Researchers found vapour boosts production of inflammatory chemicals and disables key immune cells in the lungs that keep 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 respiratory tract’s other mechanical defences.
Vaping is increasing in popularity, with around three million regular users in the UK.
Britain is the most popular market for the practice.
But most of the existing body of research has focused on the chemical composition of e-cigarette liquid before it is vaped.
This latest small experimental study has been 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 cigs. But we should have a cautious scepticism 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.
They concluded: “We suggest continued caution against the widely held opinion that e-cigarettes are safe.”
A survey of adolescents carried out by researchers at Coventry University showed that fewer than half of e-cigarette users knew vape products contained nicotine.