Brainstem Auditory Evoked Potentials in Individuals Exposed to Long-term Low Concentrations of Toluene

Brainstem auditory evoked potentials (BAEPs) were examined in 49 workers employed in a printing press, who were occupationally exposed to low concentrations of toluene for an average of 20.3 years, and in 59 subjects in a control group. In the group of exposed workers, a significant decrease was found in all wave amplitudes examined, a significant prolongation of P1 wave latency, and an increased interval of interpeak latencies (P3-P5), indicating that the extramedullary and high medullary part of the auditory pathway are biologically most frequently affected by chronic exposure to low concentrations of toluene. The level of exposure to toluene in both groups was evaluated by defining the concentration of toluene in peripheral blood and the concentration of hippuric acid and ortho-cresol in urine.