Nicotine-containing vapes are likely to cause lung and oral cancers in humans, just like they do in mice, according to a new review. Led by researchers from the University of New South Wales in Sydney, the document compiles a range of evidence including mouse studies, case reports, biomarker studies in humans and a chemical analysis of the ingredients in nicotine-based vapes.
Until now, most studies into vaping simply compared it to smoking. This new review, published in Carcinogenesis, considered whether vapes on their own had the potential to cause cancer by comparing the cancer risk in non-smokers who use nicotine vapes with people who have never used them. Experts from multiple disciplines, including pharmacists, epidemiologists, thoracic surgeons and public health researchers examined the evidence from over 100 clinical studies, animal experiments and laboratory research examining the chemicals produced by e-cigarettes.
This is “by far the strongest evidence” that vapes likely cause oral and lung cancer, claims cancer researcher Dr Bernard Stewart who co-authored the study. Dr Stewart described one study that showed 23% of mice that inhaled e-cigarette vapor later developed lung cancer as "the clearest and almost definitive evidence" of the link between cancer and vaping.
Many compounds in vapes have been shown to be carcinogenic, including volatile organic compounds (such as formaldehyde and acrolein), metals (such as nickel and chromium), and cytotoxic flavouring chemicals. People who vape have elevated levels of toxic chemicals in their urine and have tissue injury, oxidative stress markers and DNA damage, all of which are associated with cancer.
However, the experts’ assessment of risk in humans remains qualitative, waiting on longer-term studies of vape users to estimate cancer risk or burden. "The definite proof [that vaping causes cancer] will take possibly decades," says Dr Stewart, “there [is] still no epidemiological link between vaping and cancer.” But it should come as no surprise given that vapes have only been available for 20 years and it took researchers 100 years to prove smoking caused cancer.
Cancer risk aside, the researchers also found a range of other diseases that could be attributable to vaping. For them, the key question is not whether vaping is identical to smoking. Rather, it is whether the habit introduces a new wave of health risks that could affect millions of people in the coming decades.
Regulations governing animal testing for tobbacco and vaping products
The testing of tobacco products on animals has been banned in the UK since 1997. Even though vaping and tobacco are often compared, the Health Act 2006 defines "smoking" as burning tobacco or another substance, and e-cigarettes don't involve combustion. Vaping heats a liquid rather than burning a leaf. That is why vaping falls outside the scope of smoke-free legislation that governs cigarettes for instance. This difference is important. Burning tobacco is responsible for producing tar and carbon monoxide, substances linked to smoking-related disease, but that are not implicated in vaping. However, that doesn't mean vaping is risk-free. While the international scientific community broadly agrees vaping is significantly less harmful than smoking, the long-term risks remain unclear. Vaping deserves its own dedicated research rather than being assessed with the same evidence base as smoking. However, many nicotine e-liquids are still regulated under the Tobacco and Related Products Regulations 2016, and the nicotine is often derived from tobacco.
Read more about regulations in animal research.
Last edited: 7 July 2026 13:40
