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Particle inhalability curves for humans and small laboratory animals
M G Ménache1, F J Miller, O G Raabe
1Center for Extrapolation Modeling, Duke University Medical Center, Durham, NC 27710, USA.
The Annals of Occupational Hygiene
|June 1, 1995
Summary
Inhalability curves, crucial for understanding particle deposition in the lungs, differ significantly between humans and laboratory animals. This study estimates animal inhalability, revealing important differences for accurate dose assessment in toxicological research.
Area of Science:
- Environmental Health Sciences
- Toxicology
- Respiratory Physiology
Background:
- Human inhalability curves are established, but animal-specific curves are lacking.
- Previous research indicates minimal pulmonary deposition of large particles in laboratory animals.
- Accurate particle deposition assessment is vital for interspecies dose comparisons.
Purpose of the Study:
- To develop an inhalability function for laboratory animals.
- To compare animal and human inhalability curves.
- To highlight the importance of inhalability adjustments in interspecies dose estimations.
Main Methods:
- The logistic function was applied to existing animal deposition data (Raabe et al., 1988).
- The logistic function was also applied to human data (Breysse and Swift, 1990) for comparative analysis.
- Particle size-dependent inhalability was modeled for both species.
Main Results:
- For humans, ambient concentration predicts inhaled concentration for particles < 11 microns.
- For animals, 95% inhalability is predicted for 0.7-micron particles, decreasing to 45% for 10-micron particles.
- Significant differences in inhalability exist between humans and small laboratory animals.
Conclusions:
- Inhalability significantly impacts dose delivered to target tissues in animals.
- Adjusting for inhalability is critical when comparing delivered doses between species.
- Failure to account for inhalability differences may alter conclusions about interspecies toxicity.