[Changes in blood toluene concentrations in rats under various kinds of exposure conditions and physical loads]

The present experiment was conducted under the assumption that exposure conditions (time of exposure, concentration of exposed substances and working intensity) should be taken into account in estimating the level of invasion of injurious substances into the human body. Experiments were carried out on rats under various exposure conditions of toluene and the toluene concentration in the blood was monitored for the estimation of its intake. The results were as follows; 1. It was confirmed that toluene concentration in blood increased and plateau-time was delayed in proportion to increase in exposure concentration. 2. Light exercise (5.0, 7.0 m/min) increased toluene concentration in blood and it was proportioned to intensity of physical exercise. 3. Light daily exercise (2.7 m/min) for six days increased toluene concentration in blood gradually day after day when compared to exposure without exercise, though the exposure conditions were the same every day. It is thus considered that physical exercise is one of the very important factors in estimation of exposure.