KINETICS OF 1,1,1-TRICHLOROETHANE IN VOLUNTEERS - INFLUENCE OF EXPOSURE CONCENTRATION AND WORK LOAD

Six male volunteers were exposed for 4 h to 70 ppm 1,1,1-trichloroethane (methylchloroform, MC) at rest, to 145 ppm MC at rest and to 142 ppm MC at rest combined with work load (2 times 30 min, 100 work). Minute volume and concentration in exhialed air were measured to estimate the uptake. MC and its metabolites trichloroethanol (TCE) and trichloroacetic acid (TCA) were determined in blood, exhaled air and urine. The uptake/min decreased in the course of exposure to 30% of the initial uptake. The total uptake was more influenced by minute volume than by body weight or amount of adipose tissue. During work load the uptake increased to 2.3-fold and the minute volume to 3-fold the value at rest. In the post exposure period the quotients of the concentrations in blood and in exhaled air for MC and TCE remained nearly constant at 8.2 and 14,000, respectively. Following exposure about 60-80% of the amount taken up was excreted unchanged by the lungs, while until 70 h after exposure the amount of TCE and TCA excreted in urine represented about 2% and 0.5% of the uptake. [This study is relevant to occupational toxicology.].