Anti-Pesticide Claims Warrant Skepticism

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As public health officials consider spraying pesticides to control the mosquito-borne West Nile virus, anti-pesticide activists claim that spraying devastate birds and other wildlife. But such claims should be viewed with skepticism.

It seems that West Nile virus and other natural factors may pose much greater threats than spraying. The Centers for Disease Control reports that West Nile has killed birds from at least 138 bird species, including some endangered species. In the Midwest last year, 400 great horned owls were found dead from West Nile. Researchers estimate that for each dead bird reported, there are probably 100 to 1,000 unreported cases, which means there could have been as many as 40,000 to 400,000 great horned owl deaths from West Nile last year alone.


Still, environmentalists claim that there is clear evidence that the pesticides are a far greater risk to birds. They claimed back in 2001 that data from New York State (NYS) showed that more birds were dying from “toxins” like pesticides than from West Nile. But science writer Steven Milloy obtained NYS data in 2001 that showed the toxins that affected the birds in this sample were mostly naturally occurring.

According to Milloy, the New York State analysis of 3,216 dead birds found that natural diseases and toxins caused the majority of the bird deaths (1,263 from West Nile virus and 1,100 from botulinum). Meanwhile, the data included 219 pesticide-related bird deaths, of which 30 were from intentional poisonings of pest birds and 100 were from illegal use of pesticides for intentional killing of birds. Twenty-seven bird deaths resulted from lawn care products.

More recently, the Audubon Society says that data collected by New York State in subsequent years from a sample of 80,000 dead birds shows that pesticides, primarily lawn products, are killing the majority of birds. Yet NYS has not released the data in any report, nor has anything been peer reviewed. This “majority” of such toxin-related deaths may again include natural toxins, like botulinum, and it is not clear that the data they obtained was for all 80,000 birds.

Unfortunately, the data on bird deaths from all sources isn’t particularly clear, despite Audubon’s suggestions to the contrary. The researcher who conducts NYS bird pathology (who reportedly gave the data to the Audubon Society) has told the press that he doubts spraying will do much harm to birds — at least not as much as does the virus. The U.S. Environmental Protection Agency asserts that spraying poses a negligible risk to birds.

In addition to birds, activists also say that aquatic life is at grave risk. When a massive lobster die-off occurred in Long Island Sound in 1999, environmentalists and lobstermen claimed that New York City’s malathion spraying had reached the waters and caused the die-off.

Yet the die off began before New York State sprayed, and several years of federally funded research hasn’t found a definitive link to the pesticides. The University of Connecticut’s Dr. Richard French explained in a 2001 report: “There is no quantitative evidence of pesticide toxicity