Abstract View
The Fate of an Inhaled Puff Generated by an Electronic Nicotine Delivery System in The Human Oral and Lung Airways
AKINA MORI, Owen Price, Shigeaki Ito, Takuya Suzuki, Hitoshi Fujimoto, Hiroaki Suzuki, Bahman Asgharian, Japan Tobacco Inc.
Abstract Number: 159
Working Group: Health-Related Aerosols
Abstract
The fate of an inhaled puff generated by an electronic nicotine delivery system (ENDS) in the respiratory tract is crucial information in the assessment of its health impact. The puff of ENDS is a mixture of volatile multi-constituent aerosol and vapor constituents. The aerosols undergo continuous phase change. The phase change is expedited by temperature change, vapor uptake, aerosol deposition, and coagulation. Existing ENDS and combustible cigarette models have made strides in filling the gaps between measurements and predictions. To further enhance the dosimetry model for a puff of ENDS, we developed a new generation of dosimetry model that in addition to all previous mechanisms, accounted for the mixing of the puff with the dilution air after the mouth-hold and convective mixing of the puff with the reserved air in the deep lung. In addition, air-tissue interactions were included for medium vapor pressure constituents of the puff such as nicotine and propylene glycol. Model predictions revealed that mixing did not seem to affect uptake but resulted in increased airborne concentration of vapor and aerosols in the lung airways at the end of the puff exhalation. Thus, it increases the opportunity for the mixture to be taken up during the next puffing cycle. In addition, tissue concentrations of nicotine were similar among different generations of the lungs, and the predicted uptake of nicotine throughout the lung, particularly in the deep lung, is significantly higher than the prediction by existing models. We consider that the model enhancement improved matching of predictions with actual, but its confirmation is remained for the future studies. The model developed in this study provides a scientific tool for risk assessment of an inhaled ENDS puff.