Insect repellants

An anthropologist who knew nothing about our culture might well be fascinated by our traditional summer folk dance. You know the one: it’s where we jump about from foot to foot, waving our hands in the air and occasionally slapping parts of our body. It’s called the “Mosquito Mazurka.”

Our hypothetical anthropologist might also note that not everyone dances this quaint dance: many people choose instead to celebrate summer by anointing their bodies with lotions and sprays.

Insect repellents come in a variety of formulas from many different manufacturers, but they almost all have one thing in common: N, N-diethyl-m-toluamide, better known as DEET.

DEET was first synthesized in the 1950s, and it soon became apparent that many insects hate it. DEET repels a variety of mosquitoes, chiggers, ticks, fleas and biting flies, but don’t spray it on and then going out to tend the beehives: no skin-applied repellent is effective against stinging insects.

The concentration of DEET in insect repellents varies. The U.S. Army uses a mixture of 75-percent DEET in ethanol, ansd some commercial products that are even stronger. Deep Woods Off!, for instance, is 95 percent DEET, and Muskol is 100 percent DEET. (Pure DEET is unpleasantly oily, however, and lower concentrations work just about as well under most circumstances.)

Millions of people use DEET every year with no problems, but a few have unpleasant–even dangerous–reactions to it. The Journal of Toxicology and Environmental Health estimates that as much of 56 percent of all DEET applied to the skin is rapidly absorbed and enters the bloodstream; 10 to 15 percent of each dose can be recovered from the urine. The rest remains in the body for up to two months. Because of this, even people who aren’t sensitive to the chemical should use it only lightly, and wash it off promptly once they’ve returned indoors.

Children seem to be particularly prone to adverse reactions to DEET, probably because of their small size, so only products containing lower concentrations of DEET should be used on children, and then only sparingly.

One way to minimize skin exposure to DEET is to spray clothing instead. Unfortunately, DEET can damage spandex, rayon and acetate, as well as the plastic in sunglasses and vinyl car seats.

Of course, another way to minimize exposure to DEET is to use alternate methods of insect repellent. Permethrin is one. It’s actually a pesticide used for treatment of lice, but in some places it’s available as a clothing spray, usually sold specifically as a tick repellent. Although putting a pesticide on your clothes may sound worse than spraying DEET on your skin, the fact is that although permathrin is toxic to the nervous systems of insects, it is poorly absorbed or rapidly inactivated by mammals. Only a few minor adverse skin reactions have been reported.

Treating clothing with permathrin and exposed skin with a DEET formula would give you extremely effective protection against mosquitoes, black flies and ticks, our most common summer-time enemies, but some people would rather not use anything that sounds like it came out of their childhood chemistry set.

Instead, they turn to plant-based repellents (although just because something comes from a plant doesn’t mean it’s harmless: ever hear of deadly nightshade and poison ivy, to name just two?). Citronella-based repellents are probably the most common; they appear to provide short-term protection against mosquitoes, but aren’t very effective against ticks.

Other plant-based repellents have been made from cedarwood, eucalyptus and lemongrass, all of which smell pleasant to humans but apparently not to insects. Unfortunately, most of them are pretty ineffective against mosquitoes, at least compared to DEET; although they do seem to work pretty well against flies.

The latest “folk remedy” for repelling mosquitoes it a commercial concentrated bath oil called Skin So Soft. “Skin So Soft” certainly sounds more natural and pleasant, but it contains formidable-sounding chemicals like di-isopropyl adipate, isopropyl palmitate, dioctyl sodium sulfosuccinate and the sunscreen benzophenone-11, along with fragrance and mineral oil. One study indicates that the bath oil did indeed repel the type of mosquito that carries yellow fever, but the protection appears to last for only 15 to 30 minutes, and no one has studied the safety of repeated applications.

Ultimately, the choice is yours: DEET, “natural” repellents, Skin so Soft, or that mixture of various kitchen ingredients your grandmother passed on to you.

Or you can make visiting anthropologists happy–and dance the Mosquito Mazurka.

Permanent link to this article:

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Easy AdSense Pro by Unreal