Smoking is a leading cause of bladder cancer, accounting for around half of all cases. Vaping can be an aid to quitting smoking, but the rapid uptake of vaping – notably among young people – raises questions regarding the safety of long-term use. In this article we explore the potential health risks associated with vaping, including bladder cancer, and how these compare to smoking.

Vaping versus smoking: current use

Whereas smoking burns tobacco leaf, vaping heats a liquid ( ‘e-liquid’) to form an aerosol, or vapor, that is inhaled. E-liquid generally includes nicotine, although nicotine-free options are available (including cannabis-derived extracts, which are outside the current topic). The various types of disposable or refillable vaping devices (‘vapes’) used to heat the e-liquid are collectively referred to here as e-cigarettes for simplicity.

Fewer people are smoking in the US, with only 7% of young adults aged 18–24 years reporting being current cigarette smokers in 2020.2 Instead, vaping has been the preferred choice of teenagers since 2014.3 In 2022, about one in seven high school students (14%) reported vaping in the past 30 days, compared with only 2% who had smoked cigarettes over the same period.3

Man Vaping

What is in a vape – and what are the health risks?

E-liquid components vary, but typically include nicotine, sometimes at high levels, in a base containing propylene glycol (PG), vegetable glycerin (VG) and flavorings. Vaping side effects can include dry mouth, sore throat, cough, and chest pain, as well as symptoms like dizziness or nausea associated with nicotine in new users. More research is needed to know the long-term health effects of vaping, but a large US study found e-cigarette users had a significantly increased risk of developing respiratory diseases, independent of their smoking history.4 Based on current knowledge, the short- and medium-term risk of vaping is much less than the risk of smoking, but vaping is not risk-free, especially for non-smokers.5

Factors that may influence the risk of adverse health effects include the e-liquid components, chemical changes that occur after heating, the vaping device and user technique, and whether an individual has existing health conditions such as asthma.6

  • Nicotine is addictive and is unsafe for young people and pregnant women. Nicotine can alter normal brain development in adolescents, and younger people are more likely to become addicted.7 Vapes often deliver nicotine in a more palatable form (e.g., nicotine salts) masked with appealing flavors such as fruit, ice, candy and menthol. Nicotine is also unsafe for pregnant women due to its ability to cross the placenta and harm the unborn baby.7 However, most of the serious harms associated with tobacco result from the carcinogenic and toxic mix of compounds that smokers inhale, rather than nicotine.7
  • E-liquid additives may be safe to eat, but not to vape. A specific consideration with vaping is that chemicals that are generally recognized as safe in foods and medicines may be unsafe when vaporized and inhaled. For example, when heated, PG and VG can form toxic chemicals such as acetaldehyde, formaldehyde, and acrolein.6 Laboratory and animal studies have raised questions about the safety of some flavor compounds, including cinnamaldehyde (cinnamon flavor).6
  • Vape aerosol contains metals. Various metals have been detected and may come from the heating coil (used to vaporize the e-liquid), other parts of the vaping device, or the e-liquid.

Is vaping safer than smoking?

Vaping is safer than smoking, but this does not mean it is harmless – the only safe and healthy option is not to smoke or vape. Cigarette smoke contains over 7,000 chemicals, including around 70 known to be cancer-causing agents (carcinogens).8 Vaping aerosol contains far fewer of these known toxic chemicals, although heating e-liquid may result in exposure to a wide range of previously unstudied chemicals with unknown health effects.9

While there is real concern over young people who take up vaping with no prior history of cigarette smoking, for adults who already smoke, switching completely to vaping is safer than smoking.5 There is now strong evidence that vaping can help smokers to quit cigarettes with a higher success rate than nicotine replacement therapy,10 although many former smokers continue to vape rather than quit all nicotine products. Vaping while continuing to smoke cigarettes is also common, but dual use is at least as harmful as exclusive cigarette smoking and may be more harmful.11

Vaping vs Smoking

Does vaping cause cancer?

Cancer due to cigarette smoking may take decades to develop; vaping’s long-term risks are not yet known. E-liquids and/or vaping aerosols do contain definite, probable and possible carcinogens such as formaldehyde, acetaldehyde, acrolein, tobacco-specific nitrosamines, volatile organic compounds (e.g., benzene), phthalates, residual solvents, and metals (including arsenic, cadmium, chromium, lead and nickel).12 However, levels are mostly much lower than in cigarettes, and short-term studies suggest that smokers who switch to vaping have reduced exposure to carcinogens.12

Vaping and bladder cancer

Smoking is the largest preventable risk factor for bladder cancer. Overall, smokers are at least three times more likely than non-smokers to develop bladder cancer.13 This is because the body eliminates many toxins in the urine, exposing the bladder lining to carcinogens from cigarette smoke for extended periods. Could this happen with vaping too? It’s too soon to know, but the available evidence points to a potential risk:

  • 63 toxic or carcinogenic metabolite biomarkers were identified in the urine of e-cigarette users, including elevated levels of biomarkers with a strong known link to bladder cancer.14
  • Mice exposed to e-cigarette aerosol for 3 months developed carcinogenic DNA changes in the bladder and lungs; similar damage to human epithelial bladder cells was also observed in laboratory testing.15 After 1 year, mice developed lung tumors and precancerous changes in the bladder (epithelial hyperplasia).16

It's important to remember that cigarette smoke contains more toxic substances than e-cigarette vapor. Researchers analyzed tobacco-related toxic substances in urine samples from over 5,100 people, finding that:17

  • Compared with people who had never used tobacco products, e-cigarette users had significantly higher levels of biomarkers of nicotine, tobacco-specific nitrosamines, volatile organic compounds, and metals (cadmium and lead).
  • Compared with cigarette smokers, exclusive e-cigarette users had significantly lower levels of most biomarkers.
  • Dual users who combined vaping and cigarette smoking had the highest levels (significantly higher than exclusive smokers for most biomarkers).

Is vaping harmful to others?

The known risks of breathing second-hand cigarette smoke include heart disease, stroke and lung cancer. Aerosol from vaping is the equivalent of second-hand smoke and can also contain harmful components, including carcinogens and tiny particles that penetrate deep into the lungs.

Second-hand nicotine vape exposure at home is associated with an increased risk of respiratory symptoms among young adults after controlling for factors like individual vaping and exposure to tobacco and cannabis.18 Young people exposed to second-hand vaping at home were 40% more likely to report bronchitic symptoms and 53% more likely to report being short of breath.18

Accidental exposure to nicotine-containing e-liquid has resulted in poisoning and death in young children. E-liquid is classified as an acute hazardous waste and should not be flushed down the sink, nor should lithium batteries and vaping devices be disposed of in household rubbish.19

Symptom awareness for (former) smokers

Quitting smoking and/ or reducing your exposure to tobacco smoke is one of the most impactful choices you can make to improve your overall health and will also reduce your risk of bladder cancer over time. As smoking is a major cause of bladder cancer, it’s important for current and former smokers – including those who have switched to vaping – to remain alert to potential symptoms.

Blood in the urine (hematuria) is the most common symptom of bladder cancer and often the first sign. If you're experiencing blood or tests confirm the presence of blood, it's important to consult your doctor as soon as possible whether you're at increased risk due to a history of smoking or not. When you speak to them, ask about Cxbladder, a non-invasive genomic urine test that can help rule out urothelial bladder cancer, the most common form of the disease.
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  15. Lee HW, 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. Proc Natl Acad Sci U S A. 2018;115(7):E1560-E1569. [Journal]
  16. Tang MS, et al. Electronic-cigarette smoke induces lung adenocarcinoma and bladder urothelial hyperplasia in mice. Proc Natl Acad Sci U S A. 2019;116(43):21727-21731. [Journal]
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Additional sources

  • Centers for Disease Control and Prevention (US). About Electronic Cigarettes (E-Cigarettes) [reviewed: November 10, 2022].
  • National Academies of Sciences, Engineering, and Medicine (NASEM). Public Health Consequences of E-CigarettesSummary. Eaton DL, Kwan LY, Stratton K, editors. Washington (DC): National Academies Press (US); 2018.
  • Office on Smoking and Health (US). The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General. Atlanta, GA: Centers for Disease Control and Prevention; 2006. 7. Cancer Among Adults from Exposure to Secondhand Smoke.
  • Stefaniak AB, et al. Toxicology of flavoring- and cannabis-containing e-liquids used in electronic delivery systems. Pharmacol Ther. 2021;224:107838. [PubMed]

Last Updated: 10 Jun 2024 03:24 pm