Enhanced toxicity of bisphenol F compared to its predecessor bisphenol A in rainbow trout (Oncorhynchus mykiss) during a six-week feeding trial

Abstract

This study aimed to assess the toxicity of bisphenol A (BPA) and bisphenol F (BPF) in rainbow trout following six weeks of dietary exposure. Fish were exposed to BPA, BPF, or their combination at nominal concentrations of 10 and 1000 µg/kg (i.e., BPA_low, BPA_high, BPF_low, BPF_high, BPA+BPF_low). Haematological analysis revealed a significant reduction (p < 0.05) in leukocytes and lymphocytes, but only in the BPF_high group. Plasma biochemical markers showed significant increases (p < 0.05) in creatinine in BPA_low and elevated amylase activity in both BPF groups. Surprisingly, markers of endocrine disruption, such as vitellogenin and thyroxine, were significantly elevated (p < 0.05) only in BPF_high and BPA+BPF_low, despite no pathological changes being observed in the gonads. Oxidative stress markers were significantly affected, with increased catalase activity (p < 0.05) in the liver, kidney, and gill across all groups. Additionally, plasma DNA damage was significantly (p < 0.05) reduced in BPA_low and BPF_high. In contrast, significant elevations (p < 0.05) of ceruloplasmin and ferric reducing/antioxidant power were observed in the BPA+BPF_low and both BPF groups, respectively. Histological examination revealed liver congestion and dystrophy in both BPA groups, hyaline droplet degeneration in the tubular epithelial cells of the caudal kidney across all exposed groups, and deformation of gill filaments in BPA+BPF_low and both BPA groups. Our findings underscore that the increasing use of BPA analogues may pose a greater risk than the original compound in certain contexts, emphasizing the need for further studies to understand the long-term effects of bisphenol analogues, particularly at environmentally relevant concentrations and in mixtures.