World Water Crisis (LIFE)

[funmaxus]

Tap water contaminant 'castrates' frogs
http://www.usatoday.com/tech/science/2010-03-02-1Aatrazine02_ST_N.htm

Updated 3/1/2010 9:24 PM

By Liz Szabo, USA TODAY

An herbicide that contaminates the tap water
consumed by millions of Americans has been found
to produce gender-bending effects in male frogs,
"chemically castrating" some and turning others into
females, a study shows.

Frogs in the experiment were exposed to amounts
of the weedkiller atrazine that are comparable to the
levels allowed in drinking water by the
Environmental Protection Agency, says lead
researcher Tyrone Hayes of the University of
California-Berkeley.

The study was released Monday in the Proceedings
of the National Academy of Sciences.

In Hayes' earlier studies, atrazine caused male frogs
to begin growing eggs in their testes. In this
experiment, 10% of the males exposed to atrazine —
one of the most commonly used herbicide in the
world — actually changed sex; some were able to
breed and lay eggs. Nearly all of the other males
had low testosterone and sperm levels, which made
them unable to reproduce, Hayes says.

The experiment can't tell scientists whether atrazine
affects humans in a similar way, Hayes says. But it
does raise new questions about the safety of
atrazine, which other studies have linked to human
birth defects, low birth weight, prematurity and low
sperm count.

The EPA said in October that it planned to reassess
atrazine's safety, including its cancer risk. The
European Union has banned the chemical.

About 75% of stream water samples and 40% of
groundwater samples contain atrazine, according to
the U.S. Geological Survey. The Natural Resources
Defense Council, an environmental advocacy group,
detected atrazine in 90% of tap water samples from
139 water systems. Inexpensive faucet-top water
filters can remove the chemical, says Jennifer Sass, a
scientist with the group.

Several water systems in Illinois, where atrazine is
commonly used on corn and other crops, are suing
the chemical's manufacturers, asking them to pay
the cost of taking the herbicide out of drinking
water.

The principal scientist for Syngenta Crop Protection,
the leading manufacturer of atrazine, says the
chemical is safe. Company-sponsored studies that
met rigorous EPA standards found atrazine has "no
effect on frog sexual development," Tim Pastoor
says.

He criticized the new study and notes that Hayes
tested only one dose of atrazine. A stronger study
would have exposed frogs to several doses and
noted any trends, he says.

Given that atrazine has survived years of scrutiny by
the EPA, Pastoor says, he sees no reason to re-
examine atrazine's safety now. "As far as we're
concerned, it's unnecessary," he says.

Although scientists still have many questions about
atrazine, Sass says, the chemical should be phased
out as a precaution.


NPR interview lead scientists on this issue

Researcher: Pesticide 'Castrates' Male Frogs
http://www.npr.org/templates/story/story.php?storyId=124422894
http://www.npr.org/templates/story/story.php?storyId=124422894