Neurotoxicity in workers exposed to styrene

Abstract

Quantitative electroencephalography (EEG) for 99 workers exposed to styrene in the reinforced-plastics industry was analysed and compared with exposure parameters. The work places and factories from which the subjects were selected had been evaluated previously, and exposure levels were known relatively accurately. That information and data on individual exposures were combined to create an exposure index, which reliably reflected long-term exposure to styrene in various occupational settings. All of the subjects underwent careful medical and neurophysiological examinations. Quantitative EEG was recorded on 19 channels and analysed for absolute and relative power, asymmetry, coherence, frequency distribution, and statistical normative data base comparisons (neurometrics). When the workers were divided into three groups on the basis of exposure, workers with the highest exposure had significantly more EEGs classified as abnormal and had higher absolute EEG power in alpha band in the fronto-temporal regions of the brain. The findings indicate that abnormalities can occur in cerebral function even after relatively low mean exposures. We conclude that the efforts to lower regulatory hygienic levels of styrene are justified.