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UPDATE: As of Sep. 6, the U.S. Centers for Disease Control and Prevention reported they'd logged five deaths and more than 450 vaping-related illnesses across 33 states. The agency noted many of those cases related to THC oil.

Original story:

Hundreds of people have become sick with mysterious lung illnesses across the country this summer — and two people have died. One man is in a medically-induced coma and may require a lung transplant. And the common link behind all the chaos might be an otherwise innocent chemical found in some shady cannabis vaping products.

Medical investigators with New York State’s Department of Health recently analyzed some the vaping products used in the state’s 34 cases of severe lung illness. While they discovered all the patients used various vape cartridges, one particular kind — those containing cannabis — had “very high” levels of vitamin E not found in nicotine cartridges, according to a press release. State health officials who took part in a national call with the FDA also reportedly heard that an oil derived from vitamin E was a common link in many cases, though not all, according to the Washington Post.

Vitamin E is an otherwise safe substance found in everyday products like dietary supplements and skincare. But it’s unclear whether it’s safe to vape, especially since it’s not an approved vaping product in New York State. One chemistry professor, Michelle Francl, said the oil is essentially grease and gets very hot before it vaporizes. Once it decomposes, “you’re breathing in who-knows-what,” she told the Post.

The FDA told NPR that more information is needed before the agency determines whether or not any specific product is behind the mysterious vaping illnesses. In the meantime, vapers are being told to stay cautious of their cartridges, particularly concerning unapproved products purchased on the black market.

As of Aug. 27, the U.S. Centers for Disease Control and Prevention had logged 215 possible lung illnesses related to vaping, and many of those cases are still under investigation. The two deaths from those illnesses, which occurred in Illinois and Chicago, may also be linked to vaping.

"The FDA is analyzing samples submitted by the states for the presence of a broad range of chemicals, including nicotine, THC and other cannabinoids along with cutting agents/diluents and other additives, pesticides, opioids, poisons and toxins. No one substance, including Vitamin E acetate, has been identified in all of the samples,” FDA senior adviser Michael Felberbaum wrote in an emailed statement to NPR Thursday.

New York’s health department has also shared photos of a few of the vape products used by those who became sick; some cartridges were from Dank Vapes, a shadowy vaping package company — it’s unclear who makes the cartridges or liquids that wind up in the branded packaging — while the other brand was candy-flavored Chronic Carts.

One 18-year-old in Illinois, Adam Hergenreder, told CBS News from his hospital bed that he picked up a cannabis vaping products from a drug dealer after vaping for about two years. But the product made him feverish and left him gasping for breath as he vomited.

He said he now regrets buying the product off the street. "I'm 18 years old. My lungs are like a 70-year-old's," he told CBS News.