Per and Polyfluoroalkyl Substance (PFAS) Neurotoxicology Hazard Data: A Systematic Evidence Map

Per and polyfluoroalkyl substances (PFAS) are a research priority for the US EPA. Because PFAS include thousands of structurally diverse chemicals, there is a pressing need for identifying what data are available to assess human health hazard of these compounds. As part of that research, systematic evidence maps (SEM) have been developed which collate toxicological and epidemiological evidence for roughly 14,735 PFAS chemicals. Literature searches of multiple scientific databases were conducted to identify references most relevant to human health hazard identification. Systematic review methods were used to identify and screen references.  Broad Populations, Exposures, Comparators, and Outcomes (PECO) criteria were used to identify references most relevant to human health hazard identification. After screening, PECO-relevant references underwent a focused data extraction to create a literature inventory of study details (e.g., health effect category, exposure route, exposure duration, species) and study quality evaluation (SQE). These inventories were used to characterize the database of neurotoxicology studies of PFAS-exposed mammals.  Over 152,000 references were identified from the literature searches. After full text screening, roughly 214 PFAS chemicals had any PECO relevant mammalian toxicology or epidemiology studies available.  Of that subset, 111 PFAS chemicals had at least one animal toxicology study evaluating neurotoxicology endpoints, and only 30 of those chemicals had any developmental or reproductive experimental designs.  In conclusion, thousands of the PFAS assessed in this SEM were data-poor, with most retrieving no literature search results for human health hazard information. This emphasizes the need for robust toxicological and epidemiological information that can inform human health risk assessments of PFAS. The views expressed in this abstract are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.

Impact/Purpose

EPA has developed systematic evidence maps (SEM) to collate toxicological and epidemiological evidence for roughly 14,735 PFAS. This presentation will summarize the available neurotoxicology data for PFAS chemicals into a systematic evidence map. The evidence map will collate available toxicological endpoints to identify areas of robust research, data gaps, research needs, and trends across the available data. Preliminary results indicate 110 PFAS chemicals had at least one mammalian toxicology study evaluating neurotoxicology endpoints specifically, and 28 PFAS chemicals evaluated neurotoxicity with a developmental or reproductive experimental design. In conclusion, thousands of the PFAS assessed in this SEM were data-poor, with most retrieving no literature search results for human health hazard information.

Citation

Carlson, L., R. Jones, B. Allen, C. Lin, C. lemeris, K. Chialton, AND A. Shirke. Per and Polyfluoroalkyl Substance (PFAS) Neurotoxicology Hazard Data: A Systematic Evidence Map. International Neurotoxicology Association, Sommaroy, NORWAY, September 07 - 12, 2025.