A special investigation by the BBC’s Countryfile programme has found that on some stretches of river as many as 100% of the male fish are changing sex and that some are completely sterile.

The programme has uncovered worrying new evidence over the effects of “gender-bender” chemicals in sewage effluent on fish and other wildlife.

Studies on roach from five English rivers by Brunel University have revealed that nearly half of all male fish are changing sex and most are completely sterile

The most worrying aspect is that chemicals that mimic the female hormone oestrogen may be getting into drinking water. The Environment Agency is so concerned about the problem it is about to announce radical proposals for upgrading all major sewage works.

A wide range of chemicals discharged to rivers from sewers are known to disrupt the hormone system of fish and other wildlife but scientists have discovered a particular problem with ethinyl oestrodiol – the main ingredient in the contraceptive pill.

Prof Charles Tyler, of Exeter University, said, “We cannot be sure that some of these compounds, albeit at very low concentrations, aren’t getting into our drinking water.”

The official body responsible for drinking water, the Drinking Water Inspectorate, says it’s confident that existing treatment methods are effective at stripping out oestrogens.

Countryfile