Influence of aliphatic alcohols on the hepatic response to halogenated olefins.

The role of alcohols in potentiating the toxicity of halogenated hydrocarbon solvents has been reviewed. The toxicity of carbon tetrachloride and chloroform can be markedly potentiated by prior treatment with ethanol or phenobarbital. Trichloroethylene toxicity may also be potentiated by ethanol ingestion. Prior ethanol ingestion acts by altering biochemical parameters that result in an increased response to subsequent solvent exposure. Simultaneous exposure to both ethanol and trichloroethylene allows for competitive substrate inhibition of metabolism since these compounds share several common enzymatic pathways. Thus the toxic response to multiple exposures varies depending upon the time sequence and the comparative levels of the individual components. Phenobarbital apparently potentiates solvent toxocity by induction of the microsomal mixed function oxidase system. Ethanol, either on a chronic or single dose basis, also has the ability to stimulate this enzyme system. Although alteration of the microsomal mixed function oxidase system by chronic ethanol ingestion may play an important role in potentiation of solvent toxicity, the potentiation seen following a single dose of ethanol cannot be fully accounted for by the known effects of ethanol on the mixed function oxidase system. In addition to ethanol a large number of other alcohols will markedly potentiate the hepatotoxic response to solvents such as carbon tetrachloride and chloroform. The mechanisms involved in such potentiation are not known at the present time.