Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride.
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Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride.
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DDT was first synthesized in 1874 by the Austrian chemist Othmar Zeidler.
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DDT was used in the second half of World War II to limit the spread of the insect-borne diseases malaria and typhus among civilians and troops.
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Opposition to DDT was focused by the 1962 publication of Rachel Carson's book Silent Spring.
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The book cited claims that DDT and other pesticides caused cancer and that their agricultural use was a threat to wildlife, particularly birds.
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DDT still has limited use in disease vector control because of its effectiveness in killing mosquitos and thus reducing malarial infections, but that use is controversial due to environmental and health concerns.
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DDT is similar in structure to the insecticide methoxychlor and the acaricide dicofol.
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DDT has been marketed under trade names including Anofex, Cezarex, Chlorophenothane, Dicophane, Dinocide, Gesarol, Guesapon, Guesarol, Gyron, Ixodex, Neocid, Neocidol and Zerdane; INN is clofenotane.
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Commercial DDT is a mixture of several closely related compounds.
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DDT has been formulated in multiple forms, including solutions in xylene or petroleum distillates, emulsifiable concentrates, water-wettable powders, granules, aerosols, smoke candles and charges for vaporizers and lotions.
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In insects, DDT opens voltage-sensitive sodium ion channels in neurons, causing them to fire spontaneously, which leads to spasms and eventual death.
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DDT resistance is conferred by up-regulation of genes expressing cytochrome P450 in some insect species, as greater quantities of some enzymes of this group accelerate the toxin's metabolism into inactive metabolites.
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Genomic studies in the model genetic organism Drosophila melanogaster revealed that high level DDT resistance is polygenic, involving multiple resistance mechanisms.
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DDT was first synthesized in 1874 by Othmar Zeidler under the supervision of Adolf von Baeyer.
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DDT is the best-known of several chlorine-containing pesticides used in the 1940s and 1950s.
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Enthusiasm regarding DDT became obvious through the American government's advertising campaigns of posters depicting Americans fighting the Axis powers and insects and through media publications celebrating its military uses.
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In 1945, DDT was made available to farmers as an agricultural insecticide and played a role in the temporary elimination of malaria in Europe and North America.
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DDT was a way for American influence to reach abroad through DDT-spraying campaigns.
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However, failure to sustain the program, increasing mosquito tolerance to DDT, and increasing parasite tolerance led to a resurgence.
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DDT was less effective in tropical regions due to the continuous life cycle of mosquitoes and poor infrastructure.
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The book argued that pesticides, including DDT, were poisoning both wildlife and the environment and were endangering human health.
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DDT became a prime target of the growing anti-chemical and anti-pesticide movements, and in 1967 a group of scientists and lawyers founded Environmental Defense with the specific goal of enacting a ban on DDT.
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DDT continued to be produced in the United States for foreign markets until 1985, when over 300 tons were exported.
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DDT is applied to the inside walls of homes to kill or repel mosquitoes.
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DDT is a persistent organic pollutant that is readily adsorbed to soils and sediments, which can act both as sinks and as long-term sources of exposure affecting organisms.
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DDT is toxic to a wide range of living organisms, including marine animals such as crayfish, daphnids, sea shrimp and many species of fish.
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Primarily through the tendency for DDT to build up in areas of the body with high lipid content, chronic exposure can affect reproductive capabilities and the embryo or fetus.
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In 2006 WHO reversed a longstanding policy against DDT by recommending that it be used as an indoor pesticide in regions where malaria is a major problem.
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Once the mainstay of anti-malaria campaigns, as of 2008 only 12 countries used DDT, including India and some southern African states, though the number was expected to rise.
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When it was introduced in World War II, DDT was effective in reducing malaria morbidity and mortality.
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DDT can still be effective against resistant mosquitoes and the avoidance of DDT-sprayed walls by mosquitoes is an additional benefit of the chemical.
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The researchers argued that DDT was the best pesticide for use in IRS because the other pesticides worked primarily by killing or irritating mosquitoes – encouraging the development of resistance.
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Unlike other insecticides such as pyrethroids, DDT requires long exposure to accumulate a lethal dose; however its irritant property shortens contact periods.
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For example, DDT use is widespread in Indian agriculture, particularly mango production and is reportedly used by librarians to protect books.
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DDT has one of the longest residual efficacy periods of any IRS insecticide, lasting 6 to 12 months.
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IRS with DDT did not play an important role in mortality reduction in these countries.
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