Neurobehavioral effects of occupational exposure to low-level styrene

Eighty-six workers in six fiberglass-reinforced plastics manufacturing plants in Taiwan were given a detailed evaluation including medical and occupational questionnaires, symptom questionnaires, blood sampling, and neurobehavioral tests, including cognitive performance, vibratory perception threshold, and thermal perception threshold. A Chinese version of cognitive tests modified from the Neurobehavioral Evaluation System 2 was applied. Forty-one workers directly exposed to styrene at the mean concentration of 22 ppm are compared with 45 workers not subject to styrene exposure. Multiple linear regression analysis controlling for age, sex, education, and alcohol intake revealed significant associations between styrene exposure and responses in some neuropsychologic measurements. No acute or chronic symptom had significant correlation with styrene exposure. Among the neurobehavioral tests, only the continuous performance test and vibration threshold were significantly and adversely affected in workers exposed to styrene. Significant changes in the central and peripheral nervous system were thus detected at a mean styrene exposure of 22 ppm.