Trending Science: Switching to e-cigarettes? Vaping could also lead to cancer, new study suggests

The key finding of the new study, published in ‘Proceedings of the National Academcy of Sciences’, was evidence that nicotine inhaled from e-cigarettes could be converted into chemicals that damage the DNA in a number of organs and that these chemicals dampen down the body’s genetic repair mechanisms.

Moon-shong Tang, professor of environmental medicine at the New York University School of Medicine, said the DNA changes were similar to those linked to secondhand smoke, but added that more work was needed to see whether vaping really did increase cancer rates. "Nicotine is not as innocent as conventional wisdom thinks," he commented.

The study exposed the mice to e-cigarette smoke (ECS) 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 animal’s lungs, bladders and hearts, as well as limiting lung proteins and important DNA repair.

In total 6.1 million Europeans have quit smoking with the use of e-cigarettes and more than 9 million have reduced their smoking consumption by switching from regular cigarettes to vaping, as reported in a 2016 study published in the journal ‘Addiction’.

Overall, a number of studies have tried to examine the long-term health consequences of vaping but 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 August 2017, compared cancer potencies of e-cigarettes and tobacco smoke and found vaping to have a cancer risk of less than 1 % of that from smoking.

This new study has also provoked some powerful responses, with some researchers arguing the new work is important whilst others have all but dismissed it. They have argued that the mice were exposed to high levels of e-cigarette smoke (three hours a day, five days a week for three months) and the effects may be very different in people who inhale nicotine from vaping.
“This study shows nothing at all about the dangers of vaping,” said Peter Hajek, director of the Tobacco Dependence Research Unit at Queen Mary University of London. “It doesn’t show that vaping causes cancer. This is one in a long line of false alarms which may be putting people off the switch from smoking to vaping which would undoubtedly be of great benefit to them,” he added. “The best current estimate is that vaping poses, at worst, some 5 % of risks of smoking.”

This latest study is not, by itself, conclusive. Tumours can’t develop in 12 weeks, the length of time the mice were exposed to the e-cigarette smoke, and if tobacco smoke-induced cancer is indeed a model for e-cigarette smoking-induced cancer, then meaningful human evidence won''t be available for at least another decade.

In the meantime, scientists are conducting animal experiments that may be able to provide further evidence as to the full comprehensive effects of e-cigarette smoking, the first results hopefully being available in about a year’s time.