The Air Force Reserve’s 910th Airlift Wing began flying sorties over Harris County and the city of Houston, the 4th-largest city in America. Modified C-130 cargo planes staged missions on Thursday evening from Kelly Air Force Base in San Antonio and conducted aerial bombardment of the entire metropolitan area with a mist of Dibrom, an insecticide also known as Naled, that is intended to suppress the millions upon millions of mosquitoes to pose a human health risk.
In the wake of Hurricane Harvey, thousands of pools of stagnant water were left behind in the wake of flooding, thus offering ideal places for mosquitoes to breed and pupate. Flying into the air, female mosquitoes seek to suck the blood of their victims in order to produce the eggs that will hatch another generation of the disease-bearing pests.
Harris County public health officials called on citizens who might “concerned about the exposure” to remain indoors during the nighttime aerial spraying, which may go into Friday night. The insecticide also poses a risk to bees, which are essential to pollinizing plants and trees, and are thus essential to farmers and gardeners.
The notice declared that Diprom, when applied according to label instructions by a licensed professional, is the “most effective way to rapidly reduce the number of mosquitoes in a large area and does not present a risk to people, pets or other animals.”
“A small amount of insecticide, one to two tablespoons per acre, is dispersed by airplanes equipped with nozzles that create ultra-low volume droplets just the right size to kill mosquitoes. The tiny droplets are calibrated to float in the air for a period of time and kill adult mosquitoes on contact while limiting exposure to other animals and people. Once any remaining droplets settle to the ground, they quickly break down on surfaces, in water and in sunlight,” read the release.
The release also noted that there may be effects for bees. Applications will be done starting around dusk when mosquitoes are most active and after bees have returned to their hives for the night. “The insecticides dissipate and break down quickly in the environment, and when bees emerge in daylight, they are not affected. Although this type of application will not cause a significant exposure for bees, beekeepers may choose to cover their colonies and prevent bees from exiting during treatment,” said the release.
Apart from Harris County and the city of Houston, mosquito-control flights will be conducted by Clarke, Texas’ environmental services contractor, using three twin-engine Beechcraft King Air planes.
Diprom (Naled) is stable in anhydrous condition and degrades in the presence of water and alkali, and produces toxic chloride fumes if exposed to acids or acidic fumes. Diprom is used primarily to control adult mosquitos, but it can also control black flies, and leaf eating insects on a variety of fruits, vegetables, and nuts. It has been used extensively within the United States since the 1950s. Naled was used in New Orleans after Hurricane Katrina and has been used historically in Puerto Rico to control dengue.
The Environmental Protection Agency has determined that exposure levels from eating crops treated with Naled are below the level of concern. But with higher exposures, Diprom can overstimulate the human nervous system causing nausea, dizziness, confusion, and at very high exposures, respiratory paralysis and death. It has the UN hazard classification of 6.1 (inhalation hazard) and is prohibited for use as an insecticide within the EU. Persons who work closely with Diprom or other organophosphate pesticides should undergo regular testing of their cholinesterase levels.