E-cigarettes may be causing similar damage to lung cells as regular smoking and therefore could be much more harmful than previously thought, a study has suggested.
Researchers found vapour boosts the production of inflammatory chemicals and disables key immune cells in the lung that keep the air spaces clear of potentially harmful particles. The vapour from e-cigarettes impairs the activity of alveolar macrophages, which engulf and remove dust particles, bacteria and allergens that have evaded the other mechanical defences of the respiratory tract.
Vaping is increasing in popularity, with three million regular users in the UK, making it the most popular market with the US and Japan.
But most research has focused on the chemical composition of e-cigarette liquid before it is vaped. In this latest small experimental study, published online in the journal Thorax, researchers devised a mechanical procedure to mimic vaping and produce condensate from the vapour.
They extracted alveolar macrophages from lung tissue samples provided by eight non-smokers who had never had asthma or chronic obstructive pulmonary disease (COPD). A third of the cells were exposed to plain e-cigarette fluid, a third to different strengths of the artificially vaped condensate with and without nicotine and a third to nothing for 24 hours.The condensate was found to be more harmful to the cells than plain e-cigarette fluid.
The effects worsened as the “dose” was increased.
Professor David Thickett, lead author from the University of Birmingham, said: “In terms of cancer causing molecules in cigarette smoke, as opposed to cigarette vapour, there are certainly reduced numbers of carcinogens.
“They are safer in terms of cancer risk, but if you vape for 20 or 30 years and this can cause COPD, then that’s something we need to know about.
“I don’t believe e-cigarettes are more harmful than ordinary cigarettes. But we should have a cautious scepticism that they are as safe as we are being led to believe.”
In an accompanying podcast, Professor Thickett said the tobacco giants, who have bought up many of the e-cigarette companies, have an agenda to portray e-cigarettes as safe.
The team said further work was needed to fully understand the effects of vapour exposure in humans.
It concluded: “We suggest continued caution against the widely held opinion that e-cigarettes are safe.”
A survey of adolescents by researchers at Coventry University showed less than half of e-cigarette users knew vape products contained nicotine.
Professor John Britton, director of the UK Centre for Tobacco and Alcohol Studies at the University of Nottingham, said: “This [study] indicates that long-term use of electronic cigarettes is likely to have adverse effects, as is widely recognised by leading health authorities in the UK, including the Royal College of Physicians and Public Health England.
“However, since electronic cigarettes are used almost exclusively in the UK by current or former smokers, the key question is how this adverse effect compares with that of exposure to cigarette smoke.”
Prof Britton added: “The harsh truth is that smoking kills and smokers who switch completely to electronic cigarettes are likely to substantially reduce the likelihood of premature death.”