Neurotoxicity of solvent mixtures in spray painters

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Abstract
A multidisciplinary cross-sectional study was performed to examine the chronic neurotoxicity of organic solvents. Participating in the study were 105 persons employed as spray painters and having long-term solvent exposure (10–44 years) and a control group consisting of 58 construction workers, electricians, and plumbers without occupational contact to solvents. Samples were matched for age, preexposure intelligence level, occupation, and socioeconomic status. After controlling for potentially non occupational confounding factors (neuropsychiatric diseases, metabolic disorders, high blood pressure, alcohol intake) 83 spray painters and 42 controls were entered finally into the study. The evaluation included work history, self-rating questionnaire, neurologic investigation, psychiatric analysis using the Present State Examination (PSE), psychological testing, and computerized axial tomography (CAT) of the brain. Physical and neurologic examinations demonstrated no case of overt disorders of the central or peripheral nervous system. An important result of the psychiatric analysis was that the syndromes “special features of depression” and “loss of interest and concentration” occurred significantly more frequently among spray painters than among controls. Further analyses demonstrated an association with chronic exposure over 30 years and repeated acute neurotoxic effects during solvent exposures. Neither psychological nor performance tests demonstrated any statistically significant differences in the performance sets after adjustment according to premorbid intelligence level; this finding supports the presumption of only a low grade of mental dysfunction. Correlation analyses indicated a relationship between subjective health complaints and long-term solvent exposure; however, the effect of age cannot be completely ruled out. Visual evaluation of CAT scans of the brain demonstrated significantly higher values for spray painters on the Cella media index, a measure of the inner liquor system of the brain. None of the other CAT parameters of inner or external brain atrophy showed significant differences. The rate of diffuse cerebral atrophy was not increased in spray painters. No statistical relationship between the solvent exposure index and CAT parameters was found by correlation analysis. In summary, the results do not support the hypothesis of an increased risk of solvent-induced encephalopathy among spray painters. It is not possible to establish a typical picture of central nervous system dysfunction due to chronic solvent exposure. Differences in the frequency of PSE symptoms “special features of depression” and “loss of interest and concentration” could be considered solvent related only if long-term (on average 30-year) exposure in combination with repeated acute neurotic effects had occurred. Cerebral atrophy beyond that of normal aging was not found in long-term exposed spray painters.