Chemical Pesticides

Old Pesticides Never Die, They Just Won't Even Fade Away

Most of us don't know a whole lot about the pesticide DDT other than it almost caused the extinction of bald eagles and it was banned decades ago. Well, the first part is true—and we can thank the US ban on DDT, the Endangered Species Act, and the efforts of scientists and volunteers for bringing the eagles and other affected species back to a state of robust health. But the second part of the statement—that DDT was banned decades ago—is only partly true. DDT was banned in the United States but it is still used in a number of countries around the world.

Now, promoters of this toxic pesticide are linking DDT and malaria as a means for getting DDT un-banned. They argue that people in areas with malaria problems are being unfairly denied access to DDT, picture of mosquito biting which the flacks claim is the only solution possible for areas infested with malaria-carrying mosquitoes.

Is this true? Or is it just a ploy by corporations and their front men to restart the profit stream from the pesticide DDT? We'll find out in today's guest article, which was authored by Pesticide Action Network North America (PANNA).

DDT and Malaria: Setting the Record Straight

DDT is in the news again, promoted by a handful of aggressive advocates as a silver bullet solution to malaria in Africa. The DDT promoters' story goes something like this:

Malaria is killing people in Africa, but environmentalists care more about saving birds and are blocking the use of DDT to save people. DDT wiped out malaria in the US, but is now being denied to Africans. DDT is the best way to fight malaria. There are no health effects from DDT exposure, and its use should be widespread.

The only accurate part of this story is that malaria does kill millions of people in Africa every year, a preventable public health tragedy of catastrophic proportions. The rest of the story is false, but it is being pitched aggressively and effectively by well-funded sources to mainstream media outlets and members of Congress. A New York Times columnist even titled a recent article "What the World Needs Now is DDT."

Hold your horses, says Paul Saoke, M.D., Director of Physicians for Social Responsibility in Kenya: "DDT is a short-sighted response with long term consequences. While it may be effective in some cases where mosquitoes haven't yet developed resistance, it won't solve the malaria health crisis. Technical expertise and better malaria control methods already exist in Africa. It's only resources and political will that are lacking."

Public health experts, government officials, and environmentalists around the world support the approach to DDT taken by the Stockholm Convention on Persistent Organic Pollutants (POPs). The treaty targets DDT (along with eleven other dangerous chemicals) for global phase out, but allows exemptions for malaria control in countries that request it. This approach recognizes that in some cases, DDT can be an effective temporary tool for malaria control. Most importantly, the treaty also mobilizes desperately needed funds for malaria control and prevention, with an emphasis on safer, more effective strategies that don't further jeopardize the health of current and future generations.

DDT - Dichloro-Diphenyl-Trichloroethane

Malaria had been largely eliminated in the US by the time the Centers for Disease Control (CDC) first used DDT in spray campaigns in 1947. CDC's four-year spray effort was designed to prevent the reintroduction of malaria from troops coming home from World War II. Almost twenty years earlier, in 1928, the Public Health Service had already noted the decline of malaria in the US. The pockets that persisted in the South until the late 1930s were controlled by the Tennessee Valley Authority's efforts to:

* cut down on mosquito breeding sites by draining swamps, and
* protect the population by building well-screened houses.

According to one journalist investigating the issue, "About the best one CDC physician involved in the campaign could say about [the DDT campaign] was that 'we kicked a dying dog.' "

Both human health and the environmental impacts led to the 1972 DDT ban in the US, and we know even more today about DDT's human health effects than we did back then. DDT is classified by US and international authorities as a "probable" human carcinogen, and exposure is linked to human developmental disorders. Reproductive disorders associated with DDT are well documented in animal studies (which are scientists' primary tool for predicting human effects).

Recent studies have also linked DDT exposure to reduced breast-milk production among nursing women, and US researchers have found that the DDT breakdown product DDE is associated with increased risks of premature delivery and reduced infant birth weight. DDT and its breakdown products have also been found in human blood and breast milk in dozens of studies around the world.

The World Health Organization (WHO) tried to eradicate malaria worldwide with a massive DDT spraying program in the 1950s and '60s. While the program helped to control malaria in many places, wiping out malaria with DDT was an unrealistic goal that could not be met. One of the many reasons for the failure of this ambitious effort was resistance to DDT among malaria-carrying mosquitoes. Resistance was identified in Africa as early as 1955, and by 1972 nineteen species of mosquito worldwide were resistant to DDT.

DDT intended for public health use is often diverted to illegal agricultural use, hastening the development of resistant mosquito populations. More effective and safer approaches to malaria control are now being used in many countries. For example, Mexico uses an integrated approach that combines:

* early detection of malaria cases and prompt medical treatment,
* community participation in notification of malaria cases and cleaning of streams and other sites where mosquitoes breed; and
* low-volume chemical control with pyrethroid pesticides.
When DDT is used for malaria control, it is usually sprayed on the walls inside homes, so risk of exposure is very high. Researchers in Mexico and South Africa found elevated levels of DDT in the blood of those living where DDT was used to control malaria, and breast-fed children in those areas received more DDT than the amount considered "safe" by WHO and the UN Food and Agricultural Organization (FAO).

Evidence also shows that long-lasting residues from DDT house spraying seep into nearby waterways, creating additional pathways of exposure. For example, elevated DDT levels have been found in cow's milk in areas using indoor DDT treatments. In many countries, this adds to exposure from old stockpiles of DDT that are not properly contained or controlled. FAO estimates there are more than 100,000 tons of obsolete pesticide stockpiles in Africa, mostly older chemicals such as DDT.

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