E-cigarette Aerosols Versus Cigarette Smoke: Harm Reduction in Levels of Harmful and Potentially Harmful Constituents and Cytotoxicity

Background: Worldwide adoption of electronic cigarettes (e-cigarettes) has increased exponentially over the past decade due to the perception that they may represent a safer alternative to conventional cigarettes (CS) and as an effort to reduce smoking-related diseases. Various types of e-cigarettes from different brands have been emerged in the market with different design and quality. However, whether the safety risks of e-cigarettes held the trends toward positive changes need to be further certified by more scientific evidence. Methods: A systematic comparison study on the selected harmful and potentially harmful constituents (HPHCs) levels, including carbonyls, volatile organic compounds (VOCs), tobacco-specific nitrosamines (TSNAs), polycyclic aromatic hydrocarbons (PAHs), and metals in aerosols of two typical commercially available e-cigarettes and one cigarette smoke (CS) in Chinese market were proceeded, together with their cytotoxicity on Jukart, CNE-1, HONE1, Hep-2 cell lines by CCK-8 and colony formation assays. Results: The results showed that the levels of vast majority HPHCs in e-cigarette aerosols are either undetected or obviously lower than those in CS, which indicating the exposure to HPHCs was markedly reduced in the tested e-cigarettes. The CCK-8 and colony formation assay also indicated that the TPM extracts of e-cigarette aerosols also exhibited much weaker cytotoxicity than CS. Conclusion: The comparison of HPHCs levels in e-cigarette aerosols revealed that the use of e-cigarettes could lead to a significant reduction in exposure to harmful substances compared to CS. In tandem, the potential cytotoxicity of e-cigarettes on cell levels also showed potential for improvement compared to smoking. However, more attention needs to be paid to the differences in safety risks between different brands of e-cigarettes.