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THC-O Could Spark Another Vaping Injury Epidemic, Researchers Warn

By Leo Bear-McGuinness

Published: Jan 13, 2023   
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A few months before the Covid pandemic began, the US was hit with a different kind of respiratory plague, one spread not by virus but by vape.

By February 18, 2020,over 2,800 people had been hospitalized from the vaping illness and 68 had died, according to the US Centers for Disease Control and Prevention. The E-cigarette or vaping-associated lung injury (EVALI) epidemic, as it became known, then petered out.

Experts quickly identified the chemical vitamin E acetate, a cutting agent used in illicit vapes, as the likely cause behind the illness. To avoid EVALI, it seemed one only had to avoid vitamin E acetate.

But now one group of researchers is warning that another chemical, if vaped, could be just as dangerous.

Just say no to THC-O

In a research letter published in the Journal of Medical Toxicology on December 12, 2022, a team of researchers – who were from Zuckerberg San Francisco General Hospital and the Royal College of Surgeons in Ireland – say that the synthetic cannabinoid THC-O may pose just as great a risk when vaped as vitamin E acetate.

THC-O can be derived from hemp and has grown in popularity since the 2018 Farm Bill legalized hemp production in the US. With that go-ahead, many extractors inferred that any products derived from hemp, such as THC-O, were also, in turn, federally legal. As such, THC-O products are even sold in states that still prohibit recreational cannabis.

In their new letter, the research team say that, when vaped, THC-O can break down to form ketene, a highly potent lung toxicant. Indeed, ketene is thought to have played a part in the EVALI outbreak, as it is also formed during the breakdown of vitamin E acetate, according to the researchers.

To add to their assertion, the team tested a “Blue Dream” THC-O cartridge bought from Extract Labs. Mass spectrometry analysis revealed that 84% of the oil was THC-O-acetate. As the aryl acetate moieties (a part of the molecules) found in both THC-O-acetate and vitamin E acetate are structurally similar, the researchers anticipate that their thermal decomposition would also be similar, and both produce ketene.

“Clinical toxicity from vaping THC-O has not to the best of our knowledge been reported,” the researchers wrote in their letter. “However, we suggest that the use of THC-O be considered by health care providers when evaluating lung injury in people who have vaped cannabis products.”


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