INVESTIGATION ON NEUROTOXICITY OF OCCUPATIONAL EXPOSURE TO CYCLOHEXANE - A NEUROPHYSIOLOGICAL STUDY

Objectives-To examine the effect of occupational exposure to cyclohexa ne on the peripheral nervous system. Methods-A nerve conduction study was performed on 18 workers exposed to cyclohexane in a luggage factor y and on age and sex matched occupationally unexposed controls. 12 wor kers had been exposed to n-hexane (median 2.8 years) before the start of exposure to cyclohexane. To confirm the effect of exposure, a follo w up study was performed on nine workers one year after the first stud y. The mean exposure to cyclohexane was 1.2 years in the first study. A symptom survey was performed. The exposure was measured by air sampl ing of the breathing zone of each worker. The urinary metabolite cyclo hexanol was also monitored. Results-The concentration of airborne cycl ohexane ranged from 5 to 211 ppm. The urinary concentration of cyclohe xanol ranged from 0.12 to 1.51 mg/l. There was a strong correlation be tween the cyclohexane exposure in personal air and urinary cyclohexano l. No differences were found in nerve conduction velocities (NCV) betw een workers exposed to cyclohexane and age and sex matched controls. T he results of the follow up study showed significant improvements in p eroneal motor NCV (P < 0.01) and sural sensory NCV (P < 0.05) and in u lnar motor distal latency (MDL, P < 0.05) and peroneal MDL (P < 0.05) compared with the first study. Although the past n-hexane exposure aff ected the first neurophysiological Hokkaido study, the effect had disa ppeared in the second study, one year later. Conclusion-Occupational e xposure to the concentrations of cyclohexane experienced in this study had no adverse effects on the peripheral nervous system.