure Assessments ................ 10-32

10.7.2 Quantifying Risks .................................................... 10-32

10.7.3 Combining Radionuclide and Chemical Cancer Risks ......................... 10-33

10.7.4 Assessing and Presenting Uncertainties .................................... 10-33

10.7.5 Summarizing and Presenting the Baseline Risk Characterization Results .......... 10-34

10.8 DOCUMENTATION, REVIEW, AND MANAGEMENT TOOLS FOR THE RISK

ASSESSOR, REVIWER, AND MANAGER ...................................... 10-34

PART B -- REFINEMENT OF PRELIMINARY REMEDIATION GOALS

 [Reserved]

PART C -- RISK EVALUATION OF REMEDIAL ALTERNATIVES

 [Reserved]

APPENDICES

APPENDIX A ADJUSTMENTS FOR ABSORPTION EFFICIENCY ......................... A-1

A.1 ADJUSTMENTS OF TOXICITY VALUE FROM ADMINISTERED TO

ABSORBED DOSE ......................................................... A-1

A.2 ADJUSTMENT OF EXPOSURE ESTIMATE TO AN ABSORBED DOSE ............... A-3

A.3 ADJUSTMENT FOR MEDIUM OF EXPOSURE ................................... A-3

APPENDIX B INDEX .............................................................. B-1
Page xiii

LIST OF EXHIBITS

Exhibit Page

 1-1 Risk Information Activities in the RI/FS Process .................................... 1-5

 1-2 Part A: Baseline Risk Assessment ............................................... 1-7

 2-1 Relationship of Documents Governing Human Health Evaluation ....................... 2-2

 2-2 Role of the Human Health Evaluation in the Superfund Remedial Process ................. 2-6

 4-1 Elements of a Conceptual Evaluation Model ........................................ 4-6

 4-2 Examples of Modeling Parameters for Which Information May Need To Be

Obtained During a Site Sampling Investigation ...................................... 4-7

 5-1 Data Evaluation ............................................................. 5-3

 5-2 Example of Output Format for Validated Data ...................................... 5-4

 5-3 Examples of the Types of Data Potentially Unsuitable for a Quantitative

Risk Assessment ............................................................. 5-6

 5-4 CLP Laboratory Data Qualifiers and Their Potential Use in Quantitative

Risk Assessment ............................................................ 5-12

 5-5 Validation Data Qualifers and Their Potential Use in Quantitative

Risk Assessment ............................................................ 5-14

 5-6 Example of Table Format for Presenting Chemicals Sampled in

Specific Media ............................................................. 5-25

 5-7 Example of Table Format for Summarizing Chemicals of Potential

Concern in All Media Sampled ................................................. 5-26

 6-1 The Exposure Assessment Process ............................................... 6-3

 6-2 Illustration of Exposure Pathways ................................................ 6-9

 6-3 Common Chemical Release Sources at Sites in the Absence of

Remedial Action ............................................................ 6-10

 6-4 Important Physical/Chemical and Environmental Fate Parameters ...................... 6-12

 6-5 Important Considerations for Determining the Environmental Fate and

Transport of the Chemicals of Potential Concern at a Superfund Site .................... 6-13

 6-6 Flow Chart for Fate and Transport Assessments .................................... 6-14

 6-7 Matrix of Potential Exposure Routes ............................................. 6-18

 6-8 Example of Table Format for Summarizing Complete Exposure Pathways at a Site ......... 6-20

 6-9 Generic Equation for Calculating Chemical Intakes ................................. 6-21

 6-10 Example of Table Format for Summarizing Exposure Concentrations ................... 6-33

 6-11 Residential Exposure: Ingestion of Chemicals in Drinking Water

(and Beverages Made Using Drinking Water) ...................................... 6-35

 6-12 Residential Exposure: Ingestion of Chemicals in Surface Water While Swimming ......... 6-36

 6-13 Residential Exposure: Dermal Contact with Chemicals in Water ....................... 6-37

 6-14 Residential Exposure: Ingestion of Chemicals in Soil ............................... 6-40

 6-15 Residential Exposure: Dermal Contact with Chemicals in Soil ........................ 6-41

 6-16 Residential Exposure: Inhalation of Airborne (Vapor Phase) Chemicals ................. 6-44

 6-17 Residential Exposure: Food Pathway -- Ingestion of Contaminated Fish

and Shellfish ............................................................... 6-45

 6-18 Residential Exposure: Food Pathway -- Ingestion of Contaminated

Fruits and Vegetables ........................................................ 6-46
Page xiv

 6-19 Residential Exposure: Food Pathway -- Ingestion of Contaminated

Meats, Eggs, and Dairy Products ............................................... 6-48

 6-20 Example of Table Format for Summarizing Values Used to Estimate

Exposure .................................................................. 6-49

 6-21 Example of Uncertainty Table for Exposure Assessment ............................. 6-51

 6-22 Example of Table Format for Summarizing the Results of the

Exposure Assessment -- Current Land Use ........................................ 6-52

 7-1 Steps in Toxicity Assessment ................................................... 7-4

 7-2 Example of Table Format for Toxicity Values: Potential Noncarcinogenic Effects ......... 7-18

 7-3 Example of Table Format for Toxicity Values: Potential Carcinogenic Effects ............ 7-19

 8-1 Steps in Risk Characterization .................................................. 8-3

 8-2 Example of Table Format for Cancer Risk Estimates ................................. 8-7

 8-3 Example of Table Format for Chronic Hazard Index Estimates .......................... 8-8

 8-4 Example of Table Format for Subchronic Hazard Index Estimates ....................... 8-9

 8-5 Example of Presentation of Impact of Exposure Assumptions on

Cancer Risk Estimate ........................................................ 8-21

 8-6 Example of Presentation of Impact of Exposure Assumptions on

Hazard Index Estimate ....................................................... 8-23

 8-7 Example of Presentation of Relative Contribution of Individual

Chemicals to Exposure Pathway and Total Cancer Risk Estimates ...................... 8-27

 8-8 Example of Presentation of Relative Contribution of Individual

Chemicals to Exposure Pathway and Total Hazard Index Estimates ..................... 8-28

 9-1 Suggested Outline for a Baseline Risk Assessment Report ............................. 9-4

 9-2 Reviewer Checklist ........................................................... 9-9

 9-3 Checklist for Manager Involvement ............................................. 9-15

 10-1 Radiological Characteristics of Selected Radionuclides Found at Superfund Sites .......... 10-5

 10-2 Types of Field Radiation Detection Instruments ................................... 10-11

 10-3 Types of Laboratory Radiation Detection Instruments .............................. 10-13

 10-4 Examples of Lower Limits of Detection (LLD) For Selected Radionuclides

Using Standard Analytical Methods ............................................ 10-18

 10-5 Summary of EPA's Radiation Risk Factors ....................................... 10-31
Page xv

PREFACE

The Comprehensive Environmental Response, should be coordinated. An example of this type of

Compensation, and Liability Act (CERCLA) requires coordination is the sampling and analysis of fish or

that actions selected to remedy hazardous waste sites other aquatic organisms; if done properly, data from

be protective of human health and the environment. such sampling can be used in the assessment of human

CERCLA also mandates that when a remedial action health risks from ingestion and in the assessment of

results in residual contamination at a site, future damages to and potential effects on the aquatic

reviews must be planned and conducted to assure that ecosystem.

human health and the environment continue to be

protected. As part of its effort to meet these and other The two manuals in this set target somewhat

CERCLA requirements, EPA has developed a set of different audiences. The Environmental Evaluation

manuals, together entitled Risk Assessment Guidance Manual is addressed primarily to remedial project

for Superfund. The Human Health Evaluation Manual managers (RPMs) and on-scene coordinators (OSCs),

(Volume I) provides guidance for developing health who are responsible for ensuring a thorough evaluation

risk information at Superfund sites, while the of potential environmental effects at sites. The

Environmental Evaluation Manual (Volume II) Environmental Evaluation Manual is not a detailed

provides guidance for environmental assessment at "how-to" type of guidance, and it does not provide

Superfund sites. Guidance in both human health "cookbook" approaches for evaluation. Instead, it

evaluation and environmental assessment is needed so identifies the kinds of help that RPMs/OSCs are likely

that EPA can fulfill CERCLA's requirement to protect to need and where they may find that help. The

human health and the environment. manual also provides an overall framework to be used

The Risk Assessment Guidance for Superfund environmental evaluation methods compendium

manuals were developed to be used in the remedial published by EPA's Office of Research and

investigation/feasibility study (RI/FS) process at Development, Ecological Assessments of Hazardous

Superfund sites, although the analytical framework Waste Sites: A Field and Laboratory Reference

and specific methods described in the manuals may Document (EPA/600/3-89/013), is an important

also be applicable to other assessments of hazardous reference to be used with the manual.

wastes and hazardous materials. These manuals are

companion documents to EPA's Guidance for The Human Health Evaluation Manual is

Conducting Remedial Investigations and Feasibility addressed primarily to the individuals actually

Studies Under CERCLA (October 1988), and users conducting health risk assessments for sites, who

should be familiar with that guidance. The two frequently are contractors to EPA, other federal

Superfund risk assessment manuals were developed agencies, states, or potentially responsible parties. It

with extensive input from EPA workgroups comprised also is targeted to EPA staff, including those

of both regional and headquarters staff. These responsible for review and oversight of risk

manuals are interim final guidance; final guidance will assessments (e.g., technical staff in the regions) and

be issued when the revisions proposed in December those responsible for ensuring adequate evaluation of

1988 to the National Oil and Hazardous Substances human health risks (i.e., RPMs). The Human Health

Pollution Contingency Plan (NCP) become final. Evaluation Manual replaces a previous EPA guidance

Although human health risk assessment and Manual (October 1986), which should no longer be

environmental assessment are different processes, they used. The new manual incorporates lessons learned

share certain common information needs and generally from application of the earlier manual and addresses

can use some of the same chemical sampling and a number of issues raised since the earlier manual's

environmental setting data for a site. Planning for publication. Issuance of the new manual does not

both assessments should begin during the scoping invalidate human health risk assessments completed

stage of the RI/FS, and site sampling and other data before (or in progress at) the publication date.

collection activities to support the two assessments

in considering environmental effects. An

document, The Superfund Public Health Evaluation
Page xvi

The Human Health Evaluation Manual provides Even though the Human Health Evaluation Manual is

a basic framework for health risk assessment at considerably more specific than the Environmental

Superfund sites, as the Environmental Evaluation Evaluation Manual, it also is not a "cookbook," and

Manual does for environmental assessment. The proper application of the guidance requires substantial

Human Health Evaluation Manual differs, however, expertise and professional judgment.

by providing more detailed guidance on many of the

procedures used to assess health risk. This additional

level of detail is possible because of the relatively

large body of information, techniques, and guidance

available on human health risk assessment and the

extensive Superfund program experience conducting

such assessments for sites. 
Page xvii

ACKNOWLEDGEMENTS

This manual was developed by the Toxics Integration Branch (TIB) of EPA's Office of Emergency and Remedial

Response, Hazardous Site Evaluation Division. Linda Cullen provided overall project management, contract

supervision, and technical coordination for the project under the direction of Bruce Means, Chief of TIB's Health

Effects Program.

The EPA Workgroup (comprised of members listed on the following page) provided valuable input regarding

the organization, content, and policy implications of the manual throughout its development. The project manager

especially wishes to acknowledge the assistance of the Workgroup Subcommittee Chairpersons: Rebecca Madison,

Bruce Means, Sue Norton, Georgia Valaoras, Craig Zamuda, and Larry Zaragoza.

Other significant contributors to the manual included Joan Fisk, Michael Hurd, and Angelo Carasea of the

Analytical Operations Branch (Office of Emergency and Remedial Response); Paul White, Anne Sergeant, and

Jacqueline Moya of the Exposure Assessment Group (Office of Research and Development); and Barnes Johnson of

the Statistical Policy Branch (Office of Policy, Planning, and Evaluation). In addition, many thanks are offered to

the more than 60 technical and policy reviewers who provided constructive comments on the document in its final

stages of development.

ICF Incorporated provided technical assistance to EPA in support of the development of this manual, under

Contract No. 68-01-7389.

Robert Dyer, Chief of the Environmental Studies and Statistics Branch, Office of Radiation Programs, served

as project manager for Chapter 10 (Radiation Risk Assessment Guidance), with assistance from staff in the Bioeffects

Analysis Branch and the regional Radiation Program Managers. Chapter 10 was prepared by S. Cohen and Associates,

Incorporated (SC&A), under Contract No. 68-02-4375.