title: Lung clearance of inhaled particles after exposure to carbon black generated from a resuspension system.
abstract: A system to resuspend carbon black particles for providing submicron aerosols for inhalation exposure studies has been developed. The effect of continuous exposure to carbonaceous material (as a surrogate for the carbonaceous particles in diesel exhaust) on the pulmonary clearance of inhaled diesel tracer particles was studied in male Fischer 344 rats. Submicron carbon black particles with a mass median aerodynamic diameter (MMAD) of 0.22 micron and a size distribution similar to that of exhaust particles from a GM 5.7-liter diesel engine were successfully generated and administered to test animals at a nominal concentration of 6 mg/m3 for 20 hr/day, 7 days/week, for periods lasting 1 to 11 weeks. Immediately after the carbon black exposure, test animals were administered 14C-tagged diesel particles for 45 min in a nose-only chamber. The pulmonary retention of inhaled radioactive tracer particles was determined at preselected time intervals. Based upon the data collected up to 1 year postexposure, prolonged exposure to carbon black particles exhibits a similar inhibitory effect on pulmonary clearance as does prolonged exposure to diesel exhaust with a comparable particulate dose. This observation indicates that the excessive accumulation of carbonaceous material may be the predominant factor affecting lung clearance.
mesh_terms: D000336:Aerosols; D000818:Animals; D002244:Carbon / Q000008:administration & dosage*; D008168:Lung / Q000502:physiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D051381:Rats; D011916:Rats, Inbred F344; D001335:Vehicle Emissions
chemical_list: D000336:Aerosols; D001335:Vehicle Emissions; D002244:Carbon