California Study Reveals Widespread Cannabis Use and Knowledge Gaps Among Users

Researchers at the University of California San Diego have conducted a comprehensive survey, Impact 64, involving over 5,000 Californians to assess the effects of Proposition 64, which legalized recreational cannabis for adults 21 and older in 2016. The findings, recently published in the journal Cannabis and Cannabinoid Research, reveal that while a significant portion of the population is using cannabis regularly, there are notable gaps in their understanding of both the laws and the potential risks associated with its use. One of the key insights from the survey is that about a third of Californians use cannabis, either recreationally or medicinally. This widespread adoption has spurred the rapid growth of California's cannabis industry, with the California Department of Cannabis Control (DCC) reporting over $4.2 billion in cannabis sales in 2024. However, the study highlights a concerning lack of awareness among users about the legal and safety issues, particularly concerning impaired driving. Principal investigator Linda Hill, M.D., M.P.H., emphasizes the need for targeted education initiatives. "A large portion of the population is using cannabis, but there are significant gaps in knowledge regarding laws and safety, and physicians are rarely consulted for advice on use. We need more targeted education initiatives for both cannabis users and medical providers," she said. The study also noted that users primarily obtain information about cannabis from non-medical sources, such as friends, family, and online forums, rather than healthcare professionals. The survey, conducted in collaboration with market research firm Quester, utilized AI-powered tools to gather both qualitative and quantitative data, ensuring a representative sample of Californians, including Spanish speakers. Co-author Renee Dell'Acqua, M.P.H., highlighted the depth and quality of the data collected: "These methods allowed us to collect more in-depth data than is possible in a typical survey-based study. The result is an incredibly rich picture of how adults are using cannabis in California that can be used to inform future policy and public health initiatives." Future research will focus on the attitudes, knowledge, and practices of medical providers regarding cannabis use. The current findings underscore the complexity of the risk-benefit ratio of cannabis, suggesting that while it has therapeutic benefits, its potential risks, especially to public safety, need further investigation. Co-principal investigator Thomas Marcotte, Ph.D., echoed the need for ongoing research: "There is still much to be learned regarding the evolving world of legalized cannabis, including how it's being used, by whom, and the level of risks it may pose to public safety. The risk-benefit ratio for cannabis use is complex and warrants further study." The Impact 64 survey provides crucial insights into the post-legalization landscape in California, emphasizing the importance of educating the public and healthcare providers about responsible cannabis use. With cannabis becoming more mainstream due to legalization in additional states, addressing these knowledge gaps is essential for mitigating risks and promoting public safety. Industry insiders and public health experts agree that robust education campaigns are necessary to bridge the knowledge gap and ensure that cannabis users are aware of the legal and safety implications of their consumption. They also stress the need for continuous monitoring and research to adapt policies and health guidelines as the cannabis landscape evolves. UC San Diego's continued involvement in this area, along with partnerships like the one with Quester, will be vital in shaping evidence-based policies and public health strategies. The California Department of Cannabis Control and other regulatory bodies are expected to use the findings from Impact 64 to inform their future decisions and initiatives. Further studies are planned to delve deeper into the specific attitudes and practices of medical providers, providing a more comprehensive understanding of the broader impact of cannabis legalization.