Combined in situ and in vitro assessment of the estrogenic activity of sewage and surface water samples

Abstract

In order to investigate the estrogenic activities of two municipal sewage treatment plant (STP; sites A and B) effluents and of Rhine water sampled at Worms (site C; Rhine-Neckar triangle, Germany), data from in situ experiments measuring hepatic vitellogenin expression from caged rainbow trout (Oncorhynchus mykiss) were compared with data from in vitro bioassays (yeast estrogen screen [YES], ER luciferase assay with HEK 293 cells [HEK], primary rainbow trout hepatocytes [PH]) and chemical analysis. Three sampling campaigns were carried out at each site between November 2000 and September 2001. Vitellogenin (VTG)-mRNA expression in male rainbow trout exposed for two weeks ranged from 3 ± 5 to 619 + 188 and from 226 ± 38 to 3373 ± 1958 pg/μg total RNA at sites A and B, respectively. E2-equivalents obtained from the in vitro bioassays gave values up to 0.21 ± 0.04 nM (57.3 ± 10.2 ng/l, PH), 0.07 ± 0.03 nM (20.2 ± 6.9 ng/l; YES) and 0.008 ± 0.002 nM (2.1 ± 0.7 ng/l; HEK). In contrast, in one-year-old rainbow trout exposed at site C, no VTG-mRNA induction could be observed after two weeks of exposure. In vitro bioassays (YES, HEK, PH) indicated estrogenic activity at site C, which, however, was lower than at the investigated STP effluents. Chemical analysis of representative water samples from site A identified steroidal estrogens up to 5.6 ng/l 17β-estradiol (E2), 19 ng/l estrone as well as 1.5 ng/l 17α-ethinylestradiol. Furthermore, the sum of fecal- and phytosteroids, resorcyclic lactones, and flavonoid concentrations were 280 (A) and 1.200 ng/l (B). In addition, site C (river Rhine) contained 3.9 ng/l E2 and 250 ng/l of fecal- and phytosteroids, respectively. Thus, STP effluents and Rhine water contain biologically relevant concentrations of estrogenic compounds, the activity of which can be detected by means of various bioassays.