Neuropsychological function in retired workers with previous long-term occupational exposure to solvents

Abstract

Objectives: It is plausible that neurodegenerative processes of aging might have a contributing role in the development of chronic effects of exposure to organic solvents. This study evaluated the risk for neuropsychological deficits among retired workers, relative to their histories of exposure to occupational solvents.

Methods: This cross sectional study evaluated retired male workers, 62-74 years of age, including 89 people with previous long-term occupational exposure to solvents (67 retired painters and 22 retired aerospace manufacturing workers), and 126 retired carpenters with relatively minimal previous exposure to solvents. Subjects completed a standardised neuropsychological evaluation and psychiatric interview, structured interviews for histories of occupational exposure and alcohol consumption, and questionnaires assessing neurological and depressive symptoms.

Results: By comparison with the carpenters, the painters on average reported greater cumulative alcohol consumption and had lower scores on the WAIS-R vocabulary subtest, usually presumed to reflect premorbid intellectual functioning. These findings, however, were not sufficient to account for the other study findings. Controlling for age, education, vocabulary score, and alcohol use, the painters had lower mean scores on test measures of motor, memory, and reasoning ability; and a subgroup of aerospace workers with moderate to high cumulative exposure to solvents (n = 8) had lower mean scores on measures of visuomotor speed, and motor, attention, memory, and reasoning ability. Subjects were more likely to have an increased number of relatively abnormal test scores (three or more outlier scores on 17 test measures) among both the painter group (odds ratio (OR), 3.1; 95% confidence interval (95% CI) 1.5 to 6.2) and the subgroup of aerospace workers with higher cumulative exposure (OR 5.6; 95% CI 1.0 to 38). The painters, but not the aerospace workers, reported significantly more neurological and depressive symptoms.

Conclusions: The findings are consistent with residual central nervous system dysfunction from long-term exposure to organic solvents, persisting years after the end of exposure.