Vaping can be as damaging to lungs as a poison gas attack, warn doctors
Vaping damages the lungs in the same way as a poison gas attack, tests have revealed.
Experts in the US have warned of a looming "public health crisis" after examination of tissue samples found vapers suffered "direct" injuries from noxious chemicals.
For the first time, scientists reviewed lung biopsies from a group of patients who had fallen ill after smoking e-cigarettes, two of whom had died.
The team at the Mayo Clinic in Phoenix, Arizona, had been expecting to find lung damage as a result of fatty deposits from the vaping liquids.
Instead, they found more serious "acute" injuries of the type commonly seen in victims of gas attacks.
The study, published in the 'New England Journal of Medicine', was published as concern about the safety of e-cigarettes grows, and comes a week after Britain's first death linked to vaping came to light.
Last month, Donald Trump announced plans to ban flavoured e-cigarettes in the US because of fears over their appeal to young people.
Of the 17 patients from whom samples were taken, only eight had smoked. All had foamy accumulations indicating acute fibrinous pneumonitis, a type of scarring.
Dr Brandon Larsen, the study's senior author, said: "While we can't discount the potential role of lipids, we have not seen anything to suggest this is a problem caused by lipid accumulation in the lungs.
"Instead, it seems to be some kind of direct chemical injury, similar to what one might see with exposures to toxic chemical fumes, poisonous gases and toxic agents."
Of the patients in the study, 12 had vaped with marijuana or cannabis oil.
This could be significant because the vaping lobby and some scientists argue the recent spate of illnesses related to vaping are a result of THC, the principal psychoactive compound in marijuana, or cannabidiol (CBD).
The Mayo team also found small mixed brown and black particles resembling particulate matter found in smoking, leading them to conclude they may have originated from the vaping liquid or device.
"This is a public health crisis, and a lot of people are working frantically to find out what the culprit or culprits could be - and what chemicals may be responsible," said Dr Larsen.
"We suspect that most cases involve chemical contaminants, toxic by-products or other noxious agents within vape liquids."
The HSE does not encourage vaping as a means of quitting cigarettes, warning users it is not yet known how safe it is.
"Everyone should recognise that vaping is not without potential risks, including life-threatening risks, and I think our research supports that," said Dr Larsen. (© Daily Telegraph)