Experimental human exposure to toluene

Summary Six healthy male subjects exposed to various concentrations of toluene in inspired air (50, 100, and 150 ppm) under controlled conditions of rest or physical exercise, showed markedly little differences in the rate of respiratory solvent uptake. On the whole the intra-individual variations proved as important as the between subjects variations. For a given level of physical exercise the lung clearance appeared most affected by fluctuations in respiratory minute volume. In our experimental group the uptake rate was not significantly influenced by the amount of body fat.Toluene concentrations in expired air (C_E) during the first 4 h after an exposure cannot be considered a reliable measure for the individual toluene uptake. This parameter appears to reflect the influence of a number of host factors which do not affect — or at least not in the same way — the toluene uptake by itself. As a consequence the observed variability of toluene in the expired air was always much greater than for the related lung clearances. The single most important factors explaining differences in respiratory solvent excretion, were the respiratory minute volume in the post-exposure period and, after exposures at rest, the amount of body fat.The mean excretion amounted to about 4 % of the total uptake within 24 H after the end of the exposure.