West Nile Virus season has arrived and, increasingly, folks are opting to thwart mosquitoes herbally rather than use body sprays containing DEET, the most successful mosquito-repellent ingredient on the market.
DEET (N, N-diethyl-m-toluamide) has been deemed safe by the Environmental Protection Agency, the American Academy of Pediatrics, and the Centers for Disease Control and Prevention for the general population, including children over 2 months old at levels up to 30 percent concentration.
Nevertheless, DEET can dissolve nylon and plastic, is highly flammable, has caused rashes, eye and sinus irritation, headaches, insomnia, and confusion in sensitive people, and is dangerous if absorbed into the bloodstream (through open wounds). Studies on rats have shown DEET may cause brain cell death or damage. Also, products combining sunscreen with DEET are not recommended. DEET can decrease the sunscreen's efficacy by 34 percent, and although sunscreens are intended for generous, frequent use, DEET should be used sparingly.
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| Herbal-based bug repellents.(Julia Ewan - The Washington Post) |
Because of these concerns, many Americans have become afraid to use products containing DEET, and resist applying any repellent, even though the virus is a serious threat, having now appeared in all the lower 48 states and the District.
Reacting to this consumer retreat from DEET, biotech companies are bringing new herbal products to the market. "New," however, is a relative term; for centuries, gardeners have turned to herbs to fend off bugs.
One of two new CDC-sanctioned repellents is picaridin, a barrier-forming chemical used in at least one product, Cutter Advanced. The other repellent is lemon eucalyptus oil.
The lemon eucalyptus oil is available in OFF! Botanicals Insect Repellent, Repel Lemon Eucalyptus, and other sprays and lotions containing the ingredient. While nearly as effective and long-lasting as DEET, lemon eucalyptus can cause skin reactions and isn't safe for children under 3 years of age.
A repellent named Bite Blocker for Kids is made from a 2 percent concoction of soybean, vanillin, and coconut and geranium oils and is effective for 90 minutes. (Bite Blocker's adult version is good for four to eight hours).
Nature's Herbal Natural Mosquito & Insect Shield contains catnip oil, which has been shown to repel mosquitoes though perhaps not visits from every cat in the neighborhood.
Another emerging natural repellent may be as close as your vegetable patch. Michael Roe, a scientist at North Carolina State University, discovered that a substance in tomato plants is as potent as DEET. A biotech company is working to develop products containing the compound, which is awaiting EPA approval. In addition to repelling mosquitoes and flies, it has proved effective against ticks, which can carry Lyme disease.
Certainly, being "natural" or "organic" doesn't always render something safe; deadly ricin, after all, derives from a common plant. Natural products usually are made from essential oils distilled from plants that use them to fend off insect feeding. In high concentrations -- more than 5 to 10 percent -- they can be toxic and irritating, causing skin reactions or worse, particularly for children.
If you don't have these on hand, using garden plants directly may help, though first you must crush the leaves to release the essential oils. Lemon grass, a staple in Thai cookery, can be bought at Asian groceries, easily rooted and grown as a tropical plant, for wintering indoors. Rubbing a cut stalk vigorously, releasing its wonderfully perfumed oil, repels well for four to five hours. Other plant extracts mosquitoes avoid are fennel, shrub verbena, lavender, witch hazel, tansy, peppermint, basil, lemon balm, lemon oregano, lemon geranium, rosemary, sassafras and eucalyptus.
