Analysis of cannabis seizures in NSW, Australia: cannabis potency and cannabinoid profile

Abstract

Recent analysis of the cannabinoid content of cannabis plants suggests a shift towards use of high potency plant material with high levels of Δ(9)-tetrahydrocannabinol (THC) and low levels of other phytocannabinoids, particularly cannabidiol (CBD). Use of this type of cannabis is thought by some to predispose to greater adverse outcomes on mental health and fewer therapeutic benefits. Australia has one of the highest per capita rates of cannabis use in the world yet there has been no previous systematic analysis of the cannabis being used. In the present study we examined the cannabinoid content of 206 cannabis samples that had been confiscated by police from recreational users holding 15 g of cannabis or less, under the New South Wales "Cannabis Cautioning" scheme. A further 26 "Known Provenance" samples were analysed that had been seized by police from larger indoor or outdoor cultivation sites rather than from street level users. An HPLC method was used to determine the content of 9 cannabinoids: THC, CBD, cannabigerol (CBG), and their plant-based carboxylic acid precursors THC-A, CBD-A and CBG-A, as well as cannabichromene (CBC), cannabinol (CBN) and tetrahydrocannabivarin (THC-V). The "Cannabis Cautioning" samples showed high mean THC content (THC+THC-A = 14.88%) and low mean CBD content (CBD+CBD-A = 0.14%). A modest level of CBG was detected (CBG+CBG-A = 1.18%) and very low levels of CBC, CBN and THC-V (<0.1%). "Known Provenance" samples showed no significant differences in THC content between those seized from indoor versus outdoor cultivation sites. The present analysis echoes trends reported in other countries towards the use of high potency cannabis with very low CBD content. The implications for public health outcomes and harm reduction strategies are discussed.

Figure 1. Chromatograms of analysed cannabinoids.

A) Chromatogram of calibration standard mixture of all analysed cannabinoids at 100 µg/ml. B) Representative chromatogram of a typical “Cannabis Cautioning” seized sample.

Figure 2. The levels of THC-A, THC and THC_tot measured in n = 206 Cannabis Cautioning seizures from NSW.

Levels of cannabinoids are expressed as % of total weight of sample (w/w%). THC_tot levels are obtained from adding the amount of free THC seen in the cannabis to the amount found in the non-psychoactive from of THC-A while adjusting for the differing molecular weight of the cannabinoid and carboxylic conjugative components of each cannabinoid (THC_tot = THC+THC-A*(314.46/358.47)).

Figure 3. The levels of CBD_tot, CBG_tot, THC-V, CBN and CBC measured in n = 206 Cannabis Cautioning seizures from NSW.

Levels of cannabinoids are expressed as % of total weight of sample (w/w%). Note the differing scales relative to Figure 2. Note that the CBG_tot levels of two samples are not shown on the graph as they are out of scale (values = 15.83% and 13.77%).

Figure 4. The levels of THC_tot, CBD_tot and CBG_tot, in n = 13 outdoor grown (NSW North Coast) and n = 13 indoor grown (Sydney) “Known Provenance” samples.

Levels of cannabinoids are expressed as mean % of total weight of sample (w/w%), with ± SEM bars shown.

Figure 5. The levels of THC-V, CBN and CBC in n = 13 outdoor grown (NSW North Coast) and n = 13 indoor grown (Sydney) “Known Provenance” samples.

Levels of cannabinoids are expressed as mean % of total weight of sample (w/w%), with ± SEM bars shown. Note the differing scales relative to Figure 4.