E-Cigarettes Are Less Dangerous Than Cigarettes but Not Entirely Safe

Studying the safety of electronic cigarettes (e-cigarettes) on teenagers is extremely important. Rubinstein et al¹  describes the presence of certain metabolites in the urine of adolescents who smoke e-cigarettes. They also tell us many of them are carcinogenic. They conclude by advising the public to warn teenagers about “the potential risk from toxic exposure to carcinogenic compounds.” However, they fail to adequately frame the message for cigarette smokers:

1. Authors were careful to select e-cigarette–only users (they even established their eligibility by measuring the levels of urine NNAL), but they did not recruit a comparison group composed of cigarette-only users. Being able to compare both groups is important because e-cigarettes are advertised as an alternative to cigarettes (the carcinogenic hazards of cigarette consumption are well established), not as an alternative to dual use. Having measured the levels of volatile organic compounds (VOCs) in cigarette-only users, we would know by how much e-cigarettes reduce the levels of VOCs compared with cigarettes in teenagers. The authors cited a study in which this design was used,²  suggesting they deliberately decided not to have such comparison group.

2. The authors do not tell the reader the levels at which these VOCs start being toxic. This information is crucial to understand the importance of the findings. Although a statistical analysis is useful, toxicity can be better assessed by using a population-level measure of toxicity. If such information is not yet available, it should be mentioned.

Even in the absence of these data, we know that a reduced intake of VOCs is associated with a reduction of disease risk.³  It is likely that cigarette smokers would benefit by becoming e-cigarette–only users, and this should be emphasized given how lightly scientific articles can be interpreted and how prevalent smoking-related cancer is.