THE POISON GARDEN website      Arum maculatum berries on a Cannabis leaf 


This free script provided by JavaScript Kit

Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Tuesday 4th February 2014

I don’t pay a lot of attention to statistics about psychoactive substances. They are often based on incomplete data or skewed research conducted to ‘prove’ a prejudice concerning prohibition. And they can’t alter my central belief that substances that have the potential to do harm should not be left in the hands of criminals rather than being regulated by governments. Only when governments accept responsibility for minimising the harms caused is the true extent of those harms worth more scrupulous study.

But there are numbers that bounce around and I, sometimes, wonder how reliable they are. One such is the number of cannabis users who will become dependent (often described as ‘addicted’). The number favoured by drug aunt website ‘Smart Approaches to Marijuana’ is 1 in 10 but this is a rounding up from the 9% (or 1 in 11) number usually given.

My temptation is always to consider the rest. If only 9% become dependent, then 91% are not suffering serious harm. (If we could say that 91% of people are not obese, we wouldn’t be seeing any fuss made about the problems of being overweight.) But, a piece by Sunil Kumar Aggarwal for Huffington Post looking at the origin of the 9% claim, interested me.

When reading Aggarwal’s piece it is important to remember that, in the USA, healthcare is a business rather than being about caring for people’s health. Like any business, it strives to create demand for its products and, rather like the makers of Listerine who created a condition called halitosis in order to sell a product to combat it, healthcare providers in the USA have sought to create conditions in order to sell the treatment to go with them.

The American Psychiatric Association’s Diagnostic and Statistical Manual (DSM) defines the symptoms to look for when diagnosing a huge range of mental health issues. The most recent revision to this document came in for a lot of criticism over its attempt to create all manner of addictions (though not the addiction to creating new profit opportunities) but it was the 1987 revised third edition that led to the 9% statistic.

Aggarwal demonstrates how a survey, conducted between 1990 and 1992 and based on diagnostic criteria from DSM3, used biased questions to measure dependence and biased attitudes to reduce the role of alcohol in respondents’ problems.

I’m not a statistician. I did get a good grade in ‘A’ level pure maths in 1968 but Mr Phasey, whose catchphrase ‘By the well-known formula’ would produce blank stares and blushes more often than not, would be appalled at how little of it I’ve retained. But I do like to play around with numbers and see if my residual knowledge and common sense can shed light on the reliability of numerical claims.

I decided to see what it would mean if the 9% claim was true for the UK. It is important to stress that what follows has numerous broad assumptions and that, at times, figures for different years have been mixed because I couldn’t find all the data I wanted for one single year. But given that year on year variations are not dramatic, I think it is possible to reach broad conclusions based on broad assumptions.

It seems to be reasonable to say that you’d need to be using cannabis frequently to even be considered as a candidate for the term ‘dependent’. The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), in its 2012 report ‘Prevalence of daily cannabis use in the European Union and Norway’, says, in Table 2 on page 16, that, for all adults in the UK, 3.8% report last month prevalence and 15% of those monthly users report use at more than 20 days a month. 0.6% of all adults report daily use.

The CIA World Factbook estimates the UK population as 41 million 15-64 year olds.

3.8% of 41 million is 1.5 million and 15% of that is 225,000 people using cannabis more than 20 times per month.

0.6% of 41 million is 246,000 daily users.

Clearly, there are approximations at work because the number of daily users has to be lower that the number of people using more than 20 times a month but less than daily. Rather than try and resolve the discrepancy I’m going to proceed on the basis that there are between 200,000 and 250,000 very frequent cannabis users in the UK.

According to the most recent Crime Survey for England and Wales (CSEW), 30% of adults have used cannabis at least once in their life. The CSEW deals only with England & Wales but if we apply that 30% to the whole of the UK we get 12 million adults in the UK who have used cannabis at least once in their lives. If 9% of users become dependent, as claimed, then there should be 1,000,000 dependent users in the UK. Instead there are 200-250,000 very frequent users. The next stage is to see whether even that number of very frequent users can be accurately described as dependent.

The National Treatment Agency for Substance Misuse (NTA) said in its 2012 annual report that, during 2011/2, 15,750 people received treatment for cannabis dependence. 10,544 of those were new entrants. These figures are for England only. Scaling that number to take account of Wales, Scotland & Northern Ireland suggests that around 20,000 people in the UK are in treatment for cannabis dependence.

The NTA makes a broad brush assumption that half of all heroin users are in treatment so, applying that estimate to all substances, shouldn’t there be 100-125,000 cannabis users in treatment? The UK now has one of the most efficient treatment systems in Europe so it won’t do to suggest that there is a huge waiting list of dependent cannabis users waiting to enter.

As far as the UK is concerned, then, the 9% claim falls on two counts; the number of very frequent users is in the region of 1-2% of adults who have ever used cannabis and, based on numbers in treatment, dependent users account for only 0.2% of ever users.

Going back to looking at the majority percentage, it would seem that 99.8% of cannabis users do not become dependent. That number makes current policy look exceedingly stupid.

Submit a Comment

You can send comments via the contact page but please be sure to say what blog entry you are commenting on.

Follow @thepoisongarden on Twitter

Full Entries


Tuesday 25th October 2016 Saturday 20th August 2016 Sunday 6th March 2016 Wednesday 3rd February 2016


Saturday 28th November 2015 Friday 27th November 2015 Monday 17th August 2015 Wednesday 15th July 2015 Friday 26th June 2015 Thursday 25th June 2015 Thursday 30th April 2015 Wednesday 29th April 2015 Wednesday 11th March 2015 Tuesday 3rd March 2015 Saturday 28th February 2015 Sunday 22nd February 2015

November 2014


Monday 24th November 2014 Saturday 8th November 2014

October 2014

September 2014

Wednesday 24th September 2014 Monday 1st September 2014

August 2014

Tuesday 26th August 2014 Saturday 16th August 2014 Tuesday 5th August 2014 Friday 1st August 2014

July 2014

Sunday 27th July 2014 Wednesday 23rd July 2014 Sunday 13th July 2014 Sunday 6th July 2014 Tuesday 1st July 2014

June 2014

Wednesday 25th June 2014 Tuesday 24th June 2014 Sunday 22nd June 2014 Monday 9th June 2014 Wednesday 4th June 2014

May 2014

Monday 26th May 2014 Sunday 18th May 2014 Wednesday 14th May 2014

April 2014

Sunday 13th April 2014 Saturday 5th April 2014 Thursday 3rd April 2014 Tuesday 1st April 2014

March 2014

Monday 31st March 2014 Tuesday 25th March 2014 Friday 21st March 2014 Monday 17th March 2014 Sunday 16th March 2014 Tuesday 11th March 2014 Thursday 6th March 2014 Wednesday 5th March 2014 Saturday 1st March 2014

February 2014

Thursday 27th February 2014 Monday 24th February 2014 Wednesday 19th February 2014 Monday 17th February 2014 Thursday 13th February 2014 Monday 4th February 2014 Monday 3rd February 2014 Saturday 1st February 2014

January 2014

Thursday 28th January 2014 Thursday 23rd January 2014 Friday 17th January 2014 Wednesday 15th January 2014 Monday 13th January 2014 Thursday 9th January 2014 Tuesday 7th January 2014 Wednesday 1st January 2014

December 2013

Monday 23rd December 2013 Friday 20th December 2013 Tuesday 17th December 2013 Friday 14th December 2013 Thursday 12th December 2013 Sunday 8th December 2013 Wednesday 4th December 2013 Sunday 1st December 2013

November 2013

Friday 29th November 2013 Wednesday 27th November 2013 Tuesday 26th November 2013 Friday 22nd November 2013 Monday 18th November 2013 Friday 15th November 2013 Thursday 14th November 2013 Sunday 10th November 2013 Thursday 7th November 2013 Wednesday 6th November 2013 Friday 1st November 2013

October 2013

Thursday 31st October 2013 Sunday 27th October 2013 Wednesday 23rd October 2013 Monday 21st October 2013 Friday 18th October 2013 Friday 11th October 2013 Wednesday 9th October 2013 Tuesday 8th October 2013 Monday 7th October 2013 Tuesday 1st October 2013

September 2013

Monday 30th September 2013 Saturday 28th September 2013 Friday 27th September 2013 Monday 23rd September 2013 Sunday 15th September 2013 Monday 9th September 2013 Sunday 8th September 2013 Tuesday 3rd September 2013 Sunday 1st September 2013

August 2013

Tuesday 27th August 2013 Sunday 25th August 2013 Monday 19th August 2013 Friday 16th August 2013 Tuesday 13th August 2013 Friday 9th August 2013 Friday 2nd August 2013 Thursday 1st August 2013

July 2013

Saturday 27th July 2013 Sunday 21st July 2013 Wednesday 17th July 2013 Monday 15th July 2013 Saturday 13th July 2013 Friday 12th July 2013 Thursday 11th July 2013 Wednesday 10th July 2013 Tuesday 9th July 2013 Saturday 6th July 2013

June 2013

Friday 28th June 2013 Tuesday 25th June 2013 Friday 21st June 2013 Thursday 20th June 2013 Wednesday 19th June 2013 Saturday 15th June 2013 Sunday 9th June 2013 Saturday 8th June 2013 Saturday 1st June 2013

May 2013April 2013 March 2013 February 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 blog June 2012 blog May 2012 blog April 2012 blog March 2012 blog February 2012 blog January 2012 blog December 2011 blog November 2011 blog October 2011 blog September 2011 blog August 2011 blog July 2011 blog June 2011 blog


The POISON GARDEN website is not connected with Alnwick Garden Enterprises Ltd and/or The Alnwick Garden Trust.