Impact of Bisphenol S as an Endocrine Disruptor in a Freshwater Fish, Oreochromis mossambicus

Endocrine Disrupting Chemicals (EDCs) have the potential to alter the hormonal pathways concerned with regulation of the normal homeostatic mechanisms. The adverse effects of EDCs can be observed in areas where pollution is high, particularly in aquatic ecosystems, where persistent environmental chemicals accumulate. In the present study, we investigated the endocrine disrupting effects of Bisphenol S (BPS), if any, in the levels of thyroxine, triiodothyronine, cortisol and sex steroidal [17βestradiol (E2) and testosterone(T)] hormones in juvenile as well as adult Oreochromis mossambicus . Drastic changes in serum thyroxine and triiodothyronine levels showed that BPS treatment resulted in disruption of thyroid gland function. Alteration to significant levels in serum cortisol indicated acute stress and impairment of hypothalamic-pituitaryinterrenal axis. Significant changes (p<0.05) occurred in the steroidal hormone levels which are biomarkers of endocrine disruption as they affect hypothalamic-pituitary-gonadal axis in fish. Bisphenol S also revealed estrogenic potency by inducing significant alteration in the E2/T ratio. DNA fragmentation, if any, induced by BPS was also analyzed in juvenile fish. There was no significant DNA fragmentation observed in gel electrophoresis, but a significant elevation was seen in percent fragmented DNA in the diphenylamine method. Therefore, it could be concluded that BPS at different sublethal concentrations have a profound impact on endocrine physiology of fish.