Changes induced by xylene and alcohol in human evoked potentials.

Neurotoxic effects of industrial solvents have recently aroused great interest. Few studies have applied evoked potential methods to test acute or chronic neurotoxicity of solvents or alcohol. Eight young healthy male volunteers were exposed for 4 h to about 1200 or 700 mg/m3 of xylene alone or in combination with alcohol 0.8 g/kg. Single doses of 0.4 g/kg and 0.8 g/kg alcohol were also used as test substances, and the subjects stayed for 4 h in the exposure chamber also during 3 control days. Tests were conducted single-blind and the subjects acted as their own controls. Visual (VEPs) and somatosensory (SEPs) evoked potentials as well as electroretinograms (ERGs) were recorded in the mornings before the exposure and in the afternoons immediately after exposure stopped. A single dose of alcohol 4 h prior to recording increased the latencies of P50, N60, P115 and N155 of VEP dose-dependently. Alcohol alone did not change significantly the amplitude of VEP, but xylene 1200 mg/m3 in combination with alcohol 0.8 g/kg decreased significantly the amplitude of N60-P115. The lower concentration of xylene in combination with alcohol as well as xylene 1200 mg/m3 alone tended to have similar effects. Concerning the latency changes simultaneous xylene exposure tended to counteract the effect of alcohol. No significant effects on ERGs could be shown in any of situations. The effects of SEPs were minor or lacking, and the lower exposure levels were associated with more statistically significant changes than higher exposure levels.