Chlorinated Hydrocarbon Pesticides

Chlorinated hydrocarbon pesticides are used widely in agriculture, structural pest control, and malaria control programs around the world. Lindane is used medicinally for the treatment of lice and scabies. Chlorinated hydrocarbons are of major toxicologic concern, and many (eg, DDT [dichloro-diphenyl-trichloroethane] and chlordane) have been banned from commercial use because they persist in the environment and accumulate in biological systems. Despite being banned decades ago, these substances are still being measured in the environment and food chain in ongoing studies. In 2002, sale of lindane was banned in California.

Mechanism of toxicity
1. Chlorinated hydrocarbons are neurotoxins that interfere with transmission of nerve impulses, especially in the brain, resulting in behavioral changes, involuntary muscle activity, and depression of the respiratory center. They may also sensitize the myocardium to arrhythmogenic effects of catecholamines, and many can cause liver or renal injury, possibly owing to generation of toxic metabolites. In addition, some chlorinated hydrocarbons may be carcinogenic.
2. Pharmacokinetics. Chlorinated hydrocarbons are well absorbed from the GI tract, across the skin, and by inhalation. They are highly lipid-soluble and accumulate with repeated exposure. Elimination does not follow first-order kinetics; compounds are released slowly from body stores over days to several months or years.

Toxic dose. The acute toxic doses of these compounds are highly variable, and reports of acute human poisonings are limited. Table II–21 ranks the relative toxicity of several common compounds.

Table II-21 Chlorinated Hydrocarbons

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