Analytical and toxicological evaluation of flavor chemicals in electronic cigarette refill fluids

Introduction:
This text reviews a research study comparing the cytotoxicity of electronic cigarette (e-cigarette) refill fluids and aerosols using in vitro cultured cells. The study also evaluated the cytotoxicity of aerosols made from authentic propylene glycol and glycerin, the two most commonly used refill fluid solvents. The purpose of the study was to follow up on a previous publication dealing with the cytotoxicity of refill fluids.

Key Points:

* The study used 35 e-cigarette refill fluids and e-cigarette DIY products containing various flavourings and nicotine concentrations.
* E-cigarette aerosol was produced using a smoking machine and collected into culture medium in a round bottom flask submerged into an ice bath.
* Human pulmonary fibroblasts, A549 lung epithelial cells, and pluripotent human embryonic stem cells were used to test the cytotoxicity of the refill fluids and aerosols.
* The study found that various flavours/brands of e-cigarette refill fluids and their aerosols are cytotoxic and demonstrate the need for further evaluation of e-cigarette products to better understand their potential health effects.
* E-cigarette aerosols can produce cytotoxic effects in cultured cells.
* Four patterns of cytotoxicity were found when comparing refill fluids and their corresponding aerosols.
* Fluids accurately predicted aerosol cytotoxicity 74% of the time.
* Stem cells were often more sensitive to aerosols than differentiated cells.
* 91 % of the aerosols made from refill fluids containing only glycerin were cytotoxic, even when produced at a low voltage.

Main Message:
The main message of this study is that various flavours/brands of e-cigarette refill fluids and their aerosols are cytotoxic, demonstrating the need for further evaluation of e-cigarette products to better understand their potential health effects. The study highlights the importance of considering the cytotoxicity of e-cigarette aerosols, as they can produce cytotoxic effects in cultured cells and stem cells are often more sensitive to aerosols than differentiated cells. Additionally, the study found that 91 % of the aerosols made from refill fluids containing only glycerin were cytotoxic, indicating that glycerin alone may be more harmful than propylene glycol or mixed solvent products. Overall, the study underscores the need for continued research and regulation of e-cigarette products to ensure their safety.

Behar, Rachel Z., Wentai Luo, Kevin J. McWhirter, James F. Pankow, and Prue Talbot. “Analytical and Toxicological Evaluation of Flavor Chemicals in Electronic Cigarette Refill Fluids.” Scientific Reports 8, no. 1 (May 29, 2018): 8288. https://doi.org/10.1038/s41598-018-25575-6.