Analysis of Cannabis Poisonings in Australia (2014-2024): Impact of Medicinal Cannabis Legalisation

Analysis of Cannabis Poisonings in Australia 2014-2024

Cannabis poisonings have emerged as an urgent public health concern in Australia, challenging widespread assumptions about the drug’s safety profile. A decade ago, Australia embarked on a significant policy shift by legalising cannabidiol (CBD) in June 2015, followed by cannabis and tetrahydrocannabinol (THC) in November 2016. These decisions placed Australia among a growing number of nations experimenting with cannabis reform, creating an unprecedented opportunity to examine the public health consequences of medicinal cannabis legalisation.

Critical insights into these consequences emerge from the New South Wales Poisons Information Centre (NSWPIC), which manages half of Australia’s poison-related emergencies. Drawing from a comprehensive dataset spanning 2014 to 2024, this analysis reveals troubling patterns in cannabis poisoning incidents across the nation. The NSWPIC’s extensive reach—handling calls from both NSW (65%) and other states (35%)—provides a unique window into how legislative changes have affected public health outcomes, particularly through the lens of poisoning events and adverse reactions.

Methodology

The research methodology employed a comprehensive analytical framework examining NSWPIC data from July 2014 to June 2024. The analysis incorporated multiple statistical approaches to ensure robust interpretation of trends and patterns. Demographic data was analysed using standardised age-adjustment techniques to account for population distribution changes over the study period. The investigation utilised Joinpoint regression analysis (version 4.9.0.1) to identify significant trend changes and calculate annual percentage changes (APCs) in age-adjusted rates.

The study’s statistical framework incorporated confidence intervals at the 95% level to ensure statistical significance in trend identification. This approach allowed for precise tracking of changes in poisoning patterns, particularly around key legislative changes in 2015 and 2016. The methodology included careful categorisation of exposure types, distinguishing between intentional and unintentional exposures, while also tracking the evolution of product types involved in poisoning incidents.

Exposure Patterns and Demographics

The decade-long analysis revealed a complex pattern of cannabis poisoning incidents, with 3,796 documented cases showing distinct demographic and circumstantial characteristics. The gender distribution showed a slight male predominance, with 2,039 cases (54%) involving male subjects. This gender disparity aligns with broader patterns of substance use in Australia but presents a smaller gap than typically seen in other substance-related poisonings.

The severity of these incidents is particularly noteworthy, with 3,184 cases (84%) presenting active poisoning symptoms at the time of reporting. The high hospital intervention rate, affecting 2,783 cases (74%), indicates the serious nature of many exposures. The annual increase rate of 12.8% (95% CI: 10.3-15.4%) represents a consistent upward trend that transcends simple population growth patterns.

Intentional Versus Unintentional Exposure Analysis

The study revealed a marked distinction between intentional and unintentional exposures, each following different growth trajectories and presenting unique challenges for public health intervention. Intentional exposures, totaling 2,981 cases (79%), showed a steady annual increase of 9.2% (95% CI: 6.3-12.2%). These cases encompassed recreational use, deliberate self-poisoning, and various forms of intentional misuse, reflecting changing social attitudes toward cannabis use and accessibility.

Unintentional exposures, while representing a smaller portion at 815 cases (21%), demonstrated a more dramatic annual increase of 30.0% (95% CI: 23.5-36.8%). This category included therapeutic errors, accidental exploratory exposures, and adverse reactions to prescribed products. The rapid rise in unintentional exposures suggests increasing availability of cannabis products in homes and communities, raising concerns about storage practices and product safety measures.

Age-Specific Risk Patterns

The age-stratified analysis revealed critical vulnerability patterns that demand targeted intervention strategies. Adolescents aged 15-19 years emerged as the highest-risk group, with an age-adjusted poisoning rate of 11.4 calls per 100,000 population annually. This peak in adolescent exposure rates suggests particular susceptibility to both intentional and unintentional poisoning events during this developmental period.

The toddler age group (1-4 years) showed concerning patterns in unintentional exposure, with 1.9 calls per 100,000 population annually. This rate reflects the unique risks posed by cannabis products to young children, particularly given their lower body weight and the increasing prevalence of edible cannabis products that may be mistaken for conventional confectionery.

Evolution of Product Types and Associated Risks

The changing landscape of cannabis products has introduced new challenges in poisoning prevention and management. Traditional plant-based cannabis, while remaining the predominant form with 2,663 cases (70%), showed a notable decline from 72% in 2014-15 to 61% in 2023-24. This shift reflects broader changes in consumption patterns and product availability.

The emergence of cannabis concentrates as a significant source of poisoning presents new challenges for medical management and public health intervention. The rise from negligible numbers to 124 calls (22%) by the study’s end indicates rapid market penetration of these high-potency products. Their involvement in 39% (320 calls) of unintentional exposures raises particular concerns about their safety profile and storage requirements.

The edibles category has shown perhaps the most concerning trend, with an increase from 9 calls (5%) to 88 calls (16%). The post-2019 surge in gummy and lolly form exposures (89 cases) highlights the specific risks posed by these products, particularly to children. The palatability and delayed onset of effects associated with edibles create unique risks for overconsumption and accidental ingestion.

Clinical Manifestations and Management Challenges

The study challenges the widespread perception of cannabis as benign in overdose scenarios. Clinical presentations encompassed a broad spectrum of effects, from central nervous system manifestations to cardiovascular complications. The documented effects included CNS excitation and depression, hallucinations, psychosis, and cardiac dysrhythmias.

Pediatric cases presented particular challenges, with the potential for severe outcomes including apnea and coma. The concentration-dependent effects of various cannabis products, particularly in children, necessitate careful consideration in both clinical management and public health policy. The delayed onset of symptoms with edible products often complicates initial assessment and may lead to underestimation of exposure severity.

Regulatory Framework and Access Patterns

The study found no clear correlation between initial cannabis rescheduling and poisoning trends, suggesting a complex relationship between regulatory changes and public health outcomes. The implementation of the Special Access Scheme B (SAS-B) and its subsequent streamlining in 2018 marked significant shifts in access patterns, though their direct impact on poisoning rates remains unclear.

The finding that only 3.9% of medicinal cannabis users obtained their products through prescription channels raises important questions about the effectiveness of current regulatory frameworks. This low rate of prescribed access suggests that most cannabis-related poisonings may involve products obtained outside the regulated medical system, complicating efforts at quality control and safety monitoring.

International Context and Policy Implications

Australia’s experience with cannabis poisoning trends following medicinal legalisation provides valuable insights for international policy development. The patterns observed, particularly regarding edible products and youth exposures, mirror experiences in other jurisdictions that have implemented various forms of cannabis legalisation.

The study’s findings suggest the need for careful consideration of regulatory models that have shown success in other countries. For example, the variation in pediatric hospitalisation rates between Canadian provinces with different approaches to edible product regulation offers valuable lessons for policy development in Australia.

Future Directions and Research Needs

The study identifies several areas requiring further investigation and monitoring. Long-term follow-up studies are needed to better understand the outcomes of severe poisoning cases, particularly in pediatric populations. Research into the effectiveness of various storage and packaging regulations could inform future policy decisions.

Additional investigation is needed into the relationship between prescription patterns, illicit market dynamics, and poisoning incidents. Understanding these connections could help develop more effective regulatory frameworks that balance access needs with public health protection.

Study Limitations and Data Considerations

Several methodological limitations warrant consideration when interpreting these findings. The reliance on caller-reported information introduces potential inaccuracies in product identification and exposure circumstances. The absence of routine follow-up data limits understanding of long-term outcomes and treatment effectiveness.

The study’s statistical power was constrained by low call numbers in the pre-2016 period, potentially masking subtle changes following initial regulatory changes. The focus on poisoning center data may underrepresent total poisoning incidents, as not all cases result in calls to poison information centers.

Closing Observations

The significant increase in cannabis poisonings in Australia during 2014-2024, particularly among vulnerable populations, presents crucial challenges for public health policy and clinical practice. The evolving nature of cannabis products, especially the rise in concentrate and edible forms, necessitates adaptive regulatory responses and enhanced public health measures.

The findings suggest that future policy development should carefully consider the specific risks posed by different cannabis products and consumption methods. Particular attention must be paid to protecting vulnerable populations while maintaining appropriate access for medical use. The experience of other jurisdictions offers valuable lessons for developing effective regulatory frameworks that balance these competing considerations.

Source

Cannabis poisonings in Australia following the legalisation of medicinal cannabis, 2014–24: analysis of NSW Poisons Information Centre data – Cairns – Medical Journal of Australia – Wiley Online Library

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