Three groups, each consisting of 6 healthy subjects, inhaled, respectively, 6-μm (aerodynamic diameter), 8-μm, and 10-μm Teflon particles, labeled with indium-111. The particles were inhaled at an extremely low flow rate, 0.05 L/s. Lung retention was measured after 0, 24, 48, and 72 h. Two models were used to calculate particle deposition in the lungs in the various generations: the Karolinska Institute model (KI model) and the University of Southampton model (US model). From the experimental clearance data and the theoretical deposition data, it was calculated that the average retention after 24 h was around 100% for particles deposited in generations 13-16 (ciliated bronchioles) and around 20% in generations 0-12 (both large and small ciliated airways). In these calculations, it was assumed that the retained fractions were independent of particle, size. The depositions in the bronchial region (generations 0-8), bronchiolar region (generations 9-15 or 9-16), and the alveolar region were calculated using the two models and compared with the recent ICRP model. On the whole, the three models agreed fairly well.
Bibliographical noteFunding Information:
Received 21 February 1997; accepted 30 June 1997. We are grateful for skillful technical assistance from Ulla Bergsten, Lars Persson, and Karin Widt-skiold-Olsson. This study was supporited by grants from the European Commission (contract no. F14PCT 950O26), the Swedish Environment Protection Agency, the Swedish Radiation Protection Institute (SSI), the Swedish Heart Lung Foundation, and the Research Funds of Karolinska Institute. Address correspondence to Prof. Per Camner, Division of Inhalation Toxicology, Institute of Environmental Medicine, Karolinska Institute, Box 210, S171 77 Stockholm, Sweden.
- Lung retention
- Mucociliary clearance
- Particle deposition