Exposure, Bioaccumulation and Biomagnification of Per- and Polyfluoroalkyl Substances (PFAS) in Mid-Atlantic Stream Food Webs

Environmental contamination of per- and polyfluoroalkyl substances (PFAS) is a major problem at hundreds of sites with historical use of firefighting foams. PFAS are transported into aquatic systems via multiple pathways and remain highly mobile and persistent. There is growing evidence that some PFAS bioaccumulate, however, the extent and mechanisms of PFAS bioaccumulation and biomagnification in food webs are not well characterized nor understood. Thus, assessing the ecological and human health risks associated with the presence of PFAS in aquatic systems requires a better understanding of the extent, pathways and rates by which PFAS enter, are taken up by and transported through streams and aquatic food webs.

We conducted a comparative field study to assess PFAS exposure, bioaccumulation and biomagnification in 4 streams in Willow Grove, PA that range in size, PFAS concentration, and PFAS transport pathway from a common source attributed to firefighting foams. Water and sediment were sampled weekly for 4 weeks, ending with a single campaign sampling the full aquatic food web, incl. algae, vascular plants, insect and non-insect macroinvertebrates, amphibians, and 17 species of fish. All samples were analyzed for 24 PFAS concentrations, biotic samples for stable isotopes, and water and sediment samples for relevant chemical parameters. The data are being analyzed to determine the variability and extent of PFAS contamination within the stream and food web; quantify bioaccumulation metrics; suggest potential routes of PFAS exposure; and assess the effect of organisms' habitat and trophic structure. Preliminary results indicate distinct environmental PFAS concentration profiles across the different sites, consistent with PFAS source and transport via stormwater runoff vs. groundwater. Temporal variability in environmental PFAS concentrations and profiles was high, as was within-site spatial variability in sediments, with implications for quantifying uptake. Concentrations in all media are dominated by PFOS. We see clear PFAS bioaccumulation with trophic level, and differences with respect to PFAS compound head group and chain length. The stable isotope results should help to further resolve the effects of trophic level and food web structure on biotic exposure route and biomagnification.