E-cigarettes may lead to cancer and heart disease, study finds

E-cigarette users are possibly putting themselves at risk for developing heart disease, lung and bladder cancers, according to a new report. The findings, while preliminary, indicate that the devices — which use nicotine in an aerosol form and contain no tobacco — may not be as safe as previously assumed.

The study, conducted by researchers from the New York University School of Medicine, exposed mice to e-cigarette smoke for 12 weeks at a dose and duration equivalent to light e-cigarette smoking for 10 years in humans. By the end of the trial, the smoke had caused DNA damage in the animals' lungs, bladders and hearts, as well as limiting lung proteins and DNA repair.

Evidence points to the “almost unambiguous” conclusion that nicotine can convert to a carcinogen once inside the human body, said study author Moon Shong-tang, a professor of environmental medicine and pathology at NYU School of Medicine. “Nicotine is not as innocent as conventional wisdom thinks,” he said.

Currently, 18 million Americans smoke e-cigarettes. Sixteen per cent of those users are high school students, according to the report. Manufacturers have advertised the devices as a safer alternative to traditional tobacco products.

A slew of studies examining the long-term health consequences of vaping have been conducted, but the conclusions have been mixed.

In 2013, a trial found the practice to be as effective in helping smokers quit as using nicotine patches. Another study, published in August 2017, compared cancer potencies of e-cigarettes and tobacco smoke and found most vapours to have a cancer risk of less than 1 per cent of that from smoking.

Many are worried that the mild flavour of vapours will hook young people on nicotine, encouraging teenagers to smoke tobacco. In 2016, the US surgeon general Vivek Murthy called e-cigarette use among American youth a "major public health concern", citing a 900 per cent growth rate among high school students.

Mr Moon would not recommend vaping to non-smokers, in particular young people: “Don’t think a vapour is harmless.” As for cigarette smokers thinking about going electronic, Mr Tang hesitated. “We don’t know which one is more harmful,” he said.

This latest study is not, by itself, conclusive. Tumours cannot develop in 12 weeks—the length of the study — and if tobacco smoke-induced cancer is indeed a model for e-cigarette smoking-induced cancer, then meaningful human evidence will not be available for at least another decade.

In the meantime, scientists are turning to animal experiments, which may be able to provide further evidence as to the full-blown effects of e-cigarette smoking in about a year.