Cannabis policy in The Netherlands: Rationale and design of an experiment with a controlled legal ('closed') cannabis supply chain.

Since the Dutch tolerance policy, allowing the purchase of cannabis in 'coffeeshops', is associated with problems of public order and safety as well as health risks, there has been a long debate about legalisation of cannabis production and supply. It was therefore decided to conduct an experiment with a controlled legal ('closed') cannabis supply chain for recreational use. This is of international relevance in view of the current illegal cannabis exports from the Netherlands, the importance of sharing knowledge about the effectiveness of cannabis policies, and the accumulation of evidence needed to evaluate and update international treaties. Here we describe and discuss the background, general approach and design of the experiment. An independent expert committee elaborated how the closed chain will operate and be evaluated, based on the experience with the medicinal cannabis chain, and round table discussions with stakeholders (mayors, coffeeshop owners, cannabis consumers, growers, regulators, scientists, and addiction experts). Ten trusted cannabis growers are contracted to produce and supply cannabis to the coffeeshops in intervention municipalities, with product quality control, law enforcement against criminal interference, and preventive efforts to reduce health risks being implemented. No changes will be made in the cannabis supply to the coffeeshops in participating control municipalities. A process evaluation will assess whether the chain from production to sale in the intervention municipalities was really closed. In a quasi-experimental study comparing intervention and control municipalities, the chain's effects on public health, cannabis-related crime, safety and public nuisance will be estimated. The fieldwork period is expected to start early 2024 and will take four years, including reporting to the government and parliament. These will then decide whether and what further steps towards legalisation of the production and supply of cannabis will be taken.

Alcohol-specific parenting and adolescents' alcohol-related problems: the interacting role of alcohol availability at home and parental rules.

OBJECTIVE: The first aim of this study was to gain more insight into the bi-directionality between alcohol-specific parental factors (i.e., parents' alcohol use, alcohol availability at home, parental rule setting, and frequency and quality of communication about alcohol) and adolescents' alcohol intake and alcohol-related problems. The second aim was to examine the relative impact of alcohol-specific parental factors on adolescents' alcohol intake and related problems by studying them in a comprehensive model. METHOD: A two-wave longitudinal study, with a 2-year interval, was conducted among a sample of 537 adolescents (56% girls) ages 12-15 years in The Netherlands. Under supervision of well-instructed teachers, students filled out questionnaires in a classroom setting. RESULTS: The findings show that perceived alcohol availability at home was the only parenting factor predicting an increase in alcohol intake and alcohol-related problems among adolescents 2 years later. Cross-sectional findings, furthermore, suggest that the effect of alcohol availability on adolescents' alcohol-related problems disappears when adolescents perceive strict alcohol rules. In addition, results indicate that parents respond to their youngsters' experienced alcohol-related problems by engaging in more rigorous alcohol-specific parenting (e.g., by increasing alcohol-specific rules and decreasing alcohol availability at home). CONCLUSIONS: The findings emphasize that parent interventions aiming at the prevention of adolescents' alcohol use should include the advice to restrict the perceived presence of alcohol beverages at home. Moreover, to prevent alcohol problems, parents should be advised to enforce strict rules about drinking, particularly when a total absence of alcohol at home is not feasible.