Psychological test methods: sensitivity to long term chemical exposure at work.

Five studies dealing with long term occupational exposure to carbon disulfide, a mixture of organic solvents, toluene, styrene and lead are reviewed. All of the studies were cross-sectional, comprising either a comparison between exposed and nonexposed groups or the determination of exposure-response relationships, or both. The tests for the cognitive functions were known clinical intelligence and memory tests. The perceptual and psychomotor tasks were the Santa Ana test, the Bourdon-Wiersma test for visual-motor speed and accuracy, the Symmetry Drawing test and the Mira test. In four of the five studies the neurotoxic effect involved both cognitive and psychomotor functions. In the carbon disulfide group, psychomotor retardation was the most pronounced effect: in the group exposed to solvent mixtures the main effects were seen in the cognitive functions. The effects of styrene were limited to perceptual and psychomotor disturbances. As the most sensitive methods have varied from study to study, the continued use of broad and diverse psychological methodology in studies dealing with long term neurotoxic effects is proposed.