Psychiatric and neurological symptoms in workers occupationally exposed to organic solvents--results of a differential epidemiological study.

It is accepted knowledge today that repeated intoxication with organic solvents damages the central nervous system and causes persistent psycho-organic symptoms. That long-term but low-level occupational exposure--typical o painters and other blue-collar workers--can also induce such disorders has not generally been recognized. The present epidemiological study was undertaken to evaluate the possible neuropsychiatric effects of such exposure. 80 laquerers exposed to a mixture of industrial solvents (average hygienic effect 0.3) and 37 printers exposed almost only to toluene (average hygienic effect 1.0) were compared with a control group of 80 age-matched non-exposed subjects. In psychiatric interviews, the painters showed more mental symptoms. Fatigue, nervousness and lack of manual dexterity were most important and formed a typical neurasthenic syndrome. A general decrease in conduction velocity and action potential amplitude was also observed for the peripheral nerves. The printers showed a large decrease of the nerve action potential amplitude only for the sural nerve. No EEG abnormalities were found. Nor could any increase in mental symptoms be detected through psychiatric interviews compared to the controls. The results are interpreted as evidence for a CNS affection with consequent neuropsychiatric signs and symptoms after long-term occupational exposure to mixtures of industrial solvents below the current threshold limit values (TLV) but not after exposure to a single substance like toluene at about the TLV. The differential effects may be explained by synergistic amplification of the toxicity of solvent mixtures.