Resurgence of contaminated samples

In 2023, a total of 404 cannabis samples were submitted to the Drug Information Center (DIZ) Zurich for analysis. Of these, 286 samples were cannabis flowers, 89 samples were hashish and 29 samples were other cannabis products such as oils, liquids, edibles and dabs (cannabis concentrate).

Synthetic cannabinoids

In 2023, 19 (4.7 %) of all cannabis samples submitted to the DIZ for analysis were laced with at least one synthetic cannabinoid. 3 of these samples (0.75 %) were spiked with two different synthetic cannabinoids. In 2022, 11 (2.8 %) and in 2021, 49 (11 %) of all cannabis samples submitted to the DIZ for analysis were spiked with at least one synthetic cannabinoid.

Semi-synthetic cannabinoids

In 2023, 27 samples with semi-synthetic cannabinoids were tested at the DIZ. Of these, 15 samples were analyzed with a conspicuously high ∆8-THC value. ∆8-THC occurs, if at all, only in very small quantities as a natural cannabinoid in the hemp plant. However, since a conspicuously high concentration of ∆8-THC was analyzed in some samples, it is suspected that it was applied to CBD flowers by non-natural means or subsequently. This suspicion is substantiated by the often simultaneously high CBD value measured.

The detailed cannabis evaluation 2023 can be found in the attached report. These are the most important findings from 2023:

- Cannabis in flower form still has a very low CBD content. Since a protective effect of CBD is assumed (reduction of the undesirable effects of THC), this is problematic from a harm reduction perspective. It is recommended to mix cannabis with CBD cannabis, especially cannabis with a very high THC content.

- CBD levels in hashish have risen again slightly. The average values are still lower than in 2021, but slightly higher than last year. It is unclear what this is due to.

- More samples containing semi-synthetic cannabinoids (delta-8-THC and HHC) were handed in. A total of 27 cases were registered, evenly distributed over the two six-month periods.

- There was an increase in contamination in the second half of the year. The 17 cases of synthetic cannabinoids were mainly located in the second half of the year, after only 2 cases were detected in the first half of the year.

- Suspected cases of synthetic cannabinoids are on the decline, but users' assessments are more accurate. In 2022, 90 suspected samples were handed in, compared to 64 in 2023. The number of confirmed suspected cases has risen significantly. In the previous year, only 5.5 % of suspected cases were confirmed. This year, the figure was 23.4 %. This indicates that consumers are aware of the possibility of contamination on the one hand, and are able to identify the symptoms of synthetic cannabinoids more accurately on the other.

- Compliance with the safer use rules is still very important in this dynamic cannabis market.

You can find more information about cannabis on our website here.

The results published here are not representative of the substance market in the city of Zurich.


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