Despite growing health concerns about atrazine, an agricultural weedkiller sprayed on farm fields across the Midwest, most drinking water is tested for the chemical only four times a year -- so rarely that worrisome spikes of the chemical likely go undetected.
High levels of the herbicide can linger in tap water during the growing season, according to more frequent tests in some agricultural communities.
Spread heaviest on cornfields, atrazine is one of the most commonly detected contaminants in drinking water. Studies have found that exposure to small amounts of the chemical can turn male frogs into females and might be more harmful to humans than once thought.
Manufacturers say their own research proves the chemical is safe. But alarmed by other studies, the Obama administration is conducting a broad review that could lead to tighter restrictions. It is also mulling changes in laws that require water utilities to test for atrazine just once a quarter or, in some cases, once a year.
"There always have been a lot of questions about atrazine, and we want to make sure the agency's regulatory posture is consistent with the science about possible health effects," said Steve Owens, the U.S. Environmental Protection Agency's assistant administrator for prevention, pesticides and toxic substances.
Even with limited official testing, atrazine in the past four years was detected in the drinking water of 60 Illinois communities where more than a million people live, according to a Tribune analysis of state and federal records.
Under a deal between the EPA and the chief manufacturer of atrazine, about 130 water utilities in 10 states are tested weekly or biweekly. The Tribune analysis showed that during 2008, four downstate towns -- Evansville, Farina, Flora and Mount Olive -- were among nine Midwest communities where the average annual level of atrazine and its breakdown products exceeded the federal safety limit of 3 parts per billion. About half of the 130 saw concentrations that jumped above 3 parts per billion at least once that year.
In Flora, about 240 miles south of Chicago, atrazine levels spiked as high as 30 parts per billion. The findings concern researchers because some studies have shown adverse affects from exposure to concentrations as small as 0.1 parts per billion. The chemical has not been found in Chicago tap water, in part because Lake Michigan dilutes farm runoff.
The more frequent tests are done outside the EPA's official monitoring program and don't count when regulators consider whether communities meet the legal limit for atrazine.
Growing Concern over Atrazine in the Water
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By Michael Hawthorne
Chicago Tribune - IL, April 18, 2010
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