28/02/2018 12:32 GMT | Updated 28/02/2018 15:17 GMT

Most UK Cannabis High-Strength Skunk, Research Finds, Prompting Mental Health Fears

Skunk was in 94% of cannabis tested - almost twice as much as in 2005.

Drug experts and campaigners on Wednesday blamed drug “prohibition” for news that high-strength skunk is now dominating the UK cannabis market. 

Researchers examined almost 1,000 seizures in London, Kent, Derbyshire, Merseyside and Sussex from 2016 and found that 94% was skunk - almost twice as much (51%) as it was when they tested it in 2005.

It accounted for 85% in 2008.

While the potency of the Class B drug  - measured by the psychoactive ingredient THC  - remained the same as it was in 2005 - at 14% - the fact skunk featured more heavily in the sample tested has prompted mental health fears. 

Dr Marta Di Forti, Medical Research Council clinician scientist at King’s College London’s Institute of Psychiatry, Psychology & Neuroscience, said: “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.

“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.”

Forti said “more attention, effort and funding” should be given to public education on the different types of street cannabis and the consequences of using it. 

Previous work by the same team of researchers, based on a study of 780 people and published in The Lancet, suggests the risk of psychosis is three times higher for users of potent “skunk-like” cannabis than for non-users. 

The increased presence of skunk among seizures was put down to a reduction in the availability of weaker cannabis resin, which dropped to just 6% of seizures in 2016.

In 2005, this resin was present in 43% of seizures analysed.

Johann Hari, author of Chasing The Scream: The First and Last Days of the War on Drugs, said the rise in cannabis potency was “appalling” but said it was “entirely because of the fact we have banned this drug”.

Hari’s comments were echoed by groups pushing for drugs reform, including Leap UK and Transform Drug Policy.

Steve Rolles, a senior policy analyst for Transform, said on Twitter that the figures were “simply repeating what is already known” and urged authorities to better regulate the drug, “to control youth access and make products safer”. 

Drugs training consultant, Kevin Flemen, reiterated Rolles’ claim, saying “high THC hybrids have dominated market for years”, something the Global Drug Survey also suggested today in a tweet beginning, “nothing new here”. 

David Smith, chief executive for Mind for Better Mental Health called the news “terrifying”, adding on Twitter: “I’ve seen so many lives , especially young ones, ruined by high potency cannabis/skunk/weed.” 

The research, published in the journal Drug Testing and Analysis, is the first comprehensive survey of cannabis strength published in the UK for nearly a decade.

Cannabis was the most commonly used drug in 2016/17, with 6.6% of adults aged 16 to 59 having used it in the last year -  around 2.2 million people - according to Home Office statistics.