title: Deposition and clearance of particles inhaled by beagle dogs previously exposed to SO2.
abstract: The effect of preexisting pulmonary disease on the deposition and retention of inhaled relatively insoluble radiolabeled particles was studied. Two dogs were exposed to 500 ppm sulfur dioxide 2 h/day, 5 days/week for 16 weeks and two dogs were sham-exposed to filtered air for the same period. Dogs exposed to sulfur dioxide developed chronic bronchitis during this exposure period. After the bronchitis had been established for 10 weeks, all 4 dogs were exposed by inhalation to 1.7 micron aerodynamic diameter 134Cs-labeled fused aluminosilicate particles (FAP) and the exposures to SO2 were discontinued. The bronchitis resolved within 4 weeks after SO2 was discontinued. Dogs were periodically whole-body counted and excreta were periodically collected and counted over a 385-day period following the 134Cs exposure. Deposition of the [134Cs]FAP in the pulmonary region averaged 42% for control dogs and 16% for dogs exposed to SO2; deposition in extrapulmonary regions of the respiratory tract averaged 58% for control dogs and 84% for dogs exposed to SO2. Although deposition patterns were different, early and long-term clearance pathways and rates were the same for all dogs, as indicated by analysis of whole body, excreta, and tissues for their burdens of 134Cs.
authors.affiliation: Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico.
authors.forename: S A
authors.initials: SA
authors.lastname: Greene
authors.forename: D L
authors.initials: DL
authors.lastname: Lundgren
authors.forename: M B
authors.initials: MB
authors.lastname: Snipes
authors.forename: R K
authors.initials: RK
authors.lastname: Wolff
mesh_terms: D000336:Aerosols; D000538:Aluminum Silicates / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D000818:Animals; D001991:Bronchitis / Q000139:chemically induced / Q000378:metabolism*; D002908:Chronic Disease; D004285:Dogs; D008168:Lung / Q000378:metabolism; D013458:Sulfur Dioxide; D014018:Tissue Distribution
chemical_list: D000336:Aerosols; D000538:Aluminum Silicates; D013458:Sulfur Dioxide; C049037:aluminosilicate