West Nile Epidemic in Ada County, Idaho

Aerial Mosquito Spraying in Boise- Practical or Political?

By Contributing Writer, 8-20-06

By Nathaniel Hoffman

Boise residents, given 104 hours notice of an air assault on mosquitoes, are scrambling to harvest or cover their crops, pick up their kids’ outdoor toys and get out of town.

On Monday and Tuesday night, two small airplanes will drop a brand name nerve agent over large swaths of the county, mainly in residential areas.

County officials say the plan will save people from the West Nile virus, but a researcher at Cornell University who has studied the disease says aerial spraying is a wholly political decision.

The high number of West Nile virus infections in Idaho – the highest in the nation this summer – is a concern, said David Pimentel, editor of the Encyclopedia of Pest Management.

“But then we ought to do it in a sound scientific manner and not just spray for political reasons,” Pimentel said.

“The politicians normally react that way to quiet the public.”

On August 10, on the recommendation of county mosquito abatement director Brian Wilbur, Ada County commissioners declared a West Nile epidemic.

No members of the public were present at the last minute emergency declaration meeting, county spokesman Rich Wright said.

A week later commissioners signed a contract to spray Dibrom, commonly known as Naled, over about 50,000 acres of the county on two successive days.

Two women who declined to give their names spoke against the plan at the meeting, Wright said.

The county held a press conference Thursday afternoon and scheduled spraying for Monday and Tuesday nights.

Mary Rohlfing at the pesticide-free Morning Owl Farm returned to town Friday and did not have time to contact the county about the spraying.

“It seems absurd that there was no opportunity for input,” Rohlfing said Sunday, taking a break from harvesting. She is trying to pick the ripe crops for her customers before the spraying, but still hopes to have the planes skip her acreage off Warm Springs Road.

“Would it have mattered if they said, ‘this is our plan in two weeks. In the meantime lather up on the DEET?’”

The planes will not release the chemical over the Boise zoo or over four registered organic farms, but Rohlfing is not registered with the county as an organic farm.

Wilbur said the county has been fighting West Nile with other tools all season. The district monitors and sprays mosquito larvae at about 1,800 sites. And with more than 80 complaints a day about mosquitoes it sends out trucks to spray permethrin, a naturally-occurring chemical linked to breast cancer.

Under numerous state and national West Nile plans, Ada County’s “multiple human cases” – 68 as of Thursday - make it a Category 5 emergency situation. That calls for a stepped up attack on the mosquitoes that carry the virus, mainly of the genus Culex, Wilbur said.

“The residents are telling us ‘get out here and fog,’” Wilbur said. “We’ve done that and our Culex populations are still climbing.”

Wilbur said the Dibrom spray that the planes will apply at very low doses is expected to cut down the Culex adult mosquito population by 90 percent, based on information from the Vector Disease Control, the Florida-based company contracted for the job.

Such an efficient kill is possible on a golf course, but unlikely in treed or residential areas, Pimental said, referring to his recent study and another from Harvard.

Even worse, Pimentel added is that 75 to 90 percent of the pesticide drifts off into the environment at large potentially affecting people pets and beneficial organisms, like ones that eat mosquitoes.

“This is an environmental hazard that exists,” he said.

County officials have given conflicting messages about the hazards of the spray. Wilbur has said repeatedly that it is fine to leave windows open and air conditioning on and that he has no concerns about any health risks to people or to beneficial insects.

“What we go by is the chemical label and the chemical label does not give us any indication at all, it gives us no reservations at all,” Wilbur said.

State Health and Welfare spokesman Tom Shanahan said the aerial spraying is an approved public health measure to control the spread of West Nile, but that if people are concerned they should close windows and stay inside.

Though Naled is approved by the Environmental Protection Agency for low dose aerial application to control mosquitoes, it has been found to make people and fish sick and is an extremely toxic chemical.

A preliminary EPA review of Naled in 1995 found “significant potential to cause chronic effects in mammals, acute and chronic effects in aquatic organisms, and acute hazard to honey bees.”

And a 2003 Centers for Disease Control report found that while the risk of acute illness from properly applied insecticides is low, 133 people were possibly sickened by them in nine states between 1999 and 2002.

A growing list of municipalities are banning or curbing the use of aerial spraying for mosquitoes.

“If they are going to use this they have to do it responsibly and not start blanketing our community within a couple of days,” said Elizabeth Congdon, who lives and works in Boise’s North End with her husband, 8-year-old daughter and pets.

The Congdons plan to leave town during the spraying.

“We’re not trying to be histrionic about it and we’re not trying to minimize the problem of West Nile,” she said. “There’s no pesticide that’s going to be 100 percent safe for creatures and people.”

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