By Catharine Richert

MPR News/90.1 FM

A new study by Mayo Clinic researchers shows that vaping-related lung injuries are likely caused by noxious chemical fumes.

Mayo researchers biopsied the lungs of people who had or were suspected of having vaping-associated lung injuries. Most patients involved in the study, which was published in the latest issue of the New England Journal of Medicine, had vaped marijuana or cannabis oils. The study includes biopsies from 17 patients from all three Mayo Clinic sites.

Co-author Dr. Jennifer Boland, a pulmonary pathologist at Mayo Clinic, said the findings run counter to a popular theory that the injuries were the result of fatty substances such as mineral oils. Instead, the biopsies displayed patterns of injuries caused by chemicals, she said.

“What we did find were various patterns of acute lung injury. The pattern would be more indicative of maybe a chemical-based injury rather than a build up of lipid or other toxins in the lung,” Boland said.

She added that little is understood about the relatively new vaping-related lung injuries.

“Even though the sample size is small, it’s concrete data regarding the changes we are seeing in the lungs of these patients,” said Boland.

According to the Minnesota Department of Health, the state has seen up to 55 confirmed or probable cases of vaping-related severe lung injuries, and one death. Nationally, the toll has topped 800 with at least 14 deaths. Most of those who got sick vaped THC, the compound that gives marijuana its high, though some patients reported that they vaped only nicotine.

On Wednesday, Gov. Tim Walz directed his administration to launch an aggressive outreach campaign to schools and to come up with policy proposals for the 2020 Legislature to combat youth vaping, following new survey results showing the spike in vaping rates among Minnesota teens.

The Associated Press contributed to this story.

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Read more on What we know about the US vaping illness outbreak.