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eNews from Tuesday, June 1, 2010

New Missouri Studies Show Atrazine's Potential Harm

Columbia Daily Tribune (MO) -- May 30, 2010 -- Atrazine is one of the oldest herbicides on the market. It's also still one of the most popular and can be found almost anywhere corn, sorghum or sugar cane are grown. More than 76 million pounds of the chemical are sprayed on U.S. farmland each year, making it second in volume only to Roundup.

But two new studies by Columbia researchers are raising major questions about the chemical's persistent infiltration into Missouri waterways and its effect on aquatic life.

Bob Lerch, a U.S. Department of Agriculture Agricultural Research Service soil scientist found that over a 15-year period Atrazine regularly seeped into Goodwater Creek in Audrain County at rates high enough to harm plant life.

In an unrelated study, Don Tillitt, a research chemist at the U.S. Geological Survey's Columbia Environmental Research Center, found that fathead minnows exposed to Atrazine produce fewer eggs and spawn less often than control groups. The study is one of the first to suggest that Atrazine can be harmful to fish at levels far lower than the benchmarks set by the Environmental Protection Agency.

The research is prompting a growing chorus of critics to ask why the popular herbicide, already banned in Europe, is so lightly regulated in the United States.

Lerch's research looked at about 28 square miles of land surrounding Goodwater Creek. With data collected by rain gauges and weirs set up in the stream to capture water samples, researchers found that between 0.56 and 14 percent of the Atrazine sprayed in the fields washed into the creek each year. The median annual amount was 5.9 percent, which Lerch said was among the highest ever reported in scientific literature. The data showed that Atrazine concentration in the Goodwater Creek exceeded benchmarks set by the EPA for harming aquatic plant growth for weeks or months at a time.

And Lerch said this high level of herbicide runoff is normal for the thin claypan in northeast Missouri.

"It's actually quite typical of the claypan region," Lerch said. "That's what we came to realize. After we first discovered this starting in 1992 or 1994, we realized this wasn't just one year and it wasn't just one creek. It wasn't an anomaly; this is a real problem here."

Perhaps most frustrating for Lerch and others is the fact that despite spending tens of thousands of dollars in outreach to Audrain County farmers with education programs about how to build natural buffers and use safer methods of herbicide application, the amount of Atrazine flowing into the creek did not change much over the 15-year period.

Lerch said he believes his study on Goodwater Creek could have been done almost anywhere in northeast Missouri or southern Iowa.

"We are one of the worst anywhere in the world," Lerch said of the amount of the herbicide running off into waterways. "That is not an overstatement. And it's kind of shocking."

It might take years of additional research to determine exactly what kind of impact this is having on aquatic life. In a study just published in the journal Aquatic Toxicology, Tillitt found that minnows exposed to Atrazine spawn less often and produce fewer eggs than control groups. He also observed gonad abnormalities in male and female fish exposed to the chemical.

Most alarmingly, Tillitt observed these negative effects in groups exposed to Atrazine at levels as low as 0.5 micrograms per liter of water. The EPA benchmark for harm to aquatic life is 65 micrograms per liter, meaning concentrations well above the levels tested by Tillitt are permissible in streams.

"It would be very common to see levels" higher than .5 micrograms "especially in the spring," Tillitt said.

Tillitt said because the effects he saw on minnows are hard to observe in the wild, it is easy for them to go unnoticed even on closely observed streams. Tillitt and his fellow researchers are unsure whether the breeding problems were a result of chemical changes, molecular changes or behavioral changes in the minnows.

"This is an herbicide, so it's designed specifically to affect photosynthesis," Tillitt said. "So you wouldn't think it would have effects on animals or humans," but what happens with chemicals "is they interact and they can have unintentional side affects and we're learning more and more about that all the time."

Atrazine, when present in water supplies, is removed by using activated carbon. According to the 2009 water quality control study by Columbia Water & Light, no Atrazine was detected in the city's drinking water.

Author: T.J. Greaney

Copyright (c) 2010, Columbia Daily Tribune, Mo.
Distributed by McClatchy-Tribune Information Services.

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