ELECTROPHYSIOLOGICAL INVESTIGATION OF CENTRAL, PERIPHERAL AND AUTONOMIC NERVE FUNCTION IN WORKERS WITH LONG-TERM LOW-LEVEL EXPOSURE TO CARBON-DISULFIDE IN THE VISCOSE INDUSTRY

Objective: Neurotoxicity of carbon disulphide (CS2) is well known. The air concentration at the workplace at which such adverse effects can first be observed is the subject of controversial discussion. Methods: In a cross-sectional study on CS2-exposed workers peripheral motor an d sensory nerve conduction studies, somatosensory evoked potentials, t hermotesting and investigation of forced respiration sinus arryhtmia h ave been carried out. The data from 222 workers exposed to CS2 in the viscose industry were evaluated and compared with data from 191 employ ees from the same factory with similar physical and psychological stre ss factors but without detectable occupational contact to neurotoxic s ubstances. Median exposure to CS2 was below the currently valid occupa tional-medical threshold limit value (MAK-value) of 10 ppm. Multiple l inear or multiple logistic regression analysis was used to check for s tatistical differences. Results: Binary evaluation (comparison of expo sed persons versus controls after multiple linear regression) revealed a slightly lower value in the exposed group for the motor nerve condu ction velocity (MNCV, -0.76 m/s, median 48 m/s), but a long way from p athological thresholds. No dose-response relationship could be found w ithin the exposed group for any evaluation criteria of CS2-exposure. S omatosensory evoked potentials, thermotesting and analysis of heart ra te variability yielded no indication of a neurotoxic effect of CS2. Co nclusion: Isolated decrease of MNCV in binary evaluation is, with rega rd to the known mechanism of CS2-neurotoxicity and the lack of a dose- response relationship, obviously not due to toxic effects. We interpre t our results as showing that an adverse effect of carbon disulphide a t the exposure ranges found was not detectable in the exposed group.