Among the many questions surrounding per- or polyfluoroalkyl substances (PFAS) are their potential effects on aquatic communities. While much of the initial research effort has focused on ecological effects of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), there is a much wider range of PFAS that can occur in the environment―both as a result of more recently developed compounds and the breakdown products of other PFAS. Effective management of PFAS in aquatic systems requires understanding of the potential effects of a more complete range of PFAS chemicals.

EPA is working to explore the relationships between PFAS toxicity and chemical structure for several aquatic species to help identify and predict the toxicity of PFAS and PFAS mixtures of greatest ecological concern in support of the development of water quality guidelines. This involves measuring the toxicity of PFAS with varying structural features, determining variation in sensitivity across species, and grouping PFAS chemicals by their inferred toxic modes of action (MoA). This webinar will discuss initial findings that sublethal toxicity is strongly related to fluorinated chain length as well as the structure of the non-fluorinated “head” group, and that differences in toxicity of certain PFAS across structures suggest that multiple PFAS MoAs likely exist.