Ddt
DDT ranks among the most infamous acronyms in history. During the mid-twentieth century, its effectiveness at killing insects made it one of the miracle products of wartime investments in science and technology. Yet within thirty years, many industrialized countries banned the synthetic insecticide due to fears of its long-term effects on humans and wildlife. At the turn of the twenty-first century, the devastating resurgence of malaria across the developing world reignited debates over the ethics of using DDT.
The chemical compound that is DDT, dichlorodiphenyl-trichloroethane, was first synthesized in 1873, but not until 1939 did Swiss chemist Paul Müller discover its insecticidal properties. The U.S. military used DDT during World War II to protect soldiers and civilians from the destructive insect-borne diseases typhus and malaria. DDT's persistence and its broad spectrum of action made it extremely successful at killing insects over a long period, in small doses, and at low cost. In response to civilian demand, the U.S. government made the celebrated chemical available to the public in 1945, despite private concerns among federal scientists of potential long-term hazards. The agricultural and public health promise of DDT led to mass aerial spraying programs, and Müller won the 1948 Nobel Prize in physiology or medicine. Production by U.S. companies increased from 10 million pounds in 1944 to more than 100 million pounds in 1951.
Rachel Carson burst the bubble of confidence concerning the safety of DDT in 1962 with her best-selling exposé of the overuse of synthetic chemical pesticides, Silent Spring. The book publicized scientific evidence of the toxic effects of DDT on humans and animals, including nervous system dysfunction, reproductive abnormalities, and cancer. It explained how DDT's insolubility in water and fat-solubility enable it to persist in the soil and water, enter the food chain, and accumulate in the fatty tissues of non-target organisms such as the bald eagle, whose plummeting numbers were linked to DDT-induced eggshell thinning. Silent Spring also showed how mosquitoes and other target insect populations develop genetic resistance to DDT, thereby undermining its efficacy.
Carson criticized the arrogance of entomologists who presumed they could control pests by waging chemical warfare. She made a strong ethical argument for the need to respect the other creatures with which humans share the earth. Although some critics accused her of privileging wildlife over people, she testified to Congress on behalf of "the right of the citizen to be secure in his own home against the intrusion of poisons applied by other persons" (Lear 1997, p. 454). Spurred by increasing evidence of DDT's carcinogenicity, Congress banned the sale of DDT in the United States in 1972. Within three decades DDT was banned in thirty-four countries, and severely restricted in thirty-four others. It continued to be used in several developing nations, primarily in the malaria belt.
Since the 1970s, malaria has become one of the deadliest infectious diseases in the world, killing at least 1.1 million people each year. Children under age five comprise more than half the victims. Many environmentalists and health experts blame malaria's huge resurgence on the overuse of both chemical insecticides and anti-malarial drugs, which led their respective targets—anopheles mosquitoes and plasmodium parasites—to develop genetic resistance. Anti-DDT groups advocate preventive methods, including the use of mosquito nets dipped in the nontoxic insecticide permethrin and the cultivation of fish that consume mosquito larvae, as part of a systematic approach to the disease. In their opinion, DDT should be used only as a last resort due to its well-documented negative effects.
In contrast a strong opposition movement argues that DDT is still the cheapest, most effective anti-malarial measure, and that its declining use is responsible for the recent resurgence of malaria. Pro-DDT groups condemn environmentalists for scaring developing countries from using the chemical, and for caring more about bald eagles than suffering children. They point to scientific studies that fail to confirm evidence of long-term risks of exposure to DDT, and contend that it serves as a crucial insect repellent even in placeswhere mosquitoes have become resistant. From their perspective, it is unethical not to utilize DDT as a first resort against malaria, because its life-saving capacity for millions of people outweighs any potential negative environmental or human health effects.
Two women are sprayed with DDT. Although widely used in pesticides in the 1940s and 50s, the compound has been banned in North America and most of Europe since the 1970s due to fears of detrimental long-term effects. (The Library of Congress.)Despite such conflicting outlooks, a compromise was struck in 2001, when delegates from 127 nations signed an international treaty to phase out twelve toxic, persistent, fat-soluble chemicals, including DDT. After intense debate, developing nations received exemptions permitting them to continue using DDT against the mosquito vectors of malaria until safer, affordable substitutes become available. The Stockholm Convention on Persistent Organic Pollutants entered into force on May 17, 2004.
Agricultural Ethics;; Carson, Rachel;; Food Science and Technology.
Bibliography
Carson, Rachel. (1962). Silent Spring. Boston: Houghton Mifflin. A must-read for anyone interested in the impact of synthetic pesticides on human and environmental health.
Lapkin, Ted. (2003). "DDT and the New Colonialists." Quadrant 47: 16–19. Argues for the use of DDT for malaria control.
Lear, Linda. (1997). Rachel Carson: Witness for Nature. New York: Holt. The definitive biography of Carson.
McGinn, Anne Platt. (2002). "Malaria, Mosquitoes, and DDT." WorldWatch 15: 10–17. Argues against the use of DDT for malaria control.
Russell, Edmund P. (1999). "The Strange Career of DDT: Experts, Federal Capacity, and Environmentalism in World War II." Technology and Culture 40: 770–796. Presents new historical evidence about early DDT research.
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