Vaping-related lung injuries are most likely caused by exposure to toxic chemicals rather than fatty substances like mineral oils, according to a new analysis of patient tissue by Mayo Clinic pathologists.
The results, based on lung biopsies from 17 patients from around the U.S., may help investigators narrow the long list of suspects in the mysterious outbreak that has sickened 805 people and killed at least 12. The study is among the first to examine a large group of biopsies from patients with lung injuries linked to vaping nicotine or THC, the ingredient in marijuana that produces a high.
In particular, the findings cast doubt on one theory of what’s causing the problem: that vaping lung injuries represent a rare type of so-called lipoid pneumonia caused by accumulation of oil from vaping liquid inside the lungs.
None of the 17 cases showed clear signs of lipoid pneumonia, such as the presence of large oil droplets in the lungs, said Brandon Larsen, a surgical pathologist at the Mayo Clinic in Scottsdale, Arizona. He is an author on the study, published Wednesday in the New England Journal of Medicine.
“The type of injury we see in the lung is not injury from oil accumulation,” Larsen said. “It is a kind of injury that appears to be a toxic chemical injury” similar to that caused by toxic fumes or poison gas. The lung biopsies don’t provide hints as to what the toxin might be, but Larsen said he suspected it could be some sort of contaminant in the vaping liquid.
The Mayo Clinic study also provided new evidence that vaping-related lung injuries aren’t entirely new. The 17 cases include two previously unreported early cases, from 2016 or 2017, that predate the current outbreak. Bloomberg News previously reported that there have been at least 15 early cases of vaping lung injury prior to this year.
“This is not a new phenomenon,” said Larsen. While the number of cases has spiked recently, “this has been going on for at least the last few years.”
Two of the biopsies were from Mayo Clinic patients and the rest were from hospitals around the country that sent samples to the Mayo Clinic for a second opinion. Consistent with previous findings, 12 of the 17 patients had a history of vaping with marijuana or cannabis oils.
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