Report No FR/D0008



Oct 1992


Sewage treatment works effluents nationwide were tested for estrogenic activity using vitellogenin radioimmunoassay in rainbow trout. All sites proved positive. Similar studies with a newly developed carp vitellogenin assay were positive for some sites and negative for others. It is possible that the carp assay was adversely affected by cold weather. Deployment of the trout assay along rivers suggests that in most cases the vitellogenic response is not detectable downstream from sewage treatment works, but in one case a positive effect downstream was noted.

A desk study of potential causes of the vitellogenic response identified some natural estrogens and synthetic analogues used in contraceptive pills. Laboratory tests showed that the synthetic steroid 17 a-ethynylestradiol is extremely potent in inducing vitellogenesis in fish. These studies established a basis for assessing the consequences of dose, duration of treatment, temperature and the physiological state of the fish to the production of vitellogenin. The observed effects in effluents and river water could be generated by 17 a-ethynylestradiol concentrations of about 10ng/l, and 1ng/l, respectively. Analysis of river water and effluent water by GCMS identified the presence of natural steroids and a variety of other organics, none of which were at concentrations adequate to explain the observed vitellogenin response in fish. A tentative identification of ethynylestradiol was achieved at two sites but the concentrations of 10ng/l and 1ng/l are at or below the resolving power of the GCMS (SIR) techniques.

These results neither contest the project's hypothesis that the production of vitellogenin in the fish is caused by the presence of estrogenic substances in sewage effluent, nor suggest an alternative hypothesis. The most plausible interpretation of the observed production of vitellogenin in the fish is the presence in sewage effluents of traces of 17 z-ethynylestradiol.

The Department of the Environment has commissioned research to investigate this further and to identify other possible causes of the vitellogenin response in fish.

Copies of the report are available from FWR, price 15.00, less 20% to FWR Members.