Identification of estrogenic chemicals in STW effluent. 2. In vivo responses in trout and roach

The occurrence of certain natural and synthetic steroidal estrogens in the final effluent from STW has been demonstrated. 17 beta-Estradiol and estrone were present at concentrations in the tens of nanograms per liter range, and the synthetic estrogen 17 alpha-ethynylestradiol was also identified, albeit in the low nanogram per liter range. The findings from subsequent in vivo tank trial experiments, in which adult male rainbow trout (Oncorhynchus mykiss) and adult roach (Rutilus rutilus) were exposed for 21 days via the water to environmentally relevant concentrations of 17 beta-estradiol and estrone are presented. In addition, the response of adult male and female roach following exposure to 17 beta-estradiol (1, 10, and 100 ng/L) was compared to the response to the alkylphenolic xenoestrogen, 4-tert-octylphenol (1, 10 and 100 mu g/L). plasma levels of vitellogenin were determined using previously validated radioimmunoassays in order to measure the estrogenic response of the fish to the varying concentrations of the compounds tested. The results indicate that environmentally relevant concentrations of natural steroidal estrogens are sufficient to account for the levels of vitellogenin synthesis observed in caged male fish placed downstream of certain STW effluent discharges in British rivers.