Navigating cannabis access in zurich: A road safety perspective from early observations of the 'Züri Can' study

Background: Cannabis is the most used illicit substance worldwide. New forms of regulated access to recreational cannabis use are currently considered in many countries to minimize health and social risks. Contextual factors like urbanity, e.g. distance between consumers and point of sales, need to be addressed differently between countries and regions. One of the most prominent public health concerns currently discussed (e. g. in Germany) regards the risks of a potential increase of cannabis-impaired driving. However, evidence of long-term effects of regulated cannabis sale on road safety is still scarce. 
Objective: In Switzerland, ‘Züri Can – Cannabis with responsibility’ is the first study worldwide to directly compare the impact of cannabis social clubs, pharmacies and the drug information centre Zurich (DIZ) as dispensaries for recreational cannabis on various outcomes. Since August 2023 and for the following three years, the study enables up to 2100 participants, long-term cannabis-users residing in Zurich City, to purchase cannabis legally. The distance between consumers and dispensaries are short for all participants. Self-reported data on consumption behavior and associated health and social risks are assessed within an online questionnaire, filled out every 6 months. In order to assess the situation prior to cannabis access in Zurich regarding the prevalence of cannabis-impaired driving and related factors, we present first results into how many participants actually drive, their risk awareness and driving behavior. 
Methods: Our dataset includes the baseline online questionnaire filled out by the participants between August and December 2023. Our analysis compromises 4 items to assess knowledge about the risks of cannabis-impaired driving as well as questions about driving themselves or with someone else under the influence of cannabis in the previous 6 months.  
Results: Our data show that at baseline almost all participants (90%) knew about the elevated risk of driving under the influence of cannabis. The majority of participants (75%) indicate not having driven a motor vehicle over the previous six month. Among the minority who drives, 77% say that they have not driven under the influence of cannabis in the previous 6 months. Most study participants (87%) say they did not ride along with someone cannabis intoxicated in this period.  
Conclusion: Our data indicate that most of our participants are aware of the elevated risks of driving after cannabis consumption and avoid driving under the influence of cannabis. A strikingly high proportion report not driving at all. That may be due to the excellent public transport network of Zurich. Lack of public transport could be a factor that increases risks associated with cannabis-impaired driving in rural areas with low public transport availability.  In further analyses we will examine changes over time and reveal potential effects of regulated cannabis sales on driving behavior.