Wednesday, September 28, 2022
More from MPR
Respond to this story


Atrazine ban may be introduced in Minnesota
Larger view
Atrazine is used to control weeds in corn. (MPR file photo)
Atrazine, a common weed killer used by corn and sorghum farmers, is under attack in Minnesota. Environmental groups and several state lawmakers want to ban or restrict the chemical because some scientists have linked it to reproductive deformities in frogs. But the company that makes atrazine says it hasn't been able to duplicate any of those results.

St. Paul, Minn. — The research implicating atrazine in amphibian health problems comes from a variety of studies. One of the first came out of the University of California-Berkeley. In 2002, biology professor, Tyrone Hayes, reported that exposure to atrazine disrupts hormones in male frogs, causing them to develop female reproductive organs.

Hayes published his findings in the scientific journal Nature.

"Not only have I shown this hermaphroditism, it's been shown independently in a laboratory in Japan, independently in a laboratory in Canada and independently in a laboratory in Illinois," says Hayes. "The same kinds of effects that we get -- hermaphroditism and chemical castration of males."

Hayes conducted the study at the request of atrazine's maker, Syngenta, which at the time, was known as Novartis. The company hired him because Hayes had developed an amphibian test for monitoring pesticides in water. But Hayes says Syngenta wasn't happy to hear that his results revealed a problem with atrazine.

"First, they offered me quite a significant amount of money to do the work privately," says Hayes. "And then they hired statisticians to try to prove that I had interpreted data inappropriately, which they were unable to do."

Syngenta disputes that claim.

"He is contending that he was offered a private deal. That's simply not true, and that's a complete mistatement," says Dr. Tim Pastoor, the head of human safety assessment for the company. "As far as offering him large sums of money, that's not true at all."

When asked if Syngenta offered Hayes any money, Pastoor said, "We had funds available to do the necessary studies to resolve the differences. These would be studies done not just by Tyrone Hayes, but they would be done by other scientists. Not just to Tyrone."

Pastoor says Hayes' results didn't match up with what other researchers, hired by Syngenta, were finding. Those scientists didn't detect any malformations in frogs exposed to high doses of atrazine.

"Unfortunately, what Tyrone is trying to do is he's using his data to make a silk purse out of a sow's ear," Pastoor says.

Pastoor says Syngenta has conducted more than 200 studies on the safety of its product in the past 10 years, and submitted all of its results to the Environmental Protection Agency. In October 2003, the EPA recommended reregistering atrazine for approval after weighing all of the available science. But the agency did ask Syngenta to keep studying atrazine's effect on frogs, to resolve the differences in the scientific findings.

But that decision doesn't satisfy Tyrone Hayes. He thinks the EPA went easy on Syngenta, because the chairman of agency's scientific advisory panel that provides analysis of pesticides and chemicals, Ron Kendall, also has worked for Syngenta.

"Talk about conflict of interest," says Hayes. "Not only was he on the Syngenta payroll and chairing the EPA panel, he was running the lab that did all of Syngenta's work."

Hayes may be the most vocal critic of atrazine. He frequently takes his research on the road to talk about it with environmental groups across the country.

Last summer he got a lot of attention in Minnesota, when the Minnesota Pollution Control Agency canceled his keynote speech at an MPCA-sponsored conference after learning that he was going to talk about the link between atrazine and frog abnormalities. The agency explained its decision by saying Hayes had already presented those findings.

That got the attention of state Sen. John Marty, DFL-Roseville, who later invited Hayes to testify about his research at the state Capitol last October. Marty is now considering whether to introduce a ban on atrazine in Minnesota.

At a recent Capitol news conference that coincided with another Twin Cities visit by Hayes, several lawmakers, including Marty, said they want to make sure the professor's research isn't silenced.

"Science is being politicized," says Marty. "You will see great efforts nationwide to discredit Dr. Hayes, and any other scientist whose results don't match up with what the pesticide companies want. Any scientist that comes up with a negative result -- they try and trash them."

Hayes also has an ally in state Rep. Karen Clark, DFL-Minneapolis, who attended the news conference.

"His work was so carefully done," says Clark. "And the conflict of interest on the panels at the federal level -- the same people being involved who previously worked for the company that made atrazine, Syngenta -- you just really have to question that agenda."

Clark is introducing a bill that would require the state to do a better job tracking the sources of environment-related health problems related to chemicals like atrazine. She's proposing that the state merge pollution data from the MPCA with disease data from the state Health Department. Perhaps nowhere is the debate over atrazine being followed more closely than by Minnesota crop farmers. Curt Watson is a corn farmer from Renville. He's also treasurer of the Minnesota Corn Growers Association. Watson uses atrazine, and would hate to lose the chemical.

"We as producers do not want to lose a product that takes care of our weeds, and has gone through very rigorous testing," he says.

Watson says atrazine is a cheap and effective way to control weeds. Without it, he says he would lose money.

"The bigger the weeds get in a corn field, the more severe the yield reduction would be," says Watson. "It could easily be 60-70 percent yield reduction or higher. It's a big deal."

Still, Watson says he wants to use a safe product. So if it takes more testing to prove that, he's in favor of more research. But he doesn't think lawmakers should act in haste and enact a ban before they have more findings. If they do, Watson says Minnesota farmers will be at a competitive disadvantage with farmers around the U.S.

Sen. Marty says he's sensitive to that concern. That's part of the reason he's still weighing whether to introduce a ban on atrazine. He's also aware that he may be out-gunned politically.

"It's going to be a tough political sell. Very tough," says Marty. "Because Syngenta -- they've already hired one of the most expensive lobbying firms and most expensive PR firms in the state to work on them. And we're basically working on volunteers who care about the environment."

Dr. Tyrone Hayes is keeping close tabs on what Minnesota lawmakers decide to do about atrazine. But he's not putting all his eggs in one basket. Hayes says he's been talking with legislators in other states in the hopes of convincing them to consider a ban too. He won't say which states he's talking with, because he says he doesn't want to share his strategy with Syngenta.