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

Electronic cigarette (e-cigarette; e-cig) use has grown exponentially in recent years despite their unknown health effects. E-cig aerosols are now known to contain hazardous chemical compounds, including carbonyls and reactive oxygen species (ROS), and these compounds are directly inhaled by consumers during e-cig use. Both carbonyls and ROS are formed when the liquid comes into contact with a heating element that is housed within an e-cig's atomizer. In the present study, the effect of coil resistance (1.5 Omega and 0.25 Omega coils, to obtain a total wattage of 8 +/- 2W and 40 +/- 5 W, respectively) on the generation of carbonyls (formaldehyde, acetaldehyde, acrolein) and ROS was investigated. The effect of the aerosols generated by different coils on the viability of H1299 human lung carcinoma cells was also evaluated. Our results show a significant (p < 0.05) correlation between the low resistance coils and the generation of higher concentrations of the selected carbonyls and ROS in e-cig aerosols. Moreover, exposure to e-cig vapor reduced the viability of H1299 cells by up to 45.8%, and this effect was inversely related to coil resistance. Although further studies are needed to better elucidate the potential toxicity of e-cig emissions, our results suggest that these devices may expose users to hazardous compounds which, in turn, may promote chronic respiratory diseases.