Wednesday, August 02, 2006

DDT May Return

There is talk of reviving the pesticide DDT for use in preventing malaria in developing nations. It has been approved for such use by the U.S. Agency for International Development, and presumably the World Health Organization will do so as well. For now at least, DDT would be used for indoor spraying and not for agricultural use.

Very small amounts would be used to treat only house walls, so the probability of human and environmental contamination would be low.

Even small amounts of DDT deliver a lot of bang for the buck as an effective, cheaper, and longer-lasting pesticide, supporters say.

"For duration of activity there is no [competitive] chemical that even comes close to DDT, and of course the duration is a big factor in overall cost," Roberts, of Uniformed Services University, said....

"[Treating house walls] is a perimeter treatment," Roberts explained. "The people you're trying to protect are on the inside of the perimeter, so mosquitoes will come up to that wall, detect the DDT in the vapor phase, and move away from it," Roberts said.
As the article notes, there is a danger that this could open the door to more widespread use if the pesticide is not carefully controlled.

DDT was originally banned in 1972 because of its harmful effects on birds, particularly hawks and other predators high in the food chain. The chemical weakens egg shells and inhibits reproductive success. Bald eagles and other raptors declined sharply in the mid-twentieth century as a result, and some came close to extinction. In songbirds, the pesticide shrinks brain size. (More on pesticide use and birds.) DDT may harm pregnant or breastfeeding women and may inhibit brain development in young children.