Vaping Aerosols from Vitamin E Acetate and Tetrahydrocannabinol Oil: Chemistry and Composition

Abstract

The popularity of vaping cannabis products has increased sharply in recent years. In 2019, a sudden onset of electronic cigarette/vaping-associated lung injury (EVALI) was reported, leading to thousands of cases of lung illness and dozens of deaths due to the vaping of tetrahydrocannabinol (THC)-containing e-liquids that were obtained on the black market. A potential cause of EVALI has been hypothesized due to the illicit use of vitamin E acetate (VEA) in cannabis vape cartridges. However, the chemistry that modifies VEA and THC oil, to potentially produce toxic byproducts, is not well understood under different scenarios of use. In this work, we quantified carbonyls, organic acids, cannabinoids, and terpenes in the vaping aerosol of pure VEA, purified THC oil, and an equal volume mixture of VEA and THC oil at various coil temperatures (100−300 °C). It was found under the conditions of our study that degradation of VEA and cannabinoids, including Δ 9 -THC and cannabigerol (CBG), occurred via radical oxidation and direct thermal decomposition pathways. Evidence of terpene degradation was also observed. The bond cleavage of aliphatic side chains in both VEA and cannabinoids formed a variety of smaller carbonyls. Oxidation at the ring positions of cannabinoids formed various functionalized products. We show that THC oil has a stronger tendency to aerosolize and degrade compared to VEA at a given temperature. The addition of VEA to the e-liquid nonlinearly suppressed the formation of vape aerosol compared to THC oil. At the same time, toxic carbonyls including formaldehyde, 4-methylpentanal, glyoxal, or diacetyl and its isomers were highly enhanced in VEA e-liquid when normalized to particle mass.

External Factors Modulating Vaping-Induced Thermal Degradation of Vitamin E Acetate

“…Instead, a wide range of degradation products commonly observed in vaping emissions could be seen in the resulting TIC (Figure B). Ultimately, analysis of these results found the presence of 4-methyl-1-pentanal (peak 1; t R = 9.805 min), 4-methyl-1-decene (peak 2; t R = 15.830 min), 3,7,11-trimethyl-1-dodecanol (peak 3; t R = 26.84 min), durohydroquinone (DHQ) (peak 4; t R = 27.103 min), 1-pristene (peak 5; t R = 28.073 min), and 2-hydroxy-4-methoxy-3,6-dimethyl benzaldehyde (peak 6; t R = 28.834 min), all of which have been previously detected in VEA vaping emissions. ,− ,, DQ was not observed at levels above the detection limit of the instrument, though DQ formation can be assumed due to the detection of 1-pristene and DHQ. , Ultimately, it is clear that the presence of O 2 when VEA is heated results in the production of compounds often found in VEA vaping emissions, indicating the importance of oxidation pathways during vaping thermal degradation.…”

“…Regardless, the presence and enhanced formation of OH radicals are noteworthy as a recent study by Li et al suggested that many degradation products of VEA may result from OH radical- and O 2 -mediated reactions. Radicals such as OH may initiate bond homolysis, dehydration, or H-abstraction on the side chain of VEA, followed by RO 2 radical-mediated chemistry to form highly oxygenated products observed in vaping emissions. , Such degradation pathways may occur simultaneously through pyrolysis-induced degradation, producing unique compounds that cannot be explained through pyrolysis alone.…”

“…Regardless, the presence and enhanced formation of OH radicals are noteworthy as a recent study by Li et al suggested that many degradation products of VEA may result from OH radical- and O 2 -mediated reactions. Radicals such as OH may initiate bond homolysis, dehydration, or H-abstraction on the side chain of VEA, followed by RO 2 radical-mediated chemistry to form highly oxygenated products observed in vaping emissions. , Such degradation pathways may occur simultaneously through pyrolysis-induced degradation, producing unique compounds that cannot be explained through pyrolysis alone. In our results, the enhanced formation of OH radicals in an oxidizing environment and the increased number of degradation products observed in the presence of O 2 and Cu–Ni provide further evidence of oxidative pathways as a dominant factor in VEA degradation, particularly at low temperatures.…”

The E-cigarette or Vaping Product Use–Associated Lung Injury Epidemic: Pathogenesis, Management, and Future Directions: An Official American Thoracic Society Workshop Report

“…It should be noted that ketene is highly reactive and may be difficult to identify directly. Other respiratory irritants and known airway toxicants have also been identified with degradation of VEA, such as carbonyls, quinones, and other volatile products ( 120 – 123 ). In addition, VEA’s mode of action has been hypothesized to be a modification of pulmonary surfactant surface tension contributing to lung atelectasis, functioning as a linactant or line-activating molecule that binds to the boundary between lipid membranes, displacing endogenous surfactant.…”

“…Major aerosol products in nicotine e-cigarettes may include formaldehyde, acrolein, acetaldehyde, and glycolaldehyde-releasing agents ( 149 ); for cannabinoid e-cigarettes, isoprene, methacrolein, methyl vinyl ketone, isoprene epoxide, butadiene, etc. are present ( 123 , 149 , 150 ). However, given the potential for cooccurrence of cigarette smoking among patients, care in selecting degradation product metabolites unique to the delivery mode is extremely important.…”