Begin forwarded message:
From: dasg...@aol.com
Date: March 6, 2009 1:11:31 PM PST
To: ramille...@aol.com
Subject: Fwd: Sexual Mutation of Fish Worldwide Reveals HUMAN Hormone
Risk from Anti-A...
Worldwide 'She-Male' Fish Mystery Widens
Emily Sohn, Discovery News
http://dsc.discovery.com/news/2009/03/04/male-female-fish.html
March 4, 2009 -- Around the world, increasing numbers of male fish are
developing female traits -- growing new sexual organs and sometimes
even producing eggs. The phenomenon has been blamed mostly on
chemicals that get into the water and mimic the female hormone estrogen.
But a new study puts some of the blame on an entirely different class
of chemicals -- ones that block the action of male hormones. It isn't
the first study to suggest that anti-androgens might be contributing
to the feminization of fish.
But the new research found that there are far more of these chemicals
in our lakes and streams than anyone realized. And anti-androgenic
chemicals in the water might affect human health as well.
"They are going to be some potent players," said Charles Tyler, an
ecotoxicologist at the University of Exeter in England. "It is
possible that there are going to be many more chemicals that are anti-
androgenic than are estrogenic."
Tyler, along with Susan Jobling at Brunel University in London and
other colleagues, looked at chemical run-off in 51 rivers throughout
the United Kingdom. By combining concentrated water samples with
cultures of yeast genetically engineered to have androgen receptors,
the scientists were able to measure the amount of anti-androgen
activity in each sample.
The researchers' results, published in the journal Environmental
Health Perspectives, revealed a significant amount of anti-androgenic
activity in nearly all of the samples tested.
The researchers also collected fish from each site. With statistical
models, they were able to show that anti-androgens were just as
responsible for the feminization of fish as estrogenic compounds were
-- if not more so.
"The amount of anti-androgen activity is pretty much a surprise,"
Tyler said. "We expected some, but nowhere near the level of potency
we found."
Anti-androgenic chemicals usually come originally from pesticides or
pharmaceuticals that get into wastewater. Dozens of studies have
linked these chemicals with health problems in mammals, said Gerald
Ankley, an ecotoxicologist with the Environmental Protection Agency in
Duluth, Minn. But this is one of the first studies to make the link in
fish.
"This forms the basis for more focused experimental studies," Ankley
said.
For example, scientists will need to figure out exactly which anti-
androgenic chemicals are causing problems in fish. (For his part,
Tyler says he is on the verge of announcing three new anti-androgenic
chemicals that will add to the list of more commonly known compounds).
Researchers also want to test whether certain mixtures of hormone-
disrupting compounds are more harmful than any one chemical alone,
Ankley added.
And the work brings up plenty of questions about what chemicals in our
rivers and streams might be doing to human health. After all, people
and fish have similar hormonal systems.
"At the end of the day, wildlife are fantastic sentinels for potential
human impacts," Tyler said. "If it happens in fish, it can happen in
humans."
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