Environmental Biotechnology - Theory and Application

Fundamentals of Biological Intervention 63

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Case Study 3.1 Feminisation of Fish (England and Wales)

Of all the endocrine disrupters, perhaps most concern has been voiced over the

possible consequences of synthetic oestrogens. The most recent study into hormone

disruption of fish in the UK, published by the Environment Agency (EA), has

revealed that oestrogenic steroids in sewage effluent are more potent in this respect

than had been previously thought. As result of this five-year investigation of 10 river

catchments in England and Wales which receive sewage treatment effluent, it has

become clear that the reproductive health of male fish is being adversely affected.

With nearly half of all those studied either having eggs in their testes or developed

female reproductive ducts, 25% producing damaged sperm, and 10% being sterile,

the future sustainability of fish populations in a number of rivers in England and

Wales could be at risk.

Many oestrogens, both natural and manufactured, have been implicated, but the

synthetic steroid 17αethinyloestradiol, which is present in the urine of women

using the contraceptive pill, is of particular concern, producing effects in fish at

concentrations below 1μg/l.

While the resulting level of concern over this ‘feminisation’ is likely to drive the

development of a risk management strategy for oestrogens in sewage effluent, which

may ultimately necessitate changes in treatment practice or technology, it is clear

that not all fish populations are exposed to the same degree and so careful targeting

of any intended action will be essential.

The research, which was undertaken by scientists from Brunel and Exeter Uni-

versites, and funded by the EA, the Department for Environment, Food and Rural

Affairs (DEFRA) and the Natural Environment Research Council (NERC), focused on

wild populations of roach (Rutilus rutilus) and gudgeon (Gobio gobio). It specifically

examined the causes and consequences of feminisation in these species and, while

it is expected that the situation is similar for other fish species, it was not designed to

draw conclusions regarding likely human health effects. In the UK, around a third of

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