SEX AND SEWAGE: ESTROGENIC COMPOUNDS IN THE ENVIRONMENT

Among several fish populations, inter-sex (i.e. hermaphroditism) and a high proportion of females relative to males have been observed. Environmental estrogens discharged in sewage treatment plant effluents may be responsible for feminization of fish but there are many compounds in effluents with the potential to induce these responses; including natural and synthetic estrogen hormones, degradation products of alkylphenol ethoxylate surfactants and plasticizers. In our laboratory studies, the estrogen hormones, 17 alpha-ethinylestradiol, 17 beta-estradiol, estrone and estriol induced inter-sex and altered sex ratios in the aquarium fish, the Japanese medaka (Oryzias latipes) when these fish were exposed to extremely low (ng/L) concentrations of these test compounds. Degradation products of alkylphenol ethoxylate surfactants and the plasticizer, Bisphenol A had little or no estrogenic activity in these fish. Monitoring data reported in the literature indicate that concentrations of estrogen hormones detected in the final effluents of sewage treatment plants are generally greater than the Lowest Observed Effect Levels (LOEL) for alterations to gonadal development in medaka. Therefore, it is possible that female estrogen hormones released from sewage treatment plants are responsible for the feminization observed in wild fish populations.