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Vaping-associated lung injury may be caused by toxic chemical fumes

Researchers liken lung damage seen in US to injuries caused by breathing in noxious gas or fumes from a toxic chemical spill

Ingrid Torjesen

Thursday, 03 October 2019

The recent outbreak of vaping-related lung injuries associated with 17 deaths in the US was most likely caused by direct toxicity or tissue damage from noxious chemical fumes, according to the findings of the first study* to examine biopsies from patients with lung injury due to vaping.

Researchers at the Mayo Clinic reviewed lung biopsies from 17 patients, all of whom had vaped and were suspected to have vaping-associated lung injury.


Their study, published in The New England Journal of Medicine, found no evidence of tissue injury caused by accumulation of lipids, which has been suspected as a possible cause of the lung injuries associated with vaping.

"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," says Brandon Larsen, a surgical pathologist at Mayo Clinic Arizona.

The Centers for Disease Control and Prevention (CDC) has reported more than 800 lung injury cases that are associated with electronic cigarette use, or vaping, over the past few months, investigative findings suggest that products containing THC - the principal psychoactive compound in marijuana - or other cannabis oils, such as cannabidiol or CBD, may play a role in the outbreak.

Some US states have imposed a temporary ban on the sale of e-cigarettes or flavoured liquids used in them while researchers investigate health-related issues, and the US Food and Drug Administration is considering a ban on all non-tobacco flavours of vaping liquids.

Of the 17 biopsies examined, all of the patients had vaped, and 71% had vaped with marijuana or cannabis oils. All showed acute lung injury, including pneumonitis, and two of the patients died.

"We were not surprised by what we found, regarding toxicity," said Dr Larsen. "We have seen a handful of cases, scattered individual cases, over the past two years where we've observed the same thing, and now we are seeing a sudden spike in cases. Our study offers the first detailed review of the abnormalities that may be seen in lung biopsies to help clinicians and pathologists make a diagnosis in an appropriate clinical context."

Vaping-associated lung injury can be difficult to diagnose, unless clinicians and pathologists are armed with information beforehand, he added. "Based on what we have seen in our study, we suspect that most cases involve chemical contaminants, toxic byproducts or other noxious agents within vape liquids."

Professor John Britton, director of the UK Centre for Tobacco and Alcohol Studies and consultant in respiratory medicine, University of Nottingham, said the fact that the samples did not show evidence of lipid accumulation “indicates that the cause is not lipid per se, but something else in the vapour”.

“As in all disease outbreaks, it takes time to narrow down on the underlying cause: and in this example it is clearly something to do with vaping, something that often - but not exclusively - occurs in people who vape THC or other oils, and something that isn’t occurring in countries outside the USA,” he said.

“So it is something in US vape fluids, or something about the particular e-cigarettes used by those affected, but remains something separate from vaping more generally and particularly from vaping nicotine.”


*Butt YM, Smith LM, Tazelaar HD, et al. Pathology of Vaping-Associated Lung Injury. The New England Journal of Medicine. 2 October 2019, DOI:/10.1056/NEJMc1913069

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