High levels of DDT can accumulate in people in sprayed homes, such as this home in a Mozambique village.
Image: Flickr/Gates Foundation
DDT and its metabolites are all-but indestructible; they accumulate in the Arctic and concentrate atop food chains. Traces are still found in the breast milk of women worldwide. The chemical thins eggshells, causing near-extinctions of eagles and other birds in the 1960s and ‘70s. In humans, a growing body of evidence links it to miscarriages, abnormal brain development, hypertension, diabetes and cancer.
In Africa, seven countries – South Africa, Mozambique, Eritrea, Swaziland, Mauritius, Zambia and Gambia – report using DDT in the past few years, and the number of nations is likely to increase in response to the African leaders’ recent decision.
Statistics are spotty, but according to UNEP, an average of 3,716 tons of the chemical are produced each year. India is the biggest user, followed by South Africa.
Although mosquitoes are resistant in some regions, DDT remains an effective weapon. “It turns out that it’s a better repellant than a killer,” Hammock said. “DDT can be very useful in malaria control today. If we can keep the mosquitoes out of the house, we could do a lot to break the malaria cycle. We don’t have to kill every mosquito… but we can break the zoonosis [disease spreading from animals to people] and control 90 percent of malaria.
“This will undoubtedly get me thrown out of the Sierra Club [but] if we were using DDT to coat walls [in Africa] or coat mosquito nets, we could…dramatically reduce human suffering," Hammock said.
Yet people in Africa can be exposed to extremely high doses because it is sprayed on walls inside homes. The DDT concentrations in the breast milk and blood of South African villagers exceed those found in Americans and Europeans decades ago. The few health studies that have been conducted in these villages have yielded some disturbing results: DDT has been linked to low sperm counts and semen quality in highly exposed South African men, and to urogenital defects in baby boys.
Concerned about these high exposures, a panel of 15 U.S. and South African health scientists issued a statement in 2009 saying that DDT should be used only as a last resort. They also urged the monitoring of people in homes where DDT is sprayed.
That same year, UNEP executive director Achim Steiner called DDT “a simplistic option of a previous age” and promised “innovative solutions” and “sustainable choices.”
But last spring, UNEP’S DDT expert group approved the pesticide’s ongoing use for disease control, citing the “lack of new active ingredients with new modes of action and long lasting efficacy to replace DDT.”
The only other chemicals approved for indoor mosquito control – carbamates and organophosphates – are deemed too expensive and wear off too quickly to be used where the need is greatest.
“If we stop using it [DDT], we are sentencing our people to death,” the South African representative declared at the recent African leaders’ meeting, according to the Nigerian newspaper, Premium Times. “Every other continent used DDT to eradicate malaria, so why is our turn different in Africa?”