Duluth, Minn. — Four years ago, the U.S. Environmental Protection Agency gave conditional approval for a new weed-killer called Balance Pro. But the agency still had some worries.
EPA researchers thought the ingredients in Balance might accumulate in irrigation water.
Jannette Brimmer is with Minnesota Citizens for Environmental Advocacy. She says if Balance turns up in irrigation water, it could turn up in drinking water. She points to studies in which a few reservoirs have accumulated residues of isoxaflutole, the main ingredient in Balance.
"Missouri has had drinking water reservoirs contaminated with this, and contaminated within the first year of its use," she says.
Brimmer worries Balance could turn into another environmental problem like atrazine. Atrazine is a commonly used herbicide. It shows up in drinking water in many parts of the country, at very low levels. Some studies show - even at those low levels - it's causing deformities in the sexual organs of frogs, which could be contributing to drastically reduced frog populations.
Brimmer says atrazine and other pesticides might be affecting people too. "In other words," she says, "small dosages at the wrong time in fetal development, pregnancy, in a kid, can have significant impacts."
Brimmer says it's too late with atrazine - it's already in the environment. But with the new isoxaflutole, she says that may not be the case.
"We have an opportunity to do the right thing before it gets into our water," she says. "Before it poses a health threat, before it's a problem."
The EPA doesn't do any tests to find out whether herbicides affect the hormones of frogs or people. The agency did conduct tests on the reproduction rates of aquatic animals, and found no effects.
But the EPA does have one major concern: the effect Balance might have on other crops. Officials worry if farmers use water polluted with Balance to irrigate crops like cabbage or lettuce, the herbicide could hurt crop yields.
Both Michigan and Minnesota are trying to figure out how serious that threat might be. Officials at the Minnesota Department of Agriculture have been watching the field studies from other states. The results are mixed.
Some of the studies looked at how much Balance got into water supplies. They found lower concentrations than scientists originally predicted.
But the Minnesota Agriculture Department's Dan Stoddard says some parts of the state are more vulnerable than others, depending on the type of soil. Southeastern Minnesota, with its shallow bedrock limestone, is particularly vulnerable.
"What has been considered is some requirements that would restrict use of the product in those areas," Stoddard says. "Because of the chemical's potential to get into groundwater, what we would require is additional monitoring to see whether or not that is in fact happening."
Stoddard says he's weighing the risk of polluted water against the benefits Balance might offer. He's hearing from companies that have been applying Balance in other states. They say by adding the new product to their arsenal, they can cut down on their use of other herbicides.
That would be a big help with the problem of herbicide resistance, Stoddard says.
"If somebody uses the same type of herbicide over a few years," he says, "weeds can become resistant and what they wind up having to do is increase the concentration of that product. So having a new chemistry allows lower application rates of the product."
Wisconsin recently approved the use of Balance. But the Agriculture Department there imposed so many restrictions, the company decided not to market it in Wisconsin. Bob Olson is a farmer, active in the Wisconsin Corn Growers Association. He says his state is putting him at a disadvantage compared to other farmers.
"It's been registered in 17 other corn states," Olson points out. "It's just not been able to be registered here in Wisconsin because of what we think are undue concerns. And the fact that we can find it in increasingly smaller quantities. Simply because you can find something, doesn't mean that level is ever going to affect anyone."
Michigan and Minnesota are planning to decide in time for spring planting whether to let farmers use Balance in their states.