Impact of legalization on cannabis exposure calls to the British Columbia Poison Control Centre

The objective of this study was to examine whether cannabis exposure calls to the British Columbia Drug and Poison Information Centre (DPIC) were impacted by the legalization of non-medical cannabis in Canada.

We fit interrupted time series models to monthly counts of cannabis cases from 2013 to 2021, stratified by age and cannabis form. We set the intervention month to October 2018 legalization for cases involving inhaled dried cannabis and ingestible oils and capsules. We set the intervention month to January 2020 for cases involving edibles and inhaled concentrates to reflect their commercial rollout after their October 2019 legalization.

DPIC managed 3989 cases involving cannabis exposure between 2013 and 2021. The rate (95% CI) of all cannabis cases increased by 17% (14%, 20%) annually from 2013 to October 2018 legalization. The highest pre-legalization increase was in pediatric edible cases with 52% (36%, 69%) and 57% (35%, 82%) annual increases among children aged 5 and under and 6 to 12, respectively. Upon legalization, the rate of cases consuming oil and capsule products spiked by 26% (- 19%, 96%) followed by a decrease, but remaining higher than the pre-legalization rate. Legalization did not have an immediate effect on the rate of cases involving edibles or inhaled cannabis, which all continued to increase post-legalization, albeit at slower rates.

Regardless of the contributing factors to cannabis case trends at DPIC, these data highlight the importance of poisoning prevention policies, promotion of low-risk use, and routine surveillance.