Legacy and Emerging Per- and Polyfluoroalkyl Substances Surveillance in Bufo gargarizans from Inlet Watersheds of Chaohu Lake, China: Tissue Distribution and Bioaccumulation Potential

Amphibiansare sensitive biomonitors of environmental pollutantsbut reports regarding per- and polyfluoroalkyl substances (PFAS),a class of synthetic organofluorine substances, are limited. In thisstudy, samples of water and Chinese toads (Bufo gargarizo) were collected in Chaohu Lake, China. Tissue-specific bioaccumulationcharacteristics of 39 PFAS, including 19 perfluoroalkyl acids (PFAAs),8 emerging PFAS, and 12 PFAA precursors, were investigated, and thelevels of some biochemical indicators were determined. The highestPFAS concentrations were found in the liver [215.97 ng/g dry weight(dw)] of Chinese toads, followed by gonads (135.42 ng/g dw) and intestine(114.08 ng/g dw). A similar tissue distribution profile was foundbetween legacy and emerging PFAS in the toads, and the occurrenceof two emerging PFAS, 2,3,3,3-tetrafluoro-2-propanoate (HFPO-DA) and6:2 hydrogen-substituted polyfluorooctane ether sulfonate (6:2 H-PFESA)in the amphibians were for the first time reported. Field-based bioaccumulationfactors of HFPO-DA were higher than perfluorooctanoic acid, indicatingthe higher bioaccumulation potential of this emerging PFAS than thelegacy C8 compound. Males had significantly higher gonad PFAS levelsthan females while estradiol levels in gonads increased with increasingconcentrations of certain PFAS (e.g., 6:2 H-PFESA), implying thatPFAS may trigger estrogenic effects in the toads, especially for maletoads. This is the first report onthe tissue-specific bioaccumulationcharacteristic of PFAS precursor (e.g., 6:2 FTS, FPrPA, and N-EtFOSAA)and certain emerging PFAS (e.g., HFPO-DA, PFECHS, and 6:2 H-PFESA)in amphibians. The accumulation of certain emerging PFAS in gonadaltissue may pose the risk of affecting sex hormone levels in amphibians.