Smoking of conventional cigarettes with tobacco is known as a cause of severe health problems worldwide, amongst others including chronic lung diseases and cancer. One reason for the high incidence of smokers is the fact that people become addicted to the cigarettes in which it can be debated if the addiction is physically or mentally based. Anyway, there is no doubt that cigarettes are harmful and that smoking cessation is of high importance for smokers who are not ill and even more for patients who already suffer from the consequences of long-term smoking, such as chronic obstructive pulmonary disease (COPD). It has been demonstrated that smoking cessation has beneficial effects on life quality. However, it is difficult for smokers to quit. To help them, a variety of nicotine replacement products have come to the market including nicotine patch, gum, inhaler, lozenges and nasal spray – and recently e-cigarettes. When e-cigarettes first appeared, they were promoted as a non-hazardous alternative to conventional cigarettes although containing nicotine. They are currently a hot topic for both smokers and scientists/clinicians. Increasing number of chronic and amateur smokers are using e-cigarettes and even some clinicians suggest them as a replacement therapy to conventional smoking. Despite the lack of long-term effects of e-cigarettes, they are freely available, even for adolescents. However, there is increasing evidence that e-cigarettes cause similar problems to conventional cigarettes. On the other hand, it is still debatable that e-cigarette smoking will actually help quitting conventional smoking. This interactive discussion aims to challenge scientists, clinicians and other persons who are interested in this field to think about the usefulness of e-cigarettes, the pros and cons.
E-cigarettes, first marketed in China in 2004, were introduced to the international market in 2007. Awareness and usage of e-cigarettes has drastically increased since entering the market. From the scientific point of view, it was surprising that the introduction of e-cigarettes took place so easily. They contain nicotine and artificial liquids and no long-term studies were available. The majority of e-cigarette users are smokers who anticipated that they are less toxic than conventional cigarettes and help them for smoking cessation.
An online survey of smokers who had tried e-cigarettes with an aim to assess the effectiveness of e-cigarettes as a smoking cessation tool with 222 respondents showed that 31% of respondents did not smoke cigarettes for 6 months from the time they started using e-cigarettes. This study also showed that 66.8% reduced usage of the number of cigarettes(1).
Another prospective study was performed on 40 smokers who were not thinking of quitting. After following the participants for six months, the study has shown a 50% reduction in the number of cigarettes smoked per day in 55% of participants without significant withdrawal symptoms(2). However, most of efficacy studies are short-term. The effectiveness of e-cigarettes as a smoking cessation tool in long-term still should be addressed. These studies might show reduction/cessation of cigarette smoking but we should not forget the big picture here with using e-cigarette that its main ingredient nicotine (an addictive substance and the main cause of addiction to tobacco) can lead to addiction
Furthermore, e-cigarettes can cause acute effects comparable with conventional cigarettes. Right after a 42 years old woman started using e-cigarettes, she started having respiratory symptoms like dyspnea, productive cough and subjective fever. Seven months after the onset of her symptoms she was diagnosed with exogenous lipoid pneumonia which is uncommon, primarily chronic inflammatory reaction resulting from continuous aspiration of oil substance(3).
Moreover, a 20 years old healthy man had persistence cough, shortness of breath and facial flushing one hour after vaping an e-cigarette. After a series of clinical examinations he was diagnosed with acute eosinophilic pneumonia (a rare condition characterized by rapid accumulation of eosinophils in the lungs as a consequence of unidentified, nonspecific triggering agents)(4).
A laboratory-based intervention study analysed oxidative stress and lung function in 40 participants divided into two groups (30 individuals in experimental and 10 in a control group). The experimental group was provided with e-cigarettes and was using e-cigarettes only for 5 min. The level of fractional exhaled nitric oxide [FENO] (a quantitative, noninvasive and safe method of measuring airway inflammation that provides a complementary tool to other ways of assessing airways disease) was assessed before and after e-cigarette usage. FENO was significantly decreased in experimental group after using e-cigarettes. The study also shows using impulse oscillometry increased airway impedance and peripheral airway resistance in experimental group compared to control group(5).
In another study, the potential effects of e-cigarette vapor on cardiomyoblast cell viability was evaluated. They extracted the vapor from 20 different e-cigarette liquids with different flavoring substances and exposed the cells to different concentrations for 24 hours. Four out of 20 e-cigarettes showed cytotoxic effects on cardiomyoblasts. Moreover, the study addresses whether e-cigarettes are less harmful than that of conventional cigarettes and indicates that e-cigarette vapor extracts were less cytotoxic compared to cigarette smoke extract on cultured cardiomyoblasts(6).
Another study by Bahl and colleagues evaluated the cytotoxicity ability of 35 different flavored e-cigarette liquids on human embryonic stem cells (hESC), mouse neural stem cells (mNSC), and human pulmonary fibroblasts (hPF). They treated the cells with different concentration of refill liquids and evaluated cell cytotoxicity. Except one (Bubble-gum), all refill liquids were cytotoxic to the cells to various extent. The cytotoxicity of refilled solution mostly depends on the dose of refill solution and flavors as well as cell type (stem cells from embryos (hESC) and new born (mNSC) were more sensitive to refill solutions than adult lung fibroblasts)(7).
Vegetable glycine (VG) and propyl glycol (PG) go through decomposition at high temperature into low molecular carbonyl compounds such as the carcinogens formaldehyde and acetaldehyde. Using high-performance liquid chromatography and a diode array detector Kosmideret al. measured the amount of carbonyl compounds in e-cigarettes vapor. Vapor extract collected from 70ml volume of puff a total of 15 puffs from ten different commercially available e-cigarette liquids, formaldehyde and acetaldehyde release were detected in 8 of vapor extract. However, the amount of released substances was affected by battery output voltage (the higher the voltage the higher the amount of carbonyl compounds released) (8).
Frighteningly, although nobody knows about long-term effects and risk of addiction, teenagers are currently allowed to use e-cigarettes unrestrictedly. However, based on recent observations, a number of countries are considering to prohibit the easy access of e-cigarettes for young people. A recent study by Lauren Dutra and Stanton A. Glantzused data from the Centers for Disease Control and Prevention(CDC) to demonstrate that use of e-cigarettes is often associated with cigarette smoking among adolescents. E-cigarette use recently doubled among adolescents in the United States, from 3.3% in 2011 to 6.8% in 2012. The authors used a nationally representative sample of over 38,000 U.S. middle and high school students. They showed that adolescents who used e-cigarettes were more likely to be cigarette smokers and more likely to progress from experimenting with cigarettes to become regular cigarette smokers. E-cigarette users, despite having higher reports quit smoking than non-e-cigarette users, were less likely to have stopped smoking cigarettes and were heavier cigarette smokers. These results call into question e-cigarette advertisers’ claims that e-cigarettes are effective smoking cessation devices and questions whether e-cigarette use could actually contribute to cigarette smoking not only among teens(9), but also among adults.
At the annual congress of the European Respiratory Society (ERS) in Amsterdam 2015, e-cigarettes were a hot topic. There were some studies from animal models showing that e-cigarettes containing nicotine cause acute inflammatory response similar (or comparable)to that of conventional cigarettes. There was an interesting oral presentation about a retrospective view at hitherto clinical studies which tried to find out if e-cigarettes can help people to quit smoking. Interestingly, analyzing the data and study designs, the presenter concluded that in most cases e-cigarettes do not help quitting smoking but just lead to a shift from conventional to e-cigarettes. Even more often, respective people just mix between these two kinds of cigarettes. One comment from the audience during this presentation was remarkable which was in turn: “Originally, e-cigarettes were developed and introduced by the tobacco smoke industry, an industry which spent a lot of effort to make users of cigarettes addicted. Do you really believe that the same industry now wants their customers to get rid of smoking?”. Having this in mind, the outcome of studies investigating the safety and benefit of e-cigarettes in comparison to conventional ones will be of interest.
In conclusion, the idea to invent innovative solutions which can help people to stop smoking is eligible. However, the realization should be sophisticated and most notably scientifically approved and honest. It is not acceptable claiming such an alternative will be healthy, non-hazardous for adolescents and adults, and not addictive if this is not proven accurately because this is playing Russian roulette with people´s health and in particular with the future of our children. Maybe e-cigarettes helped some people to quit smoking, but in many cases it seems that there is just a shift from conventional to e-cigarettes. Finally, more rigorous studies are required to understand the significant benefit of e-cigarettes in contrast to existing smoking cessation tools. Maybe the industry reacts to recent data in a way that they focus on e-cigarettes not containing addictive substances such as nicotine. Because it is likely that such e-cigarettes could help some people to quit smoking by mimicking the ritual of smoking.
Therefore, we would like to postulate the following questions to the scientific community worldwide:
1) Are e-cigarettes a useful tool for smoking cessation?
2) What about the easy access of e-cigarettes to our children/adolescents? Do we support the risk for them of getting smokers by just not taking into account that e-cigarettes may be harmful mediators and ignoring the recent data respectively?
3) Are there real measureable advantages of e-cigarettes compared to conventional cigarettes or other smoking cessation tools?
We would like to invite all experts and other persons interested in this field to reply and express their views on this topic, in the next volume of PVRI Chronicle.
1. Cahn Z, Siegel M. Electronic cigarettes as a harm reduction strategy for tobacco control: a step forward or a repeat of past mistakes? J Public Health Policy 2011; 32: 16-31.
2. Polosa R, Caponnetto P, Morjaria JB, Papale G, Campagna D, Russo C. Effect of an electronic nicotine delivery device (e-Cigarette) on smoking reduction and cessation: a prospective 6-month pilot study. BMC Public Health 2011; 11: 786.
3. McCauley L, Markin C, Hosmer D. An unexpected consequence of electronic cigarette use. Chest 2012; 141: 1110-1113.
4. Thota D, Latham E. Case report of electronic cigarettes possibly associated with eosinophilic pneumonitis in a previously healthy active-duty sailor. J Emerg Med 2014; 47: 15-17.
5. Vardavas CI, Anagnostopoulos N, Kougias M, Evangelopoulou V, Connolly GN, Behrakis PK. Short-term pulmonary effects of using an electronic cigarette: impact on respiratory flow resistance, impedance, and exhaled nitric oxide. Chest 2012; 141: 1400-1406.
6. Farsalinos KE, Romagna G, Allifranchini E, Ripamonti E, Bocchietto E, Todeschi S, Tsiapras D, Kyrzopoulos S, Voudris V. Comparison of the cytotoxic potential of cigarette smoke and electronic cigarette vapour extract on cultured myocardial cells. Int J Environ Res Public Health 2013; 10: 5146-5162.
7. Bahl V, Lin S, Xu N, Davis B, Wang YH, Talbot P. Comparison of electronic cigarette refill fluid cytotoxicity using embryonic and adult models. Reprod Toxicol 2012; 34: 529-537.
8. Kosmider L, Sobczak A, Fik M, Knysak J, Zaciera M, Kurek J, Goniewicz ML. Carbonyl compounds in electronic cigarette vapors: effects of nicotine solvent and battery output voltage. Nicotine Tob Res 2014; 16: 1319-1326.
9. Dutra LM, Glantz SA. Electronic cigarettes and conventional cigarette use among U.S. adolescents: a cross-sectional study. JAMA Pediatr 2014; 168: 610-617.