DDT

Chem.

a white, crystalline, water-insoluble solid, C₁₄H₉Cl₅, usually derived from chloral by reaction with chlorobenzene in the presence of fuming sulfuric acid: used as an insecticide and as a scabicide and pediculicide: agricultural use prohibited in the U.S. since 1973. Also called dichlorodiphenyltrichloroethane, chlorophenothane.

[d(ichloro)d(iphenyl)t(richloroethane)]

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in full dichlorodiphenyltrichloroethane

Synthetic insecticide belonging to the family of organic halogens.

In 1939 its toxicity to a wide variety of insects was discovered (by Paul Hermann Müller, who was awarded a Nobel Prize for his work) and effectively used against many disease vectors. By the 1960s, many species of insects had developed populations resistant to DDT; meanwhile, this highly stable compound was accumulating along the food chain and having toxic effects on various birds and fishes. During the 1960s it and similar chemicals were found to have severely reduced the populations of certain birds, including the bald eagle.

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▪ chemical compound

abbreviation of  dichlorodiphenyltrichloroethane,  also called  1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane,  

 a synthetic insecticide belonging to the family of organic halogen compounds, highly toxic toward a wide variety of insects as a contact poison that apparently exerts its effect by disorganizing the nervous system.

      DDT, prepared by the reaction of chloral with chlorobenzene in the presence of sulfuric acid, was first made in 1874; its insecticidal properties were discovered in 1939 by a Swiss chemist, Paul Hermann Müller (Müller, Paul Hermann). During and after World War II, DDT was found to be effective against lice, fleas, and mosquitoes (the carriers of typhus, of plague, and of malaria and yellow fever, respectively) as well as the Colorado potato beetle, the gypsy moth, and other insects that attack valuable crops.

      Many species of insects rapidly develop populations resistant to DDT; the high stability of the compound leads to its accumulation in insects that constitute the diet of other animals, with toxic effects on them, especially certain birds and fishes. These two disadvantages had severely decreased the value of DDT as an insecticide by the 1960s, and severe restrictions were imposed on its use in the United States in 1972.

      Pure DDT is a colourless, crystalline solid that melts at 109° C (228° F); the commercial product, which is usually 65 to 80 percent active compound, along with related substances, is an amorphous powder that has a lower melting point. DDT is applied as a dust or by spraying its aqueous suspension.

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