According to a new global study published in the journal Addiction, cannabis resin is now 25% more potent.
The major international study has found that the strength of cannabis resin has increased almost 25% over the past half century.
Researchers with the Addiction and Mental Health Group at the University of Bath analyzed data from more than 80,000 cannabis street samples that have been tested in the past 50 years in the US, UK, Netherlands, France, Denmark, Italy and New Zealand.
The findings show that concentrations of THC, the intoxicating component of cannabis responsible for giving users a “high,” have drastically changed over time.
In herbal cannabis, THC concentrations grew by 14% between 1970 and 2017 while concentrations in cannabis resin, which is extracted from herbal cannabis, increased by 24% between 1975 and 2017.
The researchers note that this was the equivalent of a 5mg increase in THC per annum. One 5mg dose is enough for mild intoxication.
“Cannabis has continued to increase in strength over time, such that today it differs enormously from the type of drug used by people 50 years ago,” said lead author Dr Tom Freeman. “During this time attitudes have also shifted. There is now a greater appreciation of its complex interplay with mental health and potential medicinal uses.”
“Cannabis resin is often seen as a safer type of cannabis, but our findings show that it is now stronger than herbal cannabis,” said study co-author Sam Craft.
“Traditionally, cannabis resin contained much lower amounts of THC with equal quantities of CBD (cannabidiol, which is believed to have some health benefits), however CBD concentrations have remained stable as THC has risen substantially, meaning it is now much more harmful than it was years ago.”
“As the strength of cannabis has increased, so too has the number of people entering treatment for cannabis use problems,” Freeman said. “More Europeans are now entering drug treatment because of cannabis than heroin or cocaine.”