Nanoparticle deposition in the rat nasal cavity: prediction of dose to the olfactory epithelium.
Garcia-GJ; Nazridoust-K; Kimbell-JS
Toxicologist 2008 Mar; 102(1):204
Potential health risks associated with inhalation of nanoparticles are mostly unknown. A recent study in rats showed that nanoparticles depositing in the olfactory region can translocate along nerve axons to the olfactory bulb in the brain (Oberdoerster et al., Inhal. Toxicol. 16:437-445, 2004). An accurate estimate of the dose of inhaled nanoparticles to the rat olfactory epithelium will assist in understanding potential toxic effects and extrapolating such findings to humans. The goal of this study was to quantify nanoparticle deposition in the rat nasal cavity and, more specifically, the olfactory region. A three-dimensional, anatomically-accurate computational fluid dynamics model of the rat nasal airways was developed. A tetrahedral mesh was created in ICEM-CFD (Ansys, Inc.) with major epithelial types mapped onto its surface. Airflow and nanoparticle transport were simulated using Fluent software (Fluent, Inc.) for airflow rates corresponding to 1, 1.5 and 2 times the resting minute volume of 288 ml/min and particle sizes from 1 to 100 nm. For these particle sizes, particle deposition is dominated by diffusion, thus an Eulerian approach was used in the computations. Simulations predicted that nasal deposition decreased with increasing particle size: more than 90% of 1-nm particles and less than 1% of 100-nm particles were filtered by the nose. Olfactory deposition was maximal for particles with diameters of 2-6 nm, with 5 to 9 % of the inhaled particles deposited in the olfactory region. Deposition fractions were somewhat influenced by airflow rate, with higher airflow leading to (1) fewer particles being extracted by the nose and (2) a shift in the spatial distribution of deposited particles, with more deposition in the olfactory region. These results will help decrease uncertainty associated with estimates of potential health risks from inhaled nanoparticles.
Particle-aerodynamics; Particulate-dust; Particulates; Inhalation-studies; Quantitative-analysis; Air-monitoring; Air-sampling-equipment; Airborne-dusts; Airborne-particles; Risk-factors; Nanotechnology
The Toxicologist. Society of Toxicology 47th Annual Meeting and ToxExpo, March 16-20, 2008, Seattle, Washington