DDT–a pesticide known to kill birds and thought by some to endanger humans–has found new friends among the medical community whose responsibility it is to fight a disease once thought to be under control: malaria.
More than 370 medical researchers, including three Noble laureates, in 57 countries are urging the United Nations not to implement a proposed worldwide ban on the use of DDT. They have signed an open letter to diplomats involved in ongoing treaty negotiations, being conducted under the auspices of the United Nations Environment Program, aimed at eliminating so-called persistent organic pollutants. At the very least, the scientists want to allow the pesticide to be sprayed on the inside walls of homes, a proven method for repelling mosquitoes that carry malaria.
“As people who have dedicated our careers to health in the developing world,” the open letter reads, “we wish your country to carefully scrutinize any treaty proposal which could aggravate the burden of malaria upon your citizens. . . . In our view, setting a deadline for the elimination of DDT . . . unacceptably endangers health in countries with malaria.”
“To act ethically,” the letter continues, “we must know, with the greatest of certainty, that DDT is unnecessary before we ban it.”
Banned from use in the United States 27 years ago, DDT remains the most effective pesticide in preventing the spread of malaria, which every year kills nearly 3 million people, most of whom live in poor, undeveloped countries. According to the World Health Organization, which last year launched a Rollback Malaria campaign, 300 million to 500 million new malaria cases are identified every year.
Malaria has made a dramatic comeback in certain countries in part because many nations, pressured by environmentalists, no longer use DDT for agricultural purposes. The biggest manufacturers and users of the chemical are India, China, and Mexico, the latter promising to cease its use by 2007.
Ecuador has gone against the trend, actually increasing DDT use since 1993. It claims a 60 percent decline in new malaria cases. Bolivia, Paraguay, and Peru, all of which stopped using the chemical six years ago, have seen new cases soar 90 percent.
In an August 27, 1999 report for the New York Times, reporter Sheryl Gay Stolberg wrote that the present DDT dilemma developed when the U.N. announced a plan to “eliminate, or greatly reduce, the use of 12 toxic chemicals classified as persistent organic pollutants.” DDT is among those chemicals, known to environmentalists as the “dirty dozen,” which enter the food chain and can be spread widely through air, water, and bird migration. Begun in 1998, discussions about the pollutants are scheduled to conclude late this year, and observers say negotiators on both sides of the issue have hardened their positions.
Supporters of a complete ban, which include the World Wildlife Federation and Physicians for Social Responsibility, argue that even small amounts of DDT sprayed in homes hurt the environment. They also cite studies that suggest the chemical can be found in breast milk of nursing mothers, and may have other “subtle effects on human health.” To date, however, there is no conclusive evidence that DDT endangers human health.
Citing ethical considerations, DDT’s allies, including the American Society of Tropical Medicine and Hygiene and the Malaria Foundation International, oppose any firm deadline for a DDT ban because it would hurt poor countries the most. Any such ban, they argue, should be postponed until an equally effective–and equally affordable–substitute can be developed. DDT’s advocates warn that any rush to judgment on a replacement for DDT would be disastrous, because mosquitoes are known to quickly develop immunity to pesticides and drugs used in treating the disease.
Some countries have nevertheless turned to using pyrethroids, a more expensive and less effective alternative. According to an EPA official, the cost of spraying one house with DDT ranges between $1.60 to $8.50, compared with $4.20 to $24 using pyrethroids.
“The DDT-malaria issue is a stark illustration of the conflict between the developed and developing world,” wrote Lorraine Mooney in the September 9 Wall Street Journal. “For the sake of a possible environmental threat to birds of prey in the ‘civilized’ world, millions of people in developing countries are dying. This must stop.”
The DDT controversy first erupted in 1962, following the release of Rachel Carson’s book Silent Spring. Carson described how robins were poisoned after eating worms that fed on the leaves of Dutch elm trees sprayed with DDT. A fearful public forced changes that led to the creation of the U.S. Environmental Protection Agency and DDT’s ban in 1972. Birds once threatened with extinction, including the American bald eagle, osprey, and peregrine falcon, have made remarkable comebacks in the U.S. since the ban was implemented.
For more information
on the Roll Back Malaria initiative and the malaria-DDT relationship, visit the Web site of the Malaria Foundation International at http://www.malaria.org/. The Open Letter to DDT Treaty Negotiators is available at http://www.malaria.org/DDT_open.html and can be signed at http://www.malaria.org/ddtcover_english.html.