- Are synthetic chemicals - which we encounter daily in
everything from pesticides to plastic wraps to shampoos - damaging the
health of the human species?
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- That's a question scientists have been trying to answer
since the early 1960s, when researchers first observed some startling mutations
in wildlife: panthers born with underdeveloped testicles, alligators with
shriveled penises and seagulls born with both male and female organs.
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- New studies conducted during the past year by teams of
scientists at the U.S. Environmental Protection Agency (EPA) and the Chemical
Industry Institute of Toxicology (CIIT) show a host of common chemicals
can emasculate males by a new, ignored route: the blocking of androgens,
or male sex hormones
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- Decades of studies show similar reproductive and developmental
abnormalities are occurring in humans, say Theo Colborn, Dianne Dumanoski
and John Peterson Myers in their landmark 1996 book, Our Stolen Future
(see www.osf-facts.org).
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- Since then, other researchers have attempted to link
synthetic chemicals - or endocrine disruptors, as they are known - to an
alarming apparent drop in sperm count worldwide.
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- The suspected chemicals include phthalates, which are
found in plastics, vinyl flooring, adhesives and food packaging; alkylphenols
(industrial and domestic detergents and some shampoos); Bisphenol A (resins
that coat food cans); organochlorine pesticides (such as DDT, which is
still being used in developing countries); and dioxins, produced during
incineration and some industrial processes.
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- "Endocrine disruptors are ubiquitous in the environment
and can be found in virtually every plastic container and detergent,"
says Peter DeFur, a scientist and professor at Virginia Commonwealth University
in Richmond, Va., who has studied the impact of endocrine disruptors on
wildlife.
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- Earlier research showed that endocrine disruptors were
doing damage by mimicking the female sex hormones called estrogens. But
new studies conducted during the past year by teams of scientists at the
U.S. Environmental Protection Agency (EPA) and the Chemical Industry Institute
of Toxicology (CIIT) show a host of common chemicals can emasculate males
by a new, ignored route: the blocking of androgens, or male sex hormones.
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- "We have found that androgens do block the action
of male fetuses so that some of them look like females," explains
Dr. Earl Gray, an androgen toxicologist with the EPA, who has co- authored
five studies on the subject. "We have males with undeveloped testicles
and malformed penises and some have even been born with a vaginal pouch."
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- These startling results arise from experiments performed
on laboratory rats, leading researchers like Dr. Gray to quickly point
out how little direct research there is on the impact of endocrine disruptors
on humans.
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- Since conducting laboratory experiments on humans would
be unethical, Dr. Gray explains, the only remaining course is "to
conduct surveys of suspected exposed populations. But they are long, expensive,
complicated by some variables and difficult to do."
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- Still, the animal experiments do raise some red flags.
Those studies suggest that subjects are most vulnerable to the effects
of endocrine disruptors in the womb, early infancy, and pre-puberty. Dr.
Gray has identified about 10 chemicals as being suspect. "We haven't
defined the whole universe yet, but there seems to be more and more chemicals,"
he says.
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- There is, however, more research on the way. The U.S.
government, for instance, has initiated two new projects to learn more
about the impact of endocrine disruptors: the National Institute of Health
and the Centers for Disease Control and Prevention are collaborating on
a project to improve assessment of human exposure to environmental endocrine
disruptors, while the EPA began testing protocols to screen for endocrine
effects in September 1998.
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- Working under congressional mandate, the EPA will attempt
to screen some 87,000 chemical compounds by the end of 2000,at a cost of
more than $100 million.
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- "We will start off with a lot of chemicals - but
only a small fraction of them will be screened and tested," says Gary
E. Timm, a scientist with the EPA. "That's because a lot of the chemicals
aren't produced anymore; others are used to make another substance, and
some are polymers, which means they can't get into the (human) system."
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- Since 1998, the EPA's Endocrine Screening and Testing
Advisory Committee has dismissed fears about 20,000 of the chemicals that
were to be screened, but says 60,000 chemicals should continue to be investigated.
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- But will the EPA's mega-screening project settle the
big question - do widely used synthetic chemicals have a disastrous effect
on the reproductive systems of humans?
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- Scientists have disagreed about that one for a long time,
so don't expect the answer any time soon.
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- A native of Thunder Bay, Ontario, Ron Chepesiuk is a
freelance health writer based in Rock Hill, South Carolina http://www.straightgoods.com/item353.asp
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