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DDT


Chemical structure of DDT

Wikipedia Commons

DDT (dichloro-diphenyl-trichloroethane) was first synthesized in 1874, but its insecticidal properties were not discovered until 1939. Although only slightly toxic to mammals, the compound is lethal to most insects, acting by causing the nerves to fire uncontrollably. It is a colorless solid with a faint "chemical" smell that is insoluble in water but dissolves readily in many organic solvents. It was synthesized from chlorination of ethanol and benzene, which were then combined using sulphuric acid as a catalyst. DDT proved invaluable for controlling the mosquitos that transmit malaria. The combination of DDT for mosquito control and Atabrine for prophylaxis, together with other mosquito controls such as mosquito netting and proper clothing, reduced the incidence of malaria from up to 80% in some units to less than 10%.

Britain and the United States obtained their first samples of DDT via the American military attaché in Berne in 1942. The Allies were impressed with the new insecticide. Unlike the pyrethrins in use at the time, and which were in short supply, DDT continued killing insects for weeks following an application.Manufacture of DDT was given top priority, and the insecticide went into production in Britain and the United States in 1943.

Use of DDT was not restricted to rear areas. By 1944 DDT was being dusted over invasion beaches even before the first troops went ashore, supressing the mosquitos at the same time that conventional bombardment was supressing the Japanese. However, the use of DDT at the front lines at Peleliu did not noticeably reduce the swarms of flies that tormented the Marines. It was concluded that the insecticide, while effective against the adult flies, did not have much effect on the larvae, with the result that the flies bred more rapidly than they could be destroyed. However, the relatively low rate of malaria and other tropical diseases during the campaign suggests that DDT was effective against the usual disease vectors.

Although DDT as an insecticide was discovered by the Swiss chemist Paul Hermann Müller and its production and use was no military secret, there is no evidence the Japanese made use of DDT. As a result, and in spite of the Japanese monopoly on quinine following their seizure of Java, malaria rates among Japanese troops remained high. This was particularly true in units that were cut off by the Allied advance, where death rates from disease rose to frightening levels.

References

Hough (1950; accessed 2011-6-3)

Sherman (2011)



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