Birth Defects With Your Corn?

Photo by queenie13/FlickrCC

Since 2004, the European Union has effectively banned the use of the herbicide atrazine, which, in some studies, has been linked to cancer, low sperm count, insulin resistance, and birth defects. But according to the Environmental Protection Agency (EPA), it's perfectly OK for Americans to bathe in the stuff—literally.

Applied to our nation's fields at a rate of 60 million tons per year, atrazine is notorious for its knack for seeping into the water supply. The chemical can travel aloft on dust particles and drift for up to 600 miles, so even if you live far from the nearest cornfields, where most atrazine is deployed, you are not beyond the chemical's reach.

Last week, the EPA opened round one of a yearlong, comprehensive reevaluation of the herbicide, which is sold under such macho-sounding brand names as Bicep II Magnum. During a three-day-long meeting, the agency's Scientific Advisory Panel reviewed six papers linking atrazine to health risks in fetuses and babies.

One report, from Paul Winchester of the Indiana University School of Medicine, showed that women who conceived in the spring and early summer—peak periods of pesticide application—were at greater risk of having a child with birth defects than women who conceived at other times of the year. Another study by Hugo Ochoa-Acuña of Purdue University linked the presence of atrazine in a pregnant mother's drinking water to the birth of undersized infants.

Scientists employed by Syngenta, which manufactures atrazine, claimed that these two studies and others producing similar results were flawed. "All these studies have basic fundamental academic epidemiological flaws that render them less than useful," said Timothy Pastoor, a Syngenta researcher. "If you look at the birth defect uptick in infants that were conceived in the late spring and early summer months, it can be correlated with just about anything else that occurs with an uptick at that period of time—rainfall, tornadoes, lightening strikes. And, you see the same trend in both high-use and low-use atrazine states." Dr. Pastoor's conclusion: "There are absolutely no statistical correlations between atrazine concentrations and birth defects."

To try to make sense of the confrontation, I talked to Tyrone Hayes, a professor of integrative biology at the University of California, Berkeley. Professor Hayes has a unique vantage point on what he sarcastically refers to as "my old friend atrazine." In the late 1990s, Hayes worked as a consultant for Syngenta. According to Hayes, that relationship fell apart when it became apparent Syngenta was not going to allow him to publish the results of pioneering experiments showing that male frogs exposed to atrazine could develop female reproductive traits, up to and including the ability to produce eggs. So much for that macho image.

Dr. Pastoor disputes Hayes's version of events, saying it was not the company but his fellow academics on the company's scientific panel who deemed his research "highly questionable" and tried to dissuade him from publishing. "He did it anyway," Dr. Pastoor said.

In 2003, Professor Hayes presented the results of his research to the EPA's scientific advisors. The agency certified atrazine anyway.

This year, he thinks that Syngenta might not be in for such an easy ride. "We've got a different administration," he said. "People are starting to realize that it's not just a frog issue and that it's not just my data. I can stack up 30, 40, 100 papers showing adverse effects of atrazine. We're looking at sexual problems and cancer problems in rats, and fish, and alligators, and now there is new data coming out about birth defects in humans. All these different effects are showing up independently."

But what would be the downside from banning the popular weed killer, aside from its effects on corporate profits? Precious little. The United States Department of Agriculture calculated in 1994 that an atrazine ban would result in yield losses of only 1.2 percent.

"Who really wants to take the chance, when so much is at risk? Who wants that in their backyard?" Professor Hayes said. "If it were up to me as a citizen and a scientist, atrazine would be gone. It's a no-brainer."

The people who make up the EPA's advisory board are also citizens and scientists. When they file their report, expected in November, we'll find out whether they, too, see the issue in such open-and-shut terms.