DDT: the other viewpoint

World Marlaria Day is coming up later this month. So as public health groups gather to bring attention to the mosquito-borne disease that kills almost one million people annually, and inflicts fever and pain on some 500 million more, expect many calls for its eradication.Unfortunately, thanks to activist campaigns and ill-considered European laws, things are likely to get worse before they get better.

The sad truth about malaria is that it persists even though we have had the scientific know-how to combat it since the 1940s. That was when researchers discovered that the chemical dichloro-diphenyl-trichloroethane, or DDT, could stop epidemics of insect-borne diseases like typhus. The chemical soon surpassed all expectations in controlling malaria around the world, and went on to save millions of lives.Thanks to DDT, malaria was eradicated as an endemic disease more than 50 years ago in Europe and the U.S. It is today a disease of the poor, afflicting 109 countries across Latin America, Asia, and Africa.As environmental awareness took off in the 1960s and 1970s, activists became unduly concerned about the potentially harmful effects of DDT and other pesticides. Much of the worry was scientifically unfounded: DDT largely remains in the local area where it was sprayed, and no studies have been able to link environmental exposure to DDT as a specific cause of harm to human health.Moreover, because of the unique ways in which DDT works to keep mosquitoes out of houses, there was (and is) no alternative that combats malaria with the same efficacy.The U.S. Environmental Protection Agency banned DDT for almost all uses in the 1970s, and the anti-insecticide movement went on to achieve global momentum. Even though DDT could legally still be used for malaria control, pressure from environmentalists led international aid donors and health organizations to abandon the chemical. In developing nations with poor medical infrastructure, malaria reemerged.You would think that would have been enough to make anti-insecticide activists reconsider their stance. Instead, in 1997, even as poor countries were suffering from a global pandemic of dengue fever and resurgent malaria, the U.N. World Health Organization adopted a resolution calling on all countries to reduce the use of insecticides for disease control.A decade later, Brussels took a giant step in its own anti-insecticide campaign. In January of 2009, the European Parliament approved new rules to ban certain chemicals used in common pesticides. The new regulations created a great deal of uncertainty, and the implications are still not fully clear. For example, the EU banned substances thought to be "endocrine disruptors," but there is no agreed definition of what one is. Regulators appeared to base their decisions on whether a pesticide was proven hazardous in a lab setting—when they should have focused on the real world risks based on how pesticides are actually used.Though the rules apply only to the EU, the global harm that could come out of this is very real. Haphazard rulemaking scares away producers, even before a ban goes into effect. With fewer manufacturers in the marketplace, prices go up, making the chemical harder and harder to obtain.As a result of this process, over the past few years some 75% of the insecticides used in agriculture in Europe have come off the market. In other words, just when we need a greater variety of insecticides for public health applications, we are left with an ever-dwindling number of chemicals.Bans also scare off exporters: Many developing countries have stopped using DDT to fight human diseases for fear that their agricultural exports will not be allowed into Europe if the tiniest residues happen to be found on produce.If we really want to roll back malaria, regulators will have to start making decisions based on sound science. The decades-long drive to ban DDT and other pesticides has done just the opposite, advancing the unfounded belief that somehow all chemicals are harmful in any amount.The truth is that nearly everything we consume contains potentially hazardous chemicals. Coffee and wine have carcinogens in them, and the icing on chocolate cake includes tannins, an acidic substance that can cause anemia if ingested in excessive quantities. Whether such chemicals harm us or not depends on the dose and circumstances. To eliminate chemicals from our lives simply because they are man-made would mean eliminating most of modern medicine and agricultural science.Besides, a vast body of evidence shows that many natural substances are far more biologically active and potentially harmful than our man-made chemicals, which are heavily tested for harmful effects long before they appear as commercial products.By all means we should have big goals for World Malaria Day. But before we can achieve them, we'll have to start putting science first.Mr. Tren is the director of Africa Fighting Malaria, and Mr. Roberts is a retired entomologist and professor of tropical public health at the Uniformed Services University of the Health Sciences in Bethesda, Maryland. Their book "The Excellent Powder: DDT's Political and Scientific History," will be published later this month by Africa Fighting Malaria.
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