Why public health people are more worried than excited over e-cigarettes
BMC Medicine volume 12, Article number: 226 (2014)
The research field on e-cigarettes is characterized by severe methodological problems, severe conflicts of interest, relatively few and often small studies, inconsistencies and contradictions in results, and a lack of long-term follow-up. Therefore, no firm conclusions can be drawn on the harm of e-cigarettes, but they can hardly be called safe. Experimental studies indicate negative health effects and, amongst others, the major ingredient propylene glycol warrants concern. Growing evidence raises doubt about the efficacy of e-cigarettes as a smoking cessation aid. Unfortunately, it seems that many smokers use e-cigarettes with the intention to quit but switch to long-term use of e-cigarettes or dual use. Use is spreading rapidly to minors, ex-smokers, and never-smokers. It is questionable whether the potential health benefits obtained by some smokers outweigh the potential harm by use of non-smokers, of undermining of complete cessation, smokers’ dual use, and of eventual re-normalization of smoking. Even if e-cigarettes are significantly less harmful than conventional cigarettes, the product may have a very negative impact on public health if its use is spread to a large part of the population.
When I first heard about the e-cigarette (EC), I was excited. Was this the miraculous alternative to conventional cigarettes (CC) that could prevent millions of peoples’ suffering? Today, big tobacco companies have bought up the market, sales are exploding, and I and many other health professionals are worried .
Some harm reduction advocates claim that public health professionals are just moralists with an aversion of nicotine, an addictive drug, leading to an illogical and unfair hatred of ECs. I believe this subject is of too large public health importance to resort to mudslinging.
The harm reduction strategy (replacing a very harmful product with a less harmful product) is common sense; however, history has unfortunately shown that common sense can do harm . As a doctor, I have sworn “First Do No Harm”, as a researcher, I call for substantial evidence with very consistent findings, and as a public health professional, I am obliged to take long-term consequences for the whole population – both smokers and non-smokers – into account before recommending a new product.
The safety of e-cigarettes
ECs are marketed as safe products delivering pure nicotine and releasing harmless water vapor that vanishes in seconds ,, but is this true? The research field is characterized by severe methodological problems, severe conflicts of interest, relatively few and often small studies, inconsistencies and contradictions in results, and a lack of long-term follow-up. Therefore, no firm conclusions can be drawn on the safety of ECs ,, and much is left to subjective interpretations. Most probably ECs are less harmful than conventional cigarettes, but they can hardly be called safe. An experimental study found that cells exposed to high-nicotine vapor showed a similar pattern of gene expression to those exposed to tobacco smoke . Very short-term experimental exposure to EC vapor showed effects that are reminiscent of the obstructive effects seen with smoking -, even though the impact on lung function was smaller than with smoking. An experimental animal study found that EC fluid can exacerbate allergy-induced asthma symptoms . Furthermore, a study found that the vapor induced release of cytokines and pro-inflammatory mediators  and many studies have found cytotoxicity , and harmful substances in fluid and vapor (e.g., fine or ultrafine particles -, harmful metals ,, carcinogenic tobacco-specific nitrosamines -, carbonyls ,,,, volatile organic compounds ,, polycyclic aromatic hydrocarbons ,) or in urine . It is true that most studies found low or very low concentrations, but values below the threshold-limit do not necessarily protect against a negative health effect of 200 to 300 daily inhalations  over decades.
The EC is a radically different product than the CC and, therefore, it seems wrong to base an assessment of the safety of EC on comparisons with CCs only. Of special concern are compounds not found in CCs: the glycols (propylene glycol and sometimes glycerin) are major ingredients of ECs - used to create the visible fume. A report commissioned by vapers and vendors of ECs concluded that “estimated levels of exposure to propylene glycol and glycerin are close enough to threshold-limit values to warrant concern” and that “the threshold-limit value is based on uncertainty rather than knowledge” . Several studies on glycols have raised health concerns -. Other concerns are the flavors, metals, and silicone ,,. Finally, nicotine itself is probably not harmless , and it is highly addictive. Studies show that non-smokers passively exposed to ECs absorb nicotine ,,.
Use of e-cigarettes is no longer restricted to smokers
In the first years, the ECs were bought by smokers only; however, recently, their use has also spread to ex-smokers - and never smokers -. The intensive marketing, the novelty, the use of celebrities as role models, and the candy-like flavors appeal to young people. Experimental use in minors has doubled within one year ,,. A high proportion of adolescents have tried ECs ,,, even at age 12 to 14 years . Of special concern is that young never-smokers are experimenting with ECs - and the use of ECs might undermine decades of efforts to de-normalize smoking . A brand new study from Poland finds that almost every third adolescent is current user of ECs and more than every fifth has a dual use of CCs and ECs. However, the most alarming finding is that the prevalence of smoking increased with increasing rates of EC use, from 24% to 38% during a period of only three years, indicating a renormalization of smoking .
It would be naïve not to expect that the manufacturers will try hard to spread the use of their product to as many consumers as possible, and history has shown that the tobacco industry has no ethical constraints .
The effectiveness of the e-cigarette as an aid for smoking cessation
Making strong conclusions based on smoking rates and rates of EC-use in different countries is difficult, as smoking rates are influenced by political decisions as price and availability, changes in the social norm, etc. Some prospective studies were very promising ,, and a recent large ‘real-world’ study taking smoker’s addiction into account showed that use of ECs increased cessation rates more than no aid/nicotine replacement products bought over the counter . However, a meta-analysis based on five population-based studies found that EC users were significantly less likely than non-users to have stopped smoking , a longitudinal study in cancer patients showed that EC users were twice as likely to be smoking at the time of follow-up as non-users , and the only existing randomized smoking cessation study showed that ECs were not significantly more effective than nicotine patch therapy . A survey sponsored by EC manufacturers found that only 1% of EC users achieved permanent abstinence , but I have not seen this study cited by harm reduction advocates. Unfortunately, it seems that many smokers use ECs with the intention to quit but switch to long-term use of ECs  or end with dual use, supplementing their smoking with the EC -, – dream-scenarios for the industry.
Impact on public health
When we compare with a CC, the most harmful legal product on the market, everything seems harmless. For a smoker reluctant to stop smoking, the EC will most probably be a less harmful alternative – but we cannot focus on these smokers only! The impact of a product on public health is determined by two factors: i) the degree of toxicity or harm of the substance; and ii) how widespread the exposure is. Even if ECs are significantly less harmful than CCs, the product may have a negative impact on public health if the use is spread to a large part of the population (Figure 1). ECs might achieve popularity as high as that of CCs in the 1960s, before an awareness of harm became widespread in the population. The potential health benefits obtained by some smokers (Figure 2) must outweigh the potential harm by use of ex- and never-smokers, of smokers who intended to quit but switched to ECs, of smokers’ dual use, and of eventual re-normalization of smoking.
Most probably, ECs are less harmful than CCs, but they can hardly be called safe. Consequences of EC use must be viewed in a long-term public health perspective, including both smokers and non-smokers. Based on the limited and often conflicting evidence on safety, the doubtful efficacy as a smoking cessation aid, and the alarming rise in use in young people and non-smokers, most public health professionals urge great caution with ECs and call for regulation, monitoring, and research not biased by conflicts of interest.
As the WHO states, this is an “evolving frontier filled with promise and threat for tobacco control” . I shall be the first to celebrate if the ECs turn out to be a safe and effective weapon in tobacco control. Till then, let us focus on intensifying our fight for a smoke-free world by restricting the influence of the tobacco industry, by regulating smoking and other tobacco-/nicotine containing products, and by offering evidence-based help for smoking cessation – we know this works.
The author is a medical doctor. She has worked 10 years in hospitals – four of these in a department of pulmonary medicine and she is a trained smoking cessation counsellor. For the last 15 years she has worked at the Research Center for Prevention and Health as a tobacco researcher, public health professional, and epidemiologist. She is a member of the steering committee of a large population-based intervention study on lifestyle, the Inter99 study and an Associate Professor at the University of Copenhagen (Master of Public Health Studies). She is frequently used by the Danish Health and Medicines Authority on smoking-related topics.
Electronic Nicotine Delivery Systems. Report by WHO. Moscow, Russian Federation; 2014 July. Report No.: FCTC/COP/6/10 21 July 2014. Provisional agenda item 4.4.2. 2014
Changing concepts of sudden infant death syndrome: implications for infant sleeping environment and sleep position. American Academy of Pediatrics. Task Force on Infant Sleep Position and Sudden Infant Death Syndrome. Pediatrics 2000, 105:650–656..
The Electric Cigarette . ; 2014., [http://www.usacig.com/faq.aspx]
Smoke NV. ; 2014., [http://www.smokenv.com/faq.html]
Pisinger C, Døssing M: A systematic review of health effects of electronic cigarettes. Prev Med. 2014, 69: 248-260. 10.1016/j.ypmed.2014.10.009.
Grana R, Benowitz N, Glantz SA: E-cigarettes: a scientific review. Circulation. 2014, 129: 1972-1986. 10.1161/CIRCULATIONAHA.114.007667.
Park SJ, Walser TC, Perdomo C, Wang T, Pagano PC, Liclican EL, Krysan K, Larsen JE, Minna JD, Lenburg ME, Spira A, Dubinett SM: The effect of e-cigarette exposure on airway epithelial cell gene expression and transformation. Clinical Cancer Research Conference: 3rd AACR-IASLC Joint Conference on the Molecular Origins of Lung Cancer San Diego, CA, USA. 6 th to 9 th January, 2014. .
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. 10.1378/chest.11-2443.
Marini S, Buonanno G, Stabile L, Ficco G: Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide. Toxicol Appl Pharmacol. 2014, 278: 9-15. 10.1016/j.taap.2014.04.004.
Palamidas A, Gennimata SA, Kaltsakas G, Tsikrika S, Vakali S, Gratziou C, Koulouris N: Acute effect of an e-cigarette with and without nicotine on lung function. Tobacco Induced Dis. 2014, 12: A34.
Gennimata SA, Palamidas A, Kaltsakas G, Tsikrika S, Vakali S, Gratziou C, Koulouris N: Acute effect of e-cigarette on pulmonary function in healthy subjects and smokers. In Thematic Poster Session: Tobacco Dependence and Respiratory Disease. European Respiratory Society, Annual Congress, Munich, Germany, 6th – 10th September; 2014.
Cervellati F, Muresan XM, Sticozzi C, Gambari R, Montagner G, Forman HJ, Torricelli C, Maioli E, Valacchi G: Comparative effects between electronic and cigarette smoke in human keratinocytes and epithelial lung cells. Toxicol In Vitro. 2014, 28: 999-1005. 10.1016/j.tiv.2014.04.012.
Williams M, Villarreal A, Bozhilov K, Lin S, Talbot P: Metal and silicate particles including nanoparticles are present in electronic cigarette cartomizer fluid and aerosol. PLoS One. 2013, 8: e57987-10.1371/journal.pone.0057987.
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. 10.1016/j.reprotox.2012.08.001.
Zhang Y, Sumner W, Chen DR: In vitro particle size distributions in electronic and conventional cigarette aerosols suggest comparable deposition patterns. Nicotine Tob Res. 2013, 15: 501-508. 10.1093/ntr/nts165.
Ingebrethsen BJ, Cole SK, Alderman SL: Electronic cigarette aerosol particle size distribution measurements. Inhal Toxicol. 2012, 24: 976-984. 10.3109/08958378.2012.744781.
Fuoco FC, Buonanno G, Stabile L, Vigo P: Influential parameters on particle concentration and size distribution in the mainstream of e-cigarettes. Environ Pollut. 2014, 184: 523-529. 10.1016/j.envpol.2013.10.010.
Schober W, Szendrei K, Matzen W, Osiander-Fuchs H, Heitmann D, Schettgen T, Jörres RA, Fromme H: Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers. Int J Hyg Environ Health. 2014, 217: 628-637. 10.1016/j.ijheh.2013.11.003.
Goniewicz ML, Knysak J, Gawron M, Kosmider L, Sobczak A, Kurek J, Prokopowicz A, Jablonska-Czapla M, Rosik-Dulewska C, Havel C, Jacob P, Benowitz N: Levels of selected carcinogens and toxicants in vapour from electronic cigarettes. Tob Control. 2014, 23: 133-139. 10.1136/tobaccocontrol-2012-050859.
Kim HJ, Shin HS: Determination of tobacco-specific nitrosamines in replacement liquids of electronic cigarettes by liquid chromatography-tandem mass spectrometry. J Chromatogr A. 2013, 1291: 48-55. 10.1016/j.chroma.2013.03.035.
McAuley TR, Hopke PK, Zhao J, Babaian S: Comparison of the effects of e-cigarette vapor and cigarette smoke on indoor air quality. Inhal Toxicol. 2012, 24: 850-857. 10.3109/08958378.2012.724728.
Lauterbach JH, Laugesen M, Ross JD: Suggested Protocol for Estimation of Harmful and Potentially Harmful Constituents in Mainstream Aerosols Generated by Electronic Nicotine Delivery Systems (ENDS). Poster # 1860, Society of Toxicology, San Francisco. The Toxicologist CD, J of the Soc of Toxicology 2012 Mar;126. , [http://www.ecita.org.uk/safety.htm]
Lauterbach JH, Laugesen M: Comparison of Toxicant Levels in Mainstream Aerosols Generated by Ruyan® Electronic Nicotine Delivery Systems (ENDS) and Conventional Cigarette Products. , [http://www.healthnz.co.nz/News2012SOTposter1861.pdf]
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. 10.1093/ntr/ntu078.
Hutzler C, Paschke M, Kruschinski S, Henkler F, Hahn J, Luch A: Chemical hazards present in liquids and vapors of electronic cigarettes. Arch Toxicol. 2014, 88: 1295-1308. 10.1007/s00204-014-1294-7.
Czogala J, Goniewicz ML, Fidelus B, Zielinska-Danch W, Travers MJ, Sobczak A: Secondhand exposure to vapors from electronic cigarettes. Nicotine Tob Res. 2014, 16: 655-662. 10.1093/ntr/ntt203.
Goniewicz ML, Kuma T, Gawron M, Knysak J, Kosmider L: Nicotine levels in electronic cigarettes. Nicotine Tob Res. 2013, 15: 158-166. 10.1093/ntr/nts103.
Cheah NP, Chong NW, Tan J, Morsed FA, Yee SK: Electronic nicotine delivery systems: regulatory and safety challenges: Singapore perspective. Tob Control. 2014, 23: 119-125. 10.1136/tobaccocontrol-2012-050483.
Pellegrino RM, Tinghino B, Mangiaracina G, Marani A, Vitali M, Protano C, Osborn JF, Cattaruzza MS: Electronic cigarettes: an evaluation of exposure to chemicals and fine particulate matter (PM). Ann Ig. 2012, 24: 279-288.
Etter JF, Zather E, Svensson S: Analysis of refill liquids for electronic cigarettes. Addiction. 2013, 108: 1671-1679. 10.1111/add.12235.
Schripp T, Markewitz D, Uhde E, Salthammer T: Does e-cigarette consumption cause passive vaping?. Indoor Air. 2013, 23: 25-31. 10.1111/j.1600-0668.2012.00792.x.
Uryupin AB, Peregudov AS, Kochetkov KA, Bulatnikova LN, Kiselev SS, Nekrasov YS: Qualitative and quantitative compositions of fluids for electronic cigarettes. Pharma Chem J. 2013, 46: 687-692. 10.1007/s11094-013-0871-z.
Burstyn I: Peering Through the Mist: What Does the Chemistry of Contaminants in the Electronic Cigarettes Tell us about Health Risks? Technical report. School of Public Health, Drexel University, Philadelphia, USA: Department of Environmental and Occupational Health; 2013.
Wieslander G, Norback D, Lindgren T: Experimental exposure to propylene glycol mist in aviation emergency training: acute ocular and respiratory effects. Occup Environ Med. 2001, 58: 649-655. 10.1136/oem.58.10.649.
Choi H, Schmidbauer N, Sundell J, Hasselgren M, Spengler J, Bornehag CG: Common household chemicals and the allergy risks in pre-school age children. PLoS One. 2010, 5: e13423-10.1371/journal.pone.0013423.
Ponec M, Haverkort M, Soei YL, Kempenaar J, Bodde H: Use of human keratinocyte and fibroblast cultures for toxicity studies of topically applied compounds. J Pharm Sci. 1990, 79: 312-316. 10.1002/jps.2600790408.
Renne RA, Wehner AP, Greenspan HS, Deford HS, Ragan HA, Westerberg RB, Buschbom RL, Burger GT, Hayes AW, Suber RL, Mosberg AT: 2-Week and 13-week inhalation studies of aerosolized glycerol in rats. Inhal Toxicol. 1992, 4: 95-111. 10.3109/08958379209145307.
Elmore AR: Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller’s earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite. Int J Toxicol. 2003, 22: 37-102. 10.1177/1091581803022S115.
National Center for Chronic Disease Prevention and Health Promotion (US) Office on Smoking and Health: The Health Consequences of Smoking-50 Years of Progress: A Report of the Surgeon General. Atlanta, GA: Centers for Disease Control and Prevention; 2014.
Ballbe M, Martinez-Sanchez JM, Sureda X, Fu M, Perez-Ortuno R, Pascual JA, Saltó E, Fernández E: Cigarettes vs. e-cigarettes: Passive exposure at home measured by means of airborne marker and biomarkers. Environ Res. 2014, 135C: 76-80. 10.1016/j.envres.2014.09.005.
Flouris AD, Chorti MS, Poulianiti KP, Jamurtas AZ, Kostikas K, Tzatzarakis MN, Wallace Hayes A, Tsatsakis AM, Koutedakis Y: Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function. Inhal Toxicol. 2013, 25: 91-101. 10.3109/08958378.2012.758197.
Etter JF: Electronic cigarettes: a survey of users. BMC Public Health. 2010, 10: 231-10.1186/1471-2458-10-231.
Etter JF, Bullen C: Electronic cigarette: users profile, utilization, satisfaction and perceived efficacy. Addiction. 2011, 106: 2017-2028. 10.1111/j.1360-0443.2011.03505.x.
Adkison SE, O’Connor RJ, Bansal-Travers M, Hyland A, Borland R, Yong HH, Cummings KM, McNeill A, Thrasher JF, Hammond D, Fong GT: Electronic nicotine delivery systems: international tobacco control four-country survey. Am J Prev Med. 2013, 44: 207-215. 10.1016/j.amepre.2012.10.018.
Rapport et avis d’experts sur l’ e-cigarette. Avec le soutien de la Direction générale de la santé. Jeunes Paris 2012 & 2013. Paris: Office Francais de Prévention du Tabagisme; 2013.
Goniewicz ML, Zielinska-Danch W: Electronic cigarette use among teenagers and young adults in Poland. Pediatrics. 2012, 130: e879-e885. 10.1542/peds.2011-3448.
Dautzenberg B, Birkui P, Noël M, Dorset J, Osman M, Dautzenberg M-D: E-Cigarette: a new tobacco product for schoolchildren in Paris. Open J Respir Dis. 2013, 3: 21-24. 10.4236/ojrd.2013.31004.
CDC: Notes from the field: electronic cigarette use among middle and high school students - United States, 2011–2012. MMWR Morb Mortal Wkly Rep 2013, 62:729–730..
Czoli CD, Hammond D, White CM: Electronic cigarettes in Canada: prevalence of use and perceptions among youth and young adults. Can J Public Health. 2014, 105: e97-e102.
Camenga DR, Delmerico J, Kong G, Cavallo D, Hyland A, Cummings KM, Krishnan-Sarin S: Trends in use of electronic nicotine delivery systems by adolescents. Addict Behav. 2014, 39: 338-340. 10.1016/j.addbeh.2013.09.014.
Choi K, Fabian L, Mottey N, Corbett A, Forster J: Young adults’ favorable perceptions of snus, dissolvable tobacco products, and electronic cigarettes: findings from a focus group study. Am J Public Health. 2012, 102: 2088-2093. 10.2105/AJPH.2011.300525.
Goniewicz ML, Gawron M, Nadolska J, Balwicki L, Sobczak A: Rise in electronic cigarette use among adolescents in Poland. J Adolesc Health. 2014, 5: 713-715. 10.1016/j.jadohealth.2014.07.015.
Proctor RN: Golden Holocaust. Origins of the Cigarette Catastrophe and the Case for Abolition. 2011, University of California Press, Berkeley and Los Angeles, CA
Caponnetto P, Auditore R, Russo C, Cappello GC, Polosa R: Impact of an electronic cigarette on smoking reduction and cessation in schizophrenic smokers: a prospective 12-month pilot study. Int J Environ Res Public Health. 2013, 10: 446-461. 10.3390/ijerph10020446.
Caponnetto P, Campagna D, Cibella F, Morjaria JB, Caruso M, Russo C, Polosa R: EffiCiency and Safety of an eLectronic cigAreTte (ECLAT) as tobacco cigarettes substitute: a prospective 12-month randomized control design study. PLoS One. 2013, 8: e66317-10.1371/journal.pone.0066317.
Kotz D, Brown J, West R: ‘Real-world’ effectiveness of smoking cessation treatments: a population study. Addiction. 2014, 109: 491-499. 10.1111/add.12429.
Borderud SP, Li Y, Burkhalter JE, Sheffer CE, Ostroff JS: Electronic cigarette use among patients with cancer: characteristics of electronic cigarette users and their smoking cessation outcomes. Cancer. 2014, 120: 3527-3535. 10.1002/cncr.28811.
Bullen C, Howe C, Laugesen M, McRobbie H, Parag V, Williman J, Walker N: Electronic cigarettes for smoking cessation: a randomised controlled trial. Lancet. 2013, 382: 1629-1637. 10.1016/S0140-6736(13)61842-5.
Heavner K, Dunworth J, Bergen P, Nissen C, Philips CV: Electronic Cigarettes (e-cigarettes) as Potential Tobacco Harm Reduction Products: Results of an Online Survey of e-cigarette Users. , [http://www.tobaccoharmreduction.org/thr2010ahi.pdf]
Lee S, Grana RA, Glantz SA: Electronic cigarette use among Korean adolescents: a cross-sectional study of market penetration, dual use, and relationship to quit attempts and former smoking. J Adolesc Health. 2014, 54: 684-690. 10.1016/j.jadohealth.2013.11.003.
I thank D.M.Sci. M. Døssing, co-author of the systematic review on health effects of electronic cigarettes , and D.M.Sci. T. Jørgensen, professor in public health, for being a supportive and critical academic sparring partner.
The authors declare that they have no competing interests.
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Pisinger, C. Why public health people are more worried than excited over e-cigarettes. BMC Med 12, 226 (2014). https://doi.org/10.1186/s12916-014-0226-y
- Electronic cigarettes
- Harm reduction
- Public health