Modeled Respiratory Tract Deposition of aerosolized Oil Diluents Used in Δ9-ThC-Based Electronic Cigarette Liquid Products.

Introduction:
This article, published in the journal Frontiers in Public health, discusses a study on the respiratory tract deposition of aerosolized oil diluents used in Delta19-ThC-based electronic cigarette liquid products. The study aimed to evaluate the physical characteristics of aerosolized e-liquids prepared using various oil diluents, such as Vitamin-E-acetate, Vitamin E oil, coconut oil, and medium-chain triglycerides (MCT). The study used a smoking machine to aerosolize each e-liquid at a predetermined puff topography and collected the size-segregated aerosol using a cascade impactor. The mass median aerodynamic diameter (MMaD) and geometric standard deviation (GSD) were calculated to estimate the regional respiratory deposition and puff-based total aerosol mass for estimating the number of particles delivered to the respiratory tract.

Key Points:

* The study found that the MMaD of VEa (0.61 µm) was statistically different compared to MCT (0.38 µm) and coconut oil (0.47 µm) but not to Vitamin E oil (0.58 µm).
* Wider aerosol size distribution was observed for VEa (GSD 2.35) and MCT (GSD 2.08) compared with coconut oil (GSD 1.53) and Vitamin E oil (GSD 1.55).
* Irrespective of the statistical differences between MMaDs, dosimetry modeling resulted in similar regional and lobular deposition of particles for all e-liquids in the respiratory tract.
* The highest fractional deposition was predicted in the pulmonary region, which is consistent with the site of injury among EVaLI cases.
* Secondhand exposure calculations indicated that a substantial amount of EVP aerosols could be exhaled, which has potential implications for bystanders.
* The number of EVaLI cases has declined with the removal of VEa; however, further research is required to investigate the commonly available commercial ingredients used in e-liquid preparations.

Main Message:
The study highlights the importance of understanding the physical and chemical properties of aerosolized e-liquids to estimate the regional respiratory deposition and potential health risks associated with e-cigarette use. The findings suggest that the use of certain oil diluents, such as VEa, could result in wider aerosol size distribution and higher respiratory tract deposition, leading to potential lung injury. The study also emphasizes the need to consider the potential secondhand exposure risks associated with e-cigarette use, as a substantial amount of EVP aerosols could be exhaled, posing potential health risks to bystanders. Overall, the study underscores the need for further research to investigate the commonly available commercial ingredients used in e-liquid preparations to ensure the safety of e-cigarette users and bystanders.

Ranpara a, Stefaniak aB, Williams K, Fernandez E, LeBouf RF. Modeled Respiratory Tract Deposition of aerosolized Oil Diluents Used in Δ9-ThC-Based Electronic Cigarette Liquid Products. Frontiers in public health. 2021;9:744166. doi:10.3389/fpubh.2021.744166