Comparative analysis of four PFAS regarding their toxicity to zebrafish development

The release of poly- and perfluoroalkyl substances (PFAS) into the urban water cycle is a matter of emerging concern. Although the use of hazardous PFAS compounds such as perfluorooctanesulfonic acid(PFOS) and perfluorooctanoic acid (PFOA) has been phased out and replaced by alternative PFAS, they are still found in the environment. Moreover, little is known about the toxicity of several replacement compounds, including perfluorohexanoic acid (PFHxA) and 6:2 fluorotelomersulfonic acid (6:2 FTS), despite their presence in municipal water systems. In this study we exposed wild-type, and transgenic zebrafish embryos (ZFEs) to PFOS, PFOA, PFHxA, and 6:2 FTS to determine their effects on 1) wild-type ZFE development, and 2) on ZFE vessel formation, liver and pancreas size. No effects on wild-type zebrafish development were observed at environmental concentrations (e.g., 5 ng/L) of the four selected PFAS during 1-120 hpf. For higher concentrations, all these PFAS resulted in shortening of intersegmental vessels (PFOS from 5 µg/L, PFOA from 100 mg/L, and 6:2 FTS and PFHxA from 50 mg/L). Liver enlargement was found from 1 mg/L PFOS, 100 mg/L PFOA and 500 mg/L 6:2 FTS. In addition, concentrations from 5 mg/L PFOS, and 100 mg/L PFOA led to defects in pancreas development. In summary, our findings provide new evidence that both legacy and replacement PFAS-including PFHxA and 6:2 FTS-can adversely affect zebrafish embryonic development.