© 1983 Oxford University Press
research-article |
Clearance of Diesel Soot Particles from Rat Lung after a Subchronic Diesel Exhaust Exposure
Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute P.O. Box 5890, Albuquerque, NM 87185
Clearance of Diesel Soot Particles from Rat Lung after a Chronic Diesel Exhaust Exposure. Griffis, L.C., Wolff, R.K., Henderson, R.F., Griffith, W.C., Mokler, B.V. and McClellan, R.O. (1983). Fundam. Appl. Toxicol. 3:99-103. The participate exhaust of diesel engines consists of 0.1–0.2 µm mass median diameter particles composed of a carbonaceous core and adsorbed organic compounds. A technique was needed to determine accumulated lung burdens of particles in animals exposed to diesel exhaust as a determinant of dose. A method was developed for determining lung burdens of diesel soot particles in rats at 1 day, and at 1, 5, 15, 33 and 52 weeks after cessation of a subchronic exposure to diluted diesel exhaust. Lung tissue was dissolved in tetramethylammonium hydroxide and the diesel soot separated by centrifugation. The soot was suspended in water by sonication and the light absorption of samples was compared to standard suspensions of diesel soot. Recovery from lungs spiked with 50–1000 µg of soot was 89±5%. Rats exposed over a period of 18 weeks to diluted diesel exhaust at average net diesel particle concentrations of 150, 940 and 4100 µg/m3 had lung burdens of 35,220 and 1890 µg/g lung, respectively, one day after the last exposure. The long-term clearance rates of soot had estimated half-times of 87±28, 99±4 days, for the low and medium exposure groups, respectively. The clearance half-time for the high level exposure group of 165 ± 8 days was significantly longer (P < 0.0001) than those of the other two groups.