Thursday, August 20, 2009

The trouble with DEET

New research on DEET health risks

DEET, the active ingredient in many insect repellents used by some 200 million people every year, appears to affect proteins in mammals as well as mosquitoes and other target insects. Some previous studies have implicated DEET in seizures among children. A new study (PDF) by an international group of scientists, supported by Agence Nationale pour la Recherche in France, published August 5 at (BMCBiology), reports that DEET "is not simply a behaviour-modifying chemical but that it also inhibits cholinesterase activity, in both insect and mammalian neuronal preparations." Symptoms of lowered levels of cholinesterase, an enzyme essential to proper nervous system function, can include nausea, headaches, convulsions and, in extreme cases, death. Health risks increase when DEET and other pesticides are used together. The researchers concluded that "DEET is commonly used in combination with insecticides and we show that deet has the capacity to strengthen the toxicity of carbamates, a class of insecticides known to block acetylcholinesterase." The new findings are "consistent with previous studies, says Bahie Abou-Donia of the Duke University Medical Center in Durham, NC," speaking to Science News. Abou-Donia's research found increased toxicity when DEET and chlorpyrifos, an organophosphate insecticide hazardous by itself, were used together. "These effects should be clearly labeled on products containing DEET, or N,N-diethyl-3-methylbenzamide," says Abou-Donia. In Canada, he noted, "insect repellents can contain no more than 30 percent DEET. The United States - where 100 percent DEET repellents are available - should consider such restrictions."

- Pesticide Action Network of North America

  • Mosquito Repellants and Deterrents
  • Some Insects of British Columbia
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