“The levels of toxic chemicals in the body from e-cigarettes are considerably lower than suggested in previous studies using simulated experiments. This means some doubts about the safety of e-cigarettes may be wrong,” says Dr Lion Shahab, senior lecturer in the department of epidemiology and public health at University College London and lead author of a study published in Annals of Internal Medicine.1

Previous work on the safety of e-cigarettes has focused on the potential harmful chemicals found within the product or its vapor. In the first of its kind, Shahab and colleagues assessed the level of harmful chemicals within the body via the saliva and urine of e-cigarette and replacement nicotine therapy (NRT) users.

People who switched from smoking regular cigarettes to e-cigarette or NRT for at least 6 months had significantly lower levels of toxic chemicals in their body than those who continued to smoke tobacco cigarettes. People who smoked both tobacco cigarettes and e-cigarettes or NRT had no difference in the levels of toxic chemicals within their body. This indicates that a complete switch from tobacco is needed to lower toxin exposure.

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According to Shahab, “Our results also suggest that while e-cigarettes are not only safer, the amount of nicotine they provide is not noticeably different to conventional cigarettes. This can help people to stop smoking altogether by dealing with their cravings in a safer way.”

Alison Cox, the director of cancer prevention at Cancer Research UK said this of the study, “Around a third of tobacco-caused deaths are due to cancer, so we want to see many more of the UK’s 10 million smokers break their addiction. This study adds to growing evidence that e-cigarettes are a much safer alternative to tobacco, and suggests the long term effects of these products will be minimal.”


1. Shahab L, Goniewicz ML, Blount BC, et al. Nicotine, carcinogen, and toxin exposure in long-term e-cigarette and nicotine replacement therapy users: a cross-sectional study. Ann Intern Med. 2017 Feb 7. doi: 10.7326/M16-1107 [Epub ahead of print]