A Critical Review Amphibian PFAS Ecotoxicity Research Studies: Identification of Screening Levels in Water and Other Useful Resources for Site-specific Ecological Risk Assessments.

With the goals of aiding risk assessors conducting site-specific risk assessments at PFAS-contaminated sites, this critical review synthesizes information on the ecotoxicity of PFAS to amphibians in 10 amphibian species, and 16 peer-reviewed publications. The studies in this review consisted of spiked-PFAS chronic toxicity experiments with PFOS, PFOA, PFHxS, and 6:2 FTS that evaluated apical endpoints typical of ecological risk-based decision making (survival, growth, and development). Body mass was the most sensitive endpoint, showing clear and biologically meaningful population level adverse effect sizes (≥ 20% adverse effects). From these results, we recommended chronic no observed effect concentration (NOEC) screening levels of 590 µg/L for PFOS and 130 µg/L for PFOA. At or above recommended chronic LOEC screening levels of 1100 µg/L PFOS and 1400 µg/L PFOA, there is an increased chance of adverse biologically relevant chronic effects. Biologically relevant adverse effects were not observed for PFHxS and 6:2 FTS, so unbounded NOECs of 1300 µg/L PFHxS and 1800 µg/L 6:2 FTS are recommended. Screening levels for are also provided for concentration of PFAS in amphibian diet, amphibian tissue, and moss substrate. Additionally, we recommend bioconcentration factors that can be useful to predict concentrations of PFAS in amphibians using concentrations in water; these values are useful for food web modeling to understand risks to vertebrate wildlife that prey on amphibians. Overall, this paper provides a guide to the wealth of ecotoxicological research on PFAS conducted by this research group and highlights the need for additional work that that would improve the understanding of chemical risks to amphibians.