E-cigarette vapor contains carcinogenic compounds, and this has been proven by science
Nicotine vapes likely cause lung and oral cancer. This is the conclusion reached by an international team of researchers who analyzed over a hundred scientific papers from the past eight years. The authors emphasize that waiting another 80 years for definitive proof, as was the case with conventional cigarettes, is unwise. However, a number of independent experts believe that the review’s methods do not support such bold claims.
Studying the Harmfulness of Vapes
Vaping is usually studied in the context of smoking. Some scientists look at whether it leads to conventional cigarettes. Others try to understand whether it helps people quit smoking. And still others compare the harm of vapes and cigarettes. But an Australian team asked a different question: can vaping cause cancer on its own, regardless of any transition to tobacco?
The team, which included pharmacists, epidemiologists, thoracic surgeons, and public health specialists, analyzed peer-reviewed studies published from 2017 to 2025. The analysis covered clinical data from humans, animal experiments, and laboratory work.
Among the materials studied were biomarker studies (looking for traces of carcinogenic substances in the blood and urine of vapers), case reports of oral cancer in people who vaped but never smoked cigarettes, as well as mouse experiments and work on cellular mechanisms of tissue damage in the mouth and respiratory tract.
What Harmful Substances Are Found in Vape Aerosol
The key question in any conversation about the harm of vaping is: what exactly enters the body when inhaled? An e-cigarette does not burn tobacco, but it heats liquid to high temperatures, and this process is far from harmless.
Researchers found numerous carcinogenic compounds in e-cigarette aerosols, including volatile organic compounds and metals released by heating coils. Among these substances are formaldehyde and acrolein, which the International Agency for Research on Cancer (IARC) classifies as human carcinogens. Biomarkers also point to vaping-induced oxidative stress, epigenetic changes, and inflammation of oral and respiratory tract tissues.
The ingredients in nicotine vapes do indeed cause DNA changes in humans that could potentially lead to cancer. Simply put, the mouth and lung cells of vapers sustain damage that science considers precursors to oncological processes.
Do E-Cigarettes Cause Cancer
From 2017 to 2025, the conclusions of reviews on this topic shifted from “more data is needed” to “there are grounds for concern about the carcinogenicity of vapes.” While earlier publications noted uncertainty, more recent ones already register real alarm.
The final conclusion of the review: nicotine e-cigarettes are probably carcinogenic to the people who use them, causing an undetermined number of cases of oral and lung cancer.
At the same time, the authors openly acknowledge that their assessment is qualitative and does not contain numerical risk indicators — determining the exact scale of the threat will only be possible when long-term population studies become available. In other words, the review says “vaping probably causes cancer” but cannot answer the question “exactly how many cancer cases has it caused.”
Comparison of a regular cigarette and an e-cigarette: the mechanisms of harm differ
The Dangers of Simultaneous Smoking and Vaping
One of the most alarming findings of the review concerns people who both smoke and vape simultaneously. In practice, this is what happens most often: a person picks up a vape to quit cigarettes but cannot fully switch and ends up in a “limbo” of dual use.
A 2024 study showed a fourfold increase in lung cancer risk among those who smoked and vaped simultaneously, compared to those who only smoked. Scientists warn that many people who start vaping to quit smoking end up doing both.
This is especially important because vapes are actively promoted precisely as a smoking cessation tool. The result is a paradoxical situation: a tool designed to reduce harm may actually increase it — if the person does not fully quit cigarettes.
Why Scientists Have Doubts About the Dangers of Vaping
The publication provoked serious objections from independent experts. Professor Lion Shahab called the review “problematic” and stated that it “makes extraordinary claims not supported by the data.”
The main criticism relates to the methods used. The review did not follow standard systematic review practices: no study selection criteria were specified, no protocol was registered, which increases the risk of bias toward certain conclusions.
According to several experts, the body of published research suggests that the level of carcinogen exposure for vapers is quite low, meaning the risks are likely small as well. Several commentators emphasized that vaping does not involve inhaling combustion products, which are responsible for the main carcinogenic effect of conventional cigarettes, and therefore equating one with the other is incorrect.
Professor Peter Hajek warned that misinforming smokers could discourage them from switching to vapes, which remain one of the most effective methods of quitting tobacco.
The Parallel Between Vaping and the History of Smoking
One of the central ideas of the review is a historical analogy. It took nearly a century of scientific research — from the mid-19th century to the U.S. Surgeon General’s report in 1964 — for smoking to be officially recognized as a cause of lung cancer. Throughout that time, early warning signs were often ignored.
A similar process is now unfolding with vaping — and repeating a century-long wait should not happen. E-cigarettes appeared about 20 years ago, and data has already accumulated linking vaping to chronic obstructive pulmonary disease, heart attacks, and pneumonia.
However, as Professor Stephen Burgess noted, “perhaps the day will never come when the evidence for the safety or harm of vaping is fully convincing.” This remark aptly illustrates the scale of uncertainty: we are at an early stage of understanding the long-term consequences.
This is an important study, but it does not put an end to the debate about the harm of vaping. As both the authors and their critics acknowledge, complete certainty regarding the safety or harm of e-cigarettes may never arrive. What we already know is that vape aerosol contains carcinogens, it causes precancerous changes in cells — and this is not a reason for panic, but a serious reason not to consider e-cigarettes a harmless toy. For smokers trying to quit, switching to a vape may still be the lesser evil. But the best solution remains a complete rejection of all nicotine products.
