ESTROGENIC ACTIVITY IN 5 UNITED-KINGDOM RIVERS DETECTED BY MEASUREMENT OF VITELLOGENESIS IN CAGED MALE TROUT

It was recently demonstrated that most, if not all, effluents of sewag e-treatment works (STWs) in the United Kingdom are estrogenic to fish. As many STWs discharge into rivers, it is possible that some stretche s of rivers downstream of where the effluent enters might also be estr ogenic, To assess this possibility, the induction of vitellogenin synt hesis in caged male trout placed at various distances downstream of th e effluent entry point was used as a biomarker of estrogen exposure. I ndividual discharges into five rivers in England were studied. In four cases, fish placed in the neat effluent, or close to where it entered a river, showed very marked and rapid increases in their plasma vitel logenin concentrations, demonstrating that the effluent was estrogenic . In two of these four cases, none of the downstream sites were estrog enic, whereas in one of the four, fish placed at a site 1.5 km downstr eam did respond by synthesizing appreciable amounts of vitellogenin, a lthough sites further downstream were not estrogenic. The situation in the fourth river was quite different; not only was the effluent extre mely estrogenic (a maximum vitellogenin response in the mg/ml range wa s attained), but so were all the other study sites on the river, the l ast of which was 5 km downstream of where the effluent entered. This p articular river receives trade effluent from wool-scouring mills. whic h contains much higher concentrations of alkylphenolic chemicals than any of the other discharges studied. It is suggested that these chemic als probably account for the estrogenic activity of this river. The fi nal (fifth) river showed no estrogenic activity, not even in the neat effluent. This discharge comes from a very small STW, which receives n o trade waste, and one or both of these factors may account for why th e effluent (and hence the river) was not estrogenic.