Acute toxicity, mutagenicity, and estrogenicity of biodegradation products of bisphenol-A

Biodegradation of bisphenol-A (BPA), which is known as an estrogenic chemical, proceeds via complicated metabolic routes and leads to formation of several kinds of biodegradation products. Through the major route BPA can be completely mineralized; however, p-hydroxyacetophenone (p-HAP), p-hydroxybenzaldehyde (p-HBAL), and p-hydroxybenzoic acid (p-HBA) are transiently accumulated at relatively high concentrations. On the other hand, degradation of BPA through the minor route tends to cause the accumulation of 2,3-bis(4-hydroxyphenyl)-1,2-propanediol and p-hydroxyphenacyl alcohol as the dead-end products. To fully assess the impact of BPA discharge into the environment, the considerable BPA degradation products p-HAP, p-HBAL, and p-HBA and the mixture of the dead-end products were examined for their acute toxicity, mutagenicity, and estrogenicity using the Daphtoxkit (Creasel Ltd.), umu test system, and yeast two-hybrid system, respectively. BPA was moderately toxic to Daphnia magna (48-h EC(50) was 10 mg/L) and weakly estrogenic, with activity that was 5 orders of magnitude lower than that of 17beta-estradiol in the yeast screen, though no mutagenicity was observed. All the tested BPA biodegradation products showed very low acute toxicity compared with BPA, and none was mutagenic. A slight estrogenic activity was detected only for p-HAP among the tested degradation products. It was concluded that biodegradation can remarkably reduce the toxic effects of BPA.