The lead author of a study which found that THC potency in cannabis has doubled across Europe says regulation is the alternative if governments want to take control of the strengths hitting the market.
The study, published in the journal Addiction by researchers from the University of Bath and King’s College London, draws on data collected from across 28 EU Member states, as well as Norway and Turkey by the European Monitoring Centre for Drugs and Drug Addiction.
The findings show that for herbal cannabis, concentrations of THC (the psychoactive constituent in cannabis) increased by a similar amount each year, from 5% in 2006 to 10% in 2016.
For cannabis resin (hash), THC concentrations were relatively stable from 2006 to 2011 (from 8% to 10%) but then increased rapidly from 2011 to 2016 (from 10% to 17%). The price of cannabis resin also rose, but to a lesser extent than for herbal cannabis.
Lead author Dr Tom Freeman, from the Addiction and Mental Health Group within the Department of Psychology at the University of Bath, said: “These findings show that cannabis resin has changed rapidly across Europe, resulting in a more potent and better value product.”
Unlike herbal cannabis, cannabis resin typically contains CBD, the constituent which has been found by patients to treat medical conditions such as epilepsy, psychosis and anxiety. CBD can also offset the potency of THC.
The study said resin production techniques in Morocco and Europe have increased levels of THC, but not CBD.
Freeman added: “CBD has the potential to make cannabis safer, without limiting the positive effects users seek. What we are seeing in Europe is an increase in THC and either stable or decreasing levels of CBD, potentially making cannabis more harmful. These changes in the illicit market are largely hidden from scientific investigation and are difficult to target by policy-makers. An alternative option could be to attempt to control THC and CBD content through regulation.”
It is estimated that 24 million people (or 7.2%) of European adults used cannabis in the last year.
Greg de Hoedt, Director of UKCSC, commented: “Moroccan farmers have learned that they can increase the quality of their product by planting feminised seeds in place of the natural regular male/female seeds that have been grown for centuries there. This in turn rewards a higher price not only to the farmer but also to those supplying the product across European countries and eventually the UK.
“For years Britain has been getting the last of the hash but in recent years much higher quantities of high end traditional hash are reaching our shores. The strains are popular strains that you can grow at home so we know there has been a huge shift in the production end of the trade.”
More and more people are growing their own in the UK and Europe, meaning there is greater quality control and care over the growing, which, if the genetics allow it, results in higher potency cannabis. “We see a lot of people growing strains with higher CBD content throughout the Cannabis Social Club movement to help with medical conditions, but unless patients are busted and their medicine tested it can’t be counted in studies like this,” Greg added.