Eco Wise

Green Ways to Be Bug-Free

(By Richard T. Nowitz -- Corbis)
Sunday, August 3, 2008

Mosquitoes, ticks and other flesh-nibbling insects are not just nuisances, but potential health threats as well. The same might also be true of some popular insect repellents.

DEET and Permethrin are the most common ingredients in personal anti-bite products, and both are highly effective at keeping pests away. DEET is found in skin sprays and creams, while Permethrin is commonly woven into clothing, bed nets and camping gear, or used in home spraying systems. The debate over them, like the debates over many other chemicals in personal care products, is a polarizing one.

The Centers for Disease Control and Prevention recommend using Permethrin-treated outdoor gear. The Environmental Protection Agency's Web site says that "as long as consumers follow label directions and take proper precautions, insect repellents containing DEET do not present a health concern." However, the EPA also puts DEET in toxicity Class III , meaning it is "slightly toxic."

DEET has been linked to seizures in children and adults, according to numerous reports in medical journals, and a Duke University study found that the chemical caused brain damage as well as behavioral changes in rats. Permethrin, meanwhile, is classified as a "possible human carcinogen" by the EPA.

The compounds also raise environmental concerns. Both DEET and Permethrin are hazardous to bees, butterflies and other beneficial insects. The EPA declares Permethrin "highly toxic to both freshwater and estuarine aquatic organisms," not a good quality for washable clothing to have. Permethrin is also lethal to cats, even in small amounts -- worth noting if you're thinking of spraying your yard.

Deciding what repellent to use is a matter of weighing risk factors. The CDC recommends a product containing no more than 20 to 50 percent DEET for outdoor exposure of five hours or more; it also suggests nontoxic alternatives for shorter times spent outside. But pregnant women might want to stay away from DEET and Permethrin, and long-term and frequent exposure to the chemicals for anyone is not a good idea.

For consumers concerned about chemicals, a host of botanical-based insect repellents are on the market, and many of them work well for most people. They don't generally last as long as DEET products, however, so you'll have to reapply every couple of hours:

· Effective botanical ingredients to look for are eucalyptus, lemon and soybean oils, found in products such as Repel and Bite Blocker, which are stocked by mainstream stores as well as outdoor and natural food stores. (The Food and Drug Administration advises against the use of eucalyptus oil for children younger than 3.)

· IR3535, a biopesticide derived from plants, has been used in Europe for decades and is the active ingredient in products including Avon Skin-So-Soft and BullFrog; the EPA's Web site says that "no harmful effects to humans or the environment are expected" from its use.

· Picaridin, though synthetic, is classified by the EPA as "practically non-toxic" and appears in formulations by Cutter, Sawyer and Natrapel.

Pesticide-free ways to manage mosquito populations include eliminating standing water around the home and avoiding prime feeding hours (dawn and dusk). Mosquito coils can be burned, but some contain pesticides, and particulate-filled smoke isn't generally good to inhale. Citronella candles are a popular choice, but their effectiveness can vary. Another surprising yet effective remedy is to build or buy a bat house. Bats can eat up to their own weight in insects every night; providing a safe place for them to nest may help alleviate a mosquito problem, though you'll have to wait until next spring to try this technique out, because that's when bats nest. Then, of course, there's covering up, the easiest and greenest way to get bloodsuckers to bug off.

-- Eviana Hartman

© 2008 The Washington Post Company