Ah, summer. It’s the time to head out to the great outdoors. Fishing, camping, hiking, and backyard get-togethers are among the favorite activities this time of year.
If only the bugs would disappear.
Unfortunately, they won’t. Anytime we’re outdoors, we can expect to come into contact with insects. They’re not only irritating, but potentially dangerous to our health. Mosquitoes can carry West Nile disease, ticks are infamous for causing Lyme disease and Rocky Mountain spotted fever, and other insect bites can result in serious and potentially deadly allergic reactions.
Keeping them away is therefore a really good idea if you want to protect yourself and your family. The common insect repellant many of us grew up with, though—and which is still sold on shelves today—carries some serious risks of its own.
If you’ve used “Off!” or other similar brands lately, you’ve likely been exposed to DEET, the active ingredient in many insect repellant products. It’s there for a reason—it works. When applied to the skin or clothing, it effectively repels mosquitoes, ticks, fleas, chiggers, leeches, and other biting insects.
Dig a little deeper into this ingredient, though, and you find some concerning evidence about its potential health risks—particularly for children.
We have other, safer options, including citronella, cedar, and other oils. Here’s why we think you’d be better off using these most of the time.
The History of DEET
Chemically called “diethyltoluamide,” DEET is prepared by converting 3-methylbenzoic acid to acyl chloride and allowing it to react with diethylamine. It was developed for Army soldiers going through jungle warfare in WWII. Before that, farmers used it as a pesticide on fields. By the year 1957, manufacturers were selling insect repellants containing DEET to the general public.
The repellant is believed to work because insects don’t like the smell of it, and also because it may “blind” them to scents produced by human sweat and breath that typically are attractive to pests. However it works, studies have shown that it definitely does, repelling insects for up to 12 hours when applied at 100 percent.
Later studies, however, reported some concern about the chemical and how it may affect skin and internal health. Manufacturers now advise users to avoid applying the product to broken or damaged skin, or under clothing, and to wash it off after it’s no longer needed.
How DEET May Affect Skin and Overall Health
A 2014 report by the Environmental Protection Agency (EPA) stated that DEET “continues to meet safety standards based on current scientific knowledge.” They added that “normal use” doesn’t present a health concern to the general population, including children, but advised consumers to “read and follow label directions.”
The Centers for Disease Control and Prevention (CDC) basically agrees, though they warn that “conservative use of low-concentration DEET products is most appropriate when applying repellants to children, and DEET should not be used on children younger than 2 months of age.”
General side effects of DEET may include:
- Skin irritation (irritation, redness, rash, swelling).
- Eye irritation (if you mistakenly get it into your eyes), including pain and watery eyes.
- Stomach upset, vomiting, and nausea, if you mistakenly swallow it.
- Neurological effects, such as seizures (at higher and consistent exposures).
DEET can get inside the body when you apply it to your skin. If the product contains alcohol as well, that can improve penetration, so that more gets into the bloodstream. Health experts warn that sunscreens containing DEET should be avoided because they cause more DEET to sink inside the body.
The CDC also lists a number of studies that raised concerns about how DEET could affect health. Here’s a glimpse of those, along with a few other related studies:
- Skin effects in soldiers: A small number of soldiers who applied military-issued DEET repellants suffered serious side effects on the skin, including burning sensations, blisters, reddening of the skin, and scarring. In a controlled test, 63 soldiers applied a gauze pad soaked in DEET to the skin on the inside of their elbows. Nearly half—46 percent—developed a reaction to the treatment. Researchers advised users to always wash the DEET off their skin before going to sleep.
- Skin and respiratory effects in National Park Service employees: In a study on National Park Service employees at Everglades National Park, researchers found that about 25 percent of workers using DEET reported health effects. These included rashes, skin or mucous membrane irritation, numb or burning lips, dizziness, disorientation, and difficulty concentrating, as well as headaches and nausea.
- More skin effects: An analysis of all DEET calls into poison control centers between 1993 and 1997 found that 10.5 percent involved skin symptoms like irritation and rash. Another 21 percent involved eye effects, when users mistakenly got the chemical into their eyes.
- Brain effects: A 2002 animal study by Duke University researchers found that frequent and prolonged use of DEET caused brain cell death and behavioral changes. The chemical actually caused neurons in the brain to die—affecting regions of the brain that control muscle movement, learning, memory, and concentration. Rats exposed to an average human dose of DEET performed far worse than control rats on tasks requiring muscle control, strength, and coordination. “If used sparingly,” said Mohamed Abou-Donia, lead author of the study, “infrequently and by itself, DEET may not have negative effects—the literature here isn’t clear. But frequent and heavy use of DEET, especially in combination with other chemicals or medications, could cause brain deficits in vulnerable populations.”
- Neurotoxicity in Gulf War Veterans: After 30,000 Persian Gulf War veterans complained of neurological symptoms of unknown cause, researchers tested the chemicals they were exposed to during the war—which included DEET—on chickens. They found that hens exposed to a combination of three chemicals (DEET, an anti-nerve agent, and another insecticide) showed similar neurological side effects on the brain. Researchers noted that exposure to only one chemical alone didn’t have the same effect.
- Effects in children: This is where DEET gets especially concerning. Children are likely to put their hands in their mouths and near their eyes and noses. If those hands are covered in DEET, that gives the chemical an easy entrance into the body. The CDC notes that though rare, reports of toxicity from DEET in children can include symptoms like lethargy, headaches, tremors, seizures, and convulsions. Accidental ingestion can result in loss of muscle control, loss of consciousness, and seizures. In one case, for example, a 6-year-old girl ended up in the hospital because she couldn’t control her body movements. It turned out she had been exposed to a spray containing 15 percent DEET over extensive areas of her skin on more than 10 occasions. In the summertime, that’s not totally unheard of, so the case serves as a good caution to parents.
- Effects in pregnant women: While extremely rare, there have been a handful of reports of DEET use in pregnant women resulting in birth defects in the infant children. A 2001 study found that DEET applied in the second and third trimesters resulted in an 8 percent DEET concentration in the blood—indicating that it had crossed the placenta.
Because of these and other concerns, the CDC recommends using a DEET concentration of 30 percent or less, and advises “conservative use” of a low-concentration product in children.
The American Academy of Pediatrics also advises that children under the age of 2 months not be exposed to DEET, and that any product containing DEET be applied to any other children no more than once a day, and even then, not around the eyes or mouth.
In addition to its potential effects in humans, DEET has also been detected at low levels in 75 percent of streams sampled, where it could potentially affect drinking water.
Despite all these concerns, you may be surprised to hear that even the Environmental Working Group (EWG)—which is typically the one to blow the whistle on dangerous chemicals—has named DEET as one of its four top picks for insect repellants.
“DEET’s safety profile is better than many people assume,” the EWG states. “Its effectiveness at preventing bites is approached by only a few other repellant ingredients.” When weighed against the consequences of Lyme disease and West Nile virus, the chemical is a reasonable choice, the group concluded—particularly for those living in areas “infested with disease-carrying pests.”
(It’s other top picks included picaridin, oil of lemon eucalyptus, and IR3535, which is similar to a naturally occurring amino acid.)
Still, the EWG advises caution—always avoid the eyes, nose, and mouth when applying, and take extra precautions with children. Use products that contain no more than 30 percent DEET (less for children), and look for time-release options.
What do we think? With the demand for safer alternatives, we now have more options than ever. Picaridin, which has a long history of effectiveness against mosquitoes in other parts of the world, has now been approved in the U.S. (It’s a synthetic compound made similar to “piperine,” a compound found in plants used to produce black pepper.) Oil of lemon eucalyptus, derived from eucalyptus leaves, has also been shown to be effective. Other good options include citronella, peppermint, cedar, and lemongrass.
In the end, you have to weigh the risks. If you’re really going out into the backcountry where the risk of getting bitten by a mosquito or tick outweighs any risk of DEET exposure, you may want to go for the DEET.
In most cases, however—particularly when it comes to children—we recommend you use the more natural alternatives. Arming yourself with more than one option can also help you cut down on your overall exposure to DEET, which we think is the wisest choice.