HOUSTON -- In a move to stop a deadly outbreak of the West Nile virus carried by mosquitoes, aerial pesticide spraying was set to begin Thursday night over wide swaths of Dallas County, prompting debate among some residents about safety.
The decision to arm small planes with a pesticide that officials said posed no health risks came as Texas grappled with 465 West Nile infections and 17 deaths. The outbreak led officials in Dallas city and county, the hardest hit region in the state, to recently declare a state of emergency.
“Aerial spraying is considered the most effective and safest way to kill adult mosquitoes in heavily populated areas,” Dallas Mayor Mike Rawlings said at a Thursday briefing in front of two planes expected to do the spraying.
The county’s first spraying in more than 45 years was to begin at nightfall, when mosquitoes are most active, and continue through the night. Planes were targeting 49,000 acres north of Interstate 30.
“There’s a lot of sentiment that people don’t want this, and there’s a fear of the unknown,” Rawlings said, but added, “you have the science, the CDC and the EPA, and all of these cities across the United States that say this is OK.”
Synthetic pyrethenoids such as Duet, the pesticide that Dallas selected, pose no health risk to humans or pets, according to the Environmental Protection Agency and the Centers for Disease Control and Prevention.
Pyrethenoid insecticides are commonly used in government-run spraying programs and scores of commercial and home-use products. They are the synthetic version of pyrethrins, insecticides made from chrysanthemums, and have become a popular alternative to the more toxic organophosphates that replaced organochlorine pesticides such as DDT banned in the 1970s.
A spokeswoman for Clarke, the Roselle, Ill., company handling the Dallas spraying, said it’s the best way to flush out the local culex mosquito. The company had an 88% kill rate during recent spraying after a flood in Kentucky, she said.
Aerial spraying opponents contacted Dallas County Judge Clay Jenkins on Thursday to say they planned to request a restraining order to block all aerial and ground spraying.
However, Jenkins defended the spraying and said state emergency managers and lawyers assured him that local state of emergency declarations trump any injunction.
“Dallas is the linchpin of this — Dallas has a tremendously high infection rate and has made the right decision,” Jenkins said.
The city charter allows Rawlings to request aerial spraying, but any application after one week must be approved by the city council. Some council members and concerned residents said they worried the spraying might harm residents and animals and ultimately prove ineffective.
“It’s not that I’m against pesticides — I’m against pesticides that don’t work,” said Howard Garrett, a Dallas-based arborist, landscape architect and radio host known as the "Dirt Doctor” who spoke out against spraying at this week’s Dallas city council meeting. “They’re spending a half a million dollars on this stuff and they’re not going to control anything.”
Instead of aerial spraying, Garrett said, Dallas officials should concentrate on targeting mosquito eggs and larvae with organic pesticides on the ground.
Maria Arita, a Dallas County spokeswoman, said the amount of pesticide sprayed would be minimal, about two tablespoons, or an ounce, per acre. “People have less insecticide to be concerned about than in the flea collar on their dog,” Arita said.
“We are standing behind the science. We’ve got reams and reams of data we have pored over coming out of other municipalities including Sacramento” showing aerial spraying is safe, she said. "They had zero human consequences, no fish kills, zero wildlife consequences.” Texas officials contacted counterparts in Sacramento earlier this month for advice about aerial spraying.
Sacramento County began such spraying in urban areas seven years ago after 103 people became infected with West Nile, according to David Brown, general manager of the Sacramento-Yolo County Mosquito and Vector Control.
After the outbreak, the state issued a report that aerial spraying was safe and effective, and his office has seen no major impacts on the health of residents, animals or “beneficial” insects such as honey bees, he said.
“We think the Dallas officials are doing the right thing, trying to intervene,” Brown said, adding that given the scope of local West Nile infections, “Using an aircraft is often the only effective, viable option.”