Aquatic toxicity and ecological risk of bisphenol B, and comparison with those of bisphenol A

2,2-bis(4-hydroxyphenyl)butane (BPB), one of the 2,2-bis(4-hydroxyphenyl)propane (BPA) alternatives, has not received sufficient attention so far due to the limited environmental concentration and toxicological data available. In this study, the acute toxicity of BPB was investigated using three aquatic organisms, i.e., Tetradesmus obliquus, Daphnia magna and Danio rerio. It was showed that Daphnia magna was the most sensitive organism with a half effective concentration of 3.93 mg/L. Subsequently, Daphnia magna was exposed to BPB solutions for 21 days to explore its chronic toxicity. Results indicated that BPB restricted the body length of parent Daphnia magna and reduced the total number of broods and neonates. The no-observed effect concentration of BPB to Daphnia magna was as low as 0.01 mg/L, which was two orders of magnitude lower than that of BPA (0.86-5.00 mg/L). Furthermore, the ecological risk of BPB was quantitatively assessed using a risk quotient (RQ) method. The RQ values of BPB ranged from 0.003 to 0.914, with the mean of 0.197. BPB posed a moderate risk at most sampling sites, while BPA posed a low ecological risk with RQ < 0.1 at nearly all the sampling sites. Hence, environmental monitoring and management should also be focused on BPB contamination.