Distribution and elimination of 2-[14C]-acetone in mice after inhalation exposure

This study was undertaken to determine the tissue distribution and elimination of acetone and its metabolic radioactive fragments in mice after exposure to about 1,200 mg/m3 (500 ppm) of 2-[14C]-acetone vapor. The tissue concentrations of acetone seemed to reach steady state plateaus within 6 h of exposure. In the adipose tissue the maximal concentration was about one-third of that in the highly perfused nonadipose tissues, in which acetone was rather evenly distributed. The contents of radioactivity also reached a plateau within 6 h of exposure in all tissues except the liver and brown adipose tissue. In these tissues the radioactivity increased during exposures up to 24 h. Prolonging the exposure time from 6 h to 6 h/d for three and five consecutive days gave no or only a small additional accumulation of radioactivity in all tissues except adipose tissue. The half-times of acetone after 6 h of exposure were between 2 and 5 h in all tissues. Almost equal amounts of acetone were excreted via the lungs unmetabolized or metabolized to carbon dioxide. In all tissues endogenous levels of acetone were reached within 24 h after exposure. Thus, acetone did not accumulate after prolonged or repeated exposure to concentrations of 1,200 mg/m3.