EarthTalk: Green alternatives to DEET-based bug sprays
Q: Is it true that the DEET used in most mosquito repellents is toxic? If so, what are some nontoxic alternatives for keeping mosquitoes at bay?
– Tom Pollack, Oakland, Calif.
A: DEET is considered the king of mosquito repellents, though not everyone is keen to slather it on their skin. A study conducted in the late 1980s on Everglades National Park employees found that one-quarter of the subjects studied experienced negative health effects that they blamed on exposure to the chemical.
Duke University pharmacologist Mohamed Abou-Donia, after studying the effect of frequent and prolonged DEET exposure in rats, concluded that humans should stay away from products containing it. But other studies have shown that while a few people are sensitive to DEET applications, most are unaffected when DEET products are used sporadically and according to the instructions on the label.
The upside is that DEET is very effective. A 2002 study in the New England Journal of Medicine found that DEET-based repellents provided the longest-lasting protection against mosquitoes. A formulation containing 23.8 percent DEET completely protected study participants for more than 300 minutes, while a soybean-oil-based product only worked for 95 minutes. Several other botanical-based repellents lasted less than 20 minutes.
But a number of new concentrations of botanical repellents are reportedly better than ever. In 2005, the US Centers for Disease Control (CDC) granted approval to two alternatives to DEET – picaridin and oil of lemon eucalyptus – for protection from mosquitoes. Picaridin, long used to repel mosquitoes in other parts of the world, is now available in the US under the Cutter Advanced brand name. Oil of lemon eucalyptus, which is derived from eucalyptus leaves and is the only plant-based active ingredient for insect repellents approved by the CDC, is available in several forms, including Repel Lemon Eucalyptus, OFF! Botanicals, and Fight Bite Plant-Based Insect Repellent.
Some other good choices, according to the nonprofit National Coalition against the Misuse of Pesticides, include products containing geraniol (MosquitoGuard or Bite Stop), citronella (Natrapel), herbal extracts (Beat It Bug Buster), or essential oils (All Terrain). The group also gives high marks to oil of lemon eucalyptus.
Another leading nonprofit, Pesticide Action Network North America (PANNA), likes Herbal Armor, Buzz Away, and Green Ban, each of which contains citronella and peppermint as well as various essential oils (cedar wood, lemongrass, etc.). PANNA also lauds Bite Blocker, a blend of soybean and coconut oils that provides four to eight hours of protection and, unlike many other brands, is safe to use on young children.
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