By David Brown
Washington Post Staff Writer
Saturday, September 16, 2006
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.
"Indoor residual spraying with DDT and other insecticides will again play a major role in [WHO's] efforts to fight the disease." Arata Kochi, director of the organization's malaria department, said at a news conference in Washington. "WHO will use every possible and safe method to control malaria."
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.
WHO expects opposition to the policy change from some environmental groups. Kochi appealed directly to them in his announcement.
"I am here today to ask you, please help save African babies as you are helping to save the environment. African babies do not have a powerful movement . . . to champion their well-being," he said.
The most famous pesticide in the world, DDT has few if any adverse effects in human beings. Its chief hazard is that it persists in the environment for years. Widespread agricultural use of DDT in the 1950s and 1960s caused the thinning of bird eggshells and the steep decline in the population of some species.
Its utility in malaria control, however, is undisputed. DDT spraying helped eradicate or greatly reduce malaria in North America, southern Europe, North Africa and the Middle East in the decades after World War II. It continues to be used indoors in a few countries.
Environmental groups had a mixed reaction yesterday.
"Given the severity of the malaria epidemic now in Africa and parts of Asia, it is reasonable to be using limited amounts of DDT for indoor use," said John M. Balbus, a physician who heads the health program at Environmental Defense. He said DDT "is not the single answer, but it can be part of the solution until we find a better alternative."
The Pesticide Action Network North America in San Francisco, however, opposes its use because it believes that DDT could cause premature birth and developmental delay in children, said spokeswoman Stephenie Hendricks.
"When there are less toxic means to combat malaria, why would people want to inflict these additional health problems with a chemical they are presenting as a silver bullet, which it isn't?" she said.
Many countries use other chemicals, primarily pyretheroids, in indoor spraying. But they are generally less potent than DDT and do not last as long.
The U.S. Agency for International Development supports indoor spraying in Angola, Uganda, Tanzania and Zambia. Non-DDT compounds are used primarily, although DDT is being used in Zambia and on the island of Zanzibar. In Zanzibar, about 85 percent of households agree to its use, said Tim Ziemer, a retired admiral who is the coordinator of the President's Malaria Initiative, created by the Bush administration last year.
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.