Deposition and Fate of Inhaled Ethylene Glycol Vapor and Condensation Aerosol in the Rat. Marshall, T.C. and Cheng, Y.S. (1983).Fundam. Appl. Toxicol.3:175-181. Fischer-344 rats were exposed by nose-only inhalation for 30 min to ethylene glycol-14C vapor at a concentration of 32 mg/m3. A second group of rats was exposed for 17 min to an ethylene glycol-14C aerosol formed by condensation of the glycol on 0.1 m67Ga2O3particles. The mass median aerodynamic diameter (MMAD) of the condensation aerosol was 2.3μm (σg=1.8) with an ethylene glycol concentration of 184 mg/m3. Initial radiocarbon body burdens were at glycol levels of 0.7 mg/kg for the vapor exposure and 2.4 mg/kg for the aerosol exposure. Estimates indicated that at least 60of the ethylene glycol inhaled for both exposures was deposited in rats with the highest concentration of radioactivity being in the nasal cavities. Distribution from the site of deposition was rapid since 75 to 80of the initial body burden was found throughout the bodies of rats sacrificed immediately after exposure. The predominant routes of elimination during the first 4 days following exposure were via the expired air as14CO2(63for the vapor exposure and 70for the aerosol exposure) and urine as the unchanged glycol (20and 11). The proportion of the doses excreted as14CO2suggested more complete metabolism of ethylene glycol following inhalation relative to that observed after intravenous injections reported previously. The half-time for clearance of plasma radiocarbon was 39 and 34 hr for the vapor exposure and aerosol exposure, respectively. The studies suggested that ethylene glycol plasma levels following acute exposure to high airborne concentrations of ethylene glycol vapor and/or aerosol would not approach the toxic concentrations associated with known dose-dependent changes in the glycol's metabolis
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