Comparative toxicity of bisphenol A and analogues to the marine polychaete Arenicola marina: Another case of regrettable substitutes?

This study investigated the toxicity of bisphenol A (BPA) and three analogues - BPAP, BPZ and BPAF (BPs) - to Arenicola marina, a marine polychaete often used for assessing the toxicity of chemicals to sediment-dwelling organisms. BPA accumulates in marine sediments, while the properties of the analogues also imply that they partition to marine sediment in preference to water. BPA and the three BPs were found to cause mortality at similar concentrations. Based on nominal exposure concentrations, LC50s for BPA, BPAF, BPAP and BPZ were 7.23, 4.56, 3.84 and 5.07 mg/kg dry weight respectively. Comparison to previous studies involving BPA exposures with amphipods, that are also commonly used to benchmark the toxicity of chemicals to marine benthos, suggests that polychaetes may be more sensitive to BPA. Biomarkers selected for observation showed trends that were consistent with depletion of carbohydrate reserves and increased lipid peroxidation with exposure. Measured concentrations were found to be substantially lower than the nominal concentrations of the chemicals evaluated, particularly for BPA. This was attributed to rapid degradation of BPA over the course of the study though loss may also relate to slow equilibration and non-recovery. The conditions of this study were conducive to aerobic degradation and therefore may not be relevant to all environmental matrices. The greater loss of BPA compared to the other BPs implies greater recalcitrance of the substitutes; this, coupled with the equivalent toxicity, suggests that the substitutes may be of greater environmental concern than BPA itself.