Carbon disulfide exposure and neurotoxic sequelae among viscose rayon workers

Abstract

In Norway's only viscose rayon plant, carbon disulfide (CS₂) concentrations in ambient air usually were between 30 and 50 mg/m³ during the first 23 years of production. From 1970/1971 until the factory was closed in 1982, corresponding values were 10–25 mg/m³. Through all of these years, high peak exposures of CS₂ and H₂S occurred. In 1986, 16 of the 24 men still at work in 1982 and with at least 10 years' experience in the spinning room agreed to participate in this study. Clinical neurological examination demonstrated abnormalities in 15; neuropsychological tests showed impairments of probable organic origin in 14. Thirteen had cerebral atrophy demonstrated by cerebral computed tomography (CT). Electromyography (EMG) was abnormal in six, neurography in 11. Regional cerebral blood flow measurements indicated flow asymmetries in eight, whereas Doppler investigation of the extracranial carotid and vertebral arteries, electroencephalography (EEG), and evoked response investigations were mostly normal. Based on these results and the exposure data, a diagnosis of CS₂-induced encephalopathy was reached in eight workers; another six had an encephalopathy in which CS₂ exposure was regarded as a partial cause. Correspondingly, seven had a neuropathy probably caused by CS₂ exposure alone; in three others, CS₂ was found to be the partial cause of a neuropathy. This indicates that long-term, relatively moderate exposure to CS₂ in association with high peak exposures to CS₂ and H₂S involves a substantial risk of developing neurotoxic disease.