Long-Term Temporal Changes in the Estrogenic Composition of Treated Sewage Effluent and Its Biological Effects on Fish

Sewage treatment works (STW) effluents throughout the U.K. have been shown to be estrogenic, inducing vitellogenin (VTG) synthesis in caged and wild fish for considerable distances (up to several kilometers) downstream of the effluent discharge. Thresholds for vitellogenin induction in caged fish in those studies have been derived from short-term exposures, and may not necessarily be representative of thresholds for estrogenic responses in wild fish living in rivers that contain STW effluent. In addition, very little is known about the long-term fluctuations in the concentrations of the estrogenic components of STW effluents. In this paper, it was established that the concentrations of natural steroid estrogens and xenoestrogens (alkylphenolic chemicals) in a treated sewage effluent fluctuated temporally (over 8 months), from between 36 and 308 ng/L and between