What are the respiratory effects of e-cigarettes?

Abstract

Electronic cigarettes (e-cigarettes) are alternative, non-combustible tobacco products that generate an inhalable aerosol containing nicotine, flavors, propylene glycol, and vegetable glycerin. Vaping is now a multibillion dollar industry that appeals to current smokers, former smokers, and young people who have never smoked. E-cigarettes reached the market without either extensive preclinical toxicology testing or long term safety trials that would be required of conventional therapeutics or medical devices. Their effectiveness as a smoking cessation intervention, their impact at a population level, and whether they are less harmful than combustible tobacco products are highly controversial. Here, we review the evidence on the effects of e-cigarettes on respiratory health. Studies show measurable adverse biologic effects on organ and cellular health in humans, in animals, and in vitro. The effects of e-cigarettes have similarities to and important differences from those of cigarettes. Decades of chronic smoking are needed for development of lung diseases such as lung cancer or chronic obstructive pulmonary disease, so the population effects of e-cigarette use may not be apparent until the middle of this century. We conclude that current knowledge of these effects is insufficient to determine whether the respiratory health effects of e-cigarette are less than those of combustible tobacco products.

Fig 1

Reported effects of vaping on the human pulmonary system

Fig 2

Flowchart outlining proposed smoking cessation regimen that espouses counseling and nicotine cessation. Given the potential health risks associated with vaping, tobacco smokers looking to quit should first try nicotine patch or gum along with counseling (1, 2). If this approach fails, e-cigarettes could be used as a second attempt (3, 4). Given that nicotine is not risk-free, attempts should then be made to end nicotine dependence (5). As nicotine levels in e-liquids differ globally, the use of e-cigarettes as a smoking/nicotine cessation device may be more effective in countries with lower nicotine levels