Neurophysiological and psychophysical measurements reveal effects of acute low-level organic solvent exposure in humans.

The organic solvent tetrachloroethylene (Per) is proposed to be a human neurotoxicant. In order to evaluate whether the sensory system is affected by Per at low concentrations, two groups of male volunteers were exposed in an inhalation chamber to 10 and 50 ppm Per, respectively. During the inhalation exposure, which lasted for 4 h per day on four consecutive days, visually evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were measured. In addition, in some of these volunteers, the visual contrast sensitivity was determined psychophysically. In the group exposed to 50 ppm Per, the VEP peak latencies N75, P100 and N150 increased in the course of the inhalation period. A comparison of the two groups revealed statistically significant differences of these latency changes during Per exposure. In contrast, the BAEPs of the two groups did not differ significantly during the whole exposure period. The contrast sensitivity functions showed a tendency of increased threshold contrasts at low and intermediate spatial frequencies during exposure to 50 ppm Per. The results indicate visual system dysfunctions in terms of delayed neuronal processing time and altered contrast perception due to acute Per exposure.