Abstract
BACKGROUND: Australia has one of the highest rates of cannabis use globally, yet the concentration of Δ9-tetrahydrocannabinol (THC) of illicit street cannabis has not been formally assessed in over a decade. We aimed to comprehensively profile the concentration of THC, cannabidiol (CBD) and other cannabinoids in contemporary illicit street cannabis in regional Australia, assess variation over time, and examine how the amount of THC relates to consumer's perceived product strength.
METHODS: Participants donated two 1-gram samples of cannabis at 3 different timepoints (i.e., 6 samples total) ∼9-weeks apart, over 5 months. High-performance liquid chromatography quantified the concentrations of THC, CBD, cannabigerol, cannabichromene, cannabinol, tetrahydrocannabivarin, and their plant-based carboxylic acid precursors (THCA, CBDA, CBGA, CBNA, THCVA) in percentage and milligrams.
RESULTS: Thirty-seven participants donated 127 cannabis samples. On average, one cannabis gram contained 34.8 mg THC (6.96 Standard THC units), 12.00 % total THC (THC+(THCA*0.877)), and 0.30 % total CBD (CBD+(CBDA*0.877)). THC concentrations remained stable across participants' current and past samples over time (p > 0.05). Finally, no correlation was found between participants' subjective assessments of cannabis strength and THC or total THC content in the same product (p > 0.05).
CONCLUSIONS: Contemporary illicit street cannabis in regional Australia is high in THC and low in CBD. The concentration of THC is lower than international trends but appears to have increased compared to reports on illicit Australian cannabis collected over 10 years ago, while low concentrations of CBD have remained stable over time. Perceived cannabis strength may be influenced by factors beyond measurable THC concentrations, such as individual tolerance, consumption methods, or consumer expectations.