To keep naled airborne where it would be most effective, the agent is sprayed in very fine aerosol droplets — about two tablespoons can be dispersed to cover an area the equivalent of two football fields, a local CBS affiliate reported.
If a ‘far greater’ amount of naled were employed, according to the Florida Department of Health, ‘it could cause a person to salivate more, feel numbness, headaches, dizziness, tremors, nausea, abdominal cramps, sweating, blurred vision, difficulty breathing and a slowed heartbeat.’
Though fear of the zika virus — which may cause microcephaly, or reduced head size, in babies born to infected mothers — and lack of federal funding for a vaccine have left Florida officials desperate for options, the use of naled has stoked controversy.
Beside possible adverse health effects, experts argue whether or not spraying campaigns are even effective in diminishing mosquito populations, particularly because the insects can live indoors or in small, enclosed areas where spray wouldn’t necessarily reach.
On Wednesday, airplanes were set to begin spraying naled aerosol over an approximately 10-square-mile section of Miami, centered over the neighborhood of Wynwood, where zika has reportedly been spreading — but wind conditions forced a delay.
“Successful spraying against Aedes depends on too many factors. Do people have their windows open? What rate is the wind speed? What is the weather?” said Duane Gubler, former head of the Centers for Disease Control and Prevention’s dengue branch. “Spraying doesn’t kill larvae, and naled isn’t a residual insecticide. You’d have to spray weekly to make an impact.”
As the Miami Herald reported, aerial spraying is particularly ineffective in eradicating the exact species of mosquito responsible for transmitting the zika virus because it lives and breeds near or in covered structures, and stays near humans. But Miami-Dade Mayor Carlos Gimenez agreed to the procedure, anyway, in hopes that killing even part of the Aedes aegypti population would reduce potential health consequences for residents — besides the reported risk of microcephaly, zika is known to cause the autoimmune disorder, Guillain-Barré, which can lead to paralysis.
“Some say it’s effective. Some say it’s not that effective,” Gimenez said. “But it’s been recommended by the state and federal government and we’re going to do it.
“If it has a success rate of 10, 20, 30 percent, then that’s 30 percent more than what we had before.”
According to toxicology encyclopedia, Toxipedia’s entry for naled:
“Nearly all of the naled used is applied aerially and drift from the application is considered a problem because naled is also toxic to beneficial insects (#Cox, 2002). Contamination has been found as far away as 750 meters from the site of application in a University of Florida study which led to the suggestion that no-spray buffer zones be established to greater than 750 meters from ‘economically sensitive areas’ (#Cox, 2002). Unfortunately the most toxic route of exposure is inhalation and the most common application is as a mist making inhalation the most likely route as well (#ATSDR, 2007).”
Toxipedia also notes the EPA, itself, classified a component of naled as a “possible carcinogen,” because mice developed lung tumors.
Following protests by residents concerned for their health and potential effects on wildlife — and despite the CDC having controversially sent advanced supply to officials, which was subsequently returned — Puerto Rico opted to spray an organic larvicide known as Bti.
Nevertheless, residents, their pets, and wildlife in areas of Miami are now being subjected to an ongoing naled spraying campaign — for which officials have not yet provided an end date, much less target goal for eradication of the virus-carrying mosquito population.