The Mounting Evidence Against Electronic Cigarette Use

According to other new findings reported in Pediatrics, adolescents who had used e-cigarettes were significantly more likely to have smoked combustible cigarettes at follow-up.5 This type of dual use is especially concerning as it compounds the risks associated with both types of cigarettes.4,5

To further explore the topic and related implications for clinicians, Pulmonology Advisor checked in with Erin D. Michos, MD, MHS, FACC, FAHA, associate professor of medicine and epidemiology and associate director of preventive cardiology at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins School of Medicine in Baltimore, Maryland.

Pulmonology Advisor: Overall, what are the latest takeaways on the effects of e-cigarettes?

Dr Michos: Thought to be “safer” than traditional cigarettes, e-cigarette use has been skyrocketing in the United States since the devices were introduced [between] 2006 [and] 2007. But there are a lot of reasons to be concerned about the health implications of their usage, particularly for the cardiovascular system.

Most e-cigarettes contain nicotine. Even without the cigarette smoke, nicotine itself is not safe. Nicotine is toxic to the nervous system, which is particularly worrisome for [e-cigarette] use in youth, whose brains are still developing. Nicotine is a stimulant that has the cardiovascular effects of increasing blood pressure and heart rate, which can be a harmful for individuals with established cardiovascular disease. And nicotine is highly addictive, which is a concern for everyone.

Furthermore, the aerosol from e-cigarettes has also been shown to contain aldehydes such as acetaldehyde, acrolein, and formaldehyde, which themselves have cardiovascular toxicity.6

A study published in February 2018 by researchers from the Johns Hopkins Bloomberg School of Public Health found that e-cigarettes were also a potential source of toxic heavy metals including cadmium, chromium, lead, manganese, and nickel.7 The heating coils of the devices appear to be leaking toxic metals into the e-cigarette fluid. There was substantial variability from brand to brand in how much of the metals was found in the devices, reaffirming that e-cigarettes are not all the same.

We need more data examining this, but the number of some metals in e-cigarette aerosol could be even greater than that in traditional cigarettes, and certainly above accepted health-based limits.

Even single use of e-cigarettes can cause oxidative stress and endothelial dysfunction, as measured by flow mediated dilation.8

Pulmonology Advisor: What are the current treatment implications for clinicians?

Dr Michos: E-cigarettes have been advocated for use as a nicotine replacement therapy for many smokers who want to quit. This sounds good in theory, but we currently have limited data about the effectiveness of these devices as a smoking cessation aide. E-cigarettes may not be all that effective for smoking cessation [because they may] possibly even augment addiction and increase nicotine dependence. I do not recommend them to my patients who are trying to quit; rather I discuss with them current FDA-approved effective methods for quitting.

More worrisome is the widespread and increasing use of e-cigarettes in youth, teenagers, and young adults who were never smokers. The fancy appearance of these devices and appealing cartridge flavors have made them very attractive and even socially acceptable. E-cigarettes familiarize youth with nicotine products, which can be a gateway to traditional smoking or increase the chances of experimentation with other substances, since the cartridges can be filled with substances other than nicotine. We need targeted prevention efforts to reduce exposure to e-cigarettes in children and youth. 

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Pulmonology Advisor: What are the remaining needs in terms of research on this issue?

Dr Michos: We need more data about how effective e-cigarettes are for smoking cessation. Many e-cigarette users continue to smoke traditional cigarettes. We also need more information about the risk to others from secondhand exposure, because e-cigarettes do not emit pure water vapor. We need to learn more about potential dangers from secondhand emissions.

And we need a lot more data on the long-term health effects such as cardiovascular and cancer outcomes, which can take years to develop. The substantial variability from device to device — in terms of voltage, temperature, age, flavors, and amount of nicotine — has limited the ability of researchers to arrive at firm conclusions regarding the health consequences of e-cigarettes. We do know that when devices age or when their voltage is increased, more harmful products are produced.

The popularity and increasing use of e-cigarettes have outpaced our research in this area, and we really need many more studies about the long-term effects of these devices on cardiovascular and overall health. However, the adverse short-term effects on the cardiovascular system are a warning sign that they are not safe. By June 2018, the FDA is requiring e-cigarette manufacturers to have health warning labels on these products, just like other traditional tobacco products.9


  1. US Centers for Disease Control and Prevention (CDC). Electronic cigarettes. Accessed on March 23, 2018.
  2. Newton JN, Dockrell MMarczylo T. Making sense of the latest evidence on electronic cigarettes. Lancet. 2018;391(10121):639-642.
  3. Alzahrani T, Pena I, Temesgen N, Glantz S. Association between electronic cigarette use and myocardial infarction: results from the 2014 and 2016 National Health Interview Surveys. Presented at: the Annual Meeting of the Society for Research on Nicotine and Tobacco; February 24, 2018; Baltimore, MD. POS5-34.
  4. Rubinstein ML, Delucchi KBenowitz NLRamo DE. Adolescent exposure to toxic volatile organic chemicals from e-cigarettes. Pediatrics. 2018;141(4):e20173557.
  5. Chaffee BW, Watkins SLGlantz SA. Electronic cigarette use and progression from experimentation to established smoking. Pediatrics. 2018;141(4):e20173594.
  6. Ogunwale MA, Li MRamakrishnam Raju MV, et al. Aldehyde detection in electronic cigarette aerosols. ACS Omega. 2017;2(3):1207-1214.
  7. Olmedo P, Goessler WTanda S, et al. Metal concentrations in e-cigarette liquid and aerosol samples: the contribution of metallic coils. Environ Health Perspect. 2018;126(2):027010.
  8. Carnevale R, Sciarretta SVioli F, et al. Acute impact of tobacco vs electronic cigarette smoking on oxidative stress and vascular function. Chest. 2016;150(3):606-612.
  9. US Food and Drug Administration (FDA). Labeling of tobacco products. Last updated January 8, 2018. Accessed March 27, 2018.