Current Issues Regarding E-Cigarettes

Electronic cigarettes are battery-powered devices that vaporize a nicotine solution. The modern e-cigarette was produced in 2003 by a Chinese pharmacist (2), as he attempted to create a healthy alternative to cigarettes. Since the introduction of e-cigarettes to the American market in 2007, there has been a dramatic evolution in their form and function to cater to the consumer. The original device was underpowered and inconsistent in its ability to produce vapor. To keep up with the evolving demand of the consumer, a variety of models are being manufactured. They allow for greater control over battery voltage and heating temperature, thereby modifying the amount of vapor produced. Vaporized solutions, or e-liquids, are comprised of various ratios of propylene glycol, vegetable glycerin, water, nicotine solution, and flavorings (3).

The steady increase in popularity of e-cigarettes has become an important public health topic. In 2009, the Food and Drug Administration (FDA) attempted to block the importation and sale of these devices, stating that they were unauthorized drug delivery devices. In 2010, the U.S. Court of Appeals ruled against the ban and determined that unless marketed as therapeutic, e-cigarettes should be regulated as tobacco products. In April 2014, the FDA issued a proposal to extend its regulating authority to cover e-cigarettes and other tobacco products. Finalization of this proposal is pending (2, 4, 5).

On September 1, 2014, the World Health Organization determined that in 2014 there were 466 brands of ENDS products, with an estimated £3 billion spent globally on these devices in 2013. By 2030, sales are anticipated to increase 17 fold (6). Data on ENDS from North America, the European Union, and South Korea indicate a doubling of use in both adolescents and adults from 2008 to 2012. While the majority of e-cigarette users fall in the age range of 30–50 years old (7), the number of adolescents using ENDS is growing. The Centers for Disease Control and Prevention indicates that e-cigarette use among middle and high school students has tripled from 2013 to 2014 (8).

Initial e-cigarette advertisements promoted ENDS as safe alternatives to cigarettes. The only byproduct was said to be water vapor. The literature suggests otherwise. In an investigation of 10 commercially available e-fluids in Poland, carbonyl compounds were detected in the vapor produced. Greater ratios of propylene glycol to vegetable glycerin generated significantly higher levels of compounds such as formaldehyde, acetaldehyde, acetone, and butanal (all classified as carcinogens or irritants). Also on those e-cigarettes that allow for user adjustable batteries, increased voltages resulted in higher levels of carbonyls produced (3). Another study focused on the flavoring components of the e-liquid. Diacetyl, 2,3-pentandedione, and acetoin were detected (9). Diacetyl is a compound used in food flavoring. Although diacetyl is included in the FDA GRAS [generally recognized as safe] database, this only applies to the ingestion of the substance. The Occupational Safety and Health Administration database warns of the respiratory damage (i.e., bronchiolitis obliterans) that can be caused by the inhalation of this compound. In another study, 22 vaporizers were tested and found to produce an aerosol that contained heavy metals (tin, silver, iron, nickel, aluminum), silicate beads, and nanoparticles (10). All of the heavy metals produced are included in the FDA's database of harmful and potentially harmful chemicals. The implications of the presence of these substances are unknown. Although many chemicals are present to a lesser extent than in cigarettes, some are found in higher concentrations, and chemicals not found in cigarettes are also present. This may indicate the intrinsic problems with e-cigarettes. However, studies have not established the safety of e-cigarettes in relation to smoking. Therefore, drawing conclusions regarding e-cigarette safety is difficult, especially in an environment of change within the industry.

Nicotine is the addictive chemical in cigarettes, and the combustion of tobacco produces carcinogens. Nicotine alone is not the culprit for most diseases associated with tobacco use. Therefore, the use of non-combustible and less toxic forms of nicotine delivery is a means of decreasing use and limiting mortality from smoking (11). Long-term nicotine replacement (patch, gum, lozenge, etc.) has been established as safe, but the presence of harmful chemicals associated with ENDS use argues against the absolute safety of e-cigarettes. Forsalinos and LeHouezec (11) argued that e-cigarette safety needs to be considered in relation to smoking. For harm reduction, a balance between acceptability and risk must be considered. To do this, studies need to be conducted to determine the effectiveness of e-cigarettes in the decrease and cessation of smoking. In a randomized controlled trial of e-cigarette use for smoking cessation, conducted by Bullen et al. (12), e-cigarettes with nicotine were at least as effective as nicotine patches for successful smoking cessation at 6 months. Those subjects who relapsed but continued to use e-cigarettes smoked fewer overall cigarettes. If e-cigarettes can decrease the amount of smoking, next is to determine whether smoking reduction reduces long-term risks. Additionally, the risks of dual use of e-cigarettes and tobacco are unknown and must be explored. At this time, it cannot be concluded that e-cigarettes are a reliable method of harm reduction. However, ENDS continue to be a valuable piece of technology. The scientific community needs to continue to conduct research and collaborate with manufacturers to work toward safe devices.

Another category of users does not use e-cigarettes as a cessation tool or replacement strategy. These are tobacco-naive individuals. Within this group, the number of adolescent and youths continues to grow. The Public Health Cigarette Smoking Act of 1971 limited cigarette advertisements in the media, and the Family Smoking Prevention and Tobacco Control Act of 2009 banned the use of candy- and fruit-flavoring in cigarettes (5). These regulations limited the appeal of cigarettes to youths. These rules, however, do not yet apply to e-cigarette marketing and sales. As the number of younger users continues to grow, concerns arise that the attraction of e-cigarettes may strengthen and popularize the act of smoking itself (13). A recent study of adolescents in Los Angeles found a positive association between ever use of e-cigarettes with initiation of combustible tobacco use (14). In this study, 9th- and 10th-grade students from 10 different schools were surveyed at baseline and at 6 and 12 months to assess for tobacco use. Students with any prior use of combustible tobacco products were excluded. While other factors that could contribute to the association between e-cigarette use and initiation of combustible tobacco use can exist, the study adjusted for demographic factors (sex, race, socioeconomic status, etc.) and continued to demonstrate a statistically significant positive correlation. This study is limited in that it focuses on initiation outcomes, and the cohort examined is geographically specific. However, the study does indicate that further research is needed to determine the relationship between e-cigarette use and smoking initiation.

The escalating use and evolving culture of e-cigarettes is occurring despite little knowledge of their risks and benefits. The long-term effects are still unknown. Use in children and adolescents is associated with nicotine use and potential for renormalization of smoking. Studies have revealed the inconsistencies in production of devices and the presence of noxious chemicals. Unfortunately, due to lack of regulation, the potential harm is difficult to mitigate, let alone monitor.

As clinicians, it is often difficult to know how to advise patients regarding e-cigarette use. What we do know is that there continues to be greater than 480,000 tobacco-related deaths yearly (1), and ENDS use is not a perfectly safe alternative. Some hazardous chemicals associated with traditional tobacco are produced to a lesser degree in e-cigarettes, while others are not. There are currently no data that address the safety of these substances as they pertain to e-cigarette use, and no conclusions can yet be drawn regarding the safety of e-cigarettes in relation to smoking. With continued research and regulation by the FDA, consistency and safety of e-cigarettes will be further improved. Until that time, it is reasonable to conclude that no universal recommendation can be given to patients. What we can do for our patients is to provide data regarding the potential harms of ENDS use while stressing the hazards of traditional cigarette use.

The author thanks Sidarth Wakhlu, M.D., and Rachel Katz, M.D.