Editor’s Note: This Classic Answer Man column is from June 26, 2013.
Dear Answer Man, how safe is the mosquito spraying that goes on in some area towns? I just assume it’s not safe.
Public officials can say all they want about how harmless it is to humans and pets — I take nothing for granted about this type of thing.
They’ll be fogging in Austin on Friday, weather permitting. A news release from the city engineer’s office says, “This will be a ground application and spraying will start after 8 p.m. and continue throughout the night. The chemical that is used will not affect humans, animals or plants. The spray kills the adult mosquito.”
I asked for more details from City Engineer Steven Lang and he sent this note: “The spray will be a fog application disbursed from trucks that drive around the community. The crews monitor the wind direction and spray in a manner that will drift across designated areas. They will not drive down every street, as they use the wind direction to move the spray fog. It is a contract killer and will only kill adult mosquitoes and black flies. Hatchlings could hatch the next day and the spray fog would have no residual effect on them.”
But he said on Tuesday he didn’t know the precise name of the chemical that will be used, which is a problem for people like me who like to do a little research. He said the city budgets for three applications — one before the Fourth of July, one after and one as needed.
There are tradeoffs in everything, of course, and public health officials say it’s important to “control” mosquitoes for health reasons, including West Nile virus and encephalitis. I get that. I’d just like to know with as much precision and transparency as possible what’s being sprayed all over town to control them.
The Twin Cities has a Metropolitan Mosquito Control District to deal with skeeters, and when they spray for adult mosquitoes, they “use either permethrin – applied during the day by backpack to the edge of wooded areas as a barrier treatment; or a quick acting cold fog such as resmethrin or sumithrin, applied when mosquitoes are most active, around dusk or dawn by truck,” according to their public information. “When applied correctly, these products pose no measurable risk to human health or the environment.”
I’ll add links to this column online so you can read more about all these chemicals.
Permethrin is a “restricted use pesticide for crop and wide area applications (i.e., nurseries, sod farms) due to high toxicity to aquatic organisms, except for wide area mosquito adulticide use,” according to the U.S. Environmental Protection Agency. “It is a general use pesticide for residential and industrial applications.” It’s also classified by EPA as “likely to be carcinogenic to humans by the oral route.”
Resmethrin is “moderately toxic by ingestion and slightly toxic through the skin” for humans, but is highly toxic to fish and bees, especially, according to pesticide information service from Cornell University and other state and federal sources.
Regarding Sumithrin, the New York State Health website on mosquito control says “short-term exposures to very high levels of pyrethroid pesticides similar to sumithrin can affect the nervous system, causing such effects as loss of coordination, tremors or tingling and numbness in areas of skin contact. Short-term exposure to high levels of petroleum solvents can cause irritation of the eye, skin, nose, throat or lung. Vomiting or central nervous system depression may occur if very high levels of petroleum solvents are ingested. There are no studies examining whether the use of Anvil to control mosquitoes has caused any long-term health effects in humans.”
So, there are a lot of unknowns. What can you do to minimize your risk? Here are some tips from various health officials:
Stay inside during spraying and for at least a half-hour after.
Close your windows and turn off the AC to keep the spray from circulating inside.
Children and pregnant women, especially, should avoid exposure.
Pets, too — and bring in their food dishes if they’re outside.
If you do come into “direct contact” with the spray, wash it off and also plan to wash those clothes separately from others.
If you have any veggies in the garden that are almost ready to eat — not too likely this year — bring them in early.
Cover your swingset and picnic table before spraying, or wash them off after.
You’re not being ridiculous or paranoid to take this type of thing seriously. It’s just common sense.