Nearly all cannabis confiscated on the streets of the UK is made up of high-potency varieties that are capable of inducing psychosis in users, according to analysis conducted by researchers at King’s College London.
Highly-psychoactive strains of cannabis comprised 94% of all police seizures of the drug in Britain in 2016, while weaker forms of the substance that older people might be more familiar were found to have all but disappeared.
In the first major UK survey of cannabis potency in nearly a decade, researchers found the proportion of cannabis seizures made up high-potency varieties, colloquially referred to as “skunk”, had risen from 85% in 2008 and 51% in 2005.
The team behind the report, which was published this week in Drug Testing and Analysis, studied cannabis seized by various police forces across the country, finding that high-strength varieties of the drug had become more widely used as the availability of weaker strains decreased, falling from 43% in 2005 and 14% in 2008, to just 6% in 2016.
Analysis of the seized cannabis samples revealed a vast variation in the levels of THC, the primary psychoactive constituent of cannabis, found in different strains of the drug, with an average level of 14.2% in sinsemilla, compared to 6.3% in resin.
Medical experts believe cannabis smokers who use varieties with high THC levels are more likely to experience addiction issues and develop mental health issues.
“In previous research we have shown that regular users of high-potency cannabis carry the highest risk for psychotic disorders, compared to those who have never used cannabis,” commented senior author Dr Marta Di Forti.
“The increase of high-potency cannabis on the streets poses a significant hazard to users’ mental health, and reduces their ability to choose more benign types.”
Di Forti called for greater efforts to be made to educate the public about the different forms of cannabis that are available from street dealers, and the varying threat levels these can pose.
“Public education is the most powerful tool to succeed in primary prevention, as the work done on tobacco use has proven,” she added.
Responding to the findings of the report in an opinion piece for the Guardian, Simon Jenkins told readers that the increasing misery caused in the UK by high-potency strains of cannabis demonstrates that criminalising users of the drug is not working.
“British policy is now completely adrift of the rest of the western world. It is light years behind Donald Trump’s America, where half the states have legalised cannabis to some degree,” Jenkins wrote.
Taking to Twitter, the author Johann Hari, who has written a book on the failure of the global war on drugs, told his followers: “It’s appalling that most cannabis in the UK is now super-skunk…, and this is entirely because of the fact we have banned this drug.”