Is DEET Bad for You? What You Need to Know About Bug Spray.

Q: Everyone says DEET in bug spray is awful, but my own research seems to suggest it’s well-tested and secure. Am I risking a little cancer every time I employ it?

Even a few drops of DEET-containing insecticide can have an unpleasant odor, but when used properly, the most harmful effect of DEET may be its odor, said Dr. Joseph Kennedy, a physician and toxicologist at the University of Vermont Medical Center.

But there are still widespread concerns that DEET may be potentially toxic or cause cancer, he said, due to “many misconceptions.”

Here’s why people think DEET is bad for human health and what we know about its safety.

How does DEET work?

Scientists aren’t entirely sure how DEET repels insects. But contrary to what many people might think, DEET is not an insecticide, Dr. Kennedy said. It doesn’t kill mosquitoes and isn’t toxic to them. Instead, it simply repels them, probably by its unpleasant odor.

“The whole point of having an unpleasant odor is that you’re not the only one who feels that way,” Dr. Kennedy said. “Insects, too,” he added. And that includes other insects, such as ticks, fleas and biting flies.

Another theory about how DEET works is that it masks certain human emissions, such as carbon dioxide, that tend to attract insects, Dr. Kennedy said.

Is DEET secure?

Millions of people in the United States employ products containing DEET every year, according to the Environmental Protection Agency. Yet only about 2,800 health incidents related to the chemical were reported between 2007 and 2012, the agency said in its latest review.

DEET has also been around for about 80 years. If it were toxic or caused cancer, “it would have come out a long time ago,” said Jeffrey Bloomquist, an insect toxicologist at the University of Florida.

Most incidents reported by EPA were minor and involved skin, eye or respiratory irritation such as rashes, watery eyes or wheezing.

“If it gets in your eyes or mouth, it’s really unpleasant,” Dr. Kennedy said.

Dr. Bloomquist said products containing DEET are secure when applied correctly — meaning only to exposed skin and not sprayed directly on the face or broken skin.

And don’t employ more than you need, Dr. Bloomquist said, especially for children, who tend to absorb more of the chemical through their skin than adults. He recommended that adolescent children or infants employ products with a lower concentration of DEET (a 24 percent solution should be appropriate). And he suggested spraying it on clothes, not directly on the skin.

If used incorrectly, such as if someone swallows it or applies too much, DEET can cause stern health problems, such as seizures, low blood pressure, uncoordinated movements or death, Dr. Kennedy said. But such cases are sporadic — seizures, for example, occur only once in 100 million uses, according to the EPA

It’s also worth noting that some repellents contain high concentrations, such as 100 percent DEET, which is overkill for most people, Dr. Bloomquist and Dr. Kennedy added.

Dr. Bloomquist said there has been little quality research on DEET’s link to cancer in humans. The Centers for Disease Control and Prevention reported that that long-term exposure is not associated with an boost in cancer incidence in rodents, rats and dogs.

DEET has not been shown to cause harm to pregnant women or their fetuses.

Where did the panic come from?

In the 1980s and 1990s a few isolated reports There has been widespread concern about DEET-related seizures and deaths. However, these people were not using DEET as directed.

In the years 1960–2020, researchers only nine deaths were recorded related to DEET poisoning. Of those, four people intentionally ingested the chemical — and some of them also took other substances, such as alcohol or antidepressants, that may have played a role in their deaths. The other cases included two adolescent children and an infant whose parents used DEET every night for weeks or months, and two adults who applied more DEET than necessary. It’s unclear whether DEET or something else — such as an underlying medical condition — played a role.

DEET also sounds a lot like DDT, a toxic insecticide that is now banned. “People confuse the two chemicals,” Dr. Kennedy said.

Does DEET have any health benefits?

One of DEET’s main benefits is its ability to protect against insects that carry potentially deadly diseases such as dengue, West Nile disease, and Lyme disease.

“It’s surprisingly effective,” Dr. Kennedy said.

IN Study 2022volunteers stuck their DEET-coated arms into a cage of hungry mosquitoes. Those wearing insect repellents containing about 24 percent DEET were fully protected from insect bites for about five hours. Repellents containing only vital oils, such as citronella or peppermint, protected them for less than 20 minutes.

Dr. Kennedy said there are risks and benefits when using any chemical. But DEET’s toxic side effects are much rarer than those that can occur with insect-borne illnesses, such as the irregular heartbeat from Lyme disease or the severe anemia from tick-borne babesiosis, he added.

“These truly life-changing diseases can be prevented by taking basic precautions and using repellents,” Dr. Kennedy said.