Dose-dependent disposition of n-hexane in F-344 rats after inhalation exposure

The purpose of this study was to assess the disposition of radioactivity in rats after single inhalation exposures to varying concentrations of [1,2-14C]-n-hexane. Male Fischer 344 rats were exposed to 500, 1000, 3000 or 10,000 ppm 14C-n-hexane for 6 hr and the elimination of radioactivity followed for 72 hr after exposure. The disposition of radioactivity was dose-dependent, with 12, 24, 38 and 62% of the acquired body burden excreted as n-hexane by the lung with increasing exposure concentration. In contrast, 38, 31, 27 and 18% of the body burden of radioactivity was recovered as expired 14CO2 and 35, 40, 31 and 18% was recovered in the urine with increasing n-hexane concentration. Radioactivity remaining in the tissues and carcass 72 hr after exposure represented 6.1, 8.8, 7.4 and 5.4% of the body burden for the respective exposures. The dose-dependent elimination of radioactivity was apparently due in part to an inhibition of n-hexane metabolism, reflected by a decrease in total 14CO2 and urinary 14C excretion after 10,000 ppm exposure compared to the 3000 ppm exposure.