February 21, 2023

Neal Benowitz, MD

THC-O Acetate linked to severe lung disease

Benowitz and coworkers published a public health warning in the Journal of Medical Toxicology about the potential for inhaled delta-8 THC-O-acetate (THC-O) to cause lung injury, similar to that seen in the EVALI epidemic in 2019.  The lung injury seen in EVALI cases is believed to have been largely caused by inhalation of delta-9 THC oil containing vitamin E acetate (VEA), used as diluent. When heated, the acetate moiety of VEA is converted to ketene, a highly potent lung toxicant, similar in action to phosgene.

THC-O, a psychoactive cannabinoid, can be synthetized from cannabidiol which is legally available in hemp products. THC-O was identified in a cannabis product purchased over the internet. Mathematical calculations of the energy required to convert THC-O to ketene confirmed that this could occur at the temperatures seen with cannabis vaporizers (“vaping”). Another independent research team has confirmed that vaping THC-O can produce ketene.

 The authors encourage education of cannabis users not to use THC-O, and health care providers to consider THC-O in evaluating lung injury in people who using cannabis vaporizer products.

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