Secondhand Exposure to Simulated Cannabis Vaping Aerosols

XIAOCHEN TANG, Vi Rapp, Marion Russell, Hugo Destaillats, Lawrence Berkeley National Laboratory

     Abstract Number: 251
     Working Group: Indoor Aerosols

Abstract
Cannabis vaping is increasingly popular in the United States, especially among adolescents. Vitamin E acetate (VEA, C₃₁H₅₂O₃, MW: 472 g/mol) is a compound of low volatility, reportedly used as a thickening agent or to dilute cannabinoids in illicit vaping products. It was found in many e-cigarettes associated with the outbreak of vaping product-associated lung injury (EVALI) in 2019 and 2020, and is considered to be a key factor associated with the disease. Despite the growing amount of research on chemical emissions from cannabis use, little is known about the influence of low-volatility components, including VEA and cannabinoids, on the generation of aerosols and thermal degradation byproducts during vaping or dabbing.
This study explored how vaping liquid formulation affects the particle number and mass concentration of the formed aerosols and their chemical composition, by generating vaping aerosols from liquids of different composition under standardized conditions in a 20 m³ environmental chamber. A mixture consisting of common terpenoids found in cannabis extracts was incrementally enriched in low-volatility constituents, including VEA and the cannabinoids trans-Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Aerosol particles between 8 and 2,500 nm in size, generated by heating mixtures of various compositions at 400 °C, were monitored in real time with a Fast Mobility Particle Sizer, an Optical Particle Sizer and an Aerodynamic Particle Sizer spectrometer. In addition, airborne species were collected in sorbent tubes and analyzed by gas chromatography/mass spectrometry, and volatile carbonyls were sampled in dinitrophenylhydrazine-coated cartridges, extracted, and analyzed by liquid chromatography. These results were used to determine the aerosol yield and particle decay rates inside the chamber. The Multiple Path Particle Dosimetry (MPPD) model was used to predict the deposition of different vaping aerosols in the human respiratory tract, for subjects of different ages. Lung deposition increased with the presence of VEA and cannabinoids.