Many people use commercial insect repellents to protect themselves from the annoyance of insect bites and to help stop the transmission of insect-borne diseases like the West Nile Virus and Lyme disease. Most of these repellents contain an active ingredient known as N, N-Diethyl-meta-toluamide, more commonly referred to as DEET.
In the past few years, DEET has received lots of press coverage about its efficacy as a repellent and the safety of using it. Consumer watch groups have warned against using DEET, experts say it’s considered to be safe and health professionals are split down the middle. So what is the truth about DEET and should you be using it to protect yourself?
How Does DEET work?
DEET was developed by the US Army as a pesticide, and in fact, is very effective at controlling the spread of insects. It was originally believed to block an insect’s olfactory sensor, rendering it incapable of finding humans as the 1-octen-3-ol in human sweat and breath is what enables it to track humans and triggers the biting instinct. However, more recent studies show that DEET is simply a repellent in the most basic sense of the word – mosquitoes and other insects do not like the smell of the chemical.
Applications of DEET generally include topical ointments and lotions, and aerosol sprays to be applied to the skin and clothing. They vary in concentration, with a direct correlation between concentration and length of protection. It is often recommended by disease control agencies to help control the spread of insect-borne pathogens.
On a topical level, DEET can be a skin irritant and those who use very high concentrations of DEET can sometimes have epidermal reactions. However, DEET is also sold as a spray and can be used on clothes instead of directly applying it to the skin.
Like other members of the toluene family, DEET is absorbed through the skin and passes into the bloodstream, where it can travel to the internal organs and be absorbed. It has been found to inhibit acetylcholinesterase, a central nervous system enzyme that plays a part in controlling muscle action, in both insects and mammals. Some studies have shown that people with prolonged exposure to DEET can suffer from insomnia and impaired cognitive function. DEET has also been linked to seizures, including fatal cases, and the media has reported that people have died after ingesting it.
Is It Safe to Use DEET?
Although DEET does appear to have caused seizures in several people, the US Environmental Protection Agency estimates that the likely seizure rate is about one in 100 million users. Studies by the American Academy of Pediatrics have found that DEET is safe to use on children and adults, but recommends that it not be used on infants less than two years old.
In addition, DEET is extremely effective at preventing insect bites, which are not only irritating but can also transmit serious diseases.
If you do decide to use DEET, it’s best to use the low-concentration versions – 20% will protect you against insect bites and will last 3.5 to 4.5 hours. Spray it onto your clothes rather than your skin to avoid irritation, and wash them between applications. Do not apply to broken skin and try not to have long unbroken periods of sustained usage.