Assessment of estrogenic activity conducted by combining bioassay and chemical analyses of the effluent from wastewater treatment plants in Nanjing, China.

The estrogenic activity of the effluent from three municipal wastewater treatment plants (WWTPs) in Nanjing, China, was investigated. The water samples were enriched by solid-phase extraction and then eluted with different polar solvents, which gave 11 fractionated extracts. Chemical analysis and a vitellogenin (Vtg) assay in goldfish (Carassias auratus) were then utilized to evaluate the estrogenic activities 7 d after a single injection of the effluent extracts of WWTPs and to identify causative agents that led to the induction of Vtg in male fish. The results reveal that Vtg induction occurred primarily in response to the 75 to 90% methanol extracts, and different concentrations of the natural estrogens estrone (E(1)) and 17beta-estradiol (E(2)) were detected in these extracts. As the Vtg induction increased, the plasma E(2) levels increased, and a correlation between Vtg and E(2) does exist. Furthermore, the gonadal somatic index (GSI) did not decrease significantly (p > 0.05) when the Vtg concentrations were elevated after 7 d. Different concentrations of estrogens were detected in the effluents, which demonstrated that the current treatment processes employed by the three WWTPs could not fully remove these compounds. As a result, the aquatic organisms in the receiving water (Yangtze River) were at a risk of feminization.