Biphasic changes in mouse motor activity during exposure to toluene.

There are few careful studies of the effects of solvents on unlearned animal behavior during acute exposure, despite the importance of the prevention of acute behavioral or neurological effects in the workplace. To examine the effects of toluene on the locomotor activity of mice, we divided a plastic vacuum desiccator into six wedge-shaped compartments with diffusing plena above and below. A phototransistor in each wedge measured the movement of individual mice, thus each mouse could serve as its own control. Six groups of six mice were exposed to each of five concentrations of toluene (300-3000 ppm) or air in a Latin-square design for 1 hr on Tuesdays and Fridays. Individual animals differed in their sensitivity to toluene, and the use of each subject as its own control permitted the detection of effects at lower concentrations. The magnitude of the effect was related to concentration, the duration of exposure, and the control rate of activity. Activity increases were obvious at 560 ppm, and decreases at 3000 ppm. The concentrations at which these reversible activity increases occurred are the lowest reported to date and are only slightly greater than those that have been reported to alter human reaction time. This preparation displays sensitivity comparable to that observed in published studies of the effects of toluene on learned behavior in the rat.