Bioconcentration and Metabolic Effects of Emerging PFOS Alternatives in Developing Zebrafish

The novel PFOS alternatives, 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) and sodium p-perfluorous nonenoxybenzenesulfonate (OBS), are emerging in the Chinese market, but little is known about their ecological risks. In this study, zebrafish embryos were exposed to PFOS, F-53B, and OBS to evaluate their bioconcentration and acute metabolic consequences. Per- and polyfluoroalkyl substances (PFASs) accumulated in larvae in the order of F-53B > PFOS > OBS, with the bioconcentration factors ranging from 20 to 357. Exposure to F-53B and PFOS, but not OBS, increased energy expenditure, and reduced feed intake in a concentration-dependent manner and the expression of genes involved in metabolic pathways at the transcriptional and translational levels. Molecular docking revealed that the binding affinities of PFASs to glucokinase were decreased in the following order: F-53B > PFOS > OBS. Finally, the results of Point of Departure (PoD) indicate that metabolic end points at the molecular and organismal level are most sensitive to F-53B followed by PFOS and OBS. Collectively, F-53B has the highest bioconcentration potential and the strongest metabolism-disrupting effects, followed by PFOS and OBS. Our findings have important implications for the assessment of early developmental metabolic effects of PFOS alternatives F-53B and OBS in wildlife and humans.