Nearly all conventional insect repellents used today contain DEET, a chemical that was developed during the Second World War, used by the U.S. Army in jungle warfare. In 1957, it was registered as a pesticide where it became available to consumers and has been used ever since.
DEET works by confusing odor receptors on mosquitoes’ antennae. A blood seeking mosquito targets you by detecting three things: your body heat, the carbon dioxide you exhale, and various chemicals that the body excretes through your skin, the most important of which is lactic acid. Certain receptors on a female mosquitoes antennae are tuned into this lactic acid and nothing else. DEET turns off the receptors so that the nerves connected to them are rendered useless. Shutting down these lactic acid receptors with DEET blinds the female mosquito to a human’s presence, despite body heat, carbon dioxide and chemicals on the skin.
DEET has become the most well-known mosquito repellent in the world, and today it can be found in many forms, including sprays, towelettes, roll-ons, liquids, lotions and even wristbands. The majority of formulas contain between 10 and 30 percent DEET, though you can find products used for direct skin application with anywhere from 4 to 100 percent DEET.
The EPA estimated in 1990 that about 30 percent of Americans used DEET every year – a decade later, some 5 to 7 million pounds of the stuff was used. Those figures are believed to have remained about the same today, and while it’s considered the ultimate mosquito repellent by most, that’s certainly not true for all. A study conducted in the late 1980s on employees of Everglades National Park looked into the effects of DEET found that a full one-quarter of the subjects studied experienced negative health effects that were attributed to exposure to the chemical. Effects included rashes, skin irritation, numb or burning lips, nausea, headaches, dizziness, and difficulty concentrating.
While manufacturers, marketers and other DEET proponents insist that it’s safe and highly effective, the facts say something different.
Here’s a closer look at why you should NEVER ever use DEET on your skin.
1. It’s becoming less effective
DEET isn’t as effective as it used to be as mosquitoes have developed resistance to it. A landmark study recently revealed that while the insects are initially repelled by it, they ignore it if they’re exposed to it again. Researchers tested the response to DEET on Aedes aegypti mosquitoes, which are notorious for biting during the day and are capable of transmitting dengue fever and yellow fever viruses.
Earlier research had shown how some mosquitoes were genetically immune to the substance, but this study conducted by scientists from the London School of Hygiene and Tropical Medicine found that even those that would usually be deterred developed a resistance.
That means that using DEET not only puts you at risk of numerous possible side effects, but it may not work at all.
2. Fatalities related to DEET
From 1961 to 2002, the Agency for Toxic Substances and Disease Registry reported eight deaths related to DEET exposure. While three of the fatalities resulted from deliberate ingestion, five occurred following DEET exposure to the skin in both adults and children.
3. Serious harm to children
In children, the most frequently reported symptoms of DEET toxicity reported to poison control centers including headaches, tremors, lethargy, seizures, involuntary movements, and convulsions. Experts also say that frequent and long-term use of this chemical, especially in combination with other chemicals or medications, could cause brain deficits in vulnerable populations, especially children.
Just about every expert agrees that children, as well as those with weakened immunity and seniors, should be extra cautious and that it should never be used on infants younger than two months of age. Canada’s federal health department goes further, stating that no child under six months old should be using DEET, and that those who are six months through 12 years old should avoid products that contain more than 10 percent DEET, though that certainly should make one take note as to how potentially dangerous this substance can be.
In fact, there have been 14 cases reported involving children who suffered encephalopathy, including seizures, after using DEET on their skin. All but one was under eight years old – three children died, though the others eventually fully recovered. Proponents of DEET say that number is too minute to worry about, considering that was 14 cases since the product went onto store shelves in 1957, however, if you’re a parent, NO number of serious injuries or deaths should really be acceptable, in our opinion.
4. Negative effects on pets
DEET is toxic when ingested at high doses, and dogs and cats may lick it off and ingest it, potentially resulting in a toxicity. The ASPCA states that the chemical should never be used on pets as it can lead to significant negative effects – the higher the concentration of DEET in a product, the higher at risk your pet is. If DEET gets into your animal’s eyes, it can lead to conjunctivitis, scleritis, blepharospasm, epiphora, lethargy/depression, uveitis and corneal ulceration.
If your pet inhales it, it can cause airway inflammation and dyspnea, which could require professional treatment, including bronchodilators, steroids, and oxygen. Gastrointestinal upset is also common – other possible harmful effects include tremors, seizures, disorientation, and ataxia.
5. Common unwanted effects of DEET
There is a number of minor, but common, unwanted effects of DEET. As it can be easy for the chemical to get into the eyes while spraying, or by touching sprayed skin with the fingers and then touching the eyes, many users have experienced eye irritation, pain, and watery eyes. When the chemical is left on the skin for too long, it can lead to a rash, redness, swelling or other types of irritation.
6. A long list of serious possible effects of DEET
Not only do users of DEET commonly experience minor side effects, but there has been a long list of serious side effects associated with DEET, some of which have been demonstrated in studies.
DNA damage. DEET has been tested on animals and on human cells in the laboratory, and it’s been shown to cause damage to DNA. A study out of North Carolina’s Duke University found that the results indicated that “dermal administration of DEET could generate free radical species hence cause DNA oxidative damage in rats.” Pharmacologist Mohamed Abou-Donia of Duke University noted that the researchers found that frequent and prolonged DEET exposure led to diffuse brain cell death and behavioral changes. The experts concluded that humans should stay away from products containing it.
Negative impact on the nervous system. A 2008 study out of the Institute of Development Research in France, published in the journal BMC Biology, discovered that DEET can interfere with the activity of enzymes that are crucial in order for the nervous system to function like it should. The researchers found that DEET blocked the enzyme cholinesterase, which is required for transmitting messages from the brain to the muscles in insects. They noted that DEET may also affect the nervous systems of mammals and that more research was needed, but it certainly causes for concern. The study also showed that chemicals that interfere with the action of cholinesterase can cause excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death.
- Muscle and joint pain
- Memory loss
- Shortness of breath
- Burning lips
- Temporary numbness
- Difficulty concentrating
These symptoms are sometimes not evident until months or even years after exposure.
7. Environmental effects
DEET is also a persistent environmental contaminant that breaks down slowly in soil. A recent U.S. Geological Survey report on water contaminants listed DEET as one of the substances most frequently found in America’s streams. The U.S. EPA regards DEET as “slightly toxic” to birds, fish, and aquatic invertebrates and, given its frequency in our nation’s waterways, that should certainly give one pause. Scientists have also stated that DEET doesn’t dissolve, or mix well in water.
When DEET is sprayed or evaporates, it goes into the air as a vapor or mist, and then it starts to break down in the atmosphere. In high concentrations, it can be extremely toxic not only to insects but to fish also.
What to use instead:
Given all of this, it’s easy to see why you should never, ever put DEET on your skin, or anyone else’s skin for that matter. But what do you do to keep mosquitos away? After all, they come with a high risk too, including some rather serious diseases, like malaria, West Nile virus and encephalitis.
The good news is that there are a number of effective natural alternatives that don’t come with long list of side effects.
Lemon eucalyptus oil
The Centers for Disease Control recommends lemon eucalyptus oil and states that it offers protection that is similar to low concentration DEET products. A 40 percent or higher concentration is recommended for fighting off mosquitoes as well as ticks. You can buy pure lemon eucalyptus oil from Plant Therapy here.
If you’ve ever sat around a campfire, you’ve probably noticed that mosquitoes seem to stay away, even from those they’re most attracted to. It really does work because they don’t like being around smoke. You can use candles, or, simply enjoy sitting around the fire on a pleasant summer night.
Eat more garlic
You’ve probably heard that garlic repels vampires, and while that may all be based in fantasy, what is true is that this pungent herb can keep mosquitoes away. Although there hasn’t been much research conducted to back up that claim, many people swear that it works. Plus, garlic is filled with powerful antioxidants and is well known to help fight off infection so you’ll be getting a lot more out of it than just a natural mosquito repellent. If you’re worried about the smell, try chewing a sprig of fresh parsley after eating it.
Peppermint essential oil
Peppermint smells infinitely better than that horrible DEET chemical smell, plus it acts as a natural insecticide to repel mosquitoes, and it’s highly effective. Research published in the Malaria Journal in March of 2011, revealed the reason why. The experts discovered that it offered repellent action when applied to exposed body parts, while also demonstrating larvicidal and mosquito repellent action. Mosquito larvae were killed 24 hours after exposure to a solution of pure peppermint oil and water. If you can grow your own, you’ll have immediate access to your own natural repellent – all you’ll have to do is step outside and crush a few of the leaves on the plant to release the scent and oils.
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