Electronic cigarettes are booming in popularity, thanks to campaigns to reduce smoking and the goodwill of nicotine patches. There's no evidence foe health risks but evidence that they help people quit smoking is also limited, according to a research review in the July/August Journal of Addiction Medicine, the official journal of the American Society of Addiction Medicine.

The work was funded by the National Institute on Drug Abuse of the National Institutes of Health and the Center for Tobacco Products of the U.S. Food and Drug Administration.

Based on their review, Alison B. Breland, PhD, of Virginia Commonwealth University, Richmond, and colleagues, write, "[V]ery little is known about the acute and longer-term effects of ECIG use for individuals and the public health, especially given the dramatic variability in ECIG devices, liquids, and user behavior."  

Plasma nicotine concentrations in ECIG users. A, The mean plasma nicotine concentration before and after 13 experienced ECIG users took 10 puffs (30-second interpuff interval) from their preferred device using a cartomizer loaded with their preferred liquid (for methodological detail, see Vansickel and Eissenberg, 2013). The filled symbol indicates a significant difference in plasma nicotine after the 10 puffs (t12 = −5.3; P < 0.001). B, The plasma nicotine data from 3 individuals who participated in this study and who each took 10 puffs using the same device and liquid strength (26 mg/mL). These data demonstrate that ECIGs can deliver cigarette-like doses of nicotine to their users, but there may be considerable variability in nicotine delivery across users of the same device/liquid. ECIG indicates electronic cigarette. Source: doi: 10.1097/ADM.0000000000000049.

Limited Data

Also known as "electronic nicotine delivery systems," e-cigarettes consist of a heating element that turns an "e-liquid" solution into vapor, which the user inhales. E-cigarette solutions typically contain nicotine. E-cigarette models vary widely in design and appearance - some even resemble cigarettes - but a wide range of other designs and configurations are available.

Since nothing is burned,  e-cigarette vapor does not the toxins present in tobacco smoke. Some potentially toxic substances are found in the vapor, but at much lower levels than in tobacco smoke. Critics have raised concern about the nicotine content of e-cigarette liquids, which range from absent or minimal to very high levels.

Laboratory studies are in conflict with each other; some suggest e-cigarette use has short-term effects on lung function similar to those produced by cigarette smoking, while other studies report no impairment The effects of inhaled nicotine in e-cigarette vapor can be similar to that of nicotine in tobacco smoke.

There is little evidence on any long-term effects of e-cigarette
use. The authors write, "No existing studies address the extent to which the inhalation of ECIG vapor hundreds of times every day over a period of multiple years influences human health, particularly pulmonary function."

Are E-Cigarettes a Useful Quit-Smoking Aid?

Surveys suggest e-cigarette users are primarily cigarette smokers. In a 2013 study, 13 percent of college students said they had tried e-cigarettes.

Evidence has shown that ;e-cigarettes can reduce tobacco abstinence symptoms in cigarette smokers, but it's unclear how much this is related to nicotine delivery or to psychological effects. So far, the best available studies—two randomized clinical trials—have shown no significant difference in quit rates among in
e-cigarette users.

In the absence of high-quality research evidence, there's currently no way to analyze the ongoing arguments for and against e-cigarettes. However, research however shows that the societal price of addiction to nicotine is high—tobacco use in the US is implicated in more deaths each year than alcohol and illicit drugs combined.

Given the "substantial knowledge gaps," the authors highlight the need for further research on the health effects of e-cigarettes. They note: "Given today's inability to generalize across ECIGs, individuals, and populations, all stakeholders in the ECIG debate, regardless of their opinions concerning the public health effects of ECIGs, must acknowledge that there is much to be learned about this rapidly evolving product category…generalization in the absence of data is speculation, not science."

Citation: and, Alison B. PhD; Spindle, Tory BS; Weaver, Michael MD; Eissenberg, Thomas PhD, 'Science and Electronic Cigarettes: Current Data, Future Needs', Journal of Addiction Medicine:
July/August 2014 - Volume 8 - Issue 4 - p 223-233. doi: 10.1097/ADM.0000000000000049. Source: Wolters Kluwer Health