The writer is a senior economist at the Stockholm Environment Institute's U.S. Center at Tufts University. He is the author of the study, “The Economics of Atrazine.”
In nursery rhymes, a kingdom can be lost for want of a nail. In reality, could the Corn Belt be lost for want of a weed killer?
The debate about atrazine is heating up again, as the Environmental Protection Agency has agreed to reconsider the Bush administration's blanket approval of this controversial chemical. The defenders of atrazine are claiming it is the indispensable nail that makes it possible to grow corn in the Midwest.
But we're not living in a nursery rhyme. My research on the economics of atrazine shows that its benefits are greatly exaggerated. Corn yields and farm incomes would barely be affected by switching from atrazine to the next-best alternatives.
Why is atrazine controversial? Everyone agrees that it kills weeds. But there are two rival stories about its health risks.
Industry-sponsored research and agribusiness lobbies say that atrazine is completely safe and has been used for decades without harm to humans. Independent university researchers and peer-reviewed scientific literature say that it is a powerful endocrine disrupter, which makes male frogs into hermaphrodites at very low concentrations and causes neural damage and cancer in laboratory animals.
How great are the economic benefits of using atrazine? Several studies have estimated that atrazine boosts average corn yields by 6 percent or less.
A database of field trials, maintained by consultant Richard Fawcett and relied on by atrazine supporters, shows that it increases corn yields by an average of 3 percent to 4 percent. The most comprehensive national study, by the U.S. Department of Agriculture, estimated that bans on atrazine would lower corn yields by 1.2 percent.
In fact, atrazine might have no effect at all on corn yields!
Two corn-growing countries, Germany and Italy, both banned atrazine in 1991. I compared the trends in corn yields per acre, and in corn acreage, in the United States, Germany, and Italy for 1981-2001. Both Germany and Italy did as well or better in corn production after banning atrazine as they did in the 10 years before the ban. And both countries did as well or better than the United States after banning atrazine.
This isn't what you'll hear from the defenders of atrazine. Three years ago, Donald Coursey, a University of Chicago economist with no previous publications on agriculture or chemical hazards, did a study for Syngenta claiming that the loss of atrazine would devastate the Illinois economy.
Coursey assumed that banning atrazine would lower corn yields by about 6 percent. But then he double-counted the impact of a ban by adding his own estimates of yield losses to estimates of dollar losses from other studies; those dollar losses were based on yield loss calculations much like his own.
As a result, he projected economic impacts roughly double those of other studies that assumed similar yield losses (but only counted them once). Recent news reports suggest that Coursey has done a new study, but according to the press releases, he has just translated the exaggerated dollar losses from his older study into equally exaggerated job losses.
According to Coursey's data, substitution of other herbicides for atrazine would raise the cost of corn by 3 cents per bushel. According to the rest of the evidence, this would have little or no effect on corn yields.
If atrazine were crucial to corn yields, there might be a difficult decision to make about the economic benefits versus the health and environmental hazards of using it. But since the economic benefits are vanishingly small and the hazards could be very serious, the decision doesn't seem difficult at all.
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