Neurobehavioural effects of solvents: the role of alcohol.

Results from three recent studies suggest that solvent-exposed workers are particularly at risk of disabling psychiatric illness associated with alcoholism. A case-referent study of psychiatric admissions in Quebec found an odds ratio of 5.5 for solvent exposure in patients with a diagnosis of alcoholic dementia, while cohort studies of Swiss and Swedish painters showed greater than expected numbers with alcohol-related psychiatric diagnoses. Simple mislabeling of disease related to solvent exposure does not appear to be the explanation; in the Quebec study the excess risk was essentially confined to those reporting heavy alcohol use. This would suggest that exposure to one substance might potentiate the effect of the other. Concurrent exposure to alcohol and solvents slows clearance of the solvent and might be expected to prolong internal exposure to the neurotoxin. In regular drinkers, elimination of solvent metabolites appears to be faster than in nondrinkers, presumably through enzyme induction. With heavy exposure to alcohol, hepatic function may become impaired, with decreased capacity to detoxify organic solvents. Alcoholic dementia was not included as a diagnosis in the initial studies of the long-term effects of solvents; however, it appears that the interrelation between the two exposures may be more important than previously suspected.