Boys wont be boys - Boys won't be boys New Scientist vol...

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Boys won't be boys New Scientist vol 174 issue 2349 - 29 June 2002, page 41 Something out there could be meddling with our fertility. And the latest set of pollutants is decidedly anti-male, says Julie Wakefield. The trouble is, the culprits are a vital part of modern life and we can't easily do without them PEOPLE don't quite know what to make of Theo Colborn. Is she the prophet of a new environmental threat or an errant alarmist? Hunched over a computer at the World Wildlife Fund in Washington DC, Colborn is amassing a database of chemicals she believes are hijacking our hormone systems, damaging men's fertility - even putting them at higher risk of developing testicular cancer. And what's more these chemicals are on the increase. Colborn is at the forefront of a 14-year debate on what are known as endocrine disruptors: pollutants that mimic or block the effects of human hormones. While some researchers argue there is no proven link between endocrine disruptors and reproductive problems in people, Colborn and her team believe these chemicals can have serious side effects even at low levels. Until recently, the debate focused on oestrogen mimics - chemicals that behave like female hormones. Some researchers link these to falling sperm counts and increases in cancer rates, while others strongly dispute any link. This debate is still unresolved, but now the hot topic is a new class of chemicals called androgen disruptors, which either mimic or suppress the action of male hormones such as testosterone. In theory, they could have an even greater impact on male fertility than oestrogen mimics. How worried should we be? The first hints that pollutants might be able to interfere with male hormones turned up over 20 years ago. Mike Howell, a fish biologist at Samford University, Alabama, discovered that female mosquitofish living in Florida rivers were starting to look like males. The fish, found downstream from a paper mill, had mysteriously developed an enlarged anal fin. This is normally a characteristic of male mosquitofish and it is used in mating. Since then masculinised females have turned up in other species of fish in American, Canadian and European waterways. The answer to this particular mystery only emerged last year. Howell's team analysed samples of polluted water taken downstream from another paper mill. They found traces of several androgens, the first ever spotted in the environment. One of them was androstenedione, a precursor to testosterone and an anabolic steroid favoured by bodybuilders. This time, though, the hormone had appeared in the water because of the wood pulp churned out by the mill. Bacteria in the water were converting chemicals called sterols in the pine pulp into androstenedione. The team suspects that similar biological processes may be releasing many more androgens into the environment.
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But it's not just androgens we have to worry about, it's also anti-androgens, chemicals that block the action of normal male hormones in the body. Anti-androgens could exert
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Boys wont be boys - Boys won't be boys New Scientist vol...

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