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Oregon continues to trail blaze in the cannabis industry by moving forward with new product regulations. In late 2020, the Oregon Liquor Control Commission (OLCC) adopted a regulation prohibiting non-cannabis ingredients “most likely to cause acute harm” from cannabis vape products: vitamin E acetate (VEA), squalene, squalane, triglycerides [including medium chain triglyceride (MCT) oil and animal fats], and propylene glycol (PG) (OLCC Presentation, Slide 5; OLCC Rule Hearing; OLCC). In addition to prohibiting these ingredients, the OLCC adopted a regulation that requires companies and manufacturers to disclose additives and a full list of ingredients and their concentrations to the OLCC. It also required specific disclosures on item labels for consumers, and issued standards indicating that only products formulated for inhalation can be used in inhalable products (OLCC Presentation, Slides 6, 7). These rules apply to products that combine marijuana or hemp items with processed non-cannabis substances that are meant for inhalation (OLCC). Inhalable cannabis products manufactured after April 1, 2021 will have to follow these new standards (OLCC Rule Hearing; OLCC News Release). Products manufactured prior to this date can be sold and transferred without following the new regulations up until July 1, 2021, after which they, too, must adhere to the new rules or be destroyed (OLCC Rule Hearing; OLCC Presentation, Slide 8; OLCC News Release).

Currently, there are many diluents used in cannabis vape products, including MCT oil, PG, ethyl alcohol, squalene, and polyethylene glycol (PEG), in addition to other proprietary ingredients concealed by cannabis vape product manufacturers (OLCC). The CDC has linked vitamin E acetate (VEA) to electronic cigarette vaping-related associated lung injury (VALI or EVALI), and has stated that evidence was “not sufficient to rule out the contribution of other chemicals of concern, including chemicals in either THC or non-THC products, in some of the reported EVALI cases” (CDC, 2020). As part of the CDC’s research, Blount et al. (2019) assessed residual bronchoalveolar lavage (BAL) fluid specimens from 29 EVALI patients from ten states. Analysis of BAL fluid detected vitamin E acetate in all 29 samples, THC, or its metabolites in 23 samples, and nicotine metabolites in 16 samples. Plant oils, MCT oil, petroleum distillates (including mineral oil), and diluent terpenes were not detected in any of the samples (Blount et al. 2019).

The OLCC relied on research that showed vaping squalene and MCT oil produced short chain esters, alkanes, and carbonyls, while vaping VEA produced acetone and “quinone-like compounds” (OLCC; Huanhuan et al. 2020). The OLCC concluded that “these diluents [were] relatively safe in their intended use scenarios, but when heated, a variety of chemical reactions occur[red], some resulting in the formation of toxic chemicals” (OLCC, p. 18). The OLCC also concluded that given the molecular weight of most triglycerides, consumers who vape cannabis could inhale "some amount of triglycerides into their lungs during the vaping process," and that inhaling theseoils can cause lipoid pneumonia (OLCC, p. 18; Beck and Landsberg 2020).

Blount et al.’s2019 study demonstrated detectable VEA in the bronchoalveolar lavage (BAL) fluid of all 29 EVALI patients, and Huanhuan et al. (2020) showed vaping VEA produced acetone and quinone-like compounds. The findings raise an interesting question: Is the parent compound (VEA), the combustion by-products (acetone, quinones), or both contributing to the development of EVALI? Additional research is needed to resolve to this question. In addition, the OLCC decision to prohibit PG deserves further scrutiny, as its stated reason is the generation of formaldehyde upon heating. However, PG is used extensively as a vehicle for nicotine vape products in the United States and around the world, bringing to mind the adage expressed by the father of toxicology, Paracelsus, that “the dose makes the poison.” More studies are thus necessary to understand use patterns of THC/CBD versus nicotine vape products and the operating temperature of THC/CBD versus nicotine vape devices. Ultimately, these consumer use patterns determine the dose of both active chemicals like THC and CBD, but also chemicals of concern (e.g., formaldehyde). Both THC and CBD, however, have boiling points significantly lower than nicotine. Real-life use conditions and patterns would help inform the potential hazard of PG as a THC/CBD vape vehicle. The challenge to the cannabis vape industry going forward, then, will be to design a delivery vehicle that is sufficiently lipophilic to solubilize the highly non-polar cannabis constituents THC and CBD while avoiding the potential for a lipoid pneumonitis, or the generation of heating-related by-products that could contribute to EVALI.

Cardno ChemRisk scientists have extensive experience assisting the e-cigarette/ENDS industry with designing and conducting aerosol characterization studies as part of FDA regulatory compliance, performing human health and environmental risk assessments on a wide range of ingredients, and assisting cannabis industry manufacturers with identifying and evaluating the toxicity of appropriate delivery vehicles. For more information on Cardno ChemRisk’s capabilities, please contact Elise de Gandiaga or Heidi O’Neill.