ACUTE EFFECTS OF M-XYLENE INHALATION ON BODY SWAY, REACTION-TIMES, AND SLEEP IN MAN

Nine male volunteers were exposed to either a constant or a fluctuatin g exposure pattern of m-xylene with a time-weighted average exposure c oncentration of 200 ppm in both cases. The subjects remained sedentary throughout the exposure, or the exercised at 100W for 10 min at the b eginning of the morning and the afternoon sessions. In another experim ent, 12 sedentary male volunteers were exposed to a fixed 200 ppm of m -xylene. The effects of m-xylene on body sway, reaction time performan ce, and overnight sleep were measured. Body balance was stabilized aft er exposure to the peaks of 400 ppm of m-xylene in both sedentary and exercising subjects. Simple visual reaction times were prolonged after the peak exposures at rest whereas auditive choise reaction times wer e prolonged after peaks combined with exercise. Exposure to m-xylene a t a constant level of 200 ppm did not affect the ratio of ''active'' t o ''quite'' sleep in the volunteers as measured with the static charge sensitive bed recording, but decreased slightly the number of body mo vements in bed. On the next morning no changes were found in body sway and reaction time performance as compared to the morning before expos ure.