U.S. Environmental Protection Agency
EPA Document No. 815R24008
April, 2024
Overview of Background Information and Systematic Review Protocol
The methods used to conduct the systematic review for PFOA are consistent with the methods described in the draft and final EPA ORD Staff Handbook for Developing IRIS Assessments (U.S. EPA, 2022b, 2020a) (hereafter referred to as the Integrated Risk Information System (IRIS) Handbook) and a companion publication (Thayer et al., 2022).
EPA’s IRIS Handbook has incorporated feedback from the National Academy of Sciences (NAS) at workshops held in 2018 and 2019 and was well regarded by the NAS review panel for reflecting “significant improvements made by EPA to the IRIS assessment process, including systematic review methods for identifying chemical hazards” (NASEM, 2021). Furthermore, EPA’s IRIS program has used the IRIS Handbook to develop toxicological reviews for numerous chemicals, including some PFAS (U.S. EPA, 2023b, 2022a). Though the IRIS Handbook was finalized concurrently with the development of this assessment, the revisions in the final IRIS Handbook compared to the draft version do not conflict with the methods used in this assessment. The assessment team concluded that implementing these minor changes in study quality evaluation between the draft and final IRIS Handbook versions would not change the assessment conclusions. Therefore, EPA considers the methods described herein to be consistent with the final IRIS Handbook and cites this version accordingly. Additionally, the methods used to conduct the systematic review are also consistent with and largely mirror the Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA (anionic and acid forms) IRIS Assessments (U.S. EPA, 2020b).
The Safe Drinking Water Act (SDWA) regulatory process enables EPA to receive comments and feedback on this systematic review protocol, including through SAB early input and via the public comment period associated with rule proposal. This protocol has been updated based on SAB recommendations to improve the clarity and transparency of the methods descriptions. It now includes information about additional data sources and how they were evaluated and expands the application of systematic review through dose-response analysis.
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