Will My Body Absorb the Chemicals in My Bug Spray?

Here's what we know about DEET.
Rene Drouyer/Getty Images

The Scenario:
Your tent is pitched, your firewood gathered, and your deodorant safely forgotten in your medicine cabinet back home. This is no time for frivolity, no time for hygiene. It's time to embrace nature—you're out in the woods for the weekend, camping with your crew, and your hairy pits and body odor prove you've ditched all the luxuries of home. But then your buddies break out the bug repellent and start spritzing it from top to toe like sixth graders testing body spray for the first time. What the hell? You thought you signed on for a back-to-basics camping trip. And more importantly, won't your body absorb all those terrible chemicals?


The Facts:
The Environmental Protection Agency registers insect repellents, and it requires a battery of tests to prove the product works as stated on its label, according to an EPA spokesperson. Many EPA-registered products contain one of two active ingredients: N,N-diethyl-matatoluamide (DEET) and para-Menthane-3,8-diol (PMD).

The United States Army developed DEET in 1946 for military personnel in mosquito-dense areas, and the EPA registered it in 1980. For decades, people have slammed the chemical, saying it causes cancer, seizures, and neurological problems. They're bugging out and blogging about it, but the science doesn't back them up.

"I can't even think of substantiated claims on DEET that it actually hurts people, or enough people for it to not be an anomaly," says Stacy Rodriguez, a researcher at New Mexico State University's Hansen Lab, which focuses on new ways to control vector-borne diseases.

To learn how well repellents actually stave off these suckers, Rodriguez recruited two thrill-seeking volunteers to sit in a wind tunnel with up to 125 Aedes Aegypti mosquitos, carriers of Zika virus, chikungunya virus, and yellow and dengue fevers. Her study, published in the Journal of Insect Science, found that of the 11 products tested, the ones containing 65 percent PMD and 98 percent DEET repelled the most mosquitos—48 percent and 77 percent, respectively. We know the chemicals help us in that way, but do they hurt us in others?


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The Worst That'll Happen:
Whatever you do, please do not swallow your bug spray. In 2013, a man drank six ounces of insect repellent, leading to a seizure, cardiac arrest, and death, as reported by the American Association of Poison Control Center. Ingestion was "undoubtedly responsible" for the fatality, they say. Sniffing chemicals also won't end well: Inhaling large amounts of pyrethrins—a mixture of naturally-occurring chemicals in chrysanthemum flowers that's toxic to insects—can cause vomiting, diarrhea, and difficulty breathing.

But given that you won't do those two things, the better question is what will happen if you wear a repellent that's exempt from EPA registration, or no repellent at all. In 1995, the EPA tested products with alternative ingredients—like peppermint and cedar oil—for safety and determined that they "posed minimal risk to human health." But they weren't tested for efficacy. "You never know what kind of reaction someone might have to those, but the biggest risk they run is that they won't work," according to the EPA spokesperson.

Generally in the US we have the luxury of regarding mosquito bites as a harmless inconvenience, but in fact these bugs are considered by many experts to be the most dangerous animals in the world because of the plethora of nasty diseases they carry, even stateside. Of course, that's not even accounting for the crazy rise of Lyme-carrying ticks and other tiny, bitey disease vectors that lurk when the weather gets warm. So choosing to wear an effective bug spray strikes as the safer route.


What'll Probably Happen:
People's fears about DEET are rooted in the claim that your body absorbs the chemicals you apply to your skin, and they're not unfounded. Back in 1995, researchers put DEET on men's forearms and found that up to 8.3 percent of the dose was absorbed into their bodies. But, importantly, the men peed almost all of it out within 24 hours. And the EPA doesn't just test for efficacy, but also for safety: In 2014, the agency reinvestigated the safety of DEET and did not find "any risks of concern to human health, non-target species, or the environment."

Just like any other skin product, you could develop redness, skin irritation, or a minor rash if you're allergic to any ingredients in your insect repellent. "But that's an allergy problem," Rodriguez says. "It's a problem with the person and the chemical, and it's not necessarily going to be true for every person with that chemical."

What You Should Do:
Just like abstinence is the best way to prevent pregnancy, avoiding mosquitos is the best way to prevent a bite. "But if you cannot avoid them, then the best thing for you to do is put on a repellent so you don't get sick from a mosquito," Rodriguez says.

Repellents with DEET or PMD will work best. If you absolutely want to stray from skin-applied products, Rodriguez suggests avoiding the outdoors at dawn and dusk, when mosquitos are on the hunt for human blood. You can also cover up with clothing—preferably loose clothing, since mosquitos have a harder time puncturing your skin that way, she adds.

"Nothing's going to be 100 percent in terms of mosquito repellents," she says. "They are vicious creatures, so they will attack you." Be sure to apply and reapply as directed on the package, since most repellents last only a few hours, and know that moisture from sweat or humidity will make it wear off more quickly.

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