AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Computational Analysis of Inhaled Aerosol Deposition from E-Cigarettes for the Assessment of Potential Health Effects
YU FENG, Kwai L. Wong, Clement Kleinstreuer, Oklahoma State University
Abstract Number: 539 Working Group: Electronic Cigarettes - Health Effects
Abstract Electronic Cigarettes (ECs) are tobacco-free nicotine-delivery devices which are gaining increasing popularity, especially among teenagers and young adults. ECs are manufactured in a large variety of designs with widely varying nicotine concentrations, added flavors and glycerol, as well as propylene glycol (PG) to imitate smoke. A typical EC-droplet contains 15% water, 49% glycerol, 33% PG, 2% nicotine and various flavors. The inhaled droplets have an initial-diameter range of 260nm to 3200nm. The addictive nicotine may pose adverse health effects, especially at elevated amounts, while PG is a lung irritant and some flavor-chemicals may be toxic. Worse, EC-devices with high-voltage batteries powering the heating element generate instantaneously not only very strong nicotine vapor but possibly also formaldehyde and other toxins. Although flavors in EC-smoke are safe for ingestion, they are not guaranteed to be safe for inhalation. For example, aldehydes (e.g., benzaldehyde and vanillion) were found in a significant number of flavors which are primary irritants of mucosal tissue of the respiratory tract. Also, metallic nanoparticles have been detected in EC-smoke, e.g., aluminum, copper, magnesium, zinc, lead, and/or nickel.
Thus, it is important to numerically simulate the fate of inhaled vapor-droplet EC-aerosols, using whole lung models, to assist toxicologists as well as regulators to evaluate possible health-impacts of EC-aerosols. As a first step, we analyzed the transport, phase-change and deposition of inhaled multi-component droplet-vapor mixtures in an idealized human upper airway model (Feng et al., JAS; 96: 2016). The results indicate that liquid-vapor phase change induces hygroscopic growth of droplets, which in turn impacts significantly the deposition concentrations of aerosols as well as the vapor-specific absorption rates. Presently, extensive parametric sensitivity analyses are being performed at JICS (UT Knoxville, TN) to evaluate with a subject-specific airway model the influence of different inhalation conditions on EC-aerosol transport, interaction, and deposition.