Potentiation of occupational carbon tetrachloride toxicity by ethanol abuse.

1. Two separate cases of acute occupational poisoning following exposure to vapours of a fire extinguishing liquid are described. Analytical, clinical, pathological and toxicological data leave little doubt that toxicity was due, in both cases, to inhalation of carbon tetrachloride present at high concentrations ( > 15% and 78% by weight, respectively) in the fire extinguishing liquid. 2. Both subjects were admitted to hospital, 4 and 8 days after exposure, respectively, and developed severe hepato-nephrotoxicity with hepatomegaly, increased values of serum transaminases, blood urea nitrogen (BUN), creatinine, gamma-glutamyl-transpeptidase (gamma-GT), bilirubin and uric acid and, finally, anuria. They recovered in about three to four weeks, after several haemodialytic sessions. 3. Interestingly, in both cases the other workers exposed under the same conditions and for the same period of time as the two patients showed no signs or symptoms of toxicity. The reason for the observed different susceptibility to CCl4 is attributable to an abnormally high ethanol abuse by the two workers, as reported in the clinical records and confirmed by their relatives and colleagues (120 and 250 g per day, respectively). Daily ethanol intake by the coworkers was less than 50 g for all subjects. 4. Although the potentiating effect of ethanol on the toxicity of CCl4 is well known in experimental animals, as a result of cytochrome P-450 induction, direct evidence in humans reported in the literature so far was limited by the lack of information, in all published reports, on the presence or absence of effects in non-alcoholic exposed "controls', when these were present.