COLUMBIA — “It’s like ‘Silent Spring’ re-visited.” That was the analogy Ken Midkiff, conservation chairman for the Osage Group, used to compare the Columbia/Boone County Health Department’s use of the insecticide “Anvil 2+2” to control mosquito populations to Rachel Carson’s account of pesticide-induced disaster.
The Osage Group is the Missouri branch of the Sierra Club.
The Health Department will be spraying Anvil 2+2 on the MKT Trail and Bear Creek Trail from 4 to 8 a.m. every Friday until the season’s first frost in an effort to combat West Nile Virus, which is commonly carried by mosquitoes. Although the Health Department could not recall any deaths caused by West Nile in Boone County, the U.S. Geological Survey Web site cited Boone County as reporting 9 of Missouri’s 77 nonfatal human cases of West Nile in 2007.
The controversy over the spraying lies in the fact that Anvil 2+2 contains the chemical Sumithrin, an insecticide that kills adult mosquitoes, but can potentially be harmful to other wildlife, according to the Environmental Protection Agency.
Sumithrin is a synthetic pyrethroid, a type of insecticide similar to the natural insecticide derived from the chrysanthemum flower, according to the EPA’s Web site.
“It not only kills mosquitoes, it kills everything else: butterflies, grasshoppers, bees, everything,” Midkiff said. “It is specifically not supposed to be used near water, because it kills aquatic larva.”
Though potentially toxic to these insects, Sumithrin does not pose “unreasonable” risks to humans when applied correctly, according to the EPA’s Web site. However, high doses of Sumithrin can affect the central nervous system, and what constitutes a high dose depends on a person’s medical history, according to the National Pesticide Information Center.
“Typically, Anvil is not toxic to humans or mammals,” Midkiff said. “There are some people who are sensitive to it, primarily those with upper respiratory problems like asthma.”
The Health Department is engaging in measures to ensure the insecticide is properly and safely sprayed, including training those who will be spraying the chemical.
“The training revolves around the guidelines the CDC (Centers for Disease Control and Prevention) sets up for toxicity levels and the guidelines of the product, like specifics on temperature and time of day,” said Deidre Wood, public information specialist for the Health Department.
Since it is also Health Department policy to spray within a half-mile radius of the site where a person is infected with West Nile, it has established a notification system.
“Residents that are interested in being notified can provide their phone number and e-mail address, and prior to the spraying, we will let them know when and where we are spraying,” Wood said.
Wood said the choice of product is a matter of safety, not cost.
“Every year we review our policy, and for the last four or five years, based on scientific research, Anvil 2+2 is the safest pesticide,” she said. “It is not the least expensive, but the safest.”
Although the Health Department has been spraying for the past few years, Boone County has seen an increase in the number of human West Nile infections from 1 person in 2005 to 9 people in 2007.
“Spraying simply does not work; there are lots of other measures that control mosquito populations,” Midkiff said.
For those who are early morning walkers and joggers, the Health Department maintains that it is safe to use the trails during spraying.
“When you weigh the risk of the pesticide against the risk of West Nile, the risk of West Nile is much greater,” Wood said.
For more information on this insecticide and its possible effects, contact the National Pesticide Information Center at 800-858-7378, or the Columbia/Boone County Health Department.