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We know vaping can cause serious lung problems. A new study says it might also cause cancer.

December 19, 2019

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What's the link between vaping and cancer in mice?

In a study published this week, researchers asked tens of thousands of individuals over 12 years of age about their use of tobacco products, e-cigarettes, and their health, and conducted follow-up questions over three years.1 They found the development of lung problems like emphysema, bronchitis, asthma, and chronic obstructive pulmonary disease in individuals who had used e-cigarettes in the past or currently use them. Combined use of e-cigarette and tobacco products dramatically increased lung disease risks by an incredible 330 percent. The researchers concluded that, “Use of e-cigarettes is an independent risk factor for respiratory disease in addition to combustible tobacco smoking.” The study’s senior author, Stanton Glantz, told CNN, "I was a little surprised that we could find evidence on incident lung disease in the longitudinal study, because three years is a while but most studies that look at the development of lung disease go over 10 to 20 years.”

The Centers for Disease Control (CDC) reports that, as of December 10, 2019, there are 2,409 hospitalization cases of vaping-related lung injuries in the U.S., resulting in 52 deaths across 26 states and Washington, D.C.2 The FDA has found THC in most of the samples it’s studying from these cases and has highlighted Vitamin E acetate as a chemical linked to some of the lung injuries. But the CDC warns that it still does not know how many other chemicals and products may be involved, and says that, “the best way for people to ensure that they are not at risk while the investigation continues is to consider refraining from the use of all e-cigarette, or vaping, products.” NIDA just reported that 3.5 percent of 12th graders and 3 percent of 10th graders say they vape on a daily basis, with 14 percent of 12th graders also saying that they vaped marijuana in the previous month. That figure is twice as large as it was last year. 

Though federal officials have reportedly backed away from banning flavored vaping products3, some states have implemented such restrictions. And other national lawmakers are still considering similar options to confront the vaping epidemic.4 Dr. Scott Gottlieb, the former FDA Commissioner, has now recommended banning all cartridge-based e-cigarette products, which would include popular devices like Juul.5 Gottlieb, along with other experts, is worried about the epidemic of youth vaping, nicotine use and dependence which can lead to the use of tobacco-based products, the number one cause of preventable death, and other substances later in life. 

Stories about vaping-related severe lung diseases, the epidemic of youth use, and public policy responses are important for patients, families, medical professionals, and consumers to follow. But we should also continue to monitor research that paints an even more distressing picture of e-cigarette products. In a recent study, researchers looked at the association between e-cigarette use and cancer.

What did this study find about e-cigarette use and cancer in mice?

This study found that exposure to e-cigarettes led to tumors and precancerous growths in the lungs and bladders of mice. The nicotine vapor from e-cigarettes damaged DNA in the exposed mice’s organs. 

When tobacco burns, it can change nicotine into carcinogens called nitrosamine ketone. In individuals who use electronic cigarettes, these carcinogens in saliva and urine are 95 percent lower than they are individuals who smoke tobacco. That’s why the UK government says that electronic cigarettes are 95 percent safer than tobacco products. But it’s not as certain that nicotine from e-cigarettes gets turned into these carcinogens, so it’s also not clear if their levels in saliva and urine of individuals using e-cigarettes are a good guide to possible damage. The body can also absorb these carcinogens in other ways, as harmful to DNA. This study looked at DNA damage in mice to see if e-cigarettes might cause lung and bladder cancer, instead of carcinogenic impact in blood and urine. It’s also important to note that no experts suggest that vaping or smoking is good for you. 

Researchers exposed the full bodies of 40 mice to e-cigarette vapor for 54 weeks. 22.5 percent of these mice developed lung tumors and, in their bladders, 57.5% ended up with precancerous growths. 20 mice in a control group, subjected to e-cigarette vapor but not nicotine, did not develop tumors. E-cigarette exposure in this study is comparable to human e-cigarette use over three to six years. The study’s authors believe that the results probably indicate e-cigarette aerosol nicotine reaching far into lung tissue and causing DNA damage. They also say that, “The public should not equate the risk of ECS [e-cigarette smoke] with that of TS [tobacco smoke]. Our data simply suggest, on the basis of experimental data in model systems, that this issue warrants in-depth study in the future.” This study also had limitations. It used a small sample size and did not focus on the inhalation of e-cigarette nicotine vapor. And animal studies are not necessarily clear guides for related effects in humans.

Why is this important?

This is the first study finding an association between e-cigarette use and cancer. Though the authors are careful to offer caveats about the research’s limitations, not drawing inferences about the relative safety of e-cigarettes and tobacco products, and the need for more extensive studies, this is still a significant and troubling result.  It took many decades for experts to agree that tobacco smoke caused cancer. It seems more logical to assume that smoking and vaping are dangerous until proven otherwise. Some countries have seen enough and banned e-cigarettes completely, such as Argentina, Saudi Arabia, and Singapore. Others do not think it is safe but consider e-cigarettes as part of a harm reduction strategy. The study’s lead, New York University’s Dr. Moon-Shong Tang told CNBC, “It’s foreseeable that if you smoke e-cigarettes, all kinds of disease comes out. Long term, some cancer will come out, probably. E-cigarettes are bad news.” He also suggested that because e-cigarette products have only existed for a relatively short period of time, it may take a while for more research to measure their health effects more comprehensively—possibly up to a decade.

It’s always appropriate for researchers to be cautious about their findings and to point to countervailing factors and the need for supplemental work and corroborating studies. Even experts can be surprised. But more studies continue to indicate the dangers of e-cigarette use. It’s also worth pointing out that there are dangers beyond these studies: inhaling nicotine vapors is likely to stimulate its own continued use, while costing time, energy and money. The cost of a pack of cigarettes is quite cheap even with current taxes. Actual costs are difficult to understand. In general, we assume smoking two packs of cigarettes a day for 20 years is more expensive than the $75,000 for the cost of the cigarettes. The long-term costs are closer to $2 million, after factoring in treatments for tobacco-related cancer, lung and heart disease, and the reduction in lifespan and productivity of the individual using cigarettes. 

Prevention of adolescent smoking initiation is a very important health goal, one that we were much closer to attaining before vaping. Experts warn that vaping is causing a new nicotine addiction epidemic.6 They estimate, for example, that, because of vaping, almost 500,000 individuals between the ages of 12 and 29 who used e-cigarettes also end up using tobacco products.7 Use of e-cigarettes paves the way for use of tobacco-based cigarettes, as research suggests.8 If the full costs to society were included at the point of purchase, each pack of cigarettes would cost at least $75. Very few people would choose to spend $75/pack. Similarly, we could find a price at which vaping is less attractive to consumers. The science, in other words, is clear about the risks, and tobacco-like public health-related tax initiatives may be appropriate. Vermont recently passed a 92% wholesale tax on vaping and e-cigarette products. Federal lawmakers are also considering tax changes.

Keeping in mind that it took decades, if not centuries, to prove that cigarette smoking causes cancer, these new e-cigarette studies suggest that the products aren’t just understudied and possibly dangerous, but increasingly just dangerous, associated more frequently with chronic disease, heart problems, and even cancer.9 This study is also interesting in its full-body exposure of mice to e-cigarette vapor, which suggests that secondhand vaping may be dangerous, too. Other reports are coming out suggesting that e-cigarette inhalation is dangerous for everyone, include individuals who do not use the products but may be exposed to them. Mounting evidence shows that e-cigarette use is a highly risky proposition for current and potential consumers and that officials and experts are justified in pursuing ways to curb use. Reversing use trends will require a great deal of work given the near exponential increases in youth vaping.

References:

  1. Bhatta, D.N., Glantz, S.A. (2019) Association of E-Cigarette Use With Respiratory Disease Among Adults: A Longitudinal Analysis. American Journal of Preventive Medicine
  2. Centers for Disease Control and Prevention (CDC). (2019) Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products. Retrieved from https://www.cdc.gov/tobacco/basic_information/e-cigarettes/severe-lung-disease.html
  3. Karni, A., Kaplan, S. (2019) Trump Warns a Flavor Ban Would Spawn Counterfeit Vaping Products. New York Times. Retrieved from https://www.nytimes.com/2019/11/22/health/trump-vaping.html
  4. Hellmann, J. (2019) House Democrats to vote on flavored e-cigarettes ban next year. The Hill. Retrieved from https://thehill.com/policy/healthcare/474184-house-democrats-to-vote-on-flavored-e-cigarettes-ban-next-year
  5. Florko, N. (2019) Former FDA commissioner calls for a full ban on pod-based e-cigarettes. Stat. Retrieved from https://www.statnews.com/2019/11/12/gottlieb-ban-pod-based-e-cigarettes/
  6. Dinardo, P., Rome, E.S. (2019) Vaping: The new wave of nicotine addiction. Cleve Clin J Med.
  7. Soneji, S., Wills, T.A. (2019) Challenges and Opportunities for Tobacco Control Policies in the 21st Century. JAMA Pediatr
  8. National Academies of Sciences, Engineering, and Medicine. (2018) Public health consequences of e-cigarettes. The National Academies Press, Washington, DC
  9. Proctor, R.N. (2012) The history of the discovery of the cigarette-lung cancer link: evidentiary traditions, corporate denial, global toll. Tob Control

 

Citation:

1. Tang, M., et al. (2019) Electronic-cigarette smoke induces lung adenocarcinoma and bladder urothelial hyperplasia in mice. PNAS

 

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Mark Gold, MD

Dr. Mark S. Gold is a teacher of the year, translational researcher, author, mentor and inventor best known for his work on the brain systems underlying the effects of opiate drugs, cocaine and food. Read more by Dr. Gold here.