Exposure to xylene and ethylbenzene. I. Uptake, distribution and elimination in man.

Industrial xylene is a mixture of xylene and ethylbenzene. Twelve male subjects were exposed to industrial xylene in inspired air, six subjects in series I to 870 mg/m3 at rest (30 min) and light exercise on a bicycle ergometer (90 min) and six subjects in series II to 435 mg/m3 at rest (30 min) and during exercise of increasing work loads (90 min). The measurements of xylene uptake were performed continuously with the Douglas bag technique. In both series, about 60% of the amount of xylene supplied to the lungs was taken up. In both series, the concentration in alveolar air was relatively low throughout the entire exposure. The relative concentration in alveolar air displayed a linear correlation to the percentage uptake in the lungs. The ratio between the concentration in arterial blood (mg/kg) and alveolar air (mg/l) amounted to 30--40 at the different work loads. The total amount of xylene expired after the exposure was estimated from the alveolar concentration and alveolar ventilation. In series I, with a total uptake of 1.4 g, the subjects expired about 70 mg, i.e., about 5%. The corresponding value in series II was 40 mg of a total uptake of 1.0 g, i.e., about 4%.