Scientists Say Vaping Likely Causes Cancer and We Cannot Afford to Wait Like We Did With Smoking

For over a decade, vapes and e-cigarettes were sold as a clean exit from smoking. Swap your cigarettes for a sleek device, inhale flavored vapor instead of smoke, and walk away from cancer risk. That was the promise. But a sweeping new review covering eight years of published research has arrived at a very different conclusion. Scientists from the University of New South Wales found that nicotine-based e-cigarettes are likely carcinogenic to humans, capable of causing oral and lung cancer on their own, independent of any connection to traditional cigarettes. The researchers are not saying vaping is as dangerous as smoking. They are saying it is not safe, and that the evidence has been building for years while regulators and the public looked the other way. Their message is direct: we waited a century to act on smoking. We cannot afford to make that mistake again.

What the Review Actually Found

Lead author Bernard Stewart, a cancer researcher and adjunct professor at UNSW, assembled a team spanning pharmacy, epidemiology, thoracic research, and public health. Together, they examined peer-reviewed studies published between 2017 and mid-2025, covering the full range of evidence available: human biomarker studies, case reports from dentists identifying oral cancer in people who vaped but never smoked, animal experiments, and mechanistic studies examining what vape ingredients do to cells in the mouth and airway.

Stewart was clear about their methodology: they did not select publications that supported a particular viewpoint. The goal was to assess the evidence as a whole, across disciplines, without cherry-picking.

What they found was consistent across study types. The ingredients of nicotine vapes cause measurable DNA damage in humans. Biomarkers in blood and urine show exposure to carcinogenic chemicals, including nicotine-derived nitrosamines, volatile organic compounds, flavor-derived agents, and certain metals. Researchers also found evidence of oxidative stress, epigenetic changes, and inflammation in oral and respiratory tissue linked directly to vaping.

Stewart summarized the finding bluntly: there is no doubt about exposure. In humans, there is an unequivocal pre-carcinogenic change as a consequence of vaping.

In rodent studies, mice exposed to e-cigarette aerosol through inhalation developed lung adenocarcinomas. Mechanistic data pointed to a complex mixture of substances producing carcinogenic effects through both genotoxic and non-genotoxic pathways.

The Tone Has Shifted Dramatically Since 2017

One of the most telling patterns in the review was how the scientific conversation has changed over time. In 2017, researchers studying vaping and cancer were cautious, saying they simply did not have enough data to conclude.

By 2025, the tone had shifted to genuine concern. Successive reviews published across those eight years moved from calling for more evidence to actively warning about e-cigarette carcinogenicity.

Stewart noted that scientists can no longer definitively say that vaping is safer than smoking. That statement alone marks a dramatic departure from the messaging that launched the vaping industry.

Not All Experts Agree With the Conclusions

While several independent researchers supported the review’s findings, others raised serious methodological concerns.

Professor Lion Shahab of University College London criticized the study for not following standard systematic review practices. He noted that no information was provided about how studies were selected, no inclusion or exclusion criteria were specified, and no protocol was preregistered. He warned that this increases the risk of selection bias and urged against sensationalizing the evidence.

Professor Peter Hajek, also of Queen Mary University of London, cautioned that misinforming smokers about vaping risks could discourage them from using e-cigarettes as a quitting tool, calling them one of the most effective methods available to stop smoking.

Professor Stephen Duffy, Emeritus Professor of Cancer Screening at Queen Mary, pointed out that vaping does not involve exposure to the combustion products in smoking, which have massive carcinogenic effects. He said it would require quite a stretch of imagination to envision vaping compounds matching the cancer-causing effects of combustion smoking.

These criticisms are worth taking seriously. The debate is not over whether vaping carries risk, but over how much risk, and whether the current evidence justifies the strength of the review’s conclusions.

Why Definitive Proof Is Still Years Away

The authors acknowledged a significant limitation: they cannot quantify how many cancer cases are directly caused by vaping. E-cigarettes have only been widely used for about 15 years, which is not long enough for large-scale cancer patterns to emerge in population data.

Co-author Freddy Sitas, an epidemiologist and adjunct associate professor at UNSW, drew a parallel to tobacco. It took roughly 100 years from the first reported associations between smoking and disease (a link to tuberculosis noted in the 1860s) to definitive scientific proof that smoking causes cancer.

A similar timeline may apply to vaping, but with one crucial difference: the biological evidence of harm is accumulating much faster this time. DNA damage, carcinogenic exposure, and pre-cancerous cellular changes are already documented. What is missing is the long-term population data linking those changes to diagnosed cancers at scale.

Professor Stephen Burgess of the University of Cambridge noted that there may never be a day when evidence for the safety or harm of vaping is fully conclusive.

Sitas argued that if researchers want early answers, they need to launch very large prospective studies now and begin tracking outcomes in real time.

Dual Use: The Hidden Danger Nobody Talks About

Vapes are marketed as a tool to quit smoking. In practice, many people never fully transition away from cigarettes. They end up in what Sitas called a “limbo” of smoking and vaping at the same time, a pattern known as dual use.

A 2024 study from The Ohio State University found that combining smoking and vaping increased the risk of lung cancer fourfold compared with smoking alone. That finding is alarming because it suggests that for a significant portion of vapers, taking up e-cigarettes may have actually increased their cancer risk rather than reduced it.

Unless an effective intervention exists to move dual users off vapes entirely, Sitas warned, this population remains at much higher risk of lung cancer than people who only smoke.

Professor Nick Zwar, Chair of the RACGP’s Smoking Cessation Guidelines’ Expert Advisory Group, acknowledged the concern but cautioned against dismissing vapes as a last-line treatment option for smokers who have failed other methods. He described the new research as a really good bit of work, but said it is too early to reach a conclusion that eliminates vaping as a therapeutic option.

Australia’s current guidelines allow nicotine e-cigarettes only with a prescription or through pharmacies, and the recommendation for their use in smoking cessation is described as conditional and made with low certainty.

Young People Who Never Smoked Are Now at Risk

Perhaps the most alarming dimension of the vaping story is what is happening with young people. Millions of teenagers and young adults have taken up vaping without ever smoking a traditional cigarette. For them, vapes are not a cessation tool. They are the first and only nicotine product.

Professor Michelle Jongenelis, Director of the Melbourne Centre for Behaviour Change at The University of Melbourne, expressed deep concern about the deliberate targeting of children and young people with these products. She said the tobacco and nicotine industry needs to addict a new generation to safeguard their profits, and this evidence shows they are very likely giving children cancer in the process.

If vaping does cause cancer, even at rates lower than smoking, an entire generation that would otherwise never have been exposed to carcinogenic inhalation is now carrying that risk. The long-term consequences will not become visible for years, possibly decades.

Scientists Say We Cannot Afford to Wait

The central argument of the review is not that vaping is proven to cause cancer at the same rate as smoking. It is that the biological evidence of carcinogenicity is strong enough to justify action now, rather than waiting for decades of population data to confirm what lab studies and biomarker analyses already suggest.

In an editorial published alongside the study in Cancer Epidemiology, Stewart and Sitas wrote that although smoking was once given the benefit of the doubt, the same should not now be accorded to vaping, given the strength of relevant carcinogenicity data.

Sitas framed the opportunity in practical terms: he believes there is a very good chance to be proactive this time, to change regulatory approaches, modify how vapes are used in cessation programs, and protect young people before the full toll becomes visible.

For a product that was marketed as the safe alternative, the accumulating evidence tells a very different story. Whether regulators, healthcare systems, and the public choose to act on that evidence now, or wait another generation may determine how many people pay the price.

My Personal RX on Protecting Your Lungs and Quitting Nicotine

Whether you smoke, vape, or do both, your lungs are absorbing chemicals that damage cells and promote inflammation with every puff. Quitting entirely is the single most protective step you can take. But supporting your body’s repair systems through nutrition, sleep, and targeted supplementation can help undo some of the damage and keep your lungs functioning as well as possible. Here is what I recommend:

1. Quit Vaping and Smoking Entirely: No amount of inhaled nicotine aerosol or tobacco smoke is safe for your lungs. If you need help quitting, call 1-800-QUIT-NOW or talk to your doctor about prescription cessation aids like varenicline or nicotine replacement therapy.
   
2. Prioritize Restorative Sleep Every Night: Your body repairs damaged lung tissue and clears toxins during deep sleep. Sleep Max combines magnesium, GABA, 5-HTP, and taurine to calm your mind, support neurotransmitter balance, and promote restorative REM sleep so your body can recover from daily exposure to environmental and chemical stressors.
   
3. Know Which Supplements Your Body Needs: Smoking and vaping deplete key nutrients your body needs for repair and immune defense. Download my free guide, The 7 Supplements You Can’t Live Without, to learn which supplements fill those gaps, which “healthy” foods may be misleading you, and how to spot quality products.
   
4. Exercise to Rebuild Lung Capacity: Aerobic activity like walking, swimming, or cycling trains your lungs to work more efficiently and improves oxygen exchange. Start with 15 minutes daily and build to 30 minutes as your lung capacity improves.
   
5. Stay Well Hydrated: Water keeps the mucosal lining of your airways thin and functional, helping your lungs clear irritants and repair tissue. Aim for at least eight glasses per day.
   
6. Avoid Secondhand Vape and Smoke Exposure: Secondhand e-cigarette aerosol contains nicotine, ultrafine particles, diacetyl, benzene, and heavy metals. Protect yourself and your family by keeping indoor spaces free from both smoke and vapor.
   
7. Talk to Your Kids About Vaping Early: Children as young as 11 are now using e-cigarettes. Have honest conversations about what vape aerosol contains and what it does to lungs and developing brains before peer pressure takes over.
   
8. See a Doctor If You Have Persistent Respiratory Symptoms: Do not ignore chronic cough, chest tightness, shortness of breath, or mouth sores. Early evaluation gives you the best chance of catching reversible damage before it progresses.

Source: Stewart, B. W., Marshall, H., Bonevski, B., Griffin, H. J., Hopkins, A. M., Itchins, M., Mazza, C. J., Modi, N. D., Ryan, M., Varlow, M., & Sitas, F. (2025). The carcinogenicity of e-cigarettes: a qualitative risk assessment. Carcinogenesis, 47(1). https://doi.org/10.1093/carcin/bgag015