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Background and Aims: Many countries have recently legalized medicinal and recreational cannabis. With increasing use and access come the potential for harms. We aimed to examine the effect of cannabis legalization/decriminalization on acute poisoning. Methods: A systematic review and meta‐analysis registered with PROSPERO (CRD42022323437). We searched Embase, Medline, Scopus and Cochrane Central Register of Controlled Trials from inception to March 2022. No restrictions on language, age or geography were applied. Abstracts from three main clinical toxicology conferences were hand‐searched. Included studies had to report on poisonings before and after changes in cannabis legislation, including legalization and decriminalization of medicinal and recreational cannabis. Where possible, relative risk (RR) of poisoning after legalization (versus before) was calculated and pooled. Risk of bias was assessed with ROBINS‐I. Results: Of the 1065 articles retrieved, 30 met inclusion criteria (including 10 conference abstracts). Studies used data from the United States, Canada and Thailand. Studies examined legalization of medicinal cannabis (n = 14) and decriminalization or legalization of recreational cannabis (n = 21). Common data sources included poisons centre records (n = 18) and hospital presentations/admissions (n = 15, individual studies could report multiple intervention types and multiple data sources). Most studies (n = 19) investigated paediatric poisoning. Most (n = 24) reported an increase in poisonings; however, the magnitude varied greatly. Twenty studies were included in quantitative analysis, with RRs ranging from 0.81 to 29.00. Our pooled estimate indicated an increase in poisoning after legalization [RR = 3.56, 95% confidence interval (CI) = 2.43–5.20], which was greater in studies that focused on paediatric patients (RR = 4.31, 95% CI = 2.30–8.07). Conclusions: Most studies on the effect of medicinal or recreational cannabis legalization/decriminalization on acute poisoning reported a rise in cannabis poisoning after legalization/decriminalization. Most evidence is from US legalization, despite legalization and decriminalization in many countries. [ABSTRACT FROM AUTHOR]

Aims: To measure the impact of Canada's recreational cannabis legalization (RCL) in October 2018 and the subsequent impact of the coronavirus disease 2019 (COVID‐19) lockdowns from March 2020 on rates of emergency department (ED) visits and hospitalizations for traffic injury. Design: An interrupted time series analysis of rates of ED visits and hospitalizations in Canada recorded in population‐based databases from January/April 2010 to March 2021. Setting: ED visits in Ontario and Alberta and hospitalizations in Ontario, Alberta, British Columbia, the Prairies (Manitoba and Saskatchewan) and the Maritimes (Nova Scotia, New Brunswick, Newfoundland and Prince Edward Island). Participants: Monthly counts of presentations to the ED or hospital for motor vehicle injury or pedestrian/cyclist injury, used to calculate monthly rates per 100 000 population. Measurements An occurrence of one or more International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada (ICD‐10‐CA) code for motor vehicle injury (V20–V29, V40–V79, V30–V39 and V86) and pedestrian/cyclist injury (V01–V09 and V10–V19) within the National Ambulatory Care Reporting System and Discharge Abstract Database. Findings There were no statistically significant changes in rates of ED visits and hospitalizations for motor vehicle or pedestrian/cyclist injury after RCL after accounting for multiple testing. After COVID‐19, there was an immediate decrease in the rate of ED visits for motor vehicle injury that was statistically significant only in Ontario (level change β = −16.07 in Ontario, 95% CI = −20.55 to −11.60, P = 0.000; β = −10.34 in Alberta, 95% CI = −17.80 to −2.89, P = 0.008; α of 0.004) and no changes in rates of hospitalizations. Conclusions: Canada's recreational cannabis legalization did not notably impact motor vehicle and pedestrian/cyclist injury. The rate of emergency department visits for motor vehicle injury decreased immediately after COVID‐19 lockdowns, resulting in rates below post‐recreational cannabis legalization levels in the year after COVID‐19. [ABSTRACT FROM AUTHOR]

The author comments on the article "The implementation and public health impacts of cannabis legalization in Canada: a systematic review" by W. Hall and colleagues. Topics discussed include origin of legal access to medical cannabis in Canada, perspectives of stakeholders on the effectiveness of legal market, and significance of a mandatory legislative review of the federal Cannabis Act.

Background and Aims: In 2013, Uruguay became the first country to legalize and regulate the production and distribution of cannabis for recreational use. We measured whether Uruguay's non‐commercial model of recreational cannabis legalization was associated with changes in the prevalence of risky and frequent cannabis use among secondary school students. Design: We used data from repeated cross‐sectional surveys of secondary students in Uruguay and Chile (2007–2018). Using a difference‐in‐difference approach, we evaluated changes in the prevalence of past‐year, past‐month, any risky and frequent cannabis use following enactment (2014) and implementation (2016) of cannabis legalization among the full sample of secondary students and among students who reported past‐year/month use. We examined changes separately for students ages 12 to 17, and students for whom cannabis became legally accessible, ages 18 to 21. Setting: Uruguay and Chile (2007–2018). Participants: Secondary school students in 8th, 10th and 12th grade (n = 204 730). Measurements Past‐year and past‐month cannabis use; any risky cannabis use measured with the Cannabis Abuse Screening Test (CAST); and frequent cannabis use (10+ days in the past‐month). Findings We found a decrease in past‐year and past‐month use following enactment or implementation. Among students ages 18 to 21, post‐enactment, we observed a transitory increase in 2014 that decreased thereafter for: any risky use among those who reported past‐year use (prevalence difference [PD] = 13.5%; 95% CI: 2.0, 24.9), frequent use in the full sample (PD = 4.5%; 95% CI: 1.0, 8.1), and frequent use among those who reported past‐month use (PD = 16.8%; 95% CI: 1.9, 31.8). Conclusion: The legalization of recreational cannabis in Uruguay was not associated with overall increases in either past‐year/past‐month cannabis use or with multi‐year changes in any risky and frequent cannabis use among young people. [ABSTRACT FROM AUTHOR]

Aims: This study estimated the likelihoods of individuals transitioning to different cannabis use status following recreational cannabis legalization (RCL) in the United States. Design: Secondary analysis of a nationally representative longitudinal cohort in the United States. We used propensity score matching to balance individual characteristics between RCL and comparison states and generalized mixed regressions to estimate behavioral transitions in matched samples. Participants: A longitudinal cohort of 21 863 individuals (6925 youths and 14 938 adults) participating in the Population Assessment of Tobacco and Health waves 3 and 4. Setting: Four RCL states that implemented RCL between waves 3 and 4 (California, Massachusetts, Nevada and Maine) and comparison states in the United States. Measurements Transitions in cannabis use over the two waves: (1) from non‐users to users; (2) from non‐users to weekly users; (3) from users to non‐users. Individuals in RCL states were compared with matched individuals in (1) states with medical cannabis legalization (MCL), (2) states not legalizing cannabis (non‐legalizing) and (3) MCL and non‐legalizing states combined. Findings Among youths, the association between RCL and greater odds of transition from non‐users to users was seen in comparison with non‐legalizing states [odds ratio (OR) = 2.18, 95% confidence interval (CI) = 1.37–3.45] and combined states (OR = 1.73, 95% CI = 1.23–2.42). Evidence was lacking regarding the associations between RCL and transitions from non‐users to weekly users and from users to non‐users. Among adults, RCL was associated with greater odds of transitions from non‐users to users and non‐users to weekly users if RCL states were compared with non‐legalizing states (OR = 1.68, 95% CI = 1.15–2.46; OR = 1.82, 95% CI = 1.00–3.31, respectively) or combined states (OR = 1.51, 95% CI = 1.11–2.07; OR = 2.09, 95% CI = 1.19–3.66, respectively). RCL was also associated with lower odds of transition from users to non‐users if RCL states were compared with non‐legalizing states (OR = 0.54, 95% CI = 0.35–0.81). Conclusions: There appears to be some evidence that recreational cannabis legalization in the United States is associated with elevated odds of transition to cannabis use among both youths and adults. [ABSTRACT FROM AUTHOR]

Background and aims: Recreational cannabis was legalized in Canada in October 2018. Initially, the Government of Ontario (Canada's largest province) placed strict limits on the number of cannabis retail stores before later removing these limits. This study measured changes in cannabis‐attributable emergency department (ED) visits over time, corresponding to different regulatory periods. Design Interrupted time–series design using population‐level data. Two policy periods were considered; recreational cannabis legalization with strict store restrictions (RCL, 17 months) and legalization with no store restrictions [recreational cannabis commercialization (RCC), 15 months] which coincided with the COVID‐19 pandemic. Segmented Poisson regression models were used to examine immediate and gradual effects in each policy period. Setting: Ontario, Canada. Participants: All individuals aged 15–105 years (n = 13.8 million) between January 2016 and May 2021. Measurements Monthly counts of cannabis‐attributable ED visits per capita and per all‐cause ED visits in individuals aged 15+ (adults) and 15–24 (young adults) years. Findings We observed a significant trend of increasing cannabis‐attributable ED visits pre‐legalization. RCL was associated with a significant immediate increase of 12% [incident rate ratio (IRR) = 1.12, 95% confidence interval (CI) = 1.02–1.23] in rates of cannabis‐attributable ED visits followed by significant attenuation of the pre‐legalization slope (monthly slope change IRR = 0.98, 95% CI = 0.97–0.99). RCC and COVID‐19 were associated with immediate significant increases of 22% (IRR = 1.22, 95% CI = 1.09–1.37) and 17% (IRR = 1.17, 95% CI = 1.00–1.37) in rates of cannabis‐attributable visits and the proportion of all‐cause ED visits attributable to cannabis, respectively, with insignificant increases in monthly slopes. Similar patterns were observed in young adults. Conclusions: In Ontario, Canada, cannabis‐attributable emergency department visits stopped increasing over time following recreational cannabis legalization with strict retail controls but then increased during a period coinciding with cannabis commercialization and the COVID‐19 pandemic. [ABSTRACT FROM AUTHOR]

Background and aim: New Zealand has recently legalized medicinal cannabis and has explored the possibility of legalizing large‐scale recreational cannabis supply. In the process, concerns have emerged regarding whether corporations involved in the large‐scale production and sale of legalized cannabis will invest in tactics of influence with policymakers and the public. This paper aimed to examine the various ways a legalized cannabis industry could seek to influence governments and the public in the New Zealand reform context. Method: Based on the study of industry tactics with alcohol, tobacco and gambling, we applied a three‐chain model of industry influence that breaks tactics into the 'public good', 'knowledge' and 'political' chains. Results: Exploratory analysis of the nascent cannabis industry's activity in New Zealand provided signs of industry influence strategies related to all three chains. The medicinal cannabis industry has associated the establishment of a legal cannabis sector with regional economic development and employment, supported lobbying for recreational law reform, funded NGOs involved in lobbying for law reform, established research partnerships with universities, invited ex‐politicians on advisory boards, and participated in government public sector partnerships. Conclusion: There is emerging evidence that the legal cannabis industry is using strategies to influence the regulatory environment in New Zealand. [ABSTRACT FROM AUTHOR]

Background and Aims: Cannabis use among parents may be increasing with legalization, but perception of associated risk has declined. The study investigated the association between cannabis legalization and cannabis use among adults with children in the home over time in the United States (US). Design A difference‐in‐difference approach was applied to public and restricted‐use data from the 2004–2017 National Survey on Drug Use and Health (NSDUH), an annual cross‐sectional survey. Setting: A representative sample of the United States. Participants/Cases: Respondents ages 18+ with children living in the home drawn from the NSDUH (n = 287,624), which is administered to non‐institutionalized civilians in the 50 states and District of Columbia. Measurements Exposures were year and state‐level cannabis policy in state of residence annually. Outcomes were past‐30‐day cannabis use and daily cannabis use. Sociodemographic variables included age, gender, marital status, annual family income, race/ethnicity, educational attainment, and strength of state‐level tobacco control. Findings In 2017, past‐month cannabis use (11.9%, 9.3%, and 6.1%) and daily cannabis use (4.2%, 3.2%, and 2.3%) were more common in states with recreational marijuana laws (RML), followed by states with medical marijuana laws (MML) and without legal cannabis use, respectively. RML and MML were associated with significantly higher prevalence of past‐month cannabis use (adjusted odds ratio [AOR] = 1.28, 95% confidence interval [CI] = 1.12–1.46; AOR = 1.12, 95% CI = 1.03–1.22) and daily cannabis use (AOR = 1.25, 95% CI = 1.03–1.51; AOR = 1.16, 95% CI = 1.02–1.32), respectively. The impact of MML was particularly salient among adults ages 50+ and the highest income and education subgroups. Conclusions: Among adults with children living in the home, cannabis use appears to be more common in US states with legalized cannabis use compared with states with no legal cannabis use. Recreational legalization appears to increase use among adults with children in the home broadly across nearly all sociodemographic groups, whereas the effect of legalization for medical use is heterogeneous by age and socioeconomic status. [ABSTRACT FROM AUTHOR]

The author comments on a study by B. Han and Y. Shi which investigated the connections of recreational cannabis dispensaries' (RCD) availability, storefront marketing activities with cannabis use in residential neighborhoods in California. They suggest issues to consider in future studies including identification of user profiles that are more responsive to RCD presence and marketing activities and inclusion of samples from other jurisdictions to account for socio-demographic differences.

The article discusses a study by D. T. Myran and colleagues which reported on changes in cannabis related emergency department (ED) attendances in Ontario across a period of major policy change in Canada. Topics include the time periods that were included in the study, factors that may explain the rapidly increasing rate of ED attendances in the two years before legalization, and the most important oversight by the authors regarding the pre-legalization phase.

The article presents news briefs on addiction. The U.S. presents a plan for international action on drug addiction at the United Nations. The U.S. Senate passes a bill to combat opioid addiction. The South African Constitutional Court rules on the issue of personal use of marijuana.

This commentary refers to the article "Does Recreational Cannabis Legalization Change Cannabis Use Patterns: Evidence From Secondary School Students in Uruguay," by A. Rivera-Aguirre, A. Castillo-Carniglia, H. S. Laqueur and colleagues, that was published within the issue. Topics discussed include cannabis regulation in the U.S. versus Uruguay, availability and access to cannabis, and increased risk from designating 18 as the legal age of use.

The authors comment on a study which examined the transitions in cannabis use in the U.S. following the legalization of recreational cannabis. Cited are the potential for using causal inference methods in longitudinal settings as demonstrated by the study, the study's demonstration of the need to refine research conceptualization and methods to more clearly inform non-medical cannabis policymaking, and the ways on how researchers can increase the influence of their studies.

The article evaluates new findings in the health surveys on drugs abuse involving marijuana and cannabis and factors inducing psychic disorders. The author states that these revelations will pave the way towards tougher laws and more aggressive enforcement of prohibitions. Psychiatric disorders among drug abusers and drug dose response between schizophrenia and cannabis use are discussed. The author opines that the United States decision makers will respond to the new data.