Experimental human exposure to toluene.

The application as biologic exposure parameter of the toluene concentration in venous blood during and after an exposure to this solvent was experimentally studied. Under carefully controlled conditions 6 healthy male subjects were exposed to various concentrations of toluene in inspired air (50, 100, 125, 150 and 200 ppm) at rest or under different levels of physical effort. Peripheral venous concentrations (C) were followed in relation to the individual toluene uptake. A relatively constant relation was found between uptake rate of toluene and C under steady state conditions. Empirically, for lung clearances at rest and for differing inspired concentrations (C), this relation was given by: C (mg/l) = 0.303 CI (mg/1) x Lung clearance (1/min). Under constant C (50 ppm) and lung clearances varying from rest values to values under a continuous exercise of 50 W, the regression equation became: C (mg/l) = 0.328 C (mg/l) x Lung clearance (1/min). Under non-steady state conditions no simple relation existed between uptake rate and C, indicating that equally no simple connection could be made between C and the calculated mixed venous concentration, or, extrapolating, the expected toxic load of most inner organs. In relation to the individual dose, C always presented a much greater variability than the toluene uptake by itself. The observed differences, both intra-individually as between subjects, were mostly statistically significant. Apparently C was influenced by some host factors in another manner than the uptake rate. In this respect evidence was obtained that the local blood perfusion and the amount body fat were involved to a certain extent. For this reason C proved a somewhat less satisfactory individual dose-parameter. [ABSTRACT FROM AUTHOR]