Estimates of pulmonary and gastrointestinal deposition for occupational fiber exposures.
Dement-JM; Harris-RL Jr.
NIOSH 1979 Apr; :1-81
The fraction of seven types of airborne fibers in 19 industrial settings predicted to be deposited in the deep pulmonary spaces and that fraction that might be ingested were estimated. Deposition estimates also were generated for fibers considered significant for tumor production. An unvalidated mathematical model for predicting the deposition of uniform straight rods of high aspect ratio was used. The pulmonary deposited fraction was considered to be those fibers deposited beyond the ciliated portion of the respiratory system. The ingested or gastrointestinal fraction was assumed to be those fibers cleared by the nasopharynx and tracheobronchial clearance processes and swallowed and was approximated based on the clearance to the gastrointestinal tract of all fibers deposited in the tracheobronchial compartment and 75 percent of those deposited in the nasopharynx beyond the nasal hairs. Partially quantitative results show that the numerical fractions estimated to be deposited in the pulmonary spaces ranged from approximately 3 to 16 percent, while the gastrointestinal fractions ranged from 11 to 59 percent. Large differences in deposition patterns for fibers in the size range considered most important for tumor production in laboratory animals by Stanton et al (1977) also were noted.
NIOSH-Contract; Contract-78-2438; Airborne-particles; Aerosol-particles; Asbestos-dust; Carcinogenic; Lung-congestion; Pulmonary-fibrosis; Gastrointestinal-system-disorders; Glass-fibers; Industrial-health
NTIS Accession No.
(NIOSH) 79-135; Contract-78-2438
National Institute for Occupational Safety and Health