Contraceptives, cleaning products and other household items flushed down drains and toilets are turning male fish transgender.

Chemicals in these substances work on the fish in a similar way to the human hormone oestrogen leading to creatures with both female and male characteristics

The chemicals, which are affecting as many as one in five male river fish, can lead to a reduction in sperm production as well as triggering the production of eggs.

Chemicals with oestrogen-like effects, including the contraceptive pill (pictured), which have entered the water supply from household drains are turning male fish trans-gendered, according to a new study (stock image)

TRANSGENDER FISH Chemicals in the water supply are turning male fish trans-gendered, according to a new study. Experts from the University of Exeter found that 20 per cent of freshwater fish at 50 different sites in the UK had higher feminine characteristics. Over 200 chemicals from sewage plants have been identified with oestrogen-like effects. These include include ingredients in the contraceptive pill, and by-products of cleaning agents, plastics, and cosmetics. The chemicals, which are affecting as many as one in five river fish, can lead to a reduction in sperm production as well as triggering the production of eggs. Advertisement

Experts from the University of Exeter found that 20 per cent of freshwater fish at 50 different sites in the UK had higher feminine characteristics.

They also found that the offspring of these fish tended to be more susceptible to chemical alteration.

The chemicals causing these effects are often flushed down the loo and include ingredients in the contraceptive pill, and by-products of cleaning agents, plastics, and cosmetics.

Medications like anti-depressants were also found to be altering fish's natural behaviour.

More than 200 chemicals from sewage plants have been identified with oestrogen-like effects.

Some not only are creating 'transgender' fish but effecting fish physiology in unexpected ways.

This included displaying less aggressive and competitive behaviour, usually associated with attracting females of the species, which makes them less likely to breed successfully.

Professor Charles Tyler, a fish physiologist and eco-toxicologist from Exeter University, said: 'We are showing that some of these chemicals can have much wider health effects on fish that we expected.

'Using specially created transgenic fish that allow us to see responses to these chemicals in the bodies of fish in real time, for example, we have shown that oestrogens found in some plastics affect the valves in the heart.'

Chemical effects on fish have been a rising topic of concern for scientists in recent years.

The Potomac Conservancy in Washington DC called for more research to be done In 2010.

Experts from the University of Exeter found that 20 per cent of freshwater fish, including roach (pictured) at 50 different sites in the UK had higher feminine characteristics. This included a reduction in sperm production as well as triggering the production of eggs. (stock image)

It found that more than 80 per cent of male bass fish in the Potomoc River exhibited female traits, such as eggs in their testes, likely due to a 'toxic stew' of chemicals.

Professor Tyler added: 'Other research has shown that many other chemicals that are discharged through sewage treatment works can affect fish including antidepressant drugs that reduce the natural shyness of some fish species, including the way they react to predators.'

Professor Tyler will present his findings in the opening lecture of the 50th Anniversary Symposium of the Fisheries Society in the British Isles, held at Exeter University from today until July 7.