Carbon Tetrachloride and Chloroform
Carbon tetrachloride (CCl4, tetrachloromethane) was once used widely as a dry cleaning solvent, degreaser, spot remover, fire extinguisher agent, and antihelminthic. Because of its liver toxicity and known carcinogenicity in animals, its role has become limited; it is now used mainly as an intermediate in chemical manufacturing.
Chloroform (trichloromethane) is a chlorinated hydrocarbon solvent used as a raw material in the production of freon and as an extractant and solvent in the chemical and pharmaceutical industries. Because of its hepatic toxicity, it is no longer used as a general anesthetic or antihelminthic agent. Chronic low-level exposure may occur in some municipal water supplies owing to chlorination of biologic methanes (trihalomethanes).
Mechanism of toxicity. Carbon tetrachloride and chloroform are CNS depressants and potent hepatic and renal toxins. They may also increase the sensitivity of the myocardium to arrhythmogenic effects of catecholamines. The mechanism of hepatic and renal toxicity is thought to be a result of a toxic free radical intermediate (trichloromethyl radical) of cytochrome P-450 metabolism. This radical can bind to cellular molecules (nucleic acid, protein, lipid) and form DNA adducts. Bioactivation of CCl4