title: Ultrafine particle deposition and clearance in the healthy and obstructed lung.
abstract: Numerous epidemiologic studies have shown associations between exposure to particulate air pollution and acute increases in morbidity and mortality, particularly in persons with chronic obstructive pulmonary disease. The dosimetry of ultrafine particles in the human lung is poorly characterized. We studied the deposition and clearance of an ultrafine technetium-99m-labeled aerosol in 10 patients with chronic obstructive pulmonary disease and in 9 healthy subjects. Particle retention was followed for 2 hours after inhalation and again at 24 hours by gamma scintigraphy. Central-to-peripheral ratios indexed airway deposition. Particle accumulation in the liver was examined by quantifying activity below the right lung. The dose rate for an aerosol exposure of 10 micro g/m(3) was calculated. Patients had a significantly greater dose rate than healthy subjects (2.9 +/- 1.0 versus 1.9 +/- 0.4 micro g/h, p = 0.02). Central-to-peripheral ratios were slightly greater in patients than in healthy subjects (1.11 +/- 0.10 versus 1.01 +/- 0.11, p = 0.05). Clearance did not statistically differ between health and disease. On average, 24-hour retention was 85 +/- 8% (corrected for isotope dissolution). No accumulation in the liver's vicinity was observed. Data suggest that relative to healthy subjects, patients with moderate-to-severe airways obstruction receive an increased dose from ultrafine particle exposure.
authors.affiliation: Center for Environmental Medicine and Lung Biology, University of North Carolina at Chapel Hill, 27599, USA. brown.james@epa.gov
authors.forename: James S
authors.initials: JS
authors.lastname: Brown
authors.forename: Kirby L
authors.initials: KL
authors.lastname: Zeman
authors.forename: William D
authors.initials: WD
authors.lastname: Bennett
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000336:Aerosols / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000368:Aged; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000503:physiopathology; D008102:Liver Circulation / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009079:Mucociliary Clearance / Q000502:physiology*; D010316:Particle Size; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011877:Radionuclide Imaging; D012016:Reference Values; D012129:Respiratory Function Tests; D013997:Time Factors
chemical_list: D000336:Aerosols