Sodium p-Perfluorous Nonenoxybenzene Sulfonate (OBS) Induces Developmental Toxicity Through Apoptosis in Developing Zebrafish Embryos: A Comparison with Perfluorooctane Sulfonate

Perfluorooctane sulfonate (PFOS) is a representative persistent organic pollutant that exerts toxic effects on aquatic organisms. As an alternative to PFOS, sodium p-perfluorous nonenoxybenzene sulfonate (OBS) has been frequently detected in aquatic environments and human tissues in recent years. However, its toxic effects on aquatic organisms and potential health risks to humans remain unclear. Zebrafish embryos are transparent and amenable to in vivo manipulation and observation. Therefore, in the present study, we investigated its developmental toxicity in zebrafish embryos, with PFOS as the positive control. We exposed zebrafish embryos to different concentrations of OBS (15, 20, and 25 mg/L) and PFOS (15 mg/L) for 2–168 h post fertilization (hpf) and then examined physiological and gene expression changes. At 24 hpf, spontaneous twitches in the 25 mg/L OBS group decreased to (5 ± 0.34)/min. By 48 hpf, the 20 mg/L OBS group’s hatching rate was (47.78 ± 2.22)%, significantly lower than the control. At 72 hpf, heart rates in both the PFOS and OBS groups were elevated, at 82 ± 0.6, 84.5 ± 0.5, 89.4 ± 0.3, and 93.7 ± 0.4, respectively. Similarly to PFOS, OBS induced developmental toxicity in zebrafish embryos. In addition, both OBS and PFOS exposure downregulated the expression level of anti-apoptotic Bcl-2 in zebrafish embryos, with a notable 0.53-fold decrease observed in the 25 mg/L OBS group. Conversely, they upregulated the expression levels of pro-apoptotic Bax, Caspase-3, and Caspase-9, with Caspase-3 expression increasing 1.14-, 1.5-, and 1.7-fold in the 15 mg/L PFOS, 20 mg/L OBS, and 25 mg/L OBS groups, respectively. These OBS- and PFOS-induced changes in gene expression increased apoptosis, suggesting that OBS can induce developmental toxicity in zebrafish embryos, and that its effect is comparable to that of PFOS. Therefore, considering its aquatic toxicity, measures aimed at limiting or remediating OBS pollution in the environment are necessary.