Some of Wisconsin's largest farm groups are worried that federal regulators will increase restrictions on atrazine, a weed killer sprayed on corn fields and other crops.
This summer, the U.S. Environmental Protection Agency issued a draft ecological risk assessment of atrazine and recommended reducing the allowable levels.
Farm groups, including the Wisconsin Corn Growers Association, the Cooperative Network, Wisconsin Pork Association, Midwest Food Processors, the Dairy Business Association, Wisconsin Farm Bureau Federation and the Wisconsin Soybean Association, have asked farmers to contact the EPA and urge the agency to reconsider its position.
The reduced allowable levels would "effectively ban the use of atrazine in nearly 100 herbicide mixes," the Wisconsin Corn Growers Association said Monday.
"For more than 50 years, atrazine has been a safe and effective crop protection tool to control the spread of resistant weeds and improve crop yields. ... EPA's action would drive up the cost of production to Wisconsin corn growers and would reduce our yields," said Casey Kelleher, president of the Wisconsin Corn Growers Association.
The public has until Oct. 4 to comment on the EPA's proposed atrazine risk assessment.
The farm groups say the plan represents a "terrible precedent" and could harm the environment.
"Atrazine plays an important role in conservation tillage, a farming practice that reduces soil erosion and runoff. An atrazine ban would require more soil tillage to control profit-robbing weeds and will be a net-negative for the environment," said Tom Liebe, president and CEO of Cooperative Network.
Yet some research has shown that atrazine may be dangerous at lower concentrations than previously thought and that it may be linked to birth defects and cancer.
Hundreds of private wells in Wisconsin have some level of the herbicide in them.
"At low levels in drinking water, atrazine does not cause immediate sickness or health problems. However, if people drink water for many years that contains three parts per billion or more of atrazine or its metabolites, they may develop cardiovascular, reproductive or other health problems," the state Department of Agriculture, Trade and Consumer Protection says on its website.
Environmental groups have urged the EPA to ban atrazine. Some cities have spent millions of dollars to filter out or dilute atrazine levels from drinking water.
A study published in the Proceedings of the National Academy of Sciences found that frogs exposed to atrazine developed shrunken testes and that one in 10 male frogs exposed to atrazine became female.
There are significant environmental effects from the herbicide, including toxicity to amphibians, fish, birds and other animals, said Tyson Cook, director of science and research for the environmental group Clean Wisconsin.
The use of atrazine has been prohibited in many places in Wisconsin where tests have shown the level in drinking water is higher than the allowed limit.
Farm groups want to have some of those bans reconsidered, so that farmers could use the herbicide under tightly controlled conditions.
"Monitoring wells for water quality is still one of the goals we would want," said Tom Thieding, spokesman for the Wisconsin Corn Growers Association.
Yet atrazine doesn't break down easily in water or soil, and environmentalists worry that its harmful effects could last for many years.
Any reversal in the prohibited areas would be particularly troubling, said Tressie Kamp, attorney for Midwest Environmental Advocates, based in Madison.
"It rises almost to the level of being unacceptable to be talking about rolling those protections back," Kamp said.
Should the EPA increase restrictions on the use of atrazine, farmers say the loss in crop yields and income would come at a bad time as crop prices are at some of the lowest levels in years.
Environmentalists say the federal government should provide farmers with incentives to use fewer chemicals on their crops.