Effects of Terpenes on the Emissions of Aerosols and Carbonyls from Vaping Δ8- and Δ10-Tetrahydrocannabinol (THC)

Cannabis electronic cigarette (CEC) products, used to “vape” or aerosolize cannabinoids and their mixtures, have proliferated in recent years and are emerging sources of indoor air pollution. This work characterizes the chemical composition and emissions of inhalable aerosol from CEC vaping of the popular synthetic cannabinoids Δ8- and Δ10-tetrahydrocannabinol (Δ8-THC and Δ10-THC, respectively). Commercial Δ8-THC and Δ10-THC distillates were found to have variable purity, with the Δ10-THC distillate comprising roughly one-third of Δ8-THC. The addition of a commercial terpene oil mixture (rich in d-limonene, β-caryophyllene, β-myrcene, and others) at 0%, 7.5%, and 15% by mass to the Δ8-THC and Δ10-THC distillates significantly increases emissions of carbonyls up to 9-fold, but not those of cannabinoid oxidation products. On average, 6 ± 1 mg of aerosol was produced per puff, which did not significantly vary with added terpenes. Molecular analysis confirmed that a majority of the carbonyl products originate from the chemical oxidation of terpenes during vaping. The most abundantly observed carbonyls were acetone, acetaldehyde, propionaldehyde, and terpene-derived carbonyls. We concluded that high terpene content in CEC products gives rise to more carbonyl emissions in the aerosol due to terpene oxidation, which has adverse implications for inhalation toxicology in an indoor environment.