UPDATE: West Nile Virus vs. Pyrethroid Exposure

You can read Wellness and Equality‘s original post last week about Dallas’ efforts to combat West Nile Virus here: “Pros & Cons: West Nile Virus vs. Pyrethroid Exposure”

What’s really in the air in Dallas?

Public anxiety over the aerial spraying of insecticide in Dallas to control mosquitos has raised questions about safety, but few concrete answers.  Instead of taking the manufacturer’s word that Duet Dual-Action Adulticide is safe, the public should be provided independent studies about the contents of the product itself.  Clarke Mosquito Control, the manufacturer, has a financial incentive to stand behind their polished marketing materials and safety assurances, but what’s really behind the green label?

The insecticide is a cocktail of three active ingredients: sumithrin, prallethrin, and piperonyl butoxide.

  •  Piperonyl butoxide is listed third on the Duet Dual-Action Adulticide label, but it may be the most harmful.

What are its common uses?  Piperonyl butoxide (PBO) is not actually an insecticide itself — instead, it increases the potency of the two other chemicals.  What this means is that although the label may show “safe” levels of other chemicals, the potency of those chemicals is actually much, much stronger in practice.

How does it work? PBO is a synergist which increases the toxicity of other chemicals: the more piperonyl butoxide in a product, the more powerful the other chemicals. The presence of piperonyl butoxide makes determining true levels of the other chemicals a murkier process.  Some products contain up to ten times more PBO than insecticides themselves. Of course, manufacturers often downplay the inclusion of PBO.

Is it safe?  Piperonyl butoxide is especially harmful to the developing fetal brain. A 2011 study, conducted at Columbia University and published in the journal Pediatrics, found that infants whose mothers had been exposed to low levels of piperonyl butoxide (PBO) during their third trimester showed delayed mental development by the age of three.  You can read the full study here, or a summary here.  A more recent study by Duke University study confirmed these findings and found that the chemical also interferes with signaling in the human brain. The Duke study, which was published in the journal Toxicological Sciences, found that PBO’s disruption of the critical neurological pathway “may be the molecular basis for profound developmental defects in children exposed in utero to PBO.”

  • Sumithrin: Sumithrin, also called phenothrin, is a synthetic pyrethroid.
  • Prallethrin: Prallethrin is also a synthetic pyrethroid.

What are their common uses?  Sumethrin and prallethrin are commonly used as insecticides to kill household insects, including mosquitoes.  They appear in products such as Raid, Enforcer, Ortho, and Anvil.  One of the most common uses of sumithrin is in flea and tick products for pets.  It’s also an ingredient in head lice products for humans.

How do they work?  As pyrethroids, sumethrin and prallethrin cause nerve paralysis in the insect, effectively shutting down the insect’s functioning.

Are they safe?  Sumethrin is a known endocrine disruptor, neurotoxin, and likely carcinogen. In 2005, the Environmental Protection Agency (EPA) revoked permission to use sumethrin in flea and tick products after thousands of cats and kittens were poisoned and killed by its use.  Few long-term studies on the safety of pyrethroid insecticides exist because they have only been in widespread use since after 2000 when the the EPA phased out the use of chlorpyrifos and other organophosphorus insecticides due to risks to child neurodevelopment.  Out with the bad, in the worse?

Dallas is not alone.  Almost all cities across the United States use insecticides to control mosquitoes and other summertime insects.  The New York Department of Public Health and Mental Hygiene advises the public — especially anyone with asthma or respiratory sensitivity — to remain indoors during spraying, close vents and turn off fans and air conditioners to reduce indoor exposure, remove children’s toys and outdoor furniture from outside and/or wash them before using again, wash all produce, and wash skin and hair if exposed to the pesticide.  These are fine recommendations, but my concern is that most people are unaware of the spraying schedules in their cities.

Do you know if and when your city sprays these toxic chemicals?

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1 thought on “UPDATE: West Nile Virus vs. Pyrethroid Exposure”

  1. The broadcast news in Dallas has been totally inept in reporting the scheduled times for the sprays. In fact, I sent a text message to 48411 (according to the instructions on WFAA channel 8 news at 7:31 pm requesting this info only to be told they would send news shortly after waiting about 2 hours, I sent another text message at 9:30 pm only to get the same message. A short time later I finally got a response that spraying would start at 9 pm. But I and my family heard the planes 8:30/8:45 pm. After a search online, I found one article stating that spraying in Dallas county began at 8:30 pm. Are they serious? I think they’re using us as guinea pigs and don’t care what happens to us.

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