E-cigarettes are battery-powered devices that heat liquid to create a vapour which is inhaled. Because e-cigarettes don’t burn tobacco, the vapour contains substantially lower levels of the toxicants found in the smoke produced when tobacco is burned. This provides one indication that e-cigarettes have potential reduced-risk properties when compared with conventional cigarettes.
Consensus has been emerging that although e-cigarettes are not risk free, they have the potential to be much less risky than continuing to smoke cigarettes. Public Health England, a part of the UK Department of Health, has carried out two comprehensive reviews of the evidence1,2 and stated that they believe vaping is at least 95% less harmful than smoking. They stressed the need for product standards and for more studies on the long-term impact of use.
The gold standard for demonstrating that any product is reduced risk compared with cigarettes is epidemiological data, which can take 25 – 30 years to generate. In the absence of epidemiology, we are taking a weight of evidence approach to build the case that our e-cigarettes are indeed lower risk than combustible cigarettes. We have developed a scientific framework that covers assessment of any product. In general, the tests that we are carrying out fall into three broad categories: what’s in the emissions; what happens when cells are exposed to these emissions; and risk at both the individual and population levels.
Using the Vype ePen as a case study, we have created one of the world’s most comprehensive sets of published scientific results on a single e-cigarette3. In the emissions part of this data package, we first looked at the emissions of all known (and measurable) e-cigarette and tobacco cigarette priority compounds.
We analysed levels of 150 different compounds in smoke from a reference cigarette and compared them with levels in the vapour from Vype ePen4. The comparisons were conducted on a per-puff basis, and the results showed average reductions of 99 % of compounds in the truncated lists of the World Health Organization and the US Food and Drug Administration, and over 92 % of those on the full Food and Drug Administration list of 93 harmful and potentially harmful constituents. This comprehensive analysis filled in an important gap in the field and also provided some guidance to others on the methodological challenges of doing analyses of this kind.
Next, we carried out some standard in vitro regulatory toxicology tests that are routinely used in many industries, including for evaluation of combustible cigarettes. Cigarette smoke is highly mutagenic (causes DNA damage) and highly cytotoxic (kills cells). In contrast, we have shown that vapour from Vype ePen is not mutagenic and is over 90 % less cytotoxic than cigarette smoke3.
We have also developed a series of in vitro models that aim to represent, using human cell lines cultured in the laboratory, disease processes such as wound healing, tumour promotion and DNA mutation. The vapour from Vype ePen, even when tested at high doses, gave no biological activity in these tests. Using a systems biology approach, ePen vapour had a far lower impact on disease-relevant gene expression than cigarette smoke.
In addition to our laboratory-based studies, we have carried out some clinical studies to examine the speed of nicotine delivery for Vype ePen, and we have also done some mathematical modelling of the impact of e-cigarette use at the population level.