Scientists speak out against false cannabis claims

Leading international scientific body reviews thirteen oft-repeated claims on cannabis use and regulation, finds that none are strongly supported by scientific evidence

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Toronto, Canada – Many scientists are increasingly frustrated by the disregard of scientific evidence on cannabis use and regulation. To set the record straight, the International Centre for Science in Drug Policy (ICSDP), a global network of scientists working on drug policy issues, released two groundbreaking reports today evaluating the strength of commonly heard cannabis claims.  

“State of the Evidence: Cannabis Use and Regulation," is a comprehensive overview of the scientific research on major claims made about cannabis. It is paired with a summary report, "Using Evidence to Talk About Cannabis," which equips readers with evidence-based responses to the claims. 

“We are at a critical juncture, as more and more jurisdictions are reconsidering their policies on cannabis,” said Dr. Dan Werb, Director of the ICSDP. “Yet, the public discourse around cannabis is filled with frequently repeated claims that are simply not supported by the scientific evidence. Given that policy decisions are influenced by public opinion and media reports, there is a serious danger that misrepresenting the evidence on cannabis will lead to ineffective or harmful policy.”

To investigate this issue, the ICSDP convened scientists to conduct a review of thirteen oft-repeated claims about cannabis use and regulation. The review found that none of the claims were strongly supported by the scientific evidence.

The majority of cannabis use claims outlined in the report tend to either misinterpret or overstate the existing scientific evidence. Dr. David Bewley-Taylor, Director of the Global Drug Policy Observatory and Professor at Swansea University, said, “The Telegraph, for instance, has claimed that cannabis is as addictive as heroin. This is patently untrue. Rather, what this review of the evidence clearly shows is that the risk of cannabis dependence is estimated at less than 1 in 10 over a lifetime of use, while the risk of heroin dependence is about 1 in 4. This kind of scientific misinformation is seriously damaging to efforts to improve our policy on drugs.” 

“This in-depth global research refutes the false claim that legalising and regulating cannabis would automatically lead to huge increases in use, to levels like those seen for tobacco and alcohol,” noted Mr. Steve Rolles, Senior Policy Analyst at the Bristol-based Transform Drug Policy Foundation. “With a growing body of evidence from more and more places reforming their drug laws, it is time our leaders stopped scare-mongering and came clean with the public about the facts when it comes to regulating cannabis.”

The new reports are a resource for journalists, policymakers, and members of the general public who would like to engage with the complex issues surrounding global cannabis use and regulation. Scientists and academics will be holding an ongoing conversation on Twitter using the hashtag #CannabisClaims at the @icdsp handle starting on August 12, 2015. Interested parties can also sign up for the ICSDP newsletter to get updates on how supporters around the world are coming together to bring scientific evidence to the public discourse on cannabis.

Although regulatory frameworks for cannabis have existed in European countries, including the Netherlands, Spain, and Belgium, other states like Italy are now considering cannabis policy reform. In the United Kingdom, the success of a recent petition calling for the total legalisation of cannabis will require Members of Parliament to consider debating the issue. As the conversation progresses in Europe and beyond, these reports are intended to provide an evidence base for decisions on cannabis policy.

About the International Centre for Science in Drug Policy
The International Centre for Science in Drug Policy (ICSDP) is a network of scientists and academics from all global hemispheres committed to improving the health and safety of communities and individuals affected by illicit drugs by working to inform illicit drug policies with the best available scientific evidence. With the oversight of a Scientific Board made up of leading experts on addictions, HIV, and drug policy, the ICSDP conducts research and public education on best practices in drug policy. This work is undertaken in collaboration with communities, policymakers, law enforcement and other stakeholders to help guide effective and evidence-based policy responses to the many problems posed by illicit drugs.

For more information or to arrange a media interview, please contact:
Nazlee Maghsoudi
Knowledge Translation Manager, ICSDP
+1 (647) 694-9199
nmaghsoudi [at]


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