Damage from toxins can pass to offspring

Posted 6/2/2005 10:57 PM
http://www.usatoday.com/news/health/...ffspring_x.htm


Damage from toxins can pass to offspring
By Elizabeth Weise, USA TODAY
Scientists have shown for the first time that exposure to
environmental toxins can cause permanent genetic changes that are
passed down through generations.
The research on rats by a team of scientists led by Michael Skinner at
Washington State University in Pullman, Wash., may hold the key to the
mystery of male infertility, which some researchers say has been
increasing for unknown reasons for 20 years.

According to a report in today's edition of the journal Science,
Skinner's team was working with two commonly used chemicals, an
insecticide called methoxychlor and a fungicide called vinclozolin.
Both are known to cause infertility in the male offspring of pregnant
animals.

The scientists were looking at the rats and their offspring. But when
the offspring had offspring, the researchers were shocked by what they
found in this second generation. And they were even more surprised by
subsequent generations of the lab rats.

"Lo and behold they had the same" infertility problems, says Skinner,
director of the university's Center for Reproductive Biology.

Not only the grandsons but also the great-grandsons and great-great
grandsons of the exposed mother were similarly affected. The
scientists had discovered a mechanism that permanently changed the
reproductive cells.

"That (the changes are) carried down through the generations is what's
new and novel here," says Paul Turek, a male infertility specialist at
the University of California at San Francisco. "Everyone agrees that
exposure of the fetus at a certain critical time can cause malformed
organs and birth defects. But no one ever imagined this might persist
at some level for three more generations."

Skinner notes that rat studies cannot necessarily be applied to
humans, but he said the findings warrant a close look at the potential
health hazards of environmental chemicals.

The exposure appears to produce what's called an epigenetic effect, in
which a chemical modification of the DNA in the animal's reproductive
cells causes an alteration with potentially disastrous results — in
this case, infertility.

Epigenetic effects are generally erased with each new generation when
the cells that form the sperm or eggs are created in the embryo. But
in this case, the affected genes maintained the alteration and escaped
the reprogramming process.

Skinner cautions that the doses used in his research are higher than
those normally found in the environment. He plans to begin testing at
lower doses to see whether the same changes appear.

Human exposure to methoxychlor, which is being phased out in the USA,
and vinclozolin is