Electronic nicotine delivery systems (ENDS) aerosol constituent deposition and nicotine retention in the human oral cavity.

Introduction:
This text summarizes a scientific study on the deposition and uptake of electronic nicotine delivery systems (ENDS) aerosol constituents in the human oral cavity. The study developed a mathematical model to predict the behavior of ENDS aerosols based on physical and physiological parameters, such as droplet/vapor phase change, coagulation, heat exchange between the puff and oral cavity, and puffing maneuver. The model predictions provide insights into the dosimetry during puff withdrawal and mouth-hold of puff constituents, including water, nicotine, propylene glycol (PG), vegetable glycerin (VG), and two flavor chemicals (vanillin and benzaldehyde).

Key Points:

* The study developed a mathematical model to predict ENDS aerosol puff mixture deposition and uptake in the oral cavity.
* The model incorporates improved assumptions for droplet growth, humidity evaluation, and temperature-dependent parameters to predict droplet deposition and vapor component uptake.
* Model predictions indicate low droplet deposition (D2%) of humectants PG and VG; PG vapor exhibits higher vapor uptake (~14%).
* Deposition of nicotine in droplet form is low (D2%), but retention of nicotine in vapor form is sensitive to the nicotine activity coefficient and can be as high as 30%.
* Flavor chemical uptake is dependent on vapor pressure, with vanillin exhibiting negligible uptake and benzaldehyde exhibiting significant uptake (~45%).
* The dosimetry models demonstrate their value as a practical tool for use by regulatory agencies and the risk assessment community to assess potential health impacts to ENDS users.
* The study highlights the importance of considering ENDS constituent-specific dosimetry predictions in the oral cavity to inform evaluations of amounts entering the lungs and predict ENDS constituent levels associated with potential upper respiratory adverse effects.

Main Message:
The study emphasizes the significance of understanding the dynamics and deposition of ENDS aerosols in the human oral cavity to evaluate their potential health impacts. By developing a sophisticated mathematical model, the study provides insights into the behavior of various ENDS constituents, including nicotine and flavor chemicals, during puff withdrawal and mouth-hold. These predictions can support regulatory agencies and the risk assessment community in understanding the health implications of ENDS use and informing appropriate policies and regulations.

asgharian B, Price O, Creel a, et al. Electronic nicotine delivery systems (ENDS) aerosol constituent deposition and nicotine retention in the human oral cavity. J aerosol Sci. 2023;172:106192. doi:10.1016/j.jaerosci.2023.106192