New research proves that e-cigarette aerosol droplets are effectively delivered to cell surfaces in lab-based biological tests.
'There have been several studies comparing the impact of e-cigarette vapour with that of cigarette smoke on cellular models, and there are a lot of great data out there,' said Dr James Murphy, Head of Risk Substantiation at British American Tobacco.
'When there is a partial response or no response at all, this can be interpreted as e-cigarette vapour having a reduced biological impact compared to cigarette smoke. But what if it just means we are losing the aerosol and exposing the system to air,' he said. 'We had to be sure. These latest results suggest that we can be confident that we are effectively delivering e-cig aerosol to cells in biological tests and that we can be confident, therefore, in the results of our biological tests,'
The results are published today in Chemistry Central Journal.
The cellular tests mimic key events in the development of tobacco-related diseases like cardiovascular disease or chronic obstructive pulmonary disease. They form part of a weight of evidence approach to assess the reduced risk potential of e-cigarettes and other next generation products.
Two different smoking/vaping robots were used to produce aerosol from a reference cigarette (3R4F) and Vype ePen, a commercially available e-cigarette. The deposited particle mass in exposure chambers was measured, as well as the amount of deposited nicotine -- Exposure chambers are used to expose human lung cells to aerosol in the lab and to assess the impact of that aerosol (smoke or vapour) on the health of those cells.
The results show that, on a puff by puff basis and at a common dilution, the e-cigarette aerosol deposited greater mass than cigarette smoke in both systems. In contrast, nicotine delivery was much greater from the cigarette than from the e-cigarette.
'It may seem counter intuitive that the aerosol that delivered the most mass had the least impact, but it's about what that mass represents,' explains Murphy.
The aerosol particles produced by smoke and vapour may appear similar but they are compositionally very different. Smoke is drier and stickier and therefore lighter than the glycerine based e-cigarette droplets, which are moist and tend to be heavier.
In addition, smoke droplets carry the products of combustion: thousands of chemicals and hundreds of toxicants. Whereas e-cigarette aerosol droplets contain the aerosolised form of the 4 main ingredients that make up e-liquids: humectants, water, nicotine and flavouring.
'This means the mass deposited on the cells by the e-cigarette vapour is compositionally very different to that deposited by cigarette smoke,' says Murphy.
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 the current expert estimate is that using e-cigarettes is around 95% safer than smoking cigarettes, although 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.