|
 |
Don't place
blame just yet!
|
|
Researchers
have found the first direct evidence that chemicals in the environment --
including some in foods such as peas and beer -- mimic the effect of the
female sex hormone estrogen on the ability of sperm to fertilize eggs.
Scientists reported this week at Europe's annual human
reproduction conference that such chemicals seem to have a much more
potent effect on sperm than estrogen found in the body, and that they
might make sperm burn out before reaching the egg.
The study was
conducted with mice, but experts say human sperm behave very similarly.
Studies have shown that estrogen-like chemicals can disrupt the
development of the male reproductive system and reduce the production of
sperm, but this is the first time scientists have shown they affect sperm
itself. Sperm expert Christopher Barratt, a professor of reproductive
medicine at Birmingham University, said human sperm is even more sensitive
to female sex hormones than mouse sperm.
"If the effect is true,
it means you would need only extremely low levels in humans to affect
sperm," said Barratt.
Lynn Fraser, a professor of reproductive
biology at King's College in London, tested the effects on sperm of three
pseudo estrogen chemicals and compared the results with the action of
natural estrogen found in the vagina.
The three environmental
chemicals were genistein, found in soya, peas and other legume vegetables;
8-prenylnaringenin, found in beer, and nonylphenol, found in household
cleaners, paint and pesticides.
"All of these compounds stimulate, but if they keep on stimulating, at
least some of the sperm will undergo an acrosome reaction (cap rupturing).
That's really not a good thing because once the sperm have undergone that
reaction they can't fertilize, however much they can wiggle," Fraser said.
|
 |
|
|
|
.gif){kind=small}
