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A typical path model of tracheobronchial clearance of inhaled particles in ratsGeo-Centers Inc., NHRC/TD Building 433, 2612 5th St, Wright-Patterson AFB, Ohio 45433-7903, USA, edgar.kimmel{at}wpafb.af.mil
Geo-Centers Inc., NHRC/TD Building 433, 2612 5th St, Wright-Patterson AFB, Ohio 45433-7903, USA
Naval Health Research Center Toxicology Detachment (NHRC/TD), Wright-Patterson AFB, Ohio 45433-7903, USA A mathematical description of particle clearance from the ciliated conducting airways (tracheobronchial region) of the lungs in rats was developed, assuming that particles on the mucus blanket behave as a fluid and adhere to principles of fluid flow described by the continuity equation. Effective particle transport velocities for given generations of airways were estimated from reported tracheal mucus velocities. Using typical rat airway geometry and estimated particle transport velocities, solutions of sets of rate equations for transport from each generation of airways were summed to estimate total particle clearance from the tracheobronchial region of the lung as a function of time. Aerosol particle size distribution (MMAD ranging from 0.1 to 4.2 µm, and sg from 1 to 2.7) and concentration data from several investigators were used to predict short-term, tracheobronchial clearance (retention) in rats up to 24 h following exposure. Comparisons between predicted and observed retention showed an average difference between model predictions, and observed fractional retention of initial lung or body burden was 4.9%, with a tendency toward underprediction of clearance of particles >3.0 µm.
Key Words: aerosol • model • mucociliary clearance • tracheobronchial • typical path
Toxicology and Industrial Health, Vol. 17, No. 5-10,
277-284 (2001) |
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