Content
of cannabis consumed in the United Kingdom
6.11 Some of our witnesses
expressed concern that the preparations of illicit cannabis used
in the United Kingdom today are more potent than previously, exposing
users to a greater risk of acute intoxication and long-term adverse
effects. Professor Ashton (p 12) suggested that "a typical
1970s `reefer' contained about 10mg of THC..., while a typical
`joint' today may contain 60-150mg or more of THC. This increase
in potency results from sophisticated plant breeding and cultivation
methods leading to highly potent varieties of cannabis, such as
Skunkweed". Other witnesses made similar assertions (e.g.
Q 33).
6.12 However, the Home
Office Forensic Science Service, who have data on the THC content
of seized cannabis samples, do not support the view that most
users in the United Kingdom are exposed to material containing
ten times as much THC as in the 1960s and 1970s. They say, "Cannabis
resin...has a mean THC content of 4-5 per cent, although
the range is from less than 1 per cent to around 10 per cent.
This pattern has remained unchanged for many years" (p 218).
Cannabis resin, imported most commonly from Morocco, Afghanistan
or Pakistan (IDMU p 230), is the form of cannabis most widely
used in the United Kingdom, and accounted for two thirds by weight
of all seized material in 1996 (Home Office Statistical Bulletin
10/98). One of our witnesses, a user and convicted dealer, claimed
that most modern cannabis is in fact weaker than material from
the 1960s.
6.13 On the other hand,
there appears to have been an increase in the THC content of herbal
cannabis—probably because of the use of new strains of cannabis
plant and improved growing conditions. In the United States, the
University of Mississippi have analysed the THC content of seized
cannabis on behalf of the US government since 1980 (see Appendix
4, paragraph 13). They report an increase in the THC content of
herbal cannabis from around 2 per cent in 1980-81 to more
than 4 per cent in 1997. The Forensic Science Service report
that herbal cannabis in the United Kingdom currently also contains
an average of 4-5 per cent THC. They also report that cannabis
grown in the home, using improved growing techniques and improved
plant varieties, now produces herbal cannabis with a considerably
higher THC content, with an average close to 10 per cent
THC and a range extending to over 20 per cent (p 218).
Use of "hydroponic" cannabis (grown in a nutrient solution
rather than in soil) appears to be increasing rapidly, with plant
seizures in the United Kingdom up from 11,839 plants in 1992 to
116,119 in 1996.
6.14 Professor Hall
suggested, "More potent forms of cannabis need not inevitably
have more adverse effects on users' health than less potent forms.
Indeed, it is conceivable that increased potency may have little
or no adverse effect if users are able to titrate their dose to
achieve the desired state of intoxication. If users do titrate
their dose, the use of more potent cannabis products would reduce
the amounts of cannabis material that was smoked, thereby marginally
reducing the respiratory risks of cannabis smoking" (p 221;
cp IDMU p 235).
6.15 The overall quality
of imported cannabis resin appears to have fallen in recent years;
many users perceive cannabis resin as adulterated and forensic
analysis frequently confirms that this is the case, with the addition
of caryophyllene, a constituent of cloves, being particularly
common (IDMU p 230; Montgomery p 132 and QQ 577, 589).
Yet Professor Hall considers that concern about herbicide contamination
is unfounded, and that case history evidence of health problems
from microbial contamination is limited. Neil Montgomery
calls for research in this area.
The
state of the law
6.16 This Government
show no sign of taking a softer line against recreational use
of cannabis than their predecessors. According to the White Paper
Tackling Drugs (Cm 3945) of April 1998, "The
more evidence that becomes available about the risks of, for example,
cannabis...the more discredited the notion that any of the substances
currently controlled under the 1971 Act are harmless". This
echoes the view of Professor Edwards of the ACMD: "We are
in a rapidly changing field of knowledge"; and new knowledge
is making cannabis look more dangerous, not less (QQ 21,
27).
6.17 Most of our professional
witnesses agree that the adverse effects of cannabis fully justify
prohibition (e.g. Henry/RCPath p 224). The only argument
on the other side is that cannabis is arguably less dangerous
than alcohol or tobacco (e.g. RCGP p 281, Kendall p 268).
Professor Hall acknowledged this, but noted "the difficulty
in predicting the effect that relaxation of cannabis prohibition
would have on current patterns of cannabis use and the harms caused
by that use" (p 222).
6.18 The Under-Secretary
of State at the Home Office, George Howarth MP, told us confidently
that legalising recreational use would cause such use to increase
(Q 674). Professor Edwards, writing for the Royal Society,
is less sure: "We would expect weakening of controls over
cannabis to result in increased use levels, but this is an empirical
question on which research at present is not conclusive...Removal
of prohibition on cannabis would have to be described as a voyage
into the unknown. Some added harm and some added costs would undoubtedly
result" (p 303). There is international experience which
might throw light on this question, but we have not explored it
in detail.
6.19 We have not considered
the wider range of social and criminological issues which would
be raised by any proposal to change the law on recreational cannabis
use. These include enforcement, the impact on use of other illegal
drugs, and the international context and the danger of "drug
tourism"; as well as ethical, philosophical and religious
questions about the freedom of the individual, the nature of society
and the morality of mind-altering drugs. As we said when we began
this enquiry, these matters fall outside our remit as a Science
and Technology Committee. An Independent Inquiry into the Misuse
of Drugs Act, chaired by Lady Runciman of Doxford and supported
by the Police Foundation, is currently considering the matter
in its wider context; they expect to report next year.
23 See also the Annual Report on the State of the
Drugs Problem in the EU 1997, by the European Monitoring Centre
for Drugs and Drug Addiction. Back
24
Br. J. Gen. Pract. 1996, 46, 671. Back
