Is it safe to vape? Assessing the carcinogenic risk of "vape smoke"

Vaping was introduced as a means of quitting smoking by slowly reducing nicotine dose to wean smokers of their carcinogenic habit. In this setting the risks of vaping likely outweigh the benefits of eliminating the carcinogenic risk associated with smoking cigarettes. Soon after the introduction of vaping it caught on as a trendy alternative to smoking, particularly among young people. This means that the risk-benefit profile changed considerably because the benefit of smoking cessation was no longer part of the risk-benefit equation. Since vaping has now become a primary means of taking nicotine, a risk assessment of vaping per se is necessary to determine its potential effects on vapers' health. In this viewpoint, we use our knowledge of the chemistry of the production of "vape smoke" to identify its key toxic components. Then, using published animal toxicity data for these chemicals and estimates of vapers' exposure levels, we assess the magnitude of carcinogenic risk. We conclude that vaping is carcinogenic, but that the risk is likely lower than for smoking cigarettes. Therefore, someone taking up vaping not as a tool for smoking cessation is adding carcinogenic risk to their daily risk profile.