WHO Endorses DDT Use Indoors

Saturday's Washington Post reports:

The World Health Organization reversed a 30-year-old policy yesterday and declared its support for indoor use of the pesticide DDT to control mosquitoes in regions where malaria is a major health problem.

The Geneva-based WHO, which provides advice to many developing countries, believes the benefits of the long-acting pesticide far outweigh any health or environmental risk it may pose....

The endorsement is only for once- or twice-yearly spraying of the pesticide on the inside walls of dwellings, especially mud and thatched huts. Used that way, DDT functions as both an insect repellent and -- when a blood-engorged female mosquito lands on the wall to digest its meal -- an insecticide.

One application costs about $5. Most of that cost is labor, as it is sprayed on by professional applicators, and each packet of the pesticide must be strictly accounted for.

About 1 million people die each year of malaria, most of them African children under age 5. ...

Numerous countries in southern Africa use DDT, but the compound is generally not used in central and west Africa, which have more intense malaria transmission, said Shiva Murugasampillay, a physician at WHO in Geneva.

DDT was the chief chemical villain of Rachel Carson's book "Silent Spring," whose publication in 1962 helped nurture the modern environmental movement. The chemical was banned in the United States in 1972, and its use worldwide fell steeply after that. It is no longer used in agriculture.

A study in Zambia in 2000 found that when all houses in a neighborhood were sprayed, malaria incidence fell 35 percent compared with years when none was sprayed.

Swaziland and Madagascar each had malaria epidemics after suspending DDT spraying, the latter's outbreak killing more than 100,000 people from 1986 to 1988. Both epidemics were stopped when DDT spraying resumed.