Chemical analysis of selected harmful and potentially harmful constituents and in vitro toxicological evaluation of leading flavoured e-cigarette aerosols in the Chinese market.

Introduction:
This text provides an analysis of the levels of harmful and potentially harmful constituents (hPhCs) in aerosols from selected flavored e-cigarettes in the Chinese market. The study also evaluates the cytotoxicity and mutagenicity of aqueous extracts from e-cigarette aerosols and cigarette smoke (CS) generated under machine-smoking conditions.

Key Points:

* The study compares the levels of hPhCs, including carbonyls, volatile organic compounds (VOCs), tobacco-specific nitrosamines (TSNas), polycyclic aromatic hydrocarbons (Pahs), and heavy metals, in the aerosols of four market-leading flavored e-cigarettes and mainstream CS.
* The aqueous extracts of e-cigarette aerosols and CS were tested for cytotoxicity and mutagenicity using neutral red uptake and ames assays.
* The majority of hPhCs were either undetected or significantly lower in the e-cigarette aerosols than in commercial CS or reference CS.
* Where hPhCs were detected, there were small variations among the different flavored e-cigarettes.
* aqueous extracts of the e-cigarette aerosols did not induce obvious cytotoxicity or mutagenicity, whereas CS aqueous extract showed dose-related cytotoxicity and mutagenicity.
* The levels of hPhCs in e-cigarette aerosols are mainly dependent on the e-liquid solvent and battery output.
* The presence of VOCs, TSNas, and Pahs in CS is primarily due to the incomplete combustion of organic materials, whereas their presence in e-cigarette aerosols is rare.
* The concentrations of heavy metals in e-cigarette aerosols are generally below the safety limit, except for Ni, which is present at higher levels due to the metallic coil in the heating element.

Main Message:
The study suggests that the use of e-cigarettes might potentially lead to a significant reduction in exposure to harmful substances, with fewer cytotoxic and mutagenic effects, as compared with conventional smoking. however, further studies based on human puffing conditions and longer evaluation periods are needed to substantiate this potential. The study also highlights the importance of monitoring the levels of hPhCs in e-cigarette aerosols, particularly in relation to e-liquid flavouring agents, carrier solvents, and metals from the heating element.

Xu T, Niu ZY, Xu J, et al. Chemical analysis of selected harmful and potentially harmful constituents and in vitro toxicological evaluation of leading flavoured e-cigarette aerosols in the Chinese market. Drug testing and analysis. Published online June 17, 2022. doi:10.1002/dta.3337