Nervous system effects of occupational exposure to styrene: a clinical and neurophysiological study

Quantitative EEG of 99 workers occupationally exposed to styrene was analyzed and compared to exposure parameters. All of the workers came from reinforced plastics industry. The workplaces and factories were previously evaluated, and the exposure levels were known rather accurately. The exposure information form workplaces and the individual exposure data were combined to form an Exposure Index, which reliably reflected long-term exposure to styrene in various occupational settings. All of the subjects underwent careful medical, neurological, and neurophysiological examinations. Quantitative EEG was recorded from 19 channels and analyzed for absolute and relative power, asymmetry, coherence, frequency distribution, and statistical normative database comparisons (Neurometrics). The EEG data showed a significant increase of abnormal EEG classifications in workers with higher exposure. When the workers were divided into two groups, based on the exposure data, those with higher exposure had higher absolute EEG power in alpha and beta bands in the frontotemporal regions of the brain. The findings indicate that abnormalities in cerebral function can be demonstrated even with relatively low mean exposure levels. It is concluded that the efforts to lower the administrative hygienic levels of styrene have been in the right direction.