Study finds large amounts of sex change chemicals in English rivers

A study into the health of English rivers has found that one third of male fish are growing female reproductive tissues and organs as a result of chemical pollution in the water. This has raised fears for future fish population growth, as well as for the health of all other wildlife, and even humans.

The phenomenon was first noted in the early 1980s, in the River Lea, Hertfordshire, where 'male' roach were found to contain developing eggs, and had therefore been feminised. Subsequent research showed that treated sewage effluent in many parts of the UK were oestrogenic to fish, and that populations of male roach living downstream from eight large sewage treatment works in the UK were feminised to varying degrees.

Similar phenomena have been noted in birds, otters, seals and frogs.

Professor Charles Tyler, of Exeter University, who led the research for the Environment Agency, told edie the reason for the sexual disruptions in the populations was due to the increasing use of a group of chemicals known as endocrine disruptors which mimic the female hormone oestrogen and can alter the growth of reproductive and other organs in the body.

These chemicals are found in a wide range of industrial products such as plastics, detergents, paints, pesticides and alkyl-phenolic compounds, as well as pharmaceutical products such as steroids and contraceptive pills.

They are often then discharged into rivers through sewage works.

"From our lab based studies, we've found that the young are affected most, and are more sensitive. But, all life stages can be affected," Professor Tyler warned.

He said that studies had already shown a reduction in size of male genitalia in otters, as well as a drop in sperm count and sex drive in a number of species, and a lack of aggression and territorial behaviour in birds. Hermaphroditic changes have even been noted in polar bears, he said.

The changes are most dramatic in creatures that live in or around the water, but Professor Tyler raised concerns that the effects could be more dramatic as the chemicals become more concentrated up the food chain.

"We are not talking about a single chemical here, but a whole mixture. Anything living in the water could be ingesting a range of endocrine disruptors, so anything then feeding on those creatures will ingest them too," he said.

The fact that such reproductive abnormalities have been noted across such a wide range of animals raises obvious concerns that the same phenomena could start to affect humans.

"The jury is out on that one," Professor Tyler said. "There's not enough data to scientifically prove the effects on humans. However, the hormonal system controlling reproduction is much the same in humans as it is in a lot of animals, so there is no real reason why people shouldn't be affected."

Equally worrying, he said, was the fact that the presence of endocrine disruptors could cause a rise in the number of hormone dependent cancers, such as breast cancer, and could even be the cause for the widely reported global drop in sperm count among men.

The good news is that this problem is being addressed. Professor Tyler sat on the advisory panel for the REACH proposals on chemical legislation, and his research has been funded by the EU specifically to look at endocrine disruptors.

His department has forged links with industry and has pioneered research into removing the chemicals from sewage effluent in the first place.

"They need to be removed at the waste water treatment works. There's a number of pilot studies taking place using ozonation and activated carbon, which have proved highly effective," Professor Tyler said.

In addition, the department has developed in vivo testing systems for endocrine disrupting chemicals using fish, which have now being used in a number of industry laboratories and are under consideration by OECD for use in test guidelines for assessing the effects of endocrine disrupting chemicals.

"I have little doubt that there are alternatives to endocrine disrupting chemicals," Professor Tyler said. "Whether the chemical industry ever uses them is unfortunately a matter of economics, not public health."

By David Hopkins


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