"No one would have believed ten years ago what we're finding out today," said John Peterson Myers, a zoologist and co-author of Our Stolen Future. "Low doses matter. We're now aware that it doesn't take a lot to cause a big effect. The atrazine story is a case in point."
A research study published in the April 16 issue of Proceedings of the National Academy of Sciences found that exposure to as little as 0.1 parts per billion of atrazine, the most common weed killer in America, caused reproductive abnormalities in frogs.
Atrazine can be found everywherein rainwater, snow runoff, and groundwater. There is virtually no atrazine-free environment, according to Tyrone B. Hayes of the University of California, who led the research.
"We're in the midst of a revolution that started with Rachel Carson, and what we're learning today will require fundamental changes in how we structure regulating these chemicals," said Myers. "Faced with this kind of data, we can't keep looking at just one chemical at a time. We experience soups of chemicals that all interact with one another. There has to be a new standardthe system we have now is broken."
Change will not come easily or swiftly.
On April 12, the Bush administration announced that it was submitting the Stockholm Convention on Persistent Organic Pollutants (POPs) to Congresswith some modifications. The international treaty, approved by 127 nations in May 2001, calls for the complete elimination of the "Dirty Dozen": 12 chemicals that persist in the environment and are acknowledged to be extremely harmful to humans.
Although the United States signed the treaty, the enabling legislation sent to Congress eliminates a provision in the treaty that allows for the addition of new chemicals to the list if scientific evidence warrants it. Atrazine, the weed killer that causes frogs to develop male and female sex organs at concentrations 30 times lower than what is approved by the Environmental Protection Agency, is not one of the 12 POPs named in the treaty.
The burden of proof in regulating chemicals needs to be changed from one in which harm must be demonstrated before a product is withdrawn, to an approach where safety is ensured beyond reasonable doubt before widespread deployment is allowed, Myers argues.
"Europe is far ahead of the United States in adopting a precautionary approach on this issue," said Myers. "The Swedish Chemicals Policy Committee has developed a standard that says if it's persistent and bioaccumulative, you don't need to show toxicitythat's enough. And that's the direction we need to be heading in."
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