EPA/100/B-19/001 October 2019 www.epa.gov/risk Guidelines for Human Exposure Assessment Risk Assessment Forum EPA/100/B-19/001 October 2019 Guidelines for Human Exposure Assessment Risk Assessment Forum U.S. Environmental Protection Agency DISCLAIMER This document has been reviewed in accordance with U.S. Environmental Protection Agency (EPA) policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Preferred citation: U.S. EPA (U.S. Environmental Protection Agency). (2019). Guidelines for Human Exposure Assessment. (EPA/100/B-19/001). Washington, D.C.: Risk Assessment Forum, U.S. EPA. Page | ii TABLE OF CONTENTS DISCLAIMER ..................................................................................................................................... ii LIST OF TABLES.............................................................................................................................. vii LIST OF FIGURES ........................................................................................................................... viii LIST OF BOXES ................................................................................................................................ ix ABBREVIATIONS AND ACRONYMS .............................................................................................. x PREFACE ........................................................................................................................................... xi AUTHORS, CONTRIBUTORS AND REVIEWERS.......................................................................... xii EXECUTIVE SUMMARY ................................................................................................................ xiv CHAPTER 1. INTRODUCTION .......................................................................................................... 1 1.1. Overview ............................................................................................................................. 1 1.2. Purpose and Scope of the Guidelines .................................................................................... 1 1.3. Organization of Guidelines for Human Exposure Assessment ............................................... 2 1.4. Summary.............................................................................................................................. 3 CHAPTER 2. PRINCIPLES OF EXPOSURE SCIENCE AND EXPOSURE ASSESSMENT ............. 4 2.1. Exposure Science ................................................................................................................. 4 2.2. Definitions ........................................................................................................................... 8 2.2.1. Exposure Definitions ................................................................................................... 8 2.2.2. Dose Definitions ......................................................................................................... 8 2.3. Concepts in Exposure Assessment ...................................................................................... 12 2.3.1. The Risk Assessment Process .................................................................................... 12 2.3.2. Overview of Exposure Assessment ............................................................................ 12 2.3.3. Approaches for Exposure Assessment ....................................................................... 13 2.3.4. Uncertainty and Variability in Exposure Assessments ............................................... 16 2.4. Calculating Exposure Estimates.......................................................................................... 17 2.4.1. Inhalation Exposure .................................................................................................. 17 2.4.2. Ingestion (Dietary and Nondietary) Exposure ............................................................ 18 2.4.3. Dermal Exposure ...................................................................................................... 18 2.5. Development of Exposure Science and Exposure Assessments Related to EPA Risk Assessments ....................................................................................................................... 19 2.6. Emerging Topics ................................................................................................................ 21 2.7. Summary............................................................................................................................ 23 CHAPTER 3. PLANNING AND SCOPING AND PROBLEM FORMULATION FOR EXPOSURE ASSESSMENTS ........................................................................................... 25 3.1. Planning and Scoping ......................................................................................................... 26 3.1.1. Exposure Assessment Goals and Scope ..................................................................... 28 3.1.2. Overarching Considerations ...................................................................................... 30 3.1.3. Stakeholder Involvement ........................................................................................... 30 3.1.4. EPA’s Tribal Program and Networks ......................................................................... 33 3.1.5. Peer Review .............................................................................................................. 33 3.2. Problem Formulation.......................................................................................................... 34 3.2.1. Individuals, Lifestages, Groups, Populations ............................................................. 35 Page | iii 3.2.2. Conceptual Model ..................................................................................................... 36 3.3. Exposure Assessment Analysis Plan ................................................................................... 38 3.3.1. Data Sources, Gaps, Limitations and Quality Objectives............................................ 38 3.3.2. Exposure Scenarios ................................................................................................... 39 3.4. Summary............................................................................................................................ 40 CHAPTER 4. CONSIDERATION OF LIFESTAGES, VULNERABLE GROUPS AND POPULATIONS OF CONCERN IN EXPOSURE ASSESSMENTS .................................. 41 4.1. History of EPA Exposure Assessments for Lifestages, Vulnerable Groups and Populations of Concern ....................................................................................................... 42 4.2. Vulnerability and Susceptibility in Exposure Assessment ................................................... 42 4.3. Examples of Lifestages, Vulnerable Groups and Populations of Concern in Exposure Assessment ......................................................................................................... 45 4.3.1. Lifestages.................................................................................................................. 45 4.3.2. Tribal and Indigenous Populations............................................................................. 49 4.3.3. Other Racial and Ethnic Populations ......................................................................... 52 4.3.4. Traditional Methods .................................................................................................. 53 4.3.5. Case Studies .............................................................................................................. 53 4.3.6. Neighborhood Methods ............................................................................................. 53 4.3.7. Population-Based Methods ........................................................................................ 54 4.3.8. Social Process Methods ............................................................................................. 54 4.3.9. National-Level versus Local/Community-Specific Assessments ................................ 54 4.4. Summary............................................................................................................................ 55 CHAPTER 5. DATA FOR EXPOSURE ASSESSMENTS ................................................................ 57 5.1. Types of Data Used in an Exposure Assessment ................................................................. 57 5.1.1. Environmental Data .................................................................................................. 58 5.1.2. Biomonitoring Data................................................................................................... 58 5.1.3. Exposure Factors ....................................................................................................... 61 5.1.4. Observational Human Exposure Measurement Study Data ........................................ 64 5.1.5. Using Different Types of Data to Inform Decisions ................................................... 64 5.2. Identifying Data Gaps and Data Needs ............................................................................... 64 5.2.1. Identification of Data Gaps—Existing Data ............................................................... 66 5.2.2. Developing a New Data Sampling Program ............................................................... 66 5.3.