Cannabis is the world's most used illicit drug, with an estimated 209 million users in 2020, representing 4% of the global population.1 However, there are variations in cultural attitudes towards cannabis and related policies, and a lack of consensus regarding what degree of cannabis control holds the best outcomes. In Europe, no national government yet supports full legalization of recreational cannabis, but several countries have relaxed policies by either decriminalization or de-penalizing use and possession.1 In the US, though cannabis is still a Schedule I drug under the Controlled Substances Act, twenty-one states have approved the use of recreational cannabis.1 In contrast, no Asian country had legalized recreational use until Thailand's 2022 landmark policy change.
Since 1979, cannabis had been scheduled as a class-5 narcotic under Thailand's Narcotic Act, which prohibited smoking, possessing, and selling marijuana, along with stipulating punishment for offenders. Forty years later, as the political and economic pro-cannabis movement gained momentum, Thailand legalized medical cannabis in 2019. That same year, the most commonly reported used illicit drug was already cannabis, with 3% of the population reporting life-time use.2 Since then, Thais 20 years of age and older have been allowed to register for medical cannabis treatment without criminal risks. However, cannabis remained classified as a class-5 narcotic until June 2022, when the Thai Food and Drug Administration officially removed all parts of cannabis plants from the class-5 list, making Thailand the first Asian country to allow sales, growing, possession, and recreational use of cannabis plants without legal penalty.
The lack of regulation of cannabis products following legalization has become a national public health concern, especially around the potential effects on youth. Previous US studies have found that cannabis legalization may make cannabis more accessible to youth, exposing them to advertising and normalizing use.3 Although studies among US youth did not report an increase in cannabis use after state-based legislation,4 the impact of Thailand's legislation on youth has yet to be studied.
Evidence is inconclusive on whether cannabis legalization may increase the possibility of using other ‘harder’ drugs among youth who use cannabis.5 However, evidence suggests that cannabis legalization has led to the increasing potency of cannabis products.6 Emerging concerns related to high-potency products include the significant increases in cannabis use frequency, likelihood of cannabis dependence, and risk of psychiatric disorders among youth.7 Monitoring evolving cannabis potency and related health impacts among young users will be critical for informing Thailand's cannabis-related policy.
Cannabis-impaired driving is another growing concern, particularly among young inexperienced drivers, given that Thailand's legal driving age is 15 for motorcycles and 18 for cars. Evidence suggests that the risk of traffic accidents significantly increases after cannabis use and that it negatively affects driving performance.8 However, in Thailand, there are no cannabis-related traffic injury data, and no cannabis-impaired driving laws exist. Surveillance and research on cannabis-impaired driving would be important to inform communities around this risk and guide policies around prevention and legal penalties.
While there are concerns around negative health outcomes among Thai youth, there may be indirect benefits of cannabis legalization on social equity and long-term public health outcomes. Youth who legally obtain cannabis may avoid exposure to criminal environments and the potential for arrest and incarceration, which would have detrimental effects on social determinants of health and mental health.9
Unfortunately, the new legislation was not complemented by a public health perspective that could have minimized related socioeconomic and health risks. The legalization framework should explicitly state that public health protection is a primary goal, while aiming to prevent underage cannabis access and acknowledge the risks of cannabis-impaired driving, dependency, contaminated products, and co-use with other substances.10 Experiences from alcohol and tobacco control policy may be used as models to guide public health-oriented regulation. This may include increased prices through taxation, limitations in youth-focused marketing, restrictions on public consumption, clear guidance around the provision and monitoring of sales licenses and licensees, and surveillance and prevention of impaired driving.10 A national cannabis-related prevention program should also be implemented, focusing on improving community knowledge of cannabis risk and delaying initiation among youth.
In summary, Thailand's public health impact of cannabis legalization must be carefully monitored and evaluated to determine the extent the new policy may lead to increased cannabis use, cannabis-related health risks and how these changes affect the use of other substances. Lessons learned from cannabis legalization in Western countries underlined the necessity for research efforts to develop evidence-based guidelines to inform prevention strategies, and implement interventions for at-risk populations, including young adults.
Contributors
PY, KEL, AHS: Conceptualisation; PY: Writing original draft; KEL, AHS: Writing-review and editing.
Declaration of interests
AHS receives funding to her institution from ViiV Healthcare and Gilead Sciences. The other authors have no conflicts of interest to declare.
Acknowledgments
Funding: This work was supported through a grant from amfAR, The Foundation of AIDS Research, with support from the US National Institute of Health's Fogarty International Center and the National Institute of Mental Health (CHIMERA; D43TW011302). This work is solely the responsibility of the authors and does not necessarily represent the official views of any of the institutions mentioned above.
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