Results were: exposure of mice for 4 hours to phosgene concentrations ranging from 0.1 ppm to 0.5 ppm resulted in a significant increase in pentobarbital-induced sleeping time vs. air-exposed animals. Blood pentobarbital levels were measured following a 4 hr exposure to 0.5 ppm phosgene. Although there were no significant differences in the slopes of the clearance curves for phosgene- and air-exposed animals, the half life of pentobarbital was increased by 35%. In separate studies, cytochrome P-450, body weights and liver weights were determined for mice exposed to 0.5 ppm phosgene or to filtered air for 4 hrs. No differences were observed for any of the measurements. These results suggest that phosgene has extrapulmonary effects without causing direct effects on the cytochrome P-450 levels. (Copyright (c) 1988 Hemisphere Publishing Corp.)