The Excellent Powder
Wednesday, April 21, 2010
DDT was the most important life-saving chemical of the past century and, until a better chemical comes along, it will be one of the most important of the first few decades of this century too.
Winston Churchill was the first national leader to applaud the insecticide DDT. Sixty-six years ago, when prime minister of Britain, he praised the “excellent powder,” which was preventing thousands of allied troops, refugees, and other victims of war from dying of typhus, yellow fever, and malaria. For the next 20 years, DDT became seen as the world’s most successful public health insecticide, saving millions of lives from insect‐borne diseases. It helped eradicate lethal diseases from dozens of countries, including the United States and, by the 1970s, all of Europe.
But one book, Silent Spring by Rachel Carson, changed DDT from global savior to global pariah. Published in 1962, its influence was gradual but irrevocable. Carson made emotional claims of great harm to wildlife and human health, but these were easy to test, and most proved false. The persistence of DDT, which made it so valuable as a long-lasting insecticide, meant that it did bio-accumulate up the food chain; as a precaution, it was banned for widespread agricultural use in most countries. Yet despite decades of use in disease prevention, with hundreds of millions being exposed to moderate levels of the chemical, no one has been able to show human harm from it. Claims of DDT’s harm to human health fail the most basic epidemiological criteria required to prove cause-and-effect relationships. Indeed, after thousands of studies on its effects, DDT remains the world’s most misunderstood chemical.
Despite decades of DDT use in disease prevention, with hundreds of millions being exposed to moderate levels of the chemical, no one has been able to show human harm from it.
As the recent revelations about climate science attest, once the preferred political decision has been reached, the science supporting this conclusion is funded and promoted, leading to a reinforced policy position. But eventually truth will win out and when people understand how policy decisions have become corrupted, uncertainty and outrage remain. In many respects the misuse of scientific evidence on DDT is far worse than the recent revelations of Climategate.
The new book, The Excellent Powder: DDT’s Political and Scientific History, of which I am a secondary author, describes how, over many decades, manipulations of data, science, and opinions turned perceptions of DDT from a life-saving chemical to the totemic villain for the environmental movement. Even supporters of DDT for disease control may be surprised that DDT never caused the near extinction of several bird species, such as the bald eagle and peregrine falcon. The Excellent Powder provides a detailed account of the actual threats to these species and describes the actions, unrelated to DDT, which secured their survival.
Orchestrated, well‐financed, often earnest but erroneous campaigns forced most countries to ban DDT at huge costs in loss of human life and welfare.
Orchestrated and well‐financed campaigns to demonize DDT have driven many countries to ban the chemical at huge costs in loss of human life and welfare. The bans were based on myths and unwarranted fears. Most campaigners were guilty of nothing more than wanting to preserve the environment. But others, concerned about human population explosion, were far more pernicious. They actively opposed DDT use because of its life-saving capability.
The Excellent Powder sets the record straight about this chemical, exposes the odious and the heroic, and explains why DDT continues to save tens of thousands of lives in poor countries today—and could save tens of thousands more.
Yet while the political fights and name-calling are discussed at length in the book, some of the most important aspects are the scientific details, which have direct relevance for future disease control. Indeed, despite decades of scientific evidence about how DDT works and the effects it has on human and environmental health, widespread erroneous perceptions about the nature and function of DDT continue.
DDT’s effectiveness as a public health insecticide lies not with how many mosquitoes it kills, but in how many it repels.
Most critically, searches for alternatives to DDT, which are woefully funded, also miss the most important attribute of the chemical. DDT’s effectiveness as a public health insecticide lies not with how many mosquitoes it kills, but in how many it repels. By keeping malaria‐bearing mosquitoes away from the people they could infect, the chemical breaks the cycle of infection and death. Of course, alternatives to DDT for disease control exist and they should be deployed; unfortunately they are often used where DDT would be more effective.
Along with penicillin, DDT was the most important life-saving chemical of the past century and, until a better chemical comes along, it will be one of the most important of the first few decades of this century too.
Roger Bate is the Legatum Fellow in Global Prosperity at the American Enterprise Institute. He is co-author with Donald Roberts, Richard Tren, and Jennifer Zambone of The Excellent Powder: DDT’s Political and Scientific History.
FURTHER READING: Bates specializes in pharmaceuticals and developing countries. His most recent work for THE AMERICAN includes “Investing in India: Art of the Impossible?” “How Prosperous Are We?” and “India’s Counterfeit Claims on Counterfeit Drugs.” He and several coauthors responded to scholarly material by commenting on “DDT and Urogenital Malformations in Newborn Boys in a Malarial Area.” And he recently spoke to Harvard Medical School on “Fake Drugs.”
Image by Darren Wamboldt/Bergman Group.