Bisphenol-S exposure of zebrafish unveils the hidden risks of bisphenol paradigm with growth, developmental, and behavioral impacts similar to bisphenol-A.

The introduction of bisphenol-S (BPS) in substitution of bisphenol-A (BPA) has become argumentative owing to their endocrine destructive properties and insufficient comparative ecotoxicity assessments. Thus, comparative effects of long-term, low-dose BPA and BPS exposure on the development of juvenile zebrafish (Danio rerio) were investigated. Juvenile zebrafish (age: 21 days; weight: ~ 61.5 mg; length: ~ 7.56 mm) were exposed to environmentally-relevant 50 µg/L of BPA, BPS, and control for ~ 60 days in triplicate. Both BPA and BPS significantly increased length (p = 0.00), weight (p = 0.00), specific growth rate (p = 0.00), female preponderance (p = 0.003), mortality (p = 0.017), ammonia excretion (p = 0.00), and aggression (p = 0.00) in zebrafish compared to control. Both bisphenols significantly reduced fish swimming speed in a comparable manner (p = 0.001). A notably higher female-biased-sex ratio was observed in BPS than in BPA (p = 0.003). The length gain (p = 0.014) and aggression (p = 0.032) were higher in BPA-treated fish than in BPS. However, a significant difference was not shown in body mass index (p = 0.295) and condition factor (p = 0.256) between bisphenols and control (p < 0.05). BPA and BPS exposure led to hyperplasia, mucous secretion, aneurism in fish gills, vacuolization and necrosis in liver. Therefore, BPS (~ 50 µg/L) also imposes noteworthy threats to aquatic wildlife, emphasizing the necessity of toxicity assessments and regular monitoring aiming at bespoken environmental standards for freshwater.