Risks and Benefits of DDT

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Bis(4-chlorophenyl)-1,1,2-trichloroethane (DDT) has been shown, over the past sixty years, to be one of the few affordable and effective tools against malarial vector mosquitoes, which account for over 300 million cases of disease and more than 1 million deaths every year. However, the Review by Walter Rogan and Aimin Chen (Aug. 27, p. 763), which aims to balance the risks and benefits of DDT, consists mainly of hypothetical concerns while the reality of human suffering gets short shrift.

Rogan and Chen discuss several possible toxic endpoints, including those involving neurobehaviour, cancer, and reproductive health. Yet they point to no evidence that DDT, used as a malaria preventive, causes actual harm to human beings. For each category of illness or dysfunction offered as support for their precautionary approach, there is either no or at best weak data to support a connection to DDT. Rogan and Chen concede that even the few studies that seem to point to a possible adverse effect -- shortened gestation and decreased time until weaning -- have not been associated with actual adverse health outcomes.

The authors call for data from trials. But what sort of trials would suit them when 5,000 die every day, and the weapon to prevent these needless deaths has been known to be effective since the 1940s?

Rogan and Chen's only evidence of harm comes from animal experiments, yet they state that "Various reproductive and hormonal endpoints have been examined...and although associations have been recorded, causal links have not been confirmed," and "In people, DDT use is generally safe."

Should our concerns not be, mainly, with people? Especially when the people being discussed are dying on such a scale from a preventable disease? If this were a laboratory experiment, some debate on the issue might be tolerated. But when on one side of the scales are studies which "are not so flawed that the findings can be dismissed," while on the other side are millions of sick and dead African children, this academic discussion is unacceptable in a scholarly journal.

[1] Rogan WA, Chen A. Health Risks and Benefits of bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT). The Lancet 2005; 366:763-773.
Gilbert Ross, M.D.
Executive and Medical Director
American Council on Science and Health
New York, NY