Deposition of radon progeny in nonhuman primate nasal airways
- Inhalation Toxicology Research Institute, Albuquerque, NM (United States)
- Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)
Radon progeny are usually associated with ultrafine particles ranging in diameter from 0.001 to 0.005 {mu}m for {open_quotes}unattached{close_quotes} progeny and from 0.005 to 0.2 {mu}m for those attached to indoor aerosols. To assess the health effects of inhaling indoor radon progeny, it is necessary to study the regional deposition of these inhaled ultrafine particles. Laboratory animals are often used in studies of the toxicity of inhaled particles and vapors. Information on the deposition of particles larger than 0.2 {mu}m in the nasal passages of laboratory animals is available; however, there is little information on the deposition of particles smaller than 0.2 {mu}m. In this report, we describe the use of nasal casts of a rhesus monkey to measure total deposition of ultrafine aerosols, including unattached {sup 220}Rn progeny, in a unidirectional-flow inhalation exposure system. Deposition data were obtained for monodisperse silver aerosols with particle sizes ranging from 0.005 to 0.2 {mu}m, at several inspiratory and expiratory flow rates that represented normal breathing as well as hypo- and hyperventiliation. In addition, we studied the deposition of unattached {sup 22-}Rn progeny, at particle sizes from 0.001 to 0.003 {mu}m. The deposition efficiency decreased with increasing particle size, indicating that diffusion was the dominant deposition mechanism. The effect of flow rate was essentially negligible. Based on assumptions that turbulent flow and complete mixing of aerosols occur in the nasal airways, a general equation E = 1-exp (-a D{sup b}Q{sup c}) for d{sub p} {<=} 0.2 {mu}m, was derived, where E is the deposition efficiency, d{sub p} is the particle diameter, D is the diffusion coefficient, and Q is the flow rate. Constants a, b, and c are estimated from experimental data, for either inspiration or expiration. This mathematical expression will be useful for making modifications to both deposition and dosimetry models.
- OSTI ID:
- 45162
- Report Number(s):
- CONF-901010--Pt.1
- Country of Publication:
- United States
- Language:
- English
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