Synthetic cannabinoid poisonings and access to the legal cannabis market: findings from US national poison centre data 2016–2019

Abstract

Aim

To investigate trends in synthetic cannabinoid exposures reported to United States (US) poison control centres, and their association with status of state cannabis legalisation.

Methods

A retrospective study of National Poison Data System (NPDS) data from 2016 to 2019 identified and associated synthetic poisoning reports with annual state cannabis law and market status. State status was categorised as restrictive (cannabis illegal or limited medical legalisation), medical (allowing THC-containing medical cannabis use) and permissive (allowing non-medical use of THC-containing cannabis by adults). We categorised a subset of states with permissive policies by their implementation of legal adult possession/use and opening retail markets, on a quarterly basis. Mixed-effects Poisson regression models assessed synthetic exposures associated with legal status, first among all states using annual counts, and then among states that implemented permissive law alone using quarterly counts.

Results

A total of 7600 exposures were reported during the study period. Overall, reported synthetic exposures declined over time. Most reported exposures (64.8%) required medical attention, and 61 deaths were documented. State implementation of medical cannabis law was associated with 13% fewer reported annual exposures. Adoption of permissive state cannabis policy was independently and significantly associated with 37% lower reported annual synthetic exposures, relative to restrictive policies (IRR: 0.63, 95% CI: 0.50–0.79). Among states with permissive law during the period, implementation of legal adult possession/use was associated with 22% fewer reported quarterly exposures. Opening of retail markets was associated with 36% fewer reported exposures, relative to states with medical cannabis only.

Conclusions

Adoption of permissive cannabis law was associated with significant reductions in reported synthetic cannabinoid exposures. More permissive cannabis law may have the unintended benefit of reducing both motivation and harms associated with use of synthetic cannabis products.

Keywords:

• Synthetic cannabis
• cannabis legalisation
• poison centre

Disclosure statement

ELL: Senior Editorial Board: ToxED, online point of care toxicology resource; Elsevier Publishing; paid annual honorarium $2500.00. Up to Date: online clinical information resource; author of “Acute Iron Poisoning”; paid annual Royalty from Wolters-Kluwer Publishing. JMG: Board of Directors of the nonprofit Washington State Poison Center. JAD and TAK have no disclosures. The American Association of Poison Control Centers (AAPCC;http://www.aapcc.org/) maintains the national database of information logged by the country's poison centers (PCs). Case records in this database are from self-reported calls: they reflect only information provided when the public or healthcare professionals report an actual or potential exposure to a substance (e.g., an ingestion, inhalation, or topical exposure, etc.), or request information/educational materials. Exposures do not necessarily represent poisoning or overdose. The AAPCC is not able to completely verify the accuracy of every report made to member centers. Additional exposures may go unreported to PCs and data referenced from the AAPCC should not be construed to represent the complete incidence of national exposures to any substance(s).

Additional information

Funding

This investigation was supported in part by funds provided for medical and biological research by the State of Washington Initiative Measure No. 171.