A new study has found that the potency of cannabis has significantly increased over the past decade. The study, which was published in the journal Addiction, determined that both herbal cannabis and cannabis resin across Europe have doubled in strength with potentially harmful consequences to users.
The study was conducted by researchers from King’s College London and the University of Bath and is the first one to track the changes in cannabis across the continent. The research was for the European Monitoring Centre for Drugs and Drug Addiction and was funded by the Society for the Study of Addiction.
The research used data from 28 EU countries, including Norway and Turkey.
In herbal cannabis, the concentrations of tetrahydrocannabinol (THC) increased from 5 percent in 2006 to 10 percent in 2016. THC is the main psychoactive component in the drug and is what creates the high and the mind-altering effect.
Meanwhile, for cannabis resin, the concentrations of THC remained relatively stable between 2006 (8 percent) and 2011 (10 percent), but rapidly increased from 10 percent in 2011 to 17 percent in 2016.
Of course, the price of cannabis also went up along with the level of potency.
Herbal cannabis was sold for €7.36 per gram in 2006 to €12.22 per gram in 2016. The price of cannabis resin, on the other hand, increased from €8.21 to €12.27 per gram over the same period.
The THC levels in herbal cannabis in the UK alone remained roughly the same between 2006 and 2016. Police seizures, however, suggest that THC levels in cannabis resin increased sharply.
According to Dr. Tom Freeman of the University of Bath Department of Psychology’s Addiction and Mental Health Group, who also led the study, their findings suggest that cannabis resin changed rapidly across Europe. This change, he said, resulted in a more potent and better value product.
The rise in the potency of cannabis resin can be attributed to new production techniques in Europe and in Morocco. But while the THC concentrations have increased, cannabidiol (CBD) levels in cannabis resin have either declined or remained the same.
Freeman explained that CBD has the potential to make cannabis safer yet not limit the positive effects that those who use the drug look for. What they are seeing in Europe, he said, is an increase in THC levels and either decreasing or stable CBD levels, thus potentially making cannabis more harmful.
Freeman added that the changes in the illicit cannabis market are largely hidden away from scientific investigation and are hard for policy-makers to target.