Cannabis for Therapeutic Purposes and public health and safety: A systematic and critical review

• We synthesize the public health literature related to medical cannabis legalization.
• The most prevalent theme of investigation is the relation to illegal cannabis use.
• Many concerns regarding medical cannabis legalization are unsupported.
• There is a need to better ensure study quality in this growing research field.

BackgroundThe use of Cannabis for Therapeutic Purposes (CTP) has recently become legal in many places. These policy and legal modifications may be related to changes in cannabis perceptions, availability and use and in the way cannabis is grown and sold. This may in turn have effects on public health and safety. To better understand the potential effects of CTP legalization on public health and safety, the current paper synthesizes and critically discusses the relevant literature.MethodsTwenty-eight studies were identified by a comprehensive search strategy, and their characteristics and main findings were systematically reviewed according to the following content themes: CTP and illegal cannabis use; CTP and other public health issues; CTP, crime and neighbourhood disadvantage.ResultsThe research field is currently limited by a lack of theoretical and methodological rigorous studies. The review shows that the most prevalent theme of investigation so far has been the relation between CTP and illegal cannabis use. In addition, the literature review shows that there is an absence of evidence to support many common concerns related to detrimental public health and safety effects of CTP legalization.ConclusionAlthough lack of evidence provides some reassurance that CTP legalization may not have posed a substantial threat to public health and safety, this conclusion needs to be examined in light of the limitations of studies conducted so far. Furthermore, as CTP policy continues to evolve, including incorporation of greater commercialization, it is possible that the full effects of CTP legalization have yet to take place. Ensuring study quality will allow future research to better investigate the complex role that CTP plays in relation to society at large, and public health and safety in particular.