This article has been reviewed by Thanai Pongdee, MD, FAAAAI
Electronic cigarettes (ECs) are battery-powered devices that deliver aerosolized nicotine and other additives to users. ECs were first commercialized in China in 2003 and entered the U.S. market in 2007. Most devices resemble cigarettes, whereas others resemble pens, hookah tips, or screw drivers.
Figure 1. Electronic cigarette models. Reprinted from Grana, Rachel PhD, MPH; Benowitz, Neal MD; & Glantz, Stanton A. PhD. (2013). Background Paper on E-cigarettes (Electronic Nicotine Delivery Systems). UC San Francisco: Center for Tobacco Control Research and Education.
The liquid contained in ECs, referred to as e-liquid, generally consists of nicotine, water, propylene glycol (PG), glycerin, flavorings, and/or other additives. The e-liquid may be packaged in replaceable cartridges, refill liquids, or contained in disposable ECs themselves. Although the ingredients in the liquids appear safer than those in combustible cigarettes, there are many concerns. Once heated, the chemical components in the liquids undergo chemical reactions that create new, potentially harmful compounds not present in the original liquid. In addition, the contents of the e-liquids may not be accurately reported in the package information. Many stores make their own formulations without regulations or oversight. Sampling of some e-liquids revealed inaccurate nicotine concentration labels. E-liquids can directly irritate the lungs and passive second- or third-hand exposure has been reported to have some harmful health effects.
The EC device, usually powered by a small rechargeable lithium-ion battery, is activated by inhalation at the tip or, on some models, by pressing a button. The microprocessor controls the power light-emitting diode (LED) tip and the heating element once the EC is activated. The LED tip glows when the vaporizer is in use and the heating element produces the vapor mist that carries the nicotine vapor.
Figure 2. Components of the electronic cigarette. Reprinted from Grana, Rachel PhD, MPH; Benowitz, Neal MD; & Glantz, Stanton A. PhD. (2013). Background Paper on E-cigarettes (Electronic Nicotine Delivery Systems). UC San Francisco: Center for Tobacco Control Research and Education.
ECs are currently not federally regulated in the United States, and there are only limited safety data regarding their acute and long-term use. Despite this, the sale and use of ECs is rising. Utilizing the HealthStyles survey, an annual consumer-based survey of U.S. adults, King et al. found that between 2010 and 2013, the number who had ever used the devices increased from 3.3% to 8.5% and current use increased from 1.3% to 1.9%. The greatest increase was amongst current cigarette smokers, rising from 4.9% in 2010 to 9.4% in 2013. The 2012-2013 National Adult Tobacco Survey found that the highest prevalence of EC use was in young adults aged 18-24 at 8.3%, nearly double that of the overall adult population prevalence. Additionally, the Centers for Disease Control and Prevention (CDC) estimated that EC usage had more than doubled from 3.3% to 6.8% in youths in grades 6-12 from 2011 to 2012, with nearly 1.8 million youths ever trying ECs.
Unfortunately, there is a lack of good data on many of the health effects and questions surrounding the use of ECs. Some of the more important questions include the following.
1. Are ECs safer than combustible cigarettes?
Although the long-term and even short-term effects of ECs are not known with certainty, they do contain less toxic elements then combustible cigarettes. Combustible cigarette smoke contains at least 70 carcinogens (substances that can cause cancer) and these toxins have been measured at 9- to 240- fold greater levels than those found in the aerosol from ECs. Furthermore, second- and third-hand exposure to potential toxic elements from aerosol generated from ECs appears to be markedly less than that from combustible cigarettes. Therefore, the potential to do harm to people exposed to EC aerosol from others using them does not appear to be nearly as great as that from second- and third-hand smoke from combustible cigarettes. If you have asthma and allergies, combustible cigarettes are clearly an aggravating factor that can make both disorders worse. ECs are likely safer than combustible cigarettes in this regard. The bottom line is that ECs are very likely to be safer than combustible cigarettes for people with or without asthma, but they are not without healthcare risks as stated above. They contain less but still measurable toxic elements in the aerosol.
2. Can ECs help me quit combustible cigarettes?
The jury is still out on this. The studies that have been done to date have had conflicting results with some showing the potential of ECs to reduce combustible cigarette smoking and others not showing any effect. A potentially disturbing finding in these and epidemiologic studies is that many combustible cigarette users that try ECs often wind up using both. We do not know the potential harm with using both combustible and ECs simultaneously. The best advice if you want to quit combustible cigarettes is to get into a smoking cessation program and discuss options with healthcare providers knowledgeable in this area.
3. Are ECs a gateway to combustible cigarettes and perhaps illegal drugs?
Studies have indicated that ECs can be a gateway to the use of combustible cigarettes and illegal drugs. EC devices can be used to deliver THC from marijuana or hash. Whether or not ECs are more likely to be a gateway to the use of illegal drugs versus the use of combustible cigarettes is not known.
To summarize, the discrepancies between packaging and content of the e-liquid, sale to minors, and unsubstantiated health claims identified with ECs are very concerning. Research is needed to assess whether ECs could be an effective smoking cessation tool, whether ECs can be a gateway to other drugs and combustible cigarettes, whether EC device variability impacts users and their exposure to toxic products, and both the short-and long-term health effects of ECs. Nonetheless, ECs appear to be safer than combustible cigarettes, but the concerns listed above indicate that their use is not recommended. The best advice, whether or not you have asthma or allergies, is to not use combustible or ECs.
Materials extracted from: Cooke A, Fergeson J, Bulkhi A, Casale TB. The Electronic Cigarette: The Good, the Bad, and the Ugly. J Allergy Clin Immunol Pract. 2015 Jul-Aug;3(4):498-505.
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