The city of Boonville received a check last week for $26,000 from the manufacturer of Atrazine, a weed-killing chemical used on corn throughout the Midwest.
Boonville was one of 89 Missouri communities that became part of a class action lawsuit against Syngenta AG, the Swiss company that manufactures Atrazine. The company agreed to pay $105 million to settle the lawsuit, which was filed in 2004 in U.S. District Court in Illinois.
What is Atrazine?
Atrazine is the most heavily used herbicide in the U.S. It kills weeds by disrupting photosynthesis, starving the plants of nutrients. It was first registered for use in 1958, and it was heavily used with minor restrictions between then and 1993.
Is it harmful?
Concentration is the crucial factor in determining Atrazine’s toxicity. The Environmental Protection Agency has stated that concentrations below 3 parts per billion are safe in drinking water. However, some research has shown that Atrazine can disrupt human hormonal systems at levels below 3 ppb. Some of the confusion about Atrazine’s toxicity arises from the complexity of the human chemical networks it affects.
The EPA has stated that some of the effects of Atrazine exposure are:
- Shortening of female reproductive cycle length.
- Lowering of pituitary hormone levels.
- Changes in ovarian tissue.
- Changes in liver hormones and tissues.
Where does it come from?
Today, only a professional registered with the EPA can apply Atrazine, not the general public. It can be applied with a variety of sprayers. Once Atrazine makes it into the soil, microbes break it down into metabolites or smaller, related molecules. It takes between five and 30 days for Atrazine to break it down into its lowest metabolites.
- 76.4 million pounds of Atrazine are applied annually.
- 75 percent of field corn in the U.S. is treated with Atrazine.
Of the total, $10 million went to Missouri communities, with some receiving as little as $5,000 and others as much as $1 million. The payment is intended to reimburse the communities for the cost of removing Atrazine from drinking water.
Atrazine isn’t the biggest problem with the raw water Boonville draws from the Missouri River, said M.L. Cauthon, Boonville's public works director. Suspended sediment, fertilizers and other pesticides and herbicides also must be removed.
“We don’t specifically treat for Atrazine, but we lump Atrazine together with other contaminants that may or may not be in the Missouri River water,” Cauthon said.
Boonville removes Atrazine from its water by adding powdered carbon to basins of raw water, Cauthon said. Along with other chemical contaminants, Atrazine bonds to the carbon and sinks to the bottom of the tank, where it is removed. This method is commonly practiced for a variety of water quality contaminants, not only Atrazine.
“Because we treat for a spectrum of contaminants, we would treat for it anyway,” Cauthon said. “I can’t easily tell you that we spent X amount specifically on Atrazine.”
Atrazine enters water supplies the same way as most agricultural pollutants. In the spring, corn growers apply the chemical to destroy the weeds that threaten their crops. Atrazine is cheap and effective, which explains why it is used on 80 to 85 percent of Missouri corn.
Bob Lerch, a USDA soil scientist and MU adjunct professor who studies herbicide runoff, said during rains or after irrigation, between 2 and 10 percent of Atrazine applied flows off farmers’ fields and into streams, lakes and rivers.
Many Missouri communities rely on these surface waters as raw drinking water sources and have to pay the cost of removing Atrazine. By joining the lawsuit, a community water provider asserted that Syngenta should be responsible for these costs.
Atrazine also has been linked to human health concerns. An MU study from 2003 published in Environmental Health Perspectives tied Atrazine to poor semen quality in men.
In lower amounts, it can have environmental effects. A 2002 study published in the Proceedings of the National Academy of Sciences stated that levels as low as 0.1 parts per billion could turn male frogs into hermaphrodites.
People who consume Atrazine at concentrations of 3 parts per billion or more via their drinking water can experience cardiovascular and reproductive problems, according to the Environmental Protection Agency.
In 2006, the EPA undertook a risk assessment for Atrazine and concluded that present exposure levels are low enough to prevent health problems. The agency will review the chemical again later this year to determine whether it will continue to be available.
Lerch said holding a company responsible for how consumers use its product could be a dangerous precedent.
“Have we said that the farmer has no obligation and responsibility here?” Lerch said.
Last fall, Lerch worked with MU Extension assistant professor Bob Broz to develop farming methods that would minimize Atrazine runoff. Syngenta put forward $30,000 to fund the experiment.
They found that by using an implement called a harrow to till the soil about 2 inches deep, farmers could ensure that the herbicide is thoroughly mixed into the soil without causing too much erosion.
Now Broz’s goal is to share his findings with farmers so they can continue to use the cheapest herbicide on the market. Atrazine costs a third of the price of the second-cheapest herbicide, he said.
“Our goal is to provide farmers with science-based information that will help them keep the tools that they have,” Broz said.
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