Impact of electronic cigarette heating coil resistance on the production of reactive carbonyls, reactive oxygen species and induction of cytotoxicity in human lung cancer cells in vitro.

Introduction:
This manuscript reports on a study examining the impact of electronic cigarette (e-cigarette) heating coil resistance on the production of reactive carbonyls, reactive oxygen species (ROS), and the induction of cytotoxicity in human lung cancer cells in vitro. The study investigated the effect of aerosols generated by different coils on the viability of h1299 human lung carcinoma cells using an in vitro air-liquid interface (aLI) exposure system.

Key Points:

* The study found a significant correlation between low resistance coils and the generation of higher concentrations of selected carbonyls and ROS in e-cigarette aerosols.
* Exposure to e-cigarette vapor reduced the viability of h1299 cells by up to 45.8%, and this effect was inversely related to coil resistance.
* The study used a commercially available e-cigarette device and two different coils (1.5 Ω and 0.25 Ω) to obtain a total wattage of 8±2 W and 40±5 W, respectively.
* The e-cigarette liquids used in the study were composed of a PG/VG base (50/50, v/v) without nicotine and with nicotine (18%) to which a red fruits or raspberry flavor concentrate was added.
* Carbonyl compounds in e-cigarette aerosols were detected using headspace-solid phase microextraction (hS-SPME) coupled to gas chromatography-mass spectrometry (GC/MS).
* ROS production was estimated using the dye 2’,7’-dichlorodihydrofluorescein diacetate (DCFh-Da) and horseradish peroxidase (hRP) in both phosphate buffer and cell medium.
* h1299 cells were exposed to air or e-cigarette vapor in a modified vacuum desiccator using a specific puffing topography.
* Cell viability was assessed using the 3-(4,5-dimethylthiazol-3-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay 24 hours after e-cigarette vapor exposure.

Main Message:
The study suggests that e-cigarettes may expose users to hazardous compounds, including carbonyls and ROS, which may promote chronic respiratory diseases. The use of low resistance coils in e-cigarettes may increase the generation of these harmful compounds, leading to reduced cell viability. Further studies are needed to better elucidate the potential toxicity of e-cigarette emissions.

Cirillo S, Urena JF, Lambert JD, et al. Impact of electronic cigarette heating coil resistance on the production of reactive carbonyls, reactive oxygen species and induction of cytotoxicity in human lung cancer cells in vitro. Regulatory toxicology and pharmacology : RTP. 2019;109:104500. doi:10.1016/j.yrtph.2019.104500