Numerical modeling of nanoparticle deposition in realistic monkey airway and human airway models: a comparative study

Background One of the most promising approaches to understand inhalation toxicology and to assess the potential risks of inhaled particles is to examine the disposition of the hazardous airborne particles in the monkey airway. This study presents a comparative, numerical investigation of nanoparticle deposition in the monkey and human airway models.Materials and Methods Computational fluid dynamics (CFD) method was applied to analyze the steady flow rates under light and moderate metabolic conditions. The nanoparticles, ranging from 5 to 100 nm in diameter, were used to predict the total and regional deposition fraction in both the models.Results The Brownian and turbulent motion significantly impacted the transportation and deposition of nanoparticles as evidenced by the large fluctuations of particle acceleration. A higher deposition efficiency was observed in the monkey model at the particle size of 25 nm or less. Nonetheless, on applying the geometric factors for combined diffusion term parameters, the total deposition fraction of both models converged into a single curve. The site-specific deposition of the particles of size 5 nm in the vestibule, valve, and nasal turbinate regions of the monkey model was observed to be greater compared to the human model. A study of the deposition curves of the particle diameter ranging from 2 nm to 10 µm showed that the highest deposition rates were associated with particles of size 2 nm and 10 µm.Conclusions The results of this study can contribute to the research involving extrapolation of inhalation toxicology studies, from monkeys to humans.