Emissions from Heated Terpenoids Present in Vaporizable Cannabis Concentrates

Abstract

Vaporizable cannabis concentrates (VCCs) consumed as a liquid (vaping) or a waxy solid (dabbing) are becoming increasingly popular. However, their associated emissions and impacts have not been fully described. Mixtures containing different proportions of twelve VCC terpenoids and high-MW compounds were heated at 100 -500 °C inside a room-sized chamber, to simulate emissions. Terpenoids, thermal degradation byproducts, and ultrafine particles (UFPs) were quantified in chamber air. Air samples contained over 50% of emitted monoterpenes, and less than 40% of released sesquiterpenes and terpene alcohols. Eleven degradation byproducts were quantified, including acrolein (1.3 -3.9 µg m -3 ) and methacrolein (2.0 µg m -3 ). A large amount of UFPs were released upon heating, and remained airborne for at least three hours. The mode diameter increased from 80 nm at 100 °C to 140 nm at 500 °C, and particles smaller than 250 nm contributed to 90% of PM 1.0 . The presence of 0.5% of lignin, flavonoid and triterpene additives in the heated mixtures resulted in a threefold increase in particle formation rate and PM 1.0 concentration, suggesting that these high MW compounds enhanced aerosol inception and growth.Predicted UFP emission rates in typical consumption scenarios (6×10 11 -2×10 13 # min -1 ) were higher than, or comparable with, other common indoor sources such as smoking and cooking.

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

“…Within the C 4 –C 6 carbonyls shown in Figure , butyraldehyde, valeraldehyde, and hexanal appear to originate from the thermal degradation of cannabinoids and terpenes, which is consistent with Tang et al, while isobutyraldehyde, isovaleraldehyde, and 4-methylpentanal are from the thermal degradation of VEA (Scheme ). Although some products like formaldehyde can be produced from both VEA and THC oil, the production of formaldehyde from VEA appears more favorable since it involves a bond cleavage at a more substituted carbon (Scheme , path a), which forms a more stable alkyl radical intermediates than those from the unbranched aliphatic side chain of THC. , The same logic applies to the generation of 4-methylpentanal from VEA, which dominates the distribution of the isomer pair over hexanal.…”

“…Meehan-Atrash et al 30 identified degradation products from myrcene, limonene, and linalool, including methacrolein, hydroxyacetone, and methyl vinyl ketone. 78 Tang et al 57 found 11 thermal degradation products from a mixture of terpenoids, 7 of them are carbonyls including formaldehyde, acetaldehyde, acetone, acrolein, methacrolein, valeraldehyde, and hexanal. The methacrolein formed from vaped THC oil (Table 3) likely originates from terpene degradation, and its enhancement with VEA addition may be due to the aforementioned acceleration of volatilization or chemistry, as well as its source from VEA.…”

“…Some isomers have ambiguous identification, e.g., C 6 H 12 O (#19 in Table ) can be assignable to either hexanal or 4-methylpentanal. While hexanal can be formed from terpenes, 4-methylpentanal is uniquely formed from the thermal degradation VEA according to the proposed thermal degradation pathway in Scheme . Since C 6 H 12 O is highly enhanced in the VEA aerosol (Figure a), we assign the majority of this emission to 4-methylpentanal.…”

Nicotine or marijuana vaping exposure during pregnancy and altered immune responses in offspring

“…The evidence for cancer risk from ENDS use may be important in relation to flavorants and humectants, which are present in the ENDS aerosols resulting from the heating and aerosolization of the e-liquid [ 29 ] . Furthermore, ENDS aerosol samples showed the presence of compounds such as arsenic, manganese, nickel, chrome, and lead [ 30 ] , while acrolein, methacrolein, tetrahydrocannabinol (THC), benzene, Vitamin E acetate, and terpenes were found in vaping cannabis mixtures [ 31 ] . Additionally, formaldehyde can be formed when the glycerol or propylene glycol in ENDS products are heated [ 32 ] ; it was also found in 4/16 e-liquids assessed by a 2022 study [ 33 ] .…”

“…Likewise, newer versions of marijuana vaping come with a wide variety of chemicals, with both known and unknown cancer risks [ 41 ] . It is important to note that the experiment conducted by Tang et al may not be representative of the aerosol chemistry of cannabis vapor products by pregnant individuals or those in their households [ 31 ] . However, long-term use of nicotine and/or marijuana vaping needs to be addressed for cancer risk assessment and prevention based on available plausible biological pathways to cancer development.…”