Cannabis use in Britain

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Matthew J. Atha BSc MSc LL.B - Director - IDMU Ltd

 

1. Introduction

1.1 These lecture notes are intended as an introduction to Cannabis use in the UK. These briefly cover prevalence of cannabis use among different age groups, consumption patterns, initiation to drug use (the "progression" theory), the types of cannabis available, methods of use, driving, medicinal use and possible future policy options.

1.2 Cannabis is the most widely-used illegal drug on the planet, and has been one of the most intensively-studied substances of all time. It is also the drug which causes the most controversy, and arouses the strongest emotions on both sides. The legalisation argument has been creeping steadily up the political agenda in recent years, with the opinion polls, once 6 to one against reform, now showing public opinion to be evenly divided between the reformers and prohibitionists.

1.3 The purpose of this lecture is to shed light where there is darkness, and critically analyse some of the misinformation, myths and half-truths on both sides of the argument.

1.4 This document presents some of our own research data, mostly in graphic or tabular form, and much of it for the first time. Commentary is generally kept to a minimum.

 

2. Prevalence of Cannabis Use

2.1 The Home Office conducts the British Crime Survey every 2 years, including questions on whether people have ever used a range of drugs, and if so whether they have done so in the past year or past month. The prevalence of cannabis use has been rising in these surveys since they were first conducted in the early 1980s. In the UK, around 15 million people would now admit having tried cannabis, with between 2 and 5 million regular users.

2.2 Cannabis use is highest in the 16-29 age group, although the rise in use is sharpest among older adults. Part of this is demographic, as existing or former users progress into the older age groups, although first time use among elderly citizens, particularly for medicinal reasons, is becoming more common.

 

2.3 IDMU Surveys - Our research is based primarily on our drug user surveys, which have been conducted in 1994, and in each year since 1997, as well as my own 1984 survey which pioneered the methodology. Respondents are asked to complete anonymous questionnaires, containing a number of core variables, with other questions varying from year to year. Surveys have been distributed primarily at pop-festivals and pro-cannabis rallies, although smaller batches have been distributed via subcultural magazines, snowballing, via direct mailings to members of pressure groups, and at other events. Development has been evolutionary, and response rates have been increased via use of our own stalls and provision of clip-boards at outdoor events.

2.4 The age range of respondents would appear to be broadly representative of regular cannabis users in the UK population, with the majority falling in the 18-30 age range.

 

Cannabis Convictions 1945-1999 (Linear Scale)

(includes Cautions and all formal disposals)

2.5 The Home Office publishes annual statistics on drug seizures and drugs offenders. These have been rising steadily since the end of World War II, the millionth conviction would have occurred around December 1999. Dangerous Drugs Acts 1945-1972 = 44,834, Misuse of Drugs Act 1973-1999 = 958,688, Total - 1,003,522

Cannabis Convictions 1945-1999 (Logarithmic scale)

3. Frequencies of Cannabis Use

Frequency of Cannabis Use 1984-2000
Year	1984	1994	1995	1997	1998	1999	2000	84-00n	84-00%
Non/ex-users	2.5%	5.3%	9.4%	10.8%	11.8%	5.4%	5.5%	524	7.1%
Experimental	0.0%	2.6%	2.6%	2.5%	2.4%	3.8%	4.3%	215	2.9%
Occasional	11.2%	16.6%	2.1%	16.6%	18.5%	19.8%	21.6%	1303	17.7%
Weekly	31.8%	20.5%	29.8%	20.0%	18.3%	20.2%	20.4%	1560	21.2%
Daily	53.5%	55.0%	56.0%	50.1%	49.0%	50.8%	48.1%	3766	51.1%

3.1 The majority of users in our surveys smoked cannabis regularly, with the usage pattern more similar to that for tobacco and for caffeine than for other illicit drugs. The survey population would thus be broadly equivalent to the "used in past month"

4 Amounts used

Cannabis Use/Ratings by year
Subject	1984	1994	1995	1997	1998	1999	2000
Subjective rating (0-10)	n/a	8.8	8.5	8.8	8.4	8.3	8.4
Mean used per month	29.3g	24.8g	31.3g	23.9g	20.7g	26.9g	31.6g

Distribution of monthly cannabis use (94-00)

4.1 The majority of users smoke relatively small amounts of the drug, with mean consumption of 1g per day. Progressively smaller numbers use larger amounts, around one in 20 use 1oz per week, and one in 100 2oz per week. However, in the Caribbean Schaeffer et al described use of up to 2oz (56g) per day of herbal cannabis containing 8% THC.

Cannabis Use Percentiles (1994-2000 - n = 8146)
Percentile	Monthly Cannabis Use (g)	Daily THC @ 3% (mg)	Daily THC @ 15% (mg)	Reefers per day	Reefer content (mg)
Bottom 5%	1	<1	5	0.03	23
Lower 10%	2	2	10	0.1	35
Lower 25%	7	7	35	2	67
Median (50%)	14	14	70	4.1	122
Upper 25%	28	28	140	8.1	188
Upper 10%	56	56	280	13.8	312
Upper 5%	112	112	560	19.2	468
Top 1%	224	224	1120	31.5	1246

 

 

Cannabis Use Indices by Sex & Frequency of Use
Monthly Cannabis Spending (all drugs section)
Frequency of use	Female		Male		Not Stated		Totals by freq: p<.0001
Experimental	£15.65		£32.12		£29.67		£25.22
Occasional	£6.98		£14.30		£18.76		£11.32
Regular	£18.23		£25.08		£28.74		£22.55
Daily	£59.67		£92.52		£133.92		£85.80
Totals by sex: p=.07	£30.14		£51.31		£52.02		£44.40
Monthly Cannabis Use (g)
Frequency of use	Female		Male		Not Stated		Totals by freq: p<.0001
Experimental	6.83		15.64		19.60		12.32
Occasional	3.50		7.90		12.57		6.21
Regular	8.33		9.89		9.40		9.24
Daily	28.25		34.55		30.59		32.45
Totals by sex: p<.05	16.32		24.11		17.49		20.99
Monthly Cannabis Purchase (g)
Sex:		Female		Male		Not Stated		Totals by freq: p<.0001
Experimental		6.32		20.17		23.07		14.72
Occasional		3.19		7.10		26.70		6.36
Regular		8.79		22.84		10.70		16.53
Daily		36.83		64.24		72.78		56.87
Totals by sex: n.s.		22.13		41.85		36.26		34.88
Monthly Cannabis Spending (Cannabis section)
Frequency of use	Female		Male		Not Stated		Totals by freq: p<.0001
Experimental	£14.95		£45.56		£46.67		£33.13
Occasional	£8.60		£18.73		£20.71		£14.40
Regular	£18.48		£30.01		£32.74		£25.56
Daily	£73.24		£114.23		£136.06		£103.82
Totals by sex: n.s.	£43.35		£71.87		£67.00		£62.07
Reefers Smoked per day
Frequency of use	Female		Male		Not Stated		Totals by freq: p<.0001
Experimental	1.06		3.67		1.59		2.45
Occasional	0.76		1.88		2.91		1.44
Regular	2.05		2.33		2.52		2.23
Daily	6.46		6.80		6.88		6.70
Totals by sex:p<.001	3.60		4.93		4.28		4.43
Freq x Sex p<.05

4.2 Women as a whole tend to smoke cannabis less often than males, although differences in purchase and spending were not statistically significant. The difference is greatest amongst women who are experimental or occasional users, there was little difference between consumption of daily users of either sex. Those experimenting with cannabis will tend to buy or use more than occasional users. In couples, it is usually the man who buys the cannabis for both to use. Note also that many regular users grow their own, so spending alone is an imperfect measure of cannabis usage.

Sex	Number	%
Male	4777	58.64%
Female	2683	32.94%
Not Stated	686	8.42%

 

5. Initiation to drug use - the "stepping stone" hypothesis reconsidered

5.1 The peak years of initiation to cannabis use are 14-18 years, at age 16, roughly half of those who will eventually try cannabis have already used it. Results from school surveys should take account of the initiation to drug use by older pupils and young people who have left school.

5.2 Use of Other Drugs

5.2.1 The Drug Acquisition Curves show the numbers who had tried each drug by a given age. Very few people who have not tried a drug by age 25 will start using it afterwards, the only exception being ecstasy (and to a lesser extent crack cocaine), which both arrived on the scene when many existing drug users were in their 30s and 40s. Note - "tea/coffee" was not included in the questions from one batch of surveys. "Bliss" was included as a fictitious drug from 1994-98, when it came to our attention that a "herbal high" was being sold under that trade name, for 1999 and 2000 we used the same "bogus" drug as the Home Office (i.e. Semeron) which was given the bogus street name "space".

5.3 Drug Prevalence

5.3.1 The lifetime prevalence of using most drugs has remained relatively stable among the user population as a whole, however amphetamine and LSD appears to be declining steadily, whereas cocaine and ecstasy appear to be increasing slightly. Prevalence of magic mushroom use (not shown) is similar to that of LSD. Crack and Ecstasy were not listed options in 1984, although 1% mentioned MDA as a write-in option. Users of crack in 1984 (then known as freebase) did not report it directly, but some of the cocaine would have been used in that form.

Lifetime prevalence of use of different drugs among users of any drug by year

5.4 Frequency of use

5.4.1 Users of each drug were asked to state how often they used the drug. Other than cannabis and legal drugs (caffeine, tobacco, alcohol), there were few daily users, with experimental or occasional use the norm.

Frequency of Cannabis use by year

 

Frequency of Amphetamine use by year

Frequency of LSD use by year

Frequency of Ecstasy use by year

 

Frequency of Cocaine use by year

Frequency of Crack Cocaine use by year

Frequency of Heroin use by year

 

5.5 Busts/deterrence

5.5.1 Laws prohibiting drug use and possession are frequently justified on the basis that they deter people from using drugs. However the effect of a drugs arrest tends to consolidate or stimulate drug use, rather than deterring the user from continuing or indeed experimenting with other drugs. Drug users who have been arrested for drugs offences typically use a wider range of drugs more frequently and more heavily than users with clean records. They also tend to give higher ratings to drugs.

Drug use frequency, purchasing, Subjective Ratings & other consumption patterns by whether ever busted (1994-98 Consolidated);
	Cannabis offence			Other drug offence			Other offence
	No	Yes	p	No	Yes	p	No	Yes	p
Base (% of total)	2831 78%	792 22%		3389 94%	234 6%		3181 88%	442 12%
Age	25.71	29.01	.064	27.38	30.03	<.0001	26.24	28.52	<.0001
Caffeine
Rating	5.98	5.79	ns	6.14	5.60	ns	5.97	5.68	ns
Frequency	3.15	3.30	ns	3.19	3.27	ns	3.18	3.20	ns
Spending	4.39	5.09	ns	4.41	5.05	ns	4.50	4.87	ns
Tobacco
Rating	3.82	3.46	ns	3.72	3.56	ns	3.72	3.91	ns
Frequency	2.76	3.10	ns	2.81	3.20	<.01	2.80	3.13	<.0001
Spending	21.00	24.30	ns	18.56	24.35	ns	19.93	34.31	<.0001
Cigs/day	8.81	10.63	ns	10.14	10.82	ns	8.94	11.45	<.0001
Alcohol
Rating	5.97	5.51	ns	6.68	5.22	.0001	5.90	5.62	.057
Frequency	2.63	2.65	ns	2.88	2.66	ns	2.63	2.70	ns
Spending	33.21	32.28	ns	38.71	34.54	ns	32.64	37.13	.066
Units/ week	18.43	18.21	<.001	25.46	23.00	ns	18.25	22.09	<.001
Cannabis
Rating	8.51	9.11	ns	8.82	9.10	<.05	8.64	8.72	ns
Frequency	2.97	3.51	ns	3.19	3.53	<.0001	3.06	3.33	<.0001
Used/ month (g)	21.17	31.57	ns	21.56	40.27	<.05	23.06	87.13	<.05
Bought/ month (g)	42.18	101.7	ns	43.55	75.56	<.05	46.98	103.38	<.0001
£Spending 1	36.53	90.98	ns	29.88	79.22	<.05	44.54	78.8	<.05
£Spending 2	67.44	188.96	ns	59.53	99.29	.051	84.92	137.76	<.05
Spliffs smoked/day	5.05	6.86	<.05	5.72	8.57	<.0001	5.39	7.15	<.0001
Rolled/ day	4.82	6.24	ns	4.73	7.55	ns	5.06	6.60	ns
Pipes/ day	2.23	3.23	<0.1	2.75	4.90	<.05	2.34	4.17	<.0001
Plants Grown	13.37	25.58	ns	11.38	65.13	<.05	15.68	43.95	<.0001
% bought for own use	69.06	73.03	ns	70.15	70.06	ns	69.86	70.41	ns

 

Drug use frequency, purchasing & other consumption patterns by whether ever busted
	Cannabis offence			Other drug offence			Other offence
	No	Yes	p	No	Yes	p	No	Yes	p
LSD
Rating	6.74	7.55	ns	7.83	7.01	ns	6.97	6.68	ns
Frequency	1.01	1.31	<.0001	1.38	1.61	<.005	1.06	1.33	<.0001
Spending	1.38	2.75	ns	2.46	3.08	ns	1.54	2.92	<.01
% bought for personal use	81.25	80.89	ns	98.64	75.53	.052	80.12	86.39	ns
Ecstasy
Rating	6.56	6.64	<.05	7.44	7.32	ns	6.62	6.74	ns
Frequency	.85	1.01	<.0001	1.17	1.54	<.005	0.89	1.11	<.0001
Spending	5.58	8.65	ns	6.92	11.64	<.05	5.73	11.38	<.0001
% bought for personal use	84.52	80.10	ns	86.94	80.54	ns	83.33	83.84	ns
Amphetamine
Rating	5.21	4.82	ns	5.32	5.29	ns	5.15	5.05	ns
Frequency	1.05	1.27	<.01	1.33	1.47	<.05	1.07	1.41	<.0001
Spending (£)	4.13	5.83	<.05	12.38	8.19	ns	3.95	10.36	<.0001
% bought for personal use	76.30	78.54	ns	72.60	78.65	ns	76.74	77.26	ns
Cocaine
Rating	5.51	6.09	ns	6.23	6.32	ns	5.68	0.83	ns
Frequency	0.56	0.93	<.005	0.85	1.10	<.0001	0.62	0.93	<.0001
Spending	3.34	9.43	ns