INTRO: Spring has come to Alaska, and soon hordes of mosquitoes will descend, like tiny locusts, across the land to feed on the blood of all living things. As Alaskans get ready for their annual war with mosquitoes, a pharmacologist advises caution when using insect repellents containing the chemical DEET, the most widely used chemical in repellents. Doug Schneider has more, in this week's Arctic Science Journeys Radio.
STORY: Mohamed Abou-Donia is a pharmacologist at Duke University in North Carolina. He studied the neurological impacts of the chemical DEET as a way to unravel the mystery of Gulf War Syndrome. That's the unexplained illnesses and neurological disorders suffered by soldiers during the U.S. war with Iraq more than a decade ago.
During the war, soldiers used a number of chemical repellents to ward off biting insects. The most popular insect repellent was DEET, a chemical developed by the U.S. Army just after World War II. Today, DEET is commonly used in over 200 insect repellents sold in the U.S. each year, in concentrations as high as 100 percent.
In his study, Abou-Donia exposed laboratory rats to repellent containing 70 percent DEET, the amount used by soldiers during the Gulf War. After sixty days of exposure, the rats didn't appear any different from rats that weren't exposed. But they came up short when challenged in an obstacle course and a maze.
ABOU-DONIA: "When we used this chemical, we found there were behavioral changes that told us that the chemical exposure to DEET resulted in muscle weakness as well as problems with walking and coordination."
Abou-Donia then examined the brains of exposed rats. He discovered that DEET killed cells in areas of the brain that control muscle coordination and cognition.
ABOU-DONIA: "We looked at the brain and found specific areas of the brain were damaged. These areas are responsible for movement, cognition, as well as muscle strength, which would explain what we saw in the animals behaviorally. It might also explain the problem with Gulf War veterans. They complained of muscle weakness and difficulty walking and cognition problems."
Abou-Donia doesn't blame DEET for Gulf War Syndrome entirely, since soldiers used other chemicals in combination with DEET during the war. These chemicals need further study, he says. And Abou-Donia believes DEET is safe when used correctly. He urges consumer to use insect repellents that contain less than 30 percent DEET, and that it be used sparingly, especially on children. Canada recently mandated that insect repellents sold there contain no more than 30 percent of the chemical. Repellent manufactures also advise their products be used primarily on clothing. Abou-Donia says that's good advice.
ABOU-DONIA: "The take-home message is to use as little of it as possible and for short periods of time. I would not use it in combination with any other chemicals like insecticides or even medicine."
The U.S. Environmental Protection Agency also believes DEET is safe. According to statements published on the EPA Web site, the chemical poses no health risk as long as consumers follow label directions and take proper precautions. Still, Abou-Donia has called for further government testing of the chemical's safety in short-term and occasional use.
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. Im Doug Schneider.
Audio version and related Web sites (sidebar at top right)
Thanks to the following individual for help preparing this script:
Mohamed B. Abou-Donia
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks. The shortcut to our ASJ news home page is www.asjnews.org.
URL for this page is http://seagrant.uaf.edu/news/
Related Web sites
DEET Tips (New York State Department of Health)
TIP: To find sellers of insect repellents, search the Web using keywords such as DEET and citronella.
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