Bioconcentration, maternal transfer, and toxicokinetics of PFOS in a multi-generational zebrafish exposure

To enable risk characterization of perfluorooctane sulfonic acid (PFOS) in extended chronic and multi-generational exposures, we assessed PFOS bioconcentration in zebrafish (Danio rerio) exposed continuously to environmentally-relevant PFOS concentrations (0, 0.1, 0.6, 3.2, 20, and 100 µg/L PFOS) through 180 days postfertilization (dpf) in parental (P) and first filial generation (F1) fish. Exposures included five replicate tanks per treatment where whole-body PFOS concentrations were measured using 20-35 fish per replicate at 14 and 29 dpf in the P generation and one fish of each sex per replicate at 180 dpf for the P and F1 generations. Perfluorooctane sulfonic acid accumulation reached an apparent steady state at ≤ 14 dpf where whole-body wet-weight concentrations remained constant through 180 dpf in the P and F1 generations. The median bioconcentration factor (BCF) of 934 L/kg was observed for all PFOS exposures with a range from 255 to 2,136 L/kg which varied with PFOS exposure concentration and sex of adult fish. Significantly lower BCFs were observed in 20 and 100 µg/L PFOS exposures versus 0.1 and 0.6 µg/L indicating exposure-concentration dependance. Additionally, males had significantly increased (∼2×) PFOS accumulation and BCFs versus females in both P and F1 generations. Maternal transfer of PFOS was observed from P females to F1 eggs where maternal whole-body and egg PFOS burdens were equivalent, suggesting PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed that reliably reproduced PFOS whole-body burdens (data within 1.64-fold of predicted values) across all exposure durations spanning the P and F1 generations, providing a tool for PFOS bioaccumulation predictions relevant for risk assessment of acute, chronic, and multi-generational exposures.