The Hazards of DEET and Other Dangerous Insect Repellents

 

Many people's response to fears about mosquitoes carrying viruses and the normal annoyance of mosquito bites is to slather on the insect repellent,  especially on their children. The most common choice is a DEET based repellent. But DEET based repellents aren't just hazardous to mosquitoes. From a human health point of view, choosing a botanical-based repellent makes more sense.

 

• DEET is a registered pesticide and a member of the toluene chemical family.

• Toluene is an organic solvent used in rubber and plastic cement and paint removers.

• DEET is absorbed through the skin and passes into the bloodstream and the gut. It is most dangerous when inhaled.

• Exposure to DEET in combination with other pesticides or permethrin, a common mosquito spray and fog ingredient, can lead to motor deficits and learning and memory dysfunction, brain damage and detrimentally affects the central nervous system.

• Ethyl and isopropyl alcohols and freon which are components of  DEET repellents may have significantly greater toxicity than DEET alone.

• Canada has banned 30% or higher DEET concentrations citing health risks to humans.

• Caution label information on DEET products is not shared with the public, especially in regard to fogging.

• Every year, approximately one-third of the U.S. population uses insect repellents containing DEET to ward off mosquitoes and other pests.

• At present, DEET is used in more than 230 products with concentrations up to 100 percent.

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Another toxin used as a mosquito repellent, Permethrin, is described by the Agency for Toxic Substances and Disease Registry (U.S. Department of Health and Human Services) as “manufactured chemicals that are very similar in structure to the [naturally occurring] pyrethrins, but are often more toxic to insects, as well as to mammals, and last longer in the environment” (ATSDR Public Health Statement). Permethrin can be breathed into the lungs, absorbed through the skin or ingested. The most dangerous route is inhalation through the lungs, as this allows the chemical to move directly to target sites (e.g., the brain) without being metabolized by the liver and other organs.

 

Pesticides, including DEET, are not processed out of the body via normal functions. These toxins poison humans and animals directly. Aside from detrimental effects on the human population, toxic fogging and spraying are destroying the eco-structure of the environments that produce our food and hold the key to a vital future. The ‘shotgun’ approach of killing everything in the targeted areas means vital pollinators are killed along with non-virus mosquitoes, a food source for pollen carrying bats and birds. The beginning of the end of the food chain as we know it.

 

From the Duke University Medical Center News Office

 

The Hazards of DEET and Other Dangerous Insect Repellents

 

Many people's solution to fears about mosquitoes carrying viruses and the normal annoyance of mosquito bites is to slather on the insect repellent, especially on their children. The most common choice is a DEET based repellent.

​

But DEET based repellents aren't just hazardous to mosquitoes. From a human health point of view, choosing a botanically based repellent makes more sense.

 

DEET is a registered pesticide. DEET is short for N, Ndiethylmtoluamide (also known as N, Ndiethyl3methylbenzamide). It is a member of the toluene chemical family. Toluene is an organic solvent used in rubber, plastic cement, and paint removers. DEET is absorbed through the skin and passes into the blood. The Medical Sciences Bulletin, published by Pharmaceutical Information Associates Ltd. reports, "Up to 56% of DEET applied topically penetrates intact human skin and 17% is absorbed into the bloodstream." Blood concentrations of about 3 mg per liter have been reported several hours after DEET repellent was applied to the skin in the prescribed fashion. DEET is also absorbed by the gut.

 

The most serious concerns about DEET are its effects on the central nervous system. Dr. Mohammed AbouDonia of Duke University studied lab animals' performance of neurobehavioural tasks requiring muscle coordination. He found that lab animals exposed to the equivalent of average human doses of DEET performed far worse than untreated animals. Abou Donia also found that combined exposure to DEET and permethrin, a mosquito spray ingredient, can lead to motor deficits and learning and memory dysfunction.

 

An emergency medicine bulletin notes that DEET may have significantly greater toxicity when combined with ethyl and isopropyl alcohols and freon which are components of some DEET repellents. In 1998, the US EPA made it illegal for any product containing DEET to make any child safety claims. Products with DEET are required to carry instructions that they should not be used at all for children under 6 months. Additional required warnings state that for children 6 months to 2 years, only concentrations of less than 10% DEET should be used, and only once a day hardly useful for repelling the Zika and other virus-carrying mosquitoes. For children from 2 to 12 years old, only concentrations under 10% should be used, and repellents should not be applied more than 3 times a day. For adults, Health Canada has now banned products with DEET concentrations over 30%, citing health risks and evidence that increasing the percentage does not do much more to repel insects. Health Canada has also banned two in one products which combine sunscreen and DEET, saying they create the potential for people to be exposed to too much DEET. The ban did not take effect until December 2004, so unwary consumers were using high concentrations of DEET without prior warning.

 

Products containing DEET are now required to carry labels which specify:

 

● Do not apply over cuts, wounds, or irritated skin.

● Do not apply to hands or near eyes and mouth of young children.

● Do not allow young children to apply this product.

● After returning indoors, wash treated skin with soap and water.

● Do not use under clothing.

● Do not spray in enclosed areas.

 

Experts recommend that if using DEET, it’s best to wear long sleeves and long pants, when possible, and apply repellent to clothing rather than skin to reduce exposure. They state DEET-based products should only be applied sparingly; saturation does not increase efficiency.  DEET repellents should not be inhaled. Repellent treated clothes should be washed, or kept outside living areas to reduce exposure. Following all these precautions reduces risk, but does not eliminate it. They warn: “ USE CAUTION WHEN USING DEET” clearly on labels, but if used in fogging methods, these warnings are not shared with the public.  We’ve all see images of children running behind mosquito extermination trucks and playing in the toxic fog...

 

Approximately one-third of the U.S. population, annually, applies insect repellents containing DEET to their skin or environment to ward off mosquitoes and other pests. At present, DEET is used in more than 230 products with concentrations up to 100 percent.

 

However, DEET should be used with caution due to its possible damaging effects on brain cells. Studies have shown that DEET causes brain cell death and behavioral changes in rats after frequent and prolonged use. This exposure causes neurons to die in regions of the brain that control muscle movement, learning, memory, and concentration. Rats treated with an average human dose of DEET (40 mg/kg body weight) performed far worse when challenged with physical tasks requiring muscle control, strength and coordination. These findings are consistent with reported human symptoms following DEET's use by the military in the Persian Gulf War.

 

With heavy exposure to DEET and other insecticides, humans may experience memory loss, headache, weakness, fatigue, muscle and joint pain, tremors and shortness of breath. These symptoms may not be evident until months or even years after exposure. The most severe damage occurs when DEET is used concurrently with other insecticides, such as permethrin, for prolonged and frequent periods of time. At this time, there is little information about the short term, singular and occasional use of DEET.  Further government testing of the chemical's safety is necessary. However, frequent and long term use of DEET, especially in combination with other chemicals or medications, could cause brain deficits in vulnerable populations, particularly children. Until further studies are done, it is important to be cautious when using this insecticide. Caution 

 

Be wary of using insect repellant containing DEET on children. Children are more susceptible to subtle brain changes caused by chemicals in their environment because their skin more readily absorbs them. Also, their still-developing nervous systems are more potently affected.

 

For the same reasons:

 

• NEVER use insect repellant containing DEET on infants.

• Be aware that DEET can be present in commonly used preparations like insecticide based lice killing shampoos. Use the same precautions with such preparations as you would with insect repellent.

• Do not combine insecticides with each other or use them while using other medications. Even an over the counter antihistamine could interact with DEET to cause toxic side effects.

• Do not spray your yard for insects and then take medications afterward if there is a possibility that you've inhaled even a small amount of the insecticide that might interact negatively with the medication.

• Be sure to wash your skin thoroughly after spraying your yard. Lawn treatment chemicals are very strong but not formulated to be applied to human skin.

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The Top 10 insect repellents in the market contain DEET and are produced by Big Pharma but do not warn of the dangers of using DEET with other medications including over the counter non-prescription drugs.

 

What is also not publicized is the harmful effects of DEET when used in combination with other medications or chemicals, even those used in conjunction with DEET-baed compounds. Mosquito fogging, for example, creates a deadly formula for, not just the insects being killed, but for those inhaling or eating residual chemicals including DEET on contaminated food surfaces. With such stringent warnings, it begs the question of why this seems to be the only solution until now.  

 

A prudent solution is one that protects people while managing the crisis.