In England, four per cent of 11–15 year olds said they had used cannabis in the past month / Getty Images

Professor David Nutt says a distinction must be made between traditional varieties of cannabis and new types known as 'skunk'

A former government adviser on drugs policy has claimed that traditional “hash” varieties of cannabis are among the least harmful drugs available in the UK.

Appearing on Channel 4’s Drugs Live programme looking at the effects of cannabis on the brain, Professor David Nutt said “hash” was less harmful than tobacco, alcohol, ketamine, methadone and a host of other substances.

The Drugs Live team last night assessed the different impacts of the drug on the brain depending on the different compounds present.They roughly grouped different strains of cannabis as “skunk”, with high levels of psychoactive THC and minimal cannabidiol (CBD), and “hash” derived from strains with roughly equal levels of THC and CBD.

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And Professor Nutt said that while “skunk” is only around a third as dangerous as alcohol but worse than certain drugs like Class-C Benzodiazepines, “hash” should be ranked as the least harmful drug of all.

cannabis-index-2.jpgA professor of neuropsychopharmacology at Imperial College London, Professor Nutt was sacked from his post as the Government’s chief advisor on drugs because he disagreed with policies that ranked cannabis as more dangerous than alcohol or tobacco.

Discussing his innovative “harm index”, published in a 2010 paper in The Lancet, which ranked a range of drugs based on the damage done to both the individual and society, Professor Nutt said: “That analysis was done on what we’d learned in the past 30 years”. “In tonight’s experiment,  everyone gets the same level of THC but in one experiment there will be more cannabidiol (CBD) and in the other [skunk] there won’t – so we will see if the CBD offsets the effects of THC.

“We are now beginning to talk about hash and skunk – and by the end of the evening we will be able to see where [the different strains] should sit.”

cannabis-index.jpgSure enough, Professor Nutt concluded the programme by saying he would move hash to the bottom of his harm index, ranking it as safer than all of heroin, crack, meth, cocaine, tobacco, amphetamine, GHB, Benzobiazepines, ketamine and methadone.

The Drugs Live broadcast came as the Deputy Prime Minister, Nick Clegg, announced that the Lib Dems would make government drugs policy a matter for the Department of Health – not the Home Office.

The NHS Choices website describes cannabis as “the most widely used illegal drug in the UK”, and lists a range of risks and effects its use can have. The dangers listed include harm to the lungs, possible fertility issues and risks to mental health.

“It makes some people feel confused, anxious or paranoid, and some experience panic attacks and hallucinations,” it says. “These effects are particularly common with stronger forms of cannabis, such as skunk and sinsemilla.”

For more information, visit the NHS website.