Unless you’ve been hiding under a rock, you’ve probably heard of electronic cigarettes, or e-cigarettes. Since their emergence in 2004, the market for e-cigarettes has exploded. According to a 2016 report by the United States Surgeon General, the use of e-cigarettes increased by an astonishing 900 percent between 2011 and 2015. 1 The popularity of these “heat-not-burn” tobacco products is such that their usage is predicted to surpass conventional cigarettes in the future. And who can blame consumers? The ads for e-cigarettes are alluring. Companies have cleverly targeted cigarette smokers who are struggling to find social acceptance of their habit. “Take back your freedom” is the slogan of one leading e-cigarette company. Advertisements also promote the health benefits, even suggesting that the switch to e-cigarettes is a way to “love your lungs.” Do these companies really know what they’re talking about?  

E-cigarettes contain formaldehyde

E-cigarettes (electronic nicotine delivery systems) are battery-operated systems that heat liquid-filled cartridges to release nicotine and chemical aerosols. The New England Journal of Medicine published a study that measured formaldehyde-containing entities released during the “heating process” in multiple e-cigarette products.2 As a reminder, formaldehyde is the chemical used to embalm corpses and is a known cancer-causing agent.3,4Another disturbing fact is that researchers discovered that sometimes the concentrations of formaldehyde exceeded the concentration of nicotine in these products.2  

The industry received further bad publicity after a flavouring chemical named diacetyl, which is believed responsible for “popcorn lung,” was isolated in e-cigarettes. 5,6   (Popcorn lung is a form of bronchiolitis that was linked in the 1990s to the inhalation of a powdered form of diacetyl, used in the butter flavouring of popcorn.)7 While the name of this disease is reminiscent of a fun night at the movies, the reality is that it causes lung damage that can be long lasting and lead to shortness of breath, cough and permanently reduced lung function. Other flavourings found in e-cigarettes, such as 2,3-pentanedione, have also been implicated in flavouring-induced lung disease. 8 

Diseases associated with e-cigarettes

It is unclear whether e-cigarette users are at risk of chronic obstructive pulmonary disease (COPD), an airway disease almost exclusively linked to cigarette smoking in North America. Yet, troubling data from a study in The American Journal of Respiratory and Critical Care Medicine found that the level of oxidative stress and immune suppression in the lungs of e-cigarette users was comparable to cigarette smokers.9  Similar to cigarette smoke, e-cigarette vapour is made up of a cocktail of chemicals, metals and airway irritants that are inhaled deep into the lungs. Asthma has also been associated with e-cigarette use in youth. 10,11  In one study, the odds of having an asthma diagnosis were 3.4 times higher in current e-cigarette users compared to non-users.10 

Is there any rationale in choosing e-cigarettes as the lesser of two evils? E-cigarettes have been promoted as a method of smoking cessation but a survey of at least 75,000 American adults found that 53 percent smoked cigarettes at the same time as using e-cigarettes.12 Another study of 2,965 adult smokers proved that they were more likely to quit smoking if they were not using e-cigarettes, suggesting that their use doesn’t help in smoking cessation.13 The evidence for e-cigarettes as a smoking reduction tool is inconsistent and people who wish to quit smoking should be pointed in the direction of evidence-based strategies.14 

E-cigarettes have also been marketed as a more attractive and socially acceptable alternative to conventional cigarettes. While the rates of cigarette smoking have been on the decline in recent decades, this positive trend may be threatened by the re-normalization of smoking behaviors. E-cigarettes may also be promoting tobacco dependence in future generations. A study of Canadian high school students found that e-cigarette use was associated with the initiation of cigarette smoking.15 

Overall, the long-term health outcomes of vaping or e-cigarette use are still unknown at this time and further research is needed. As a physician who practices respiratory medicine, I treat elderly patients with severe lung diseases and cancer who were simply unaware of the dangers of cigarette smoking when they were younger because of limited evidence to counter the attractive claims made by tobacco companies. Given that there is already some scientific evidence contesting the claims made by these re-branded tobacco companies, let’s not allow history to repeat itself, or get burned by the same mistake. 



  1. U.S. Department of Health and Human Services. E-Cigarette Use Among Youth and Young Adults: A Report of the Surgeon General. 2016. 
  2. Jensen RP, Luo W, Pankow JF, et al. Hidden formaldehyde in E-cigarette aerosols. NEJM. 2015;372:392-394.  
  3. International Agency for Research on Cancer (June 2004). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 88 (2006): Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol. Retrieved December 24, 2017, from: http://monographs.iarc.fr/ENG/Monographs/vol88/index.php 
  4. National Toxicology Program (June 2011). Report on Carcinogens, Twelfth Edition. Department of Health and Human Services, Public Health Service, National Toxicology Program. Retrieved December 24, 2017, from: http://ntp.niehs.nih.gov/go/roc12. 
  5. Barrington-Trimis JL, Samet JM, McConnell R. Flavorings in electronic cigar- 
ettes: an unrecognized respiratory health hazard? JAMA. 2014; 312:2493– 
  6. Farsalinos KE, Kistler KA, Gillman G, Voudris V. Evaluation of electronic cigarette liquids and aerosol for the presence of selected inhalation toxins. Nicotine Tob Res. 2015; 17:168 – 174. 
  7. Kreiss, Kathleen, G. Ahmed, et al. Clinical Bronchiolitis Obliterans in Workers at a Microwave-Popcorn Plant. The New England Journal of Medicine. Aug. 1, 2002 347:330-338 
  8. Allen, J. Flanigan SS, LeBlanc M, et al. Flavoring chemicals in e-cigarettes: Diacetyl, 2,3-Pentanedione, and Acetoin in a sample of 51 products, including fruit-, candy-, and cocktail-flavored e-cigarettes. Environ Health Perspect. 2016;124(6):733-739. 
  9. Reidel B, Radicioni G, Clapp P, et al. E-cigarette use causes a unique innate immune response in the lung, involving increased neutrophilic activation and altered mucin secretion. AJRCCM. 2017;12(10):e0185735. 
  10. Cho JH, Paik SY. Association between Electronic Cigarette Use and Asthma among High School Students in South Korea. PLoS ONE. 2016;11(3): e0151022.  
  11. Choi K, Bernat D. E-cigarette use among Florida youth with and without asthma. Am J Prev Med. 2016;51(4):446-453. 
  12. Sharapova SR, Singh T, Agaku IT, et al. Patterns of E-cigarette use frequency-National Adult Tobacco Survey, 2012-2014. Am J Prev Med. 2017; doi: 10.1016/j.amepre.2017.09.015. 
  13. Sung B. E-cigarette use and smoking cessation among South Korean adult smokers: a propensity score-matching approach. Asia Pac J Public Health. 2017; doi: 10.1177/1010539517740054. 
  14. El Dib R, Suzumura EA, Akl EA, et al. Electronic nicotine delivery systems and/or electronic non-nicotine delivery systems for tobacco smoking cessation or reduction: a systematic review and meta-analysis. BMJ Open. 2017;7(2): e012680. 
  15. Hammond D, Reid JL, Cole AG, et al. Electronic cigarette use and smoking initiation among youth: a longitudinal cohort study. CMAJ. 2017; 189(43):E1328-E1336.