http://www.news-medical.net/news/20161005/Exposure-to-e-cigarette-vapour-induces-negligible-or-no-oxidative-damage-to-lung-epithelial-cells.aspx
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.