Australian scientific review finds vaping likely causes cancer

Vaping is likely to cause cancer, a first-of-its-kind scientific review has found, contradicting claims it is safer than smoking and highlighting the urgency of efforts to stop young people becoming addicted.

Experts have long warned the chemicals inhaled from vapes are carcinogenic and dangerous to human health, but a definitive link between vaping and cancer has not yet been established.

E-cigarette devices emerged too recently for scientists to investigate their cancer risk through decades-long epidemiological studies; the time period between exposure to a carcinogen and diagnosis with cancer can be 10 to 30 years.

But in the absence of long-term studies into vaping, Australian scientists surveyed the existing evidence, which includes lab investigations into e-cigarette vapour, animal experiments and research into biomarkers in the blood and urine of people who vape.

Taken together, the evidence led them to the most definitive conclusion yet, that “e-cigarettes are likely to cause oral and lung cancer”, said the review’s lead author Bernard Stewart, an adjunct professor from the University of NSW.

“Vaping is to be avoided as hazardous in its own right,” Stewart, a renowned cancer researcher, said. “It’s not an alternative to smoking, it’s not an alternative to illicit drugs … it is dangerous, and that’s the message.”

The review cites the case of a 19-year-old man who vaped heavily and was killed by a treatment-resistant oral squamous cell carcinoma. Given the man didn’t have any other risk factors, researchers reasoned vaping may have been a factor in his death.

The chemicals shown to pass into the body from vapes include derivatives from nicotine which can trigger tumours, toxic chemicals such as nickel, volatile organic compounds and cytotoxic flavouring agents.

Stewart said studies have shown these chemicals inflict oxidative stress, inflammation and genomic damage within tissues, which are known forerunners to cancer. Experiments into vape aerosols unequivocally showed DNA damage and long-term changes in oral and lung tissue indicative of cancer development, he said.

“One specific study stands out, where mice exposed to aerosols from e-cigarettes by respiration developed lung cancer,” Stewart said.

“Not all of them, of course, but far greater than the relevant controls, and they also developed changes in the bladder consistent with the ultimate development of cancer.”

Many studies treat vapes as a gateway to smoking rather than dangerous in their own right, and most simply compare vaping to the known evils of cigarettes. Early on, vapes were marketed as a safer alternative to smoking.

But Steward said pitting the two against each other has delayed and downplayed our understanding of vaping’s health effects, adding it was like trying to study the safety of knives by comparing them to machine guns.

“It’s played right into the hands of the tobacco companies, who don’t mind whether they make money through vapes or whether they make money through cigarettes,” he said.

The importation of vapes has been illegal since January 2024, but the disposable e-cigarettes remain ubiquitous and easy to purchase in stores and online.

Distinguished Professor Brian Oliver, a nicotine researcher who has studied the effect of vape smoke on rodents, said studies in rats and mice can’t be directly extrapolated onto people (mice are actually more resistant to cancer than humans, for example). But alongside other evidence, they do provide crucial insights into toxicology and carcinogens.

“I think that what they’re saying is probably correct,” Oliver said of the new research, which he wasn’t involved in. “There is enough evidence that within e-cigarettes, there are enough components, enough toxic chemicals, that all should cause cancer.”

The review, published in Carcinogenesis, didn’t try to ascertain how much vaping increases the risk of cancer, or compare different types of nicotine vapes for health risk.

Trying to address those questions through consistent long-term studies was going to be a “nightmare”, Oliver said, partly due to the raft of designs and thousands of flavours – each with a different chemical profile, from blueberry bliss to English marmalade – that cycle through vape stores.

Professor Becky Freeman from the University of Sydney’s School of Public Health said long-term smokers using vapes through a pharmacy to quit cigarettes should continue.

“That is absolutely that is a good thing to do. We don’t want those people going back to smoking,” said Freeman, a vaping and tobacco control researcher, adding cigarettes kill two in three people who continue to smoke.

But Freeman hoped the new review would convince people who had never vaped or smoked to avoid nicotine, and help “turn the tide” of vaping addiction for people aged 18 to 24.

Vaping rates in that age group have remained stubborn despite public health campaigns to encourage quitting. One in five 16- to 24-year-olds currently vape, according to the Cancer Institute NSW.

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