Science & Research

Outlined below is some of the recent evidence based, peer reviewed scientific research and commentary that has been published.

This section will be updated on an ongoing basis.

E-Cigarette Design Preference and Smoking Cessation: A U.S. Population Study.

Chen C, Zhuang YL, Zhu SH.

Am J Prev Med. 2016 Mar 18. pii: S0749-3797(16)00057-X.

”Electronic cigarette (e-cigarette) designs may be described as “closed” or “open.” Closed systems are disposable or reloadable with prefilled cartridges (cigalikes). Open systems feature a prominent chamber (tank), refillable with e-liquid. This study examined user design preference and its association with smoking cessation.”

Most e-cigarette users were exclusive users of one design: 51.4% used only closed systems and 41.1% used only open systems, with 7.4% using both. Former smokers were more likely to use open systems than current smokers (53.8% vs 35.2%, p=0.002). Current smokers who attempted to quit in the last 12 months were more likely to use open systems than those who did not (41.4% vs 27.7%, p=0.029). Open system users were more likely than closed system users to use e-cigarettes daily (50.2% vs 22.9%, p<0.0001). Open system users were less likely to report their devices resembled (3.1% vs 73.0%, p<0.0001) or tasted like (29.1% vs 53.3%, p<0.0001) a cigarette but were more likely to report that their devices satisfied cravings than closed system users (82.8% vs 67.2%, p=0.001).

Preference of e-cigarette design is associated with smoking cessation. A device’s ability to deliver more nicotine and its flexibility in use might contribute to users’ success in quitting smoking.

Success rates with nicotine personal vaporizers: a prospective 6-month pilot study of smokers not intending to quit.

Riccardo Polosa, Pasquale Caponnetto, Marilena Maglia, Jaymin B Morjaria and Cristina Russo.

BMC Public Health 2014, 14:1159, November 2014.

”Electronic cigarettes (e-Cigs) are an attractive long-term alternative nicotine source to conventional cigarettes. Although they may assist smokers to remain abstinent during their quit attempt, studies using first generation e-Cigs report low success rates. Second generation devices (personal vaporisers – PVs) may result in much higher quit rates, but their efficacy and safety in smoking cessation and/or reduction in clinical trials is unreported.

We conducted a prospective proof-of-concept study monitoring modifications in smoking behaviour of 50 smokers (unwilling to quit) switched onto PVs. Participants attended five study visits: baseline, week-4, week-8, week-12 and week-24. Number of cigarettes/day (cigs/day) and exhaled carbon monoxide (eCO) levels were noted at each visit. Smoking reduction/abstinence rates, product usage, adverse events and subjective opinions of these products were also reviewed.

Sustained 50% and 80% reduction in cigs/day at week-24 was reported in 15/50 (30%) and 7/50 (14%) participants with a reduction from 25cigs/day to 6cigs/day (p < 0.001) and 3cigs/day (p < 0.001), respectively. Smoking abstinence (self-reported abstinence from cigarette smoking verified by an eCO ≤10 ppm) at week-24 was observed in 18/50 (36%) participants, with 15/18 (83.3%) still using their PVs at the end of the study. Combined 50% reduction and smoking abstinence was shown in 33/50 (66%) participants. Throat/mouth irritation (35.6%), dry throat/mouth (28.9%), headache (26.7%) and dry cough (22.2%) were frequently reported early in the study, but waned substantially by week-24. Participants’ perception and acceptance of the products was very good.

The use of second generation PVs substantially decreased cigarette consumption without causing significant adverse effects in smokers not intending to quit.”

Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes.

Etter JF, Eissenberg T.

Drug Alcohol Depend. 2015 Feb 1;147:68-75. doi: 10.1016/j.drugalcdep.2014.12.007.

”To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes.

Self-reports from cross-sectional Internet and mail surveys. Comparisons of: (a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; (b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); (c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström test for nicotine dependence, the nicotine dependence syndrome scale, the cigarette dependence scale and versions of these scales adapted for e-cigarettes and nicotine gums.

Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (≤3 months) users of gums or e-cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers.

Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive.”

Comparison of select analytes in exhaled aerosol from e-cigarettes with exhaled smoke from a conventional cigarette and exhaled breaths.

Long GA

Int J Environ Res Public Health. 2014 Oct 27;11(11):11177-91.

”Exhaled aerosols were collected following the use of two leading U.S. commercial electronic cigarettes (e-cigarettes) and a conventional cigarette by human subjects and analyzed for phenolics, carbonyls, water, glycerin and nicotine using a vacuum-assisted filter pad capture system. Exhaled breath blanks were determined for each subject prior to each product use and aerosol collection session.

Total phenolic content in exhaled e-cigarette aerosol was not distinguishable from exhaled breath blanks, while total phenolics in exhaled cigarette smoke were significantly greater than in exhaled e-cigarette aerosol and exhaled breaths, averaging 66 µg/session (range 36 to 117 µg/session). The total carbonyls in exhaled e-cigarette aerosols were also not distinguishable from exhaled breaths or room air blanks. Total carbonyls in exhaled cigarette smoke was significantly greater than in exhaled e-cigarette aerosols, exhaled breath and room air blanks, averaging 242 µg/session (range 136 to 352 µg/session).

These results indicate that exhaled e-cigarette aerosol does not increase bystander exposure for phenolics and carbonyls above the levels observed in exhaled breaths of air.”


Electronic cigarettes: review of use, content, safety, effects on smokers and potential for harm and benefit

Addiction, Volume 109, Issue 11, pages 1801–1810, November 2014

Peter Hajek, Jean-François Etter, Neal Benowitz, Thomas Eissenberg and Hayden McRobbie.

”We reviewed available research on the use, content and safety of electronic cigarettes (EC), and on their effects on users, to assess their potential for harm or benefit and to extract evidence that can guide future policy.

Studies were identified by systematic database searches and screening references to February 2014.

EC aerosol can contain some of the toxicants present in tobacco smoke, but at levels which are much lower. Long-term health effects of EC use are unknown but compared with cigarettes, EC are likely to be much less, if at all, harmful to users or bystanders. EC are increasingly popular among smokers, but to date there is no evidence of regular use by never-smokers or by non-smoking children. EC enable some users to reduce or quit smoking.

Allowing EC to compete with cigarettes in the market-place might decrease smoking-related morbidity and mortality. Regulating EC as strictly as cigarettes, or even more strictly as some regulators propose, is not warranted on current evidence. Health professionals may consider advising smokers unable or unwilling to quit through other routes to switch to EC as a safer alternative to smoking and a possible pathway to complete cessation of nicotine use.”

Electronic cigarettes: fact and faction.

Robert West, Professor of Health Psychology at the Department of Epidemiology & Public Health, University College London, and Jamie Brown, Post-doctoral research fellow.

British Journal of General Practice. September 2014. Vol 64 no. 626

”To date, studies that have been claimed as addressing the gateway issue in relation to e-cigarettes have not in fact done so. Moreover, warnings about a rapid rise in e-cigarette use among the young have been based on the proportion of young people who report ever having tried an e-cigarette, not the proportion of current users. In England, the proportion of current users in people who have not smoked regularly remains extremely small at 0.2%.

This brings us back to the question as to why some individuals and bodies involved in public health are so opposed to e-cigarettes. It may be a concern over how things might turn out in the future given commercial incentives, puritanical ethics, distaste for any industry profiting from a psychoactive drug, inappropriate application of a medical rather than a public health model, or even just a gut feeling that e-cigarettes are bad. Whatever the reasons, it is important that interpretation of the evidence and communication with policy makers and the public is not distorted by a priori judgements.”

Characterization of chemicals released to the environment by electronic cigarettes use (ClearStream-AIR project): is passive vaping a reality?

G. Romagna MD ,L.Zabarini, L.Barbiero , E. Bocchietto ,S.Todeschi, E. Caravati ,D.Voster, K. Farsalinos MD. September 1, 2012

”The above experiment, within the limits of the observed parameters, has underlined that e-smoking does not produce detectable amounts of toxic and carcinogenic substances in the air of an enclosed space. Further studies are needed to better understand all the involved aspects. However this preliminary assessment indicates that passive vaping impact, when compared to the traditional cigarette smoking, is so low that it is just detectable, and it does not have the toxic and carcinogenic characteristics of cigarette smoking.”

Comparison of the effects of e-cigarette vapor and cigarette smoke on indoor air quality.

T. R. McAuley, P. K. Hopke, J. Zhao, S. Babaian. October 2012.

Inhalation Toxicology, Vol. 24, No. 12 , Pages 850-857

”Comparisons of pollutant concentrations were made between e-cigarette vapor and tobacco smoke samples. Pollutants included VOCs, carbonyls, PAHs, nicotine, TSNAs, and glycols. From these results, risk analyses were conducted based on dilution into a 40 m3 room and standard toxicological data. Non-cancer risk analysis revealed “No Significant Risk” of harm to human health for vapor samples from e-liquids (A-D). In contrast, for tobacco smoke most findings markedly exceeded risk limits indicating a condition of “Significant Risk” of harm to human health. With regard to cancer risk analysis, no vapor sample from e-liquids A-D exceeded the risk limit for either children or adults. The tobacco smoke sample approached the risk limits for adult exposure.”

Peering through the mist: systematic review of what the chemistry of contaminants in electronic cigarettes tells us about health risks.

Igor Burstyn, Department of Environmental and Occupational Health, School of Public Health, Drexel University

BMC Public Health 2014, 14:18

”Exposure of bystanders to the listed ingredients, let alone the contaminants, does not warrant a concern as the exposure is likely to be orders of magnitude lower than exposure experienced by vapers. Further research employing realistic conditions could help quantify the quantity of exhaled aerosol and its behavior in the environment under realistic worst-case scenarios (i.e., not small sealed chambers), but this is not a priority since the exposure experienced by bystanders is clearly very low compared to the exposure of vapers, and thus there is no reason to expect it would have any health effects.

In summary, analysis of the current state of knowledge about the chemistry of contaminants in liquids and aerosols associated with electronic cigarettes indicates that there is no evidence that vaping produces inhalable exposures to these contaminants at a level that would prompt measures to reduce exposure by the standards that are used to ensure safety of workplaces.”

Electronic cigarettes: achieving a balanced perspective.

Theodore L. Wagener, Michael Siegel and Belinda Borrelli.

Addiction. Volume 107, Issue 9, pages 1545–1548, September 2012.

”Concerns have been raised that the advent of electronic cigarettes (e-cigarettes) may be harmful to public health, and smokers have been advised by important agencies such as the US Food and Drug Administration not to use them. This paper argues that, while more research is needed on the cost–benefit equation of these products and the appropriate level and type of regulation for them, the harms have tended thus far to be overstated relative to the potential benefits.

In particular: concern over repeated inhalation of propylene glycol is not borne out by toxicity studies with this compound; risk of accidental poisoning is no different from many household devices and chemicals available in supermarkets; concern that e-cigarettes may promote continued smoking by allowing smokers to cope with no-smoking environments is countered by the observation that most smokers use these products to try to quit and their use appears to enhance quitting motivation; concerns over low nicotine delivery are countered by evidence that the products provide significant craving reduction despite this in some cases; and e-cigarettes may help reduce toxin exposure to non-smokers.”

Characteristics, Perceived Side Effects and Benefits of Electronic Cigarette Use: A Worldwide Survey of More than 19,000 Consumers

Konstantinos E. Farsalinos, Giorgio Romagna, Dimitris Tsiapras, Stamatis Kyrzopoulos and Vassilis Voudris.

International Journal of Environmental Research and Public Health. April 2014.

”A substantial proportion of participants reported pre-existing disease conditions, including respiratory disease, with benefits observed by the majority after initiating EC (electronic cigarette) use. As expected, former smokers were more likely to report beneficial health effects compared to current smokers (often called dual users). The latter should be encouraged to completely eliminate tobacco cigarette use; a recent longitudinal study showed that 46% of dual users managed to quit smoking at 1 year follow-up.”

Real-world effectiveness of e-cigarettes when used to aid smoking cessation: a cross-sectional population study.

Brown J, Beard E, Kotz D, Michie S, West R.

Addiction. 2014 Sep;109(9):1531-40. doi: 10.1111/add.12623.

”Electronic cigarettes (e-cigarettes) are rapidly increasing in popularity. Two randomized controlled trials have suggested that e-cigarettes can aid smoking cessation, but there are many factors that could influence their real-world effectiveness. This study aimed to assess, using an established methodology, the effectiveness of e-cigarettes when used to aid smoking cessation compared with nicotine replacement therapy (NRT) bought over-the-counter and with unaided quitting in the general population.

A large cross-sectional survey of a representative sample of the English population.

The study included 5863 adults who had smoked within the previous 12 months and made at least one quit attempt during that period with either an e-cigarette only (n = 464), NRT bought over-the-counter only (n = 1922) or no aid in their most recent quit attempt (n = 3477).

CONCLUSIONS:Among smokers who have attempted to stop without professional support, those who use e-cigarettes are more likely to report continued abstinence than those who used a licensed NRT product bought over-the-counter or no aid to cessation. This difference persists after adjusting for a range of smoker characteristics such as nicotine dependence.”