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Collateral damage risks shape mosquito wars
By Richard Stenger
(CNN) -- As communities across the nation gear up to wage chemical warfare this summer against the little blood suckers that transmit West Nile virus, some are rethinking the use of conventional weapons of mosquito destruction. Many municipalities, including those in the hard-hit New York City metropolitan region, have resorted to hard-core pesticides to combat adult mosquito populations. Critics contend such spray jobs do more harm than good, subjecting non-target species, including humans, to hazardous chemicals such as potent neurotoxins. "Scourge, Anvil [two common mosquito pesticides], this whole family of chemicals contributes to a wide number of illnesses, including cancers," said William Cooke, a government relations representative with the National Audubon Society's New York state office. Of particular concern are the possible effects on young children and especially fetuses, because many of the synthetic compounds mimic critical hormones in prenatal development, according to Cooke, who helped New York state plan its West Nile strategy. "When pregnant women are exposed to pesticides, depending on the time or stage of pregnancy, even a small exposure can have profound health effects on the [unborn] child," he said. Other veterans of the mosquito wars think that fears of mosquito pesticides are exaggerated. "You can use them safely. In order to use them safely, it must be done at the appropriate times, in appropriate ways," said Dr. Douglas Aspros, president of the board of health of Westchester County in New York, citing weather conditions, time of day and even the size of the spray droplets. The county is just outside New York City, near the heart of the first West Nile virus invasion in 1999. Aspros, a veterinarian, helped formulate Westchester's counter attacks against the mosquito. Aspros acknowledged there are risks. "In general, adulticides [pesticides used on adult mosquitoes] that are most efficacious are the ones that have the most impact on other species, mostly invertebrates," he said. Some municipalities spray with Malathion to control mosquito populations, including Canton City, Ohio, which has done so for decades. "Certainly Malathion-based products are not to be treated lightly. They are effective in controlling a disease that poses a significant public health risk, [but] we try to minimize its use," said Jim Adama, Canton's director of environmental health. "We don't spray for nuisance mosquitoes. They can be a bother, but we only spray when we think there is a risk of disease transmission," he said. Despite such precautions, some chemical critics think that spraying is done more for emotional than rational reasons. Killing adult mosquitoes "is the least effective method for mosquito management," said Jay Feldman, director of the National Coalition Against the Misuse of Pesticides. "There's evidence that it knocks down mosquito populations but there's no evidence that spraying actually is reducing West Nile. The mosquitoes can rebound within the next day," he said. Then why spray? "It gives the people a false sense of security than the problem has been handled," Feldman said. Despite their differences, almost all pro- and anti-sprayers agree: Trying to kill adult mosquitoes should be a last resort, not the first. Killing mosquito larva is more effective and poses fewer environmental risks. In fact, mosquito controllers are dispensing a solution with natural bacteria known as BTI to wipe out immature mosquito populations before they have a chance to grow up, bite humans and transmit West Nile virus and other diseases. "Am I warm and fuzzy about BTI? No, but do I think it's a reasonable part of the strategy? Yes," Cooke said. An even more effective insect cleansing measure relies on education, according to many mosquito experts. Many regional public health authorities now place primary emphasis on persuading residents to eliminate standing water where mosquitoes can breed, including places as small as plastic cup in the back yard. Public awareness campaigns are hardly as dramatic as fleets of trucks that unleash mosquito-killing fogs, but Cooke thinks public health agencies should make West Nile virus decisions based on reason, not emotion. "The truth of the matter is that thousands of people in New York City will die from the common cold. We should keep things in perspective."
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