Factors affecting perfluorooctanesulfonic acid (PFOS) serum concentration following fish consumption: implications...

Fish consumption is a major exposure pathway for perfluorooctane sulfonate (PFOS), the dominant per- and polyfluoroalkyl substance (PFAS) in fish. Health-based fish consumption advisories typically rely on assumed standard meal sizes and reference dose (RfD) derived using toxicokinetic (TK) model assumptions e.g., 100% oral bioavailability of PFOS, steady state conditions. These assumptions have not been systematically evaluated for PFOS taken in via fish consumption. This short communication synthesizes evidence from in vitro bioaccessibility studies, TK mechanistic information, and human biomonitoring data to assess whether PFOS serum levels from fish consumption are in line with TK model predictions and the possible reasons for any discrepancies. . In vitro digestion studies indicate PFOS bioaccessibility from fish can range from about 40 to 75%. TK considerations-including competition between PFOS and fatty acids for transport and binding proteins and modulation by dietary polyunsaturated fatty acids suggest reduced net absorption and retention. Critically, comparisons of predicted versus observed serum PFOS concentrations in well-characterized fish-consuming populations in Europe and the United States consistently show that default assumptions and the standard steady state one compartment toxicokinetic model overpredicts serum PFOS levels by approximately 3-5 fold. These findings have direct implications for the development of PFOS fish consumption advisories and suggest that current approaches may overestimate internal PFOS dose from dietary fish exposure.