[Somatosensory evoked potentials in workers exposed to toluene]

Abstract

The aim of our study was to evaluated by means of SEPs possible subclinical impairment of the nervous system during long-lasting toluene exposure. A group of 36 rotogravure printers (men, mean age 39.3 +/- 11.6 years) exposed to toluene from a polygraphic plant in Prague was investigated. The severity of toluene exposure was documented by the measurements of toluene concentration in the breathing zone air, by the toluene concentration in blood and by biological monitoring (urinary hippuric acid concentration). The duration of exposure was 0.1-41.0 (mean 12.0) years. Somatosensory evoked potentials (SEPs) elicited by stimulation of the median a tibial nerves, clinical neurological examinations and laboratory tests were performed on each worker. The results of SEPs investigations were compared with findings in a control group of 23 healthy men (mean age 31 +/- 10 years). Most of printers abused alcohol regularly. Peripheral conduction velocities in both extremities and central conduction time in case of lower limb stimulation were decreased statistically significant (P less than 0.05). All abnormalities of SEPs at peripheral and/or spinal and cortical levels were found in 8 cases, of these in 3 workers were found the SEP abnormalities of "central" type (the increased central conduction time at normal conduction values in the periphery). An impairment of all SEP pathways was found in 2 workers. Our results indicate an impairment in both central and peripheral parts of nervous system. Peripheral abnormalities could be interpreted as an incipient ethylic polyneuropathy and central abnormalities as an early sign of subclinical dysfunction at spinal and cortical levels due to toluene exposure potentiated by alcohol consumption.