The lung damage in some people who have become ill after vaping nicotine or marijuana products resembles a chemical burn, doctors from the Mayo Clinic reported on Wednesday.

Their findings are based on samples of lung tissue from 17 patients around the country whose biopsy specimens were sent to Mayo to be examined under the microscope by experts in lung pathology. Two samples came from patients who died.

“All 17 of our cases show a pattern of injury in the lung that looks like a toxic chemical exposure, a toxic chemical fume exposure, or a chemical burn injury,” said Dr. Brandon T. Larsen, a surgical pathologist at the Mayo Clinic in Scottsdale, Ariz. “To be honest, they look like the kind of change you would expect to see in an unfortunate worker in an industrial accident where a big barrel of toxic chemicals spills, and that person is exposed to toxic fumes and there is a chemical burn in the airways.”

The injuries also look like those seen in people exposed to poisons like mustard gas, a chemical weapon used in World War I, he said. [Read More @ The NY Times]