E-cigarette vapour is much less harmful to lung cells than cigarette smoke. Lab tests show that, unlike tobacco smoke, which causes oxidative stress and cell death, e-cigarette vapour does not. Oxidative stress and cell death are driving factors in the development of many smoking-related diseases such as COPD and lung cancer.

Vapour from e-cigarettes has been found to contain significantly lower levels of the toxicants found in cigarette smoke (Chemical Research in Toxicology DOI: 10.1021/acs.chemrestox.6b00188), but suitable lab tests and clinical studies are necessary to understand whether this translates into reductions in biological responses and disease.

Researchers at British American Tobacco have developed a standardized way of measuring and comparing the potential of conventional cigarette smoke and e-cigarette vapour to cause oxidative stress in an in vitro model of lung epithelium.

To do this they bubbled matched amounts of smoke (from a reference cigarette) or vapour (from Vype ePen or Vype eStick) through cell-growth medium to produce a stock that could be diluted into various concentrations. They then exposed lung epithelial cells to the same concentrations of either smoke or vapour extract and, following exposure, used a panel of commercially available assays to measure and compare the stress responses of the cells.

Lung cells exposed to any of the concentrations of cigarette smoke showed signs of oxidative stress and, at higher doses, cytotoxicity. In stark contrast, vapour from e-cigarettes tested had no such effects, even at the highest concentration.

The research is published in a special edition on e-cigarettes of Toxicology Mechanisms and Methods DOI: 10.1080/15376516.2016.1222473.

"These data suggest that exposure to vapour from the e-cigarettes tested induces negligible or no oxidative damage to lung epithelial cells at the range of doses tested," says Dr Chris Proctor, Chief Scientific Officer at British American Tobacco. 'This highlights the scale of difference in potency between e-cigarette vapour and cigarette smoke and adds to the weight of evidence on the reduced risk potential of e-cigarettes."

Although sensitive enough to detect the damaging pro-oxidant effects of tobacco smoke, the assays used in the study could not detect a response from e-cigarette vapour, which contains comparable levels of nicotine but very low levels of potentially harmful chemicals.

These tests form part of a suite of tests being developed to test novel tobacco and nicotine products and could be used to help develop standards for these products in the future.

Many in the public health community believe e-cigarettes offer great potential for reducing the public health impact of smoking. Public Health England, an executive body of the UK Department of Health, recently published a report saying that e-cigarettes are 95% safer than cigarettes, but more research is needed. The Royal College of Physicians have said that the public can be reassured that e-cigarettes are much safer then smoking and that they should be widely promoted as an alternative to cigarettes though they also called for more research. Cancer Research UK, Action on Smoking and Health and the British Heart Foundation are also of the view that e-cigarettes are substantially less harmful than smoking.

Source: R&D at British American Tobacco