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Systematic Review Protocol for the PFBA, Pfhxa, Pfhxs, PFNA and PFDA

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Systematic Review Protocol for the PFBA, Pfhxa, Pfhxs, PFNA and PFDA EPA/635/R-20/131 IRIS Assessments Protocol www.epa.gov/iris Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA (anionic and acid forms) IRIS Assessments CASRN 335-76-2 (PFDA) CASRN 375-95-1 (PFNA) CASRN 307-24-4 (PFHxA) CASRN 355-46-4 (PFHxS) CASRN 375-22-4 (PFBA) Supplemental Information―Appendix A Initial draft posted November 2019 Update posted July 2020 (in response to public comments) Update posted January 2021 This document was posted for public comment on November 8, 2019 (link to more information), and subsequently updated in response to those comments (updates are outlined in Section 12). It does not represent and should not be construed to represent any Agency determination or policy. Integrated Risk Information System Center for Public Health and Environmental Assessment Office of Research and Development U.S. Environmental Protection Agency Washington, DC Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments DISCLAIMER This document was posted for public comment on November 8, 2019 (link to more information), and subsequently updated in response to those comments (updates are outlined in Section 12). It does not represent and should not be construed to represent any Agency determination or policy. This document is a draft for review purposes only and does not constitute Agency policy. ii DRAFT―DO NOT CITE OR QUOTE Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments CONTENTS AUTHORS|CONTRIBUTORS|REVIEWERS ...................................................................................................... ii 1. INTRODUCTION ................................................................................................................................... 1-1 2. SCOPING AND PROBLEM FORMULATION SUMMARY ......................................................................... 2-2 2.1. SUMMARY OF BACKGROUND INFORMATION .............................................................................. 2-2 2.1.1. Chemical and Physical Properties ...................................................................................... 2-2 2.1.2. Sources, Production, and Use............................................................................................ 2-5 2.1.3. Environmental Fate and Transport ................................................................................... 2-7 2.1.4. Environmental Concentrations.......................................................................................... 2-8 2.1.5. Potential for Human Exposure ........................................................................................ 2-11 2.1.6. Populations and Lifestages with Potentially Greater Exposures ..................................... 2-12 2.1.7. Other Environmental Protection Agency (EPA) Assessments of Per- and Polyfluoroalkyl Substances (PFAS) .................................................................................. 2-13 2.1.8. Assessments and Toxicity Values from Other Sources .................................................... 2-13 2.2. SCOPING SUMMARY ................................................................................................................... 2-16 2.3. PROBLEM FORMULATION ........................................................................................................... 2-20 2.3.1. Preliminary Literature Inventory for the Five Per- and Polyfluoroalkyl Substances (PFAS) Being Assessed ..................................................................................................... 2-20 2.4. KEY SCIENCE ISSUES .................................................................................................................... 2-22 2.4.1. Toxicokinetic Differences across Species and Sexes ....................................................... 2-23 2.4.2. Human Relevance of Effects in Animals that Involve Peroxisome Proliferator-Activated Receptor Alpha (PPARα) .............................................................. 2-25 2.4.3. Potential Confounding by Other Per- and Polyfluoroalkyl Substances (PFAS) Exposures in Epidemiology Studies ................................................................................. 2-27 2.4.4. Toxicological Relevance of Changes in Certain Urinary and Hepatic Endpoints in Rodents ............................................................................................................................ 2-27 2.4.5. Characterizing Uncertainty Due to Missing Chemical-Specific Information ................... 2-27 3. OVERALL OBJECTIVES, SPECIFIC AIMS, AND POPULATIONS, EXPOSURES, COMPARATORS, AND OUTCOMES (PECO) CRITERIA ............................................................................................................ 3-1 3.1. SPECIFIC AIMS ............................................................................................................................... 3-2 3.2. POPULATIONS, EXPOSURES, COMPARATORS, AND OUTCOMES (PECO) CRITERIA ...................... 3-3 4. LITERATURE SEARCH AND SCREENING STRATEGIES ........................................................................... 4-1 This document is a draft for review purposes only and does not constitute Agency policy. iii DRAFT―DO NOT CITE OR QUOTE Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments 4.1. LITERATURE SEARCH STRATEGIES ................................................................................................. 4-1 4.1.1. Non-Peer-Reviewed Data .................................................................................................. 4-4 4.2. SCREENING PROCESS .................................................................................................................... 4-4 4.2.1. Multiple Publications of the Same Data ............................................................................ 4-7 4.2.2. Literature Flow Diagrams .................................................................................................. 4-8 4.3. SUMMARY-LEVEL LITERATURE INVENTORIES ............................................................................. 4-13 5. REFINED EVALUATION PLAN ............................................................................................................... 5-1 6. STUDY EVALUATION (REPORTING, RISK OF BIAS, AND SENSITIVITY) STRATEGY ................................ 6-1 6.1. STUDY EVALUATION OVERVIEW FOR HEALTH EFFECT STUDIES ................................................... 6-1 6.2. EPIDEMIOLOGY STUDY EVALUATION ........................................................................................... 6-6 6.2.1. Epidemiology Study Evaluation Criteria Specific to These Five Per- and Polyfluoroalkyl Substances (PFAS) .................................................................................. 6-16 6.3. EXPERIMENTAL ANIMAL STUDY EVALUATION ........................................................................... 6-19 6.3.1. Animal Toxicological Study Evaluation Considerations Specific to These Five Per- and Polyfluoroalkyl Substances (PFAS) .................................................................... 6-29 6.4. PHARMACOKINETIC MODEL EVALUATION ................................................................................. 6-30 6.5. MECHANISTIC STUDY EVALUATION ............................................................................................ 6-30 7. ORGANIZING THE HAZARD REVIEW .................................................................................................... 7-1 8. DATA EXTRACTION OF STUDY METHODS AND RESULTS ..................................................................... 8-1 8.1. STANDARDIZING REPORTING OF EFFECT SIZES ............................................................................ 8-2 8.2. STANDARDIZING ADMINISTERED DOSE LEVELS/CONCENTRATIONS ............................................ 8-3 9. SYNTHESIS WITHIN LINES OF EVIDENCE .............................................................................................. 9-1 9.1. HUMAN AND ANIMAL HEALTH EFFECTS EVIDENCE ..................................................................... 9-6 9.2. MECHANISTIC INFORMATION ....................................................................................................... 9-7 9.2.1. Toxicokinetic Information and Pharmacokinetic (PK)/Physiologically Based Pharmacokinetic (PBPK) Models ....................................................................................... 9-8 9.2.2. Peroxisome Proliferator-Activated Receptor Alpha (PPARα) Dependence for Health Effect(s) Observed in Animals .............................................................................. 9-11 9.2.3. Toxicological Relevance of Select Outcomes Observed in Animals ................................ 9-14 9.2.4. Other Focused Mechanistic Analyses .............................................................................. 9-16 10. EVIDENCE INTEGRATION ................................................................................................................... 10-1 10.1. INTEGRATION WITHIN THE HUMAN AND ANIMAL EVIDENCE ................................................ 10-6 10.2. OVERALL EVIDENCE INTEGRATION JUDGMENTS .................................................................. 10-16 10.3. HAZARD CONSIDERATIONS FOR DOSE-RESPONSE ................................................................ 10-22 This document is a draft for review purposes only and does not constitute Agency policy. iv DRAFT―DO NOT CITE OR QUOTE Systematic
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