Using existing studies on carcinogens found in combustible cigarettes and vaping devices, the author estimated cancer potencies under numerous conditions, including how the devices are to be used and in high-stressed conditions. The author used a model to “aggregate cancer potencies of all measured carcinogens” to overcome “incompatibilities in data reporting conventions [which enabled] direct comparison of the potencies and risks of tobacco smoke with [e-cigarette] emissions.”
The author found that e-cigarette emissions contain cancer-causing chemicals in conditions that are lower than tobacco smoke, with most analysis finding cancer potencies in e-cigarettes to be less than one percent of what was found in combustible cigarette smoke. Further, e-cigarette cancer potencies were less than 10 percent of the cancer potencies found in heat-not-burn devices. The author also found that “highly carcinogenic emissions from e-cigarettes are avoidable,” by user choice of devices and settings, liquid formulation and vaping behavior.
Implications: There is growing skepticism over the potential harms of e-cigarettes and vapor products. Although it is impossible to understand long-term use hazards, e-cigarettes are overwhelmingly less harmful than combustible cigarettes. This study adds to the growing consensus that e-cigarettes are a useful tool for smokers to use to quit smoking.
Background: Quantifying relative harm caused by inhaling the aerosol emissions of vapourised nicotine products compared with smoking combustible tobacco is an important issue for public health.
Methods: The cancer potencies of various nicotine-delivering aerosols are modelled using published chemical analyses of emissions and their associated inhalation unit risks. Potencies are compared using a conversion procedure for expressing smoke and e-cigarette vapours in common units. Lifetime cancer risks are calculated from potencies using daily consumption estimates.
Results: The aerosols form a spectrum of cancer potencies spanning five orders of magnitude from uncontaminated air to tobacco smoke. E-cigarette emissions span most of this range with the preponderance of products having potencies<1% of tobacco smoke and falling within two orders of magnitude of a medicinal nicotine inhaler; however, a small minority have much higher potencies. These high-risk results tend to be associated with high levels of carbonyls generated when excessive power is delivered to the atomiser coil. Samples of a prototype heat-not-burn device have lower cancer potencies than tobacco smoke by at least one order of magnitude, but higher potencies than most e-cigarettes. Mean lifetime risks decline in the sequence: combustible cigarettes >> heat-not-burn >> e-cigarettes (normal power)≥nicotine inhaler.
Conclusions: Optimal combinations of device settings, liquid formulation and vaping behaviour normally result in e-cigarette emissions with much less carcinogenic potency than tobacco smoke, notwithstanding there are circumstances in which the cancer risks of e-cigarette emissions can escalate, sometimes substantially. These circumstances are usually avoidable when the causes are known.
Tobacco and Alcohol News Analysis and Commentary, New Study Provides Strong Empirical Support for New FDA Approach to Tobacco Product Regulation, 2017
E-Cigarette Research, Cancer risk from e-cigarettes > 50 000 (thousand) fold lower than smoking, 2017Read Report