While e-cigarettes had increased in popularity, concerns about the potential exposure to carcinogens and toxins still persisted, according to an American College of Physicians’ study published in the Annals of Internal Medicine. It was written by Dr Lion Shahab and her colleagues at University College London.

“Some reports claim to show that e-cigarettes are as harmful as smoking, but the study authors say those reports are based on studies that bear little relationship to exposure of e-cigarette users in the real world,” Shahab said.

Researchers measured the intake of potentially harmful chemicals by e-cigarette users and compared them to people using licensed nicotine patches and cigarettes.

The study found that when smokers switched completely to e-cigarettes, their intake of cancer-causing chemicals dramatically fell to a level found in people using nicotine patches. Their intake of nicotine remained largely unchanged, however.

Using e-cigarettes or nicotine replacement patches while continuing to smoke cigarettes does not seem to offer the same benefit.

According to the authors, the results confirm that e-cigarettes, like other nicotine replacements, are much safer than conventional cigarettes and may be a useful long-term quitting aid for patients who smoke and have struggled to stop with other available support.

The authors still urged users to stop smoking completely to achieve health benefits.

The primary funding source for the research was Cancer Research UK, the Americans College of Physicians said.