Safer than smoking? RyanJLane/Getty

Are electronic cigarettes really any safer than smoking? A study that looked at the amount of cancer-causing chemicals in smoker’s bodies suggests yes.

“Less than half of current smokers in the UK believe that e-cigarettes are less harmful,” says Lion Shahab, at University College London. His team has screened urine and saliva samples from 181 people, looking for chemicals known to be linked to cancer. “What we found is that using e-cigarettes alone results in very low exposure to toxins and carcinogens,” said Shahab.

Compared with people who were currently smokers, the team found that former smokers who had been vaping only, for six months or more, had very low levels of some of the worst carcinogens found in tobacco smoke. NNAL, a chemical heavily linked to lung cancer, was 97.5 per cent lower in former smokers who now only vaped, compared with the average smoker.


A number of other carcinogens, including acrylonitrile, butadiene, and acrolein, were all much lower in the vapers. Former smokers who had switched to long-term use of nicotine patches or gums also had lower levels of carcinogens.

Continuing controversy

The researchers said the findings provided strong reassurance that vaping is safer than smoking. “I would bet my house on e-cigarettes being substantially safer than smoking,” said Robert West, another of the researchers from University College London.

“This paper adds to the body of evidence that e-cigarette use is less harmful than smoking,” says Linda Bauld at the University of Stirling, UK, and a cancer prevention adviser to Cancer Research UK, which funded the study.

But some researchers are still sceptical of the safety of e-cigarattes. Last week, a separate study warned that vaping could raise the risk of heart disease.

“It’s been established for a long time that e-cigarettes deliver much lower levels of carcinogens than cigarettes,” says Stan Glantz of the University of California at San Francisco, a long-time critic of vaping. “The health problems caused by e-cigarettes are on the cardiovascular system, increasing risks of heart and vascular disease, and non-cancer lung disease,” he says. “I think e-cigs are about 30 to 50 per cent as dangerous as cigarettes.”

West said that ultimately, epidemiological studies like those that showed that smoking caused lung cancer will provide the best evidence on e-cigarettes, but that such data would not be available for another 20 years or so.

Journal reference: Annals of Internal Medicine, DOI: 10.7326/M16-1107

Read more: Smoke without fire: What’s the truth on e-cigarettes?