West Nile Virus: Squashing those Myths Regarding Pesticide Spraying

With the mosquito-transmitted <?xml:namespace prefix = st1 ns = “urn:schemas-microsoft-com:office:smarttags” />West Nile virus in the news again, so too are many myths about the virus and the pesticides used to control it.  Want to sort fact from fiction?  Read on.<?xml:namespace prefix = o ns = “urn:schemas-microsoft-com:office:office” />

Myth:  Pesticide spraying is unsafe.

Fact:  The risks associated with pesticide spraying are negligible.  The U.S. Environmental Protection Agency (EPA) sets standards that only allow pesticide exposure levels that are 100 to 1,000 times safer than the level regulators consider safe. 

Agency standards also ensure that pesticide products are safe at what most of us would consider unrealistically high exposure levels.  Consider EPA’s risk assessment for the pesticide malathion—a product that environmentalists claim is one of the most dangerous.  The EPA assessment ensures that it would be safe for a three-year-old toddler to stand for 20 minutes in a cloud of malathion that remains at the full, legally allowed concentration level as released from a fogger truck.  Of course, real life exposures are far lower. 

The simple fact is that malathion is not particularly toxic.  Human enzymes easily break it down and it does not persist in the environment.  It is “less toxic than table salt” Scientist Dr. Keith Solomon of University of Guelph in Ontario, Canada, explained to the Canadian press. 

Myth:  West Nile risks are too trivial to justify pesticide use. 

Fact:  During 2002, West Nile sickened more than 4,000 people and killed 300.  Environmentalists might consider those deaths and illnesses “trivial,” but certainly the families of West Nile’s victims and those who suffered from this terribly painful illness, which, in extreme cases, even leads to brain damage and paralysis, don’t consider it trivial.  It’s true that we should not panic about the West Nile virus.  Fortunately, for most people the risks are relatively low.  But if we can prevent unnecessary deaths with safe use of pesticides, why shouldn’t we?

Myth:  Using pesticides to control West Nile will harm birds.

Fact:  West Nile has killed thousands of birds; spraying harms few.  Science writer Steven Milloy pointed out early during the West Nile debate that the pesticides used in the United States do not pose much of a risk to birds.  For example, he cited a New York State analysis of 3,216 dead birds.  It found that natural diseases and toxins caused the majority of the birds’ deaths (1,263 from West Nile virus and 1,100 from botulinum).  Meanwhile, the study identified 219 pesticide-related bird deaths, 130 intentional poisonings, and 27 poisonings from lawn care products.  We don’t see much documented impact from spraying.

West Nile is taking a heavy toll on birds.  The Centers for Disease Control reports that at least 110 species of birds have suffered from West Nile, including endangered species in the wild and at zoos.  Last fall, the Bird Watchers Digest reported that about 400 great horned owls have been found dead in the Midwest — killed by West Nile.  Researchers estimate that for each dead bird reported, there are probably 100 to 1,000 unreported West Nile bird deaths.  In that case, the Digest points out, there could have been as many as 40,000 to 400,000 West Nile-related great horned owl deaths this year alone.  Also at risk are red tailed hawks, bald eagles, golden eagles, snowy owls, and gyrfalcons.  

Myth:  Spraying doesn't work. 

Fact:  Spraying has proven critical in halting disease outbreaks.  “The primary goal at the onset of mosquito-borne disease epidemics is to eliminate the infective mosquitoes as quickly as possible,” noted researchers at the National Institute of Medicine, an affiliate of the National Academy of Sciences, in a 1992 report.  “Transmission can only be stopped by the effective application of a pesticide that kills adult mosquitoes,” they explained. In fact, pesticides have been used to arrest mosquito-borne disease outbreaks throughout history.  They were used to halt outbreaks during construction of the Panama Canal and to control an outbreak in 2000 in Hawaii.  In 1995 dengue spread to the Mexico-Texas border.  On the Mexican side of the border where pesticides were largely not available, approximately 4,700 individuals contracted dengue.  On the Texas side where public health officials applied pesticides, there were only 29 cases.