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Subject - Organic Chemistry, Toxicology

Dichlorodiphenyltrichlorethane (DDT)

Dichlorodiphenyltrichlorethane (DDT) was developed in 1939 by the Swiss chemist P.H. Müller (Nobel Price in 1948) as an insecticide with broad spectrum activity. It belongs to the class of chlorohydrocarbon insecticides. DDT was of great economic importance and still plays an important role in the fight against malaria because it reduces mosquito populations, the carrier of the malaria parasite.

The effect of DDT is likely based on the continuous excitation of nerve cells by the constant opening of sodium ion channels. In different animals, the mechanism is the same; the large sensitivity differences are based on different uptake mechanisms and rates of metabolism. Frequently, resistance mutations against DDT were observed in insects. In these cases, enzymatic cleavage of HCl transforms DDT into the non-poisonous 1,1-dichloro-2,2-bis[4-chlorophenyl]ethene (DDE).

Because of its broad spectrum of activity, beneficial insects and natural enemies are also effected by the poisonous effects of DDT. The problem is magnified by the long duration of action coupled with high persistence in nature. The long degradation time under typical environmental conditions (the half-life is estimated to be longer than 20 years) causes enrichment of DDT in the food chain, particularly because of its good solubility in fats. Since the disadvantages of DDT far outweigh the advantages, its application in most industrialized countries is now outlawed.

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