(Mika Baumeister, Unsplash)
This article was exclusively written for The European Sting by Ms. Mariana Marçal, a 23-year-old medical student from Lisbon, currently attending the 4th year at NOVA Medical School. She is affiliated to the International Federation of Medical Students Associations (IFMSA), cordial partner of The Sting. The opinions expressed in this piece belong to the writer and do not necessarily reflect IFMSA’s view on the topic, nor The European Sting’s one.
When it was suggested back in 1939 that cigarettes were a responsible factor for the rise in lung cancer, this idea seemed laughable at the time. Today, it is well established that tobacco is harmful and is strongly linked to cancer [1]. The recent rise in alternative products such as electronic cigarettes, however, has led to uncertainty about its true long-term effects on health. Electronic cigarettes (or e-cigarettes) are battery-operated devices that electrically heat and vaporize “e-liquids” to produce inhalable vapours without combusting tobacco. E-cigarettes started being commercialized in 2003 in China and entered the European markets in 2006.
These products present a challenge for public health due to their alarming increase in popularity. In 2017, about 15% of the European population had tried e-cigarettes at least once in their life [2]. Another study from the US showed that between 2017 and 2018, the number of high school students that reported current use of e-cigarettes increased from 12% to 21% [3]. Evidence suggests that e-cigarettes are being used among teenagers for alternative behaviours such as dripping, smoke tricks, use of flavours, and use of other substances such as marijuana [4].
The effects of chronic use of e-cigarettes are still largely unknown, and levels of toxic and carcinogenic compounds may vary greatly depending on the brand. Many e-cigarettes contain misleading or missing information on product ingredients, but across all brands, the main components are nicotine, propylene glycol, glycerol, and flavourings. Many studies found other harmful substances such as metals, carcinogenic tobacco-specific nitrosamines and carbonyls [5]. E-cigarettes do not produce the tar that is contained in traditional cigarettes. However, studies have found that it produces formaldehyde, acetaldehyde and acetone a known carcinogen at levels above recommended levels [6]. The overall health risks associated with e-cigarettes remain uncertain but they cannot be considered safe. A recent study found daily e-cigarette use is associated with increased risk of myocardial infarction [7]. In 2018, a study of mice found that e-cigarette smoke could cause mutations in DNA that could increase the risk of cancer [8]. However, we remain shockingly ignorant about the toxicity of chronic exposure to these products.
E-cigarettes have been widely marketed as a tool for smoking cessation and a safer alternative to conventional cigarettes. Although some small studies suggest that e-cigarettes could be an effective strategy to quit smoking in some people [9], there are no large, high-quality studies to support this claim thus far. There are also some concerns that e-cigarette use may be a gateway to nicotine dependence among adolescents. In 2016, the World Health Organization (WHO) urged countries to restrict the sale, promotion, and use of electronic cigarettes [10].
Overall, more research is needed in order to compare the risks and long-term effects of e-cigarettes with tobacco products. As a society, we need to get ahead of this real public health issue. More regulation and restrictions are needed, as well as an international effort to make new policies, promote more research and educate citizens on this issue.
References
[1] Viswanath, Kasisomayajula, et al. “Tobacco and Cancer: An American Association for Cancer Research Policy Statement.” Cancer Research, American Association for Cancer Research, 1 May 2010, cancerres.aacrjournals.org/content/70/9/3419.
[2] Special Eurobarometer 458 – Attitudes of Europeans towards tobacco and electronic cigarettes. Available at http://ec.europa.eu/commfrontoffice/publicopinion/index.cfm/Survey/getSurveyDetail/instruments/SPECIAL/surveyKy/2146. (accessed 25th April 2019)
[3] Cullen, Karen A., et al. “Notes from the Field: Use of Electronic Cigarettes and Any Tobacco Product Among Middle and High School Students — United States, 2011–2018.” MMWR. Morbidity and Mortality Weekly Report, 2018, doi:10.15585/mmwr.mm6745a5.
[4] Krishnan-Sarin, Suchitra, et al. “E-Cigarettes and ‘Dripping’ Among High-School Youth.” Pediatrics, vol. 139, no. 3, 2017, doi:10.1542/peds.2016-3224.
[5] Orellana-Barrios, Menfil A., et al. “Electronic Cigarettes—A Narrative Review for Clinicians.” The American Journal of Medicine, vol. 128, no. 7, 2015, pp. 674–681., doi:10.1016/j.amjmed.2015.01.033.
[6] Kosmider, Leon, et al. “Carbonyl Compounds in Electronic Cigarette Vapors: Effects of Nicotine Solvent and Battery Output Voltage.” Nicotine & Tobacco Research, vol. 16, no. 10, 2014, pp. 1319–1326., doi:10.1093/ntr/ntu078.
[7] Alzahrani, Talal, et al. “Association Between Electronic Cigarette Use and Myocardial Infarction.” American Journal of Preventive Medicine, vol. 55, no. 4, 2018, pp. 455–461., doi:10.1016/j.amepre.2018.05.004.
[8] Lee, Hyun-Wook, et al. “E-Cigarette Smoke Damages DNA and Reduces Repair Activity in Mouse Lung, Heart, and Bladder as Well as in Human Lung and Bladder Cells.” Proceedings of the National Academy of Sciences, vol. 115, no. 7, 2018, doi:10.1073/pnas.1718185115.
[9] Kulik, Margarete C., et al. “E-Cigarettes Associated With Depressed Smoking Cessation: A Cross-Sectional Study of 28 European Union Countries.” American Journal of Preventive Medicine, vol. 54, no. 4, 2018, pp. 603–609., doi:10.1016/j.amepre.2017.12.017.
[10] WHO Report to COP7 on ENDS/ENNDS. Available at http://www.who.int/tobacco/communications/statements/eletronic-cigarettes-january-2017/en/.
About the author
Mariana Marçal is a 23-year-old medical student from Lisbon, currently attending the 4th year at NOVA Medical School. In 2018, she joined Education Against Tobacco (EAT), an international non- governmental organisation run entirely by volunteer medical students and physicians from over 80 medical schools around 14 countries, whose work focuses mainly on school-based prevention of tobacco use. She is now the head of Scientific Department at her school’s EAT group and hopes their work reaches more students and further expands across more schools and countries.
E-cigs should never be made available to minors. But they can be an alternative to long year smoking tobacco and – as the cited studies show – lower health risks.
[5] CANCER RISK
The long-term effect of e-cigarette use on cancer risk is unknown. However, e-cigarette users can be exposed to known carcinogens. One study compared the aerosol generated from brands of e-cigarettes with regular cigarette smoke. The e-cigarette aerosol contained lower levels of toxicants compared with cigarettes. Carcinogen levels were 9 to 450 times lower than those in conventional tobacco products. However, a more recent study utilizing the newer “tank-style” systems with higher voltage batteries reported that these e-cigarettes might expose users to equal or even greater levels of carcinogenic formaldehyde than in tobacco smoke.
The heating element in the e-cigarette causes the incidental generation of carbonyl compounds in e-cigarette smoke mist. The vaping liquid products (glycerol and propylene glycol) are oxidized into formaldehyde, acetaldehyde, acrolein, glyoxal, and methylglyoxal. A 2009 study commissioned by the FDA found known carcinogens diethylene glycol and nitrosamines in trace amounts.68 Diethylene glycol is an organic compound used as a solvent and is currently banned from food and drugs. Nitrosamine is a known carcinogen found in cosmetics, pesticides, and most rubber products.
[6] RESULTS:
Formaldehyde and acetaldehyde were found in 8 of 13 samples. The amounts of formaldehyde and acetaldehyde in vapors from lower voltage EC were on average 13- and 807-fold lower than in tobacco smoke, respectively. The highest levels of carbonyls were observed in vapors generated from PG-based solutions. Increasing voltage from 3.2 to 4.8V resulted in a 4 to more than 200 times increase in formaldehyde, acetaldehyde, and acetone levels. The levels of formaldehyde in vapors from high-voltage device were in the range of levels reported in tobacco smoke.
[7] RESULTS:
Daily e-cigarette use was independently associated with increased odds of having had a myocardial infarction (OR=1.79, 95% CI=1.20, 2.66, p=0.004) as was daily conventional cigarette smoking (OR=2.72, 95% CI=2.29, 3.24, p<0.001). Former and some day e-cigarette use were not significantly associated with having had a myocardial infarction (p=0.608 and p=0.392) whereas former (OR=1.70, p<0.001) and some day cigarette smoking (OR=2.36, p<0.001) were. Odds of a myocardial infarction were also increased with history of hypertension (OR=2.32, p<0.001); high cholesterol (OR=2.36, p<0.001); and diabetes (OR=1.77, p<0.001); and age (OR=1.65 per 10 years, p<0.001). Women (OR=0.47, p<0.001) had lower odds of myocardial infarction.
[8] DISCUSSION
The major purpose of E-cig smoking as well as tobacco smoking is to deliver the stimulant nicotine via aerosols, which allow smokers to obtain instant gratification. Unlike TS, which contains nitrosamines and numerous carcinogenic chemicals resulted from burning, ECS contains nicotine and relatively harmless organic solvents. Therefore, E-cig has been promoted as noncarcinogenic and a safer substitute for tobacco. In fact, recent studies show that E-cig smokers, similar to individuals on nicotine replacement therapy, have 97% less 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), an isoform form of NNK, a tobacco nitrosamine and lung carcinogen, in their body fluid than tobacco smokers. Based on these results, ECS has been recommended as a substitute for TS. However, E-cig smoking is gaining popularity rapidly particularly in young individuals and it is important to note that many of these E-cig smokers have taken up E-cig smoking habit are not necessary doing it for the purpose of quitting TS, rather, it is because they are assuming that E-cig smoking is safe. Currently, there are 18 million E-cig smokers in the United States and 16% of high school students smoke E-cig. Understanding the carcinogenicity of ECS is an urgent public health issue. Since it takes decades for carcinogen exposure to induce cancer in humans, for decades to come there will be no meaningful epidemiological study to address the carcinogenicity of ECS. Therefore, animal models and cell culture models are the reasonable alternatives to address this question.
Nicotine has not been shown to be carcinogenic in animal models. However, during tobacco curing, substantial amounts of nicotine are transformed into tobacco-specific nitrosamines (TSA) via nitrosation, and many of these TSA, such as NNK and NNN, are carcinogenic in animal models (19, 53⇓–55). Because of these findings, the occurrence and the level of nitrosamines in blood fluid have been used as the gold standard for determination of the potential carcinogenicity of smoking. While the NNAL level in E-cig smokers is 97% lower than in tobacco smokers, nonetheless, it is significant higher than in nonsmokers. This finding indicates that nitrosation of nicotine occurs in the human body and that ECS is potentially carcinogenic.
BTW, you should be alerted when you read the term “e-cig smoke” in a study. E-cigs usually produce vapour, not smoke. When an e-cig is producing smoke then something is going very wrong.
BTW, air pollution is a bigger killer than tobacco smoking
=> Air pollution is the new tobacco. Time to tackle this epidemic