Examining impairment and kinetic patterns associated with recent use of hemp-derived Δ-tetrahydrocannabinol: case studies.

Background: As a result of the legalization of U.S. industrial hemp production in late 2018, products containing hemp-derived Δ-tetrahydrocannabinol (Δ-THC) are increasing in popularity. Little, however, is known regarding Δ-THC's impairment potential and the associated impacts on roadway and workplace safety, and testing for Δ-THC is not yet common. The present study explored impairment patterns and cannabinoid kinetics associated with recent use of Δ-THC.

Methods: Hemp-derived Δ-THC concentrate was administered by vaporization ad libitum to three male frequent cannabis users aged 23-25 years. In addition to self-assessments of impairment using a 10-point scale, horizontal gaze nystagmus (HGN) was evaluated in each subject as a physical means of assessing impairment before and after vaporization. To examine cannabinoid kinetic patterns, exhaled breath and capillary blood samples were collected prior to vaporization up to 180 min post-vaporization and analyzed by liquid chromatography high-resolution mass spectrometry for cannabinoid content using validated methods. The impairment and cannabinoid kinetic results were then compared to analogous results obtained from the same three subjects after they had smoked a ∆-THC cannabis cigarette ad libitum in a previous study to determine whether any similarities existed.

Results: Patterns of impairment after vaporizing Δ-THC were similar to those observed after smoking cannabis, with self-assessed impairment peaking within the first hour after use, and then declining to zero by 3 h post-use. Likewise, HGN was observed only after vaporizing, and by 3 h post-vaporization, evidence of HGN had dissipated. Cannabinoid kinetic patterns observed after vaporizing Δ-THC (short ∆-THC half-lives of 5.2 to 11.2 min at 20 min post-vaporization, presence of key cannabinoids cannabichromene, cannabigerol, and tetrahydrocannabivarin, and breath/blood Δ-THC ratios > 2 within the first hour post-vaporization) were also analogous to those observed for ∆-THC and the same key cannabinoids within the first hour after the same subjects had smoked cannabis in the previous study.

Conclusions: Hemp-derived Δ-THC and Δ-THC from cannabis display similar impairment profiles, suggesting that recent use of Δ-THC products may carry the same risks as cannabis products. Standard testing methods need to incorporate this emerging, hemp-derived cannabinoid.