Individual and joint toxic effects of pentachlorophenol and bisphenol A on the development of zebrafish (Danio rerio) embryo

Investigation of the toxicological effects of pentachlorophenol (PCP) and bisphenol A (BPA) alone and in combination was carried out following the method of the early life stage (ELS) test on zebrafish embryos. Both chemicals revealed lethal and sub-lethal effects, such as no blood flow, cardiac edema, delayed hatching, and tail malformations. According to their median effective concentrations (EC50 values) in the single exposure, the toxic level of PCP was about two orders of magnitude higher than that of BPA. Result of the joint action modes varied depending on different endpoints. Synergistic action was observed based on the endpoint of 24 h mortality and antagonistic effect displayed based on the endpoint of 72 h cardiac edema. It was also found that the toxicity of PCP would be enhanced with the addition of BPA even below its no observed effect concentration (NOEC) level at the endpoint of 32 h with no blood flow, and the level of the increase was influenced by the toxic unit (TU) ratio.