Evaluation of estrogenicity of sewage effluent and reclaimed water using vitellogenin as a biomarker

To evaluate the quality of reclaimed water, the estrogenicity of effluent from a sewage treatment plant and of reclaimed water treated with coagulation-sedimentation-filtration using the effluent as raw water was assessed using vitellogenin (VTG) as a biomarker. After a three-week exposure, significant (p < 0.05) induction of VTG occurred in female crucian carp (Carassius carassius) exposed continuously to the secondary effluent and reclaimed water with different dilutions (12.5, 25, 50, and 100% for secondary effluent; 50 and 100% for reclaimed water); no induction of VTG was detected when exposed to 12.5 and 25% reclaimed water. For male fish, however, only 100% secondary effluent induced the production of VTG (mean +/- standard deviation, 38.6 +/- 9.8 microg/ml). When the exposure time was prolonged to three months, VTG was induced significantly in both females and males at all gradient concentrations of secondary effluent and at 50 and 100% reclaimed water. The results indicated that no obvious VTG was detected in fish exposed to reclaimed water diluted more than fourfold. Ozonation of the secondary effluent under an ozone consumption dose of 8.5 mg/L resulted in a VTG level equal to that of 12.5% secondary effluent or 50% reclaimed water. Furthermore, VTG induction reflects the cumulative effects of estrogenic activity in the secondary effluent and reclaimed water compared with the in vitro assays, in which estrogenic activities in effluent changed markedly during the experiment.