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Scientists say that chemicals called parabens, which for decades have been used in cosmetics, mimic the action of oestrogens.
The increased presence of oestrogens in the environment is thought by some scientists to be responsible for reductions in sperm counts and increases in male reproductive disorders over the last 50 years.
The research found that parabens, which are used as preservatives in toiletries, can have adverse effects on laboratory animals.
Affect on pregnant women
The researchers are reported to say that the chemicals could be absorbed through the skin of a pregnant woman and make their way into the womb. Once there, they could impair the development of a male foetus, causing reproductive problems later in life.
Professor John Sumpter, of Brunel University, conducted the study, which is published in the journal Toxicology and Applied Pharmacology.
He has previously identified other chemicals that mimic oestrogens in the environment.
The research measured the similarity between parabens and oestrogens by monitoring their effects on yeast and animals.
It concluded that parabens are several thousand times less potent than oestrogen produced by a woman's ovaries but their ability to mimic the hormone means that their safety should be reassessed.
The link between oestrogen and male reproductive problems is a highly controversial one.
Toiletries are just the latest products to be implicated.
Environmental build-up
Some scientists believe that many ordinary chemicals used by industry and in the home have been slowly building up in the environment contaminating water supplies.
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Mr Peter Wardle, deputy director of the Centre for Reproductive Medicine, said that there were increased amounts of oestrogens in the environment from sources as diverse as plastics and the contraceptive pill.
He pointed out that there are many different types of oestrogen, some much weaker than others.
However, he doubted that parabens would be able to affect an unborn baby because they would be so weak.
"That would be almost impossible," he said.
There are incidents of women taking the pill when they did not realise they were pregnant.
"We know of women taking the combined contraceptive pill during pregancy and there is good evidence that even such potent oestrogens do not harm male foetuses," he said.
Similar behaviour
Colipa, the European cosmetic, toiletry and perfumery association, said that parabens did not pose a serious risk.
But Dr Michael Warhurst, a campaigner for Friends of the Earth who works in the same field as Professor Sumptor, called for action.
"This is an authoritative piece of research by a very well respected scientist and we think it really is time for action on this group of chemicals," he said.
"There is no doubt that this is of very serious concern."
Cancer link
Earlier this week researchers for the Cancer Research Campaign said that pollution could have contributed to a dramatic rise in the number of testicular cancer cases in England and Wales.
Scientists for the campaign are now investigating the role of oestrogen as a trigger for the cancer.
Meanwhile, scientists for the US Environmental Protection Agency plan to investigate up to 87,000 chemicals to see if they mimic the effects of oestrogen.
The EPA will focus on six types of chemical:
Background Briefings
Medical notes
Men at sea over 'Big C'
(05 Oct 98 | Health)
Chemicals suspected in testicular cancer increase
(05 Oct 98 | Health)
Father's Day message for testicular cancer sufferers
(20 Jun 98 | Health)
Male reproductive health problems
Centre for Reproductive Medicine
Testicular Cancer
Friends of the Earth
Cosmetic, Toiletry, and Fragrance Association (US)
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