Abstract CN02-03: Quitting or switching? Health benefits and risk of electronic cigarettes
Authors: Goniewicz Maciej Lukasz 
Published: October 2015

Abstract
Although the best way for smokers to avoid the health risks associated with smoking is to quit smoking altogether, for those who do continue to smoke the application of an exposure reduction (“harm reduction”) strategy could result in substantial reductions in mortality and morbidity. Many smokers are concerned about the health effects of smoking and might be interested in trying new products if they believed this would reduce their health risk. The concept of exposure reduction is based on the principle that if dangerous behavior, like smoking, is likely to continue, the harm caused should be minimized. One such approach for continuing smokers would be to promote the substitution of alternative, less toxic means of delivering nicotine, assuming that these were proven to be less hazardous than tobacco smoking and did not cause any additional health risks.
Electronic nicotine inhalers, commonly called electronic cigarettes or “e-cigarettes”, represent a new stage in which nicotine is delivered in a method that simulates smoking but without involving a tobacco combustion process. E-cigarette are battery-powered devices that provide inhaled doses of nicotine by delivering a vaporized liquid nicotine solution, usually including propylene glycol or glycerin. The nicotine is extracted from tobacco leaves (in the same way the pharmaceutical industry obtains nicotine for NRT production), and is then diluted and introduced into the e-cigarette's cartridge. In addition to delivering nicotine, the vapor also provides a flavor and physical sensation similar to that of inhaled tobacco smoke, although no tobacco or combustion is actually involved in its operation. When a user initiates inhalation into the device, air flow is detected by a sensor, which activates a heating element that vaporizes the nicotine solution stored in the mouthpiece cartridge. It is this vapor that is inhaled by the user. On some models an LED on the opposite end of the device is activated during inhalation to serve as an indicator of use as well as simulating the glow of burning tobacco.
E-cigarettes have been shown to reduce craving and withdrawal symptoms in abstinent smokers and, as nicotine is delivered without tobacco combustion, are thought to be substantially safer than cigarettes. While e-cigarette use is rapidly increasing, relatively little is known about their efficacy for smoking cessation, particularly compared with established nicotine-containing pharmacological aids. One randomized controlled trial by Bullen et al. showed that e-cigarettes are at least as effective as nicotine patches for smoking cessation. Interestingly, a substantial proportion of participants in this study engaged in harm reduction, becoming long-term e-cigarette users and reducing their conventional cigarette consumption. Thus, against the backdrop of ongoing debates on tighter regulation of e-cigarettes, a sole focus on smoking cessation may be misguided. From a public health perspective, the permanent switch from combustible to noncombustible products is an important endpoint in itself. Nonetheless, the finding that e-cigarettes are at least as effective as existing licensed, nicotine-containing smoking cessation products should go some way towards easing, if not completely allaying, the fears of many health professionals observing their fast uptake among smokers.
Distributors of e-cigarettes promote the product as completely free of harmful substances. However, nicotine solutions used in e-cigarettes vary with respect to concentrations of toxicants, and the quality control in e cigarette manufacturing is questionable. Although a number of toxicants have been identified in e-cigarette vapors, the levels of these toxicants are orders of magnitude lower than those found in cigarette smoke, but higher than those found in Nicotine Replacement Therapy (NRT) products. Some studies suggest that vapor from e-cigarette is significantly less cytotoxic compared to tobacco smoke. One study found that after switching from tobacco to electronic cigarettes nicotine exposure is unchanged while exposure to selected toxicants is substantially reduced. Although it cannot be said that currently marketed e-cigarettes are safe, e-cigarette vapor is likely to be much less toxic than cigarette smoke. The devices likely pose less direct hazard to the individual smoker than tobacco cigarettes and might help smokers quit smoking or reduce harm by smoking fewer cigarettes. The use of e-cigarettes as a harm reduction strategy among cigarette smokers who are unable to quit, warrants further studies. Further research is needed to evaluate long term effects of switching, including the health effects of continued use of e-cigarettes.
Citation Format: Maciej Lukasz Goniewicz. Quitting or switching? Health benefits and risk of electronic cigarettes. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr CN02-03.