Chronic exposure to 17 alpha-ethinylestradiol and bisphenol A-effects on development and reproduction in the freshwater invertebrate Chironomus riparius (Diptera: Chironomidae).

The effect of 17 alpha-ethinylestradiol (EE) and bisphenol A (BPA) on development and reproduction in Chironomus riparius was determined over two generations in chronic sediment exposure assays. A number of response criteria were examined in order to identify any chemical-related effects including median emergence times (EmT50), the number and sex ratio of emerged adults, egg production and egg viability. The results showed that emergence time and percentage adult emergence were affected by EE and BPA exposure. These effects were primarily associated with the second generation of test animals, most notably in the BPA study, where the emergence of male and female adults was significantly (P<0.05) delayed at concentrations ranging from 78 ng/l to 0.75 mg/l. At very low concentrations (1 ng/l) of EE, both the first and second generation of adults emerged significantly earlier than control animals. No effect on the percentage emergence of first generation adults was evident with either chemical or in the second generation with BPA. The number of egg-ropes produced by the first generation females varied between treatments but no dose-response pattern was evident. Although certain responses were significantly affected, results in general do not suggest that the criteria examined, although validated as indicators of general sediment toxicity, could be used to detect the oestrogenic effects of EE and BPA on C. riparius.