Environmental Agency Mulls Fate of Eco-Friendly We
July 7, 2000
by Dennis T. Avery
BRIDGE NEWS June 30, 2000
CHURCHVILLE, Va. - The most important farm chemical hearing in 30 years is under way. The Environmental Protection Agency is conducting a "special review" to decide whether the most widely used of modern weedkillers, atrazine, is safe enough to be left on the market.
EPA has long wanted to get rid of atrazine because traces of it sometimes turn up in Midwestern drinking water. Any pesticide that turns up in our drinking water (and stays on the market) forces EPA to explain how safe it is and how important it is to society. That, in turn, would raise the question of how safe and important other pesticides might be.
Neither the EPA nor the anti-pesticide lobby want that discussion. Both want to gain fame by banning pesticides, not praising them. But atrazine is so safe and so important to conservation it seems inconceivable EPA would ban it.
Last year, Stanley Trimble, a sediment expert at UCLA, completed a remarkable "soil archeology" study. Trimble found The Coon Creek watershed in Wisconsin lost 16 times more topsoil to erosion during the "Dust Bowl" days of the 1930s than it loses today. Why? Mainly because of a new farming system called conservation tillage.
Conservation tillage "discs" the huge amount of crop residue produced by today's high-yield crops into the top few inches of soil, creating a zillion tiny dams in the soil that defy wind and water, cutting runoff and soil erosion by 70 percent to 90 percent.
But it depends on chemicals instead of plowing to control weeds. Atrazine is the cheapest of these weedkillers, one of the most effective and one of the most flexible. Atrazine is also eco-friendly. It breaks down in soil within weeks.
Animals readily excrete it, so it doesn't build up in their tissues and affect the natural food chain. At the low levels found in streams, it is no threat to fish. It doesn't volatilize or drift.
It can be combined with dozens of other weedkillers that have different modes of action (or in rotation with them). It is now the only herbicide to which such invasive weeds as cocklebur, pigweed, waterhemp and wild sunflower are not showing resistance.
All this explains why atrazine was used on about two-thirds of all U.S. corn and sorghum acreage last year. Atrazine saved the farmers an average of $ 35 an acre. The rest of us got cheaper food, produced with less erosion. We also got higher yields, saving more room for wildlife somewhere.
Hundreds of university field trials show a 4.3 percent increase in plowed corn with atrazine, and a 5.5 percent gain with conservation tillage.
How safe is atrazine? More than 700 scientific studies, including 100 new ones as part of this EPA review, have discovered no adverse impact on health.
In 1996, a review for the notoriously nervous European Union found "It is expected that the use of atrazine...will not have any harmful effects on human or animal health or any unacceptable effects on the environment."
A 1997 regulatory review in Australia found data showing extra tumors in one species of laboratory rats were not relevant to human health. In 1998 the International Agency for Research on Cancer upgraded its safety rating for atrazine, putting it in the same danger category as tea, rubbing alcohol and talcum powder. But sometimes when there are heavy spring rains in the Corn Belt, it gets in the water.
Can we be sure the drinking water is safe? The answer is "yes." A 150- pound adult could drink 21,000 gallons of water a day with the allowable maximum of three parts per billion atrazine--for 70 years--without getting above the no-effect levels in the rat tests.
To address shorter-term exposure, the EPA has seven-year Health Advisory Levels, set at 200 parts per billion for adults and 50 parts per billion or kids. None of the 21,000 urban water systems in the 21 highest atrazine-using states show atrazine levels above the levels.
The EPA even concedes low doses of atrazine don't mean much. The term they use is "non-linear response." Atrazine levels in Midwest streams actually decreased 60 percent between 1989 and 1998, thanks to conservation tillage, buffer strips along streams and other best- management practices.
What about those tumors in the rats? The federal rat tests are set up to use higher and higher doses until they get some effect or until the rats die.
At ultra-high doses, one strain of lab rat got more tumors. But this strain of rats is so tumor-prone that 80 percent of them get tumors on normal diets.
The International Agency for Research on Cancer and the Australians both say the tumors in Sprague-Dawley rats don't mean risk to humans. It's pretty clear banning atrazine from our farms won't make our kids any safer, will endanger more of our topsoil and might reverse our ability to stop erosion.
In the old days, when Americans understood how their food is produced, that would have been enough to keep it on the market. Today, it might not be. Watch closely.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.