An overview of international differences among perfluorooctanoate (PFOA) health-based guideline values and strategies for global harmonization

Summary For more than a decade, the Alliance for Risk Assessment ( ARA ) has hosted a workshop series entitled “Beyond Science and Decisions” to explore and promote advances in risk assessment per the findings of the National Academy of Sciences (National Academy of Sciences, 2009, Science and decisions: Advancing risk assessment, Washington, D.C). Fourteen multi-day workshops, each consisting of multiple case studies, have been conducted to date. In 2023, an entire workshop was devoted to exploring the greater than 100,000-fold differences in international Health-Based Guideline Values (HBGVs) established for perfluorooctanoate (PFOA). The objective of this case study was twofold: (1) to examine the underlying data sets and assumptions used in the hazard identification and dose-response assessments for PFOA conducted by eight different international groups, and (2) to identify productive strategies for narrowing the range of disparate PFOA health values in order to achieve global harmonization. A science panel of experts in risk assessment, several with extensive experience in the assessment of PFOA and related chemicals, contributed to this examination. Overall, workshop discussions focused on an array of science, policy, legal, and economic considerations that may be driving the extraordinary divergence in values. Clear distinctions were found among agencies in how data were interpreted and integrated, coupled with varying applications of uncertainty factors, resulting in vastly different HBGVs worldwide for PFOA. Workshop recommendations include value-added methodological improvements among government agencies, and the need for international harmonization, recognizing that such differences can impede effective risk management and public communication efforts.