Cannabis: The Scientific and Medical Evidence
Lords Science & Technology Select Committee [1998]
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My comment:

This report distinguishes scientific evidence from other forms of evidence outside the Committee’s remit but suggests scientific evidence alone justifies the prohibition of recreational cannabis use. The Royal Society and Lancet disagree.
"1.5 We have also considered whether the continued prohibition of recreational use is justified on the basis of the scientific evidence of adverse effects. Recreational use raises other issues besides the adverse effects of the drug; these are outside our remit "to consider science and technology", belonging instead to the realms of law, sociology and even philosophy, and we have not considered them".
"8.18 It is believed in some quarters that the current absolute prohibition on the recreational use of cannabis and its derivatives is not justified by the adverse consequences for the user and the public. On the evidence before us, we disagree. On the contrary, we endorse the Government's statement in Tackling Drugs: "The more evidence becomes available about the risks of...cannabis,...the more discredited the notion that [it is] harmless" (paragraph 6.16)".
Such endorsement is not scientific. No activity is harmless. As with the ACMD the evidence that cannabis is not harmless is taken to be evidence that prohibition is the most appropriate intervention – a disproportionate and inconsistent precautionary principle that is not supported by evidence, scientific or otherwise. Their reasoning suggests alcohol, tobacco and caffeine should also be prohibited because these drugs are not harmless.

 

Quotes:

1.3     Substantial numbers of patients with various conditions are illegally self­medicating with cannabis and are convinced that they derive medical benefit.

1.5     In the light of this heightened interest in cannabis, and particularly the report by the BMA, we decided to examine the scientific and medical evidence to determine whether there was a case for relaxing some of the current restrictions on the medical uses of cannabis. We have also considered whether the continued prohibition of recreational use is justified on the basis of the scientific evidence of adverse effects. Recreational use raises other issues besides the adverse effects of the drug; these are outside our remit "to consider science and technology", belonging instead to the realms of law, sociology and even philosophy, and we have not considered them.

3.13     Recent data from animal studies reveal that, in common with various drugs of addiction (heroin, cocaine, nicotine and amphetamines), THC activates the release of the chemical messenger dopamine in some regions of the brain of rats.

4.1     The prohibition of the recreational use of cannabis, and some of the doubts about medical use, are based on the presumption that cannabis is harmful to individual and public health. We have tested the strength of that presumption.

4.5  The most familiar short-term effect of cannabis is to give a "high" — a state of euphoric intoxication. This is, of course, precisely the effect sought by the recreational user, analogous to the effect of alcohol and sought for similar reasons.

4.7 ...people intoxicated by cannabis appear to compensate for their impairment by taking fewer risks and driving more slowly, whereas alcohol tends to encourage people to take greater risks and drive more aggressively.

Box 2:

The consumption of any psychoactive drug, legal or illegal, can be thought of as comprising three stages: use, abuse, and addiction. Each stage is marked by higher levels of drug use and increasingly serious consequences.
Abuse and addiction have been defined and redefined by various organisations over the years. The most influential current system of diagnosis is that published by the American Psychiatric Association (DSM-IV, 1994).

5.2     According to the BMA report, "many normally law-abiding citizens—probably many thousands in the developed world" use cannabis illegally for therapy.

5.30 In short, there is scientific evidence that cannabinoids possess pain­relieving properties, and some clinical evidence to support their medical use in this indication.

5.41     ... individual patients are likely to differ considerably in the dose needed to control their symptoms—as with the use of opiates in the control of severe pain, where Professor Wall points out that a tenfold range of doses is commonly observed.

6.1     According to the Department of Health, "Cannabis is now the third most commonly consumed drug after alcohol and tobacco".

6.2     Cannabis dominates the drug crime statistics, and the figures are rising. Figures for the whole United Kingdom for 1996 (Home Office Statistical Bulletin 10/98) show that 72,745 drug offenders (77 per cent of the total) committed offences involving cannabis (alone or with other drugs).

6.5     The Independent Drug Monitoring Unit conducted a survey of 1,333 regular cannabis users who attended a major pop festival in Britain in the summer of 1994 (p 231). The majority were daily cannabis users with an average consumption of about 24.8g of cannabis resin per month. Respondents gave highly positive subjective ratings to cannabis (as opposed to negative subjective ratings to solvents, cocaine and heroin). More than 60 per cent believed that cannabis had been of benefit to their physical or mental health. They would prefer that the law was more liberal, but a majority (70 per cent) did not think that they would use more if it was.

6.9     Alcohol use is also common, but regular cannabis users may consume less than non-cannabis users.

6.10     According to the Department of Health, most cannabis users have discontinued by their mid to late 20s (p 46); and of those who have ever been daily users, only 15 per cent persist with daily use in their late 20s.

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.

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".

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.

6.17     Most of our professional witnesses agree that the adverse effects of cannabis fully justify prohibition. The only argument on the other side is that cannabis is arguably less dangerous than alcohol or tobacco.

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.

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.

8.1     We recognise that, in all the evidence we have received, there is not enough rigorous scientific evidence to prove conclusively that cannabis itself has, or indeed has not, medical value of any kind.

8.4     ... we recommend that research be promoted into alternative modes of administration (e.g. inhalation, sub-lingual, rectal) which would retain the benefit of rapid absorption offered by smoking, without the adverse effects.

8.9     Unlike cannabis itself, the cannabinoid THC (dronabinol) and its analogue nabilone are already accepted by the Government as having medical value (paragraphs 5.11-17)—producing the anomaly that, while cannabis itself is banned as a psychoactive drug, THC, the principal substance which makes it psychoactive, is in legitimate medical use.

8.18     It is believed in some quarters that the current absolute prohibition on the recreational use of cannabis and its derivatives is not justified by the adverse consequences for the user and the public. On the evidence before us, we disagree. On the contrary, we endorse the Government's statement in Tackling Drugs: "The more evidence becomes available about the risks of...cannabis,...the more discredited the notion that [it is] harmless".

8.19     The harms must not be overstated: cannabis is neither poisonous, nor highly addictive, and we do not believe that it can cause schizophrenia in a previously well user with no predisposition to develop the disease.

8.22     Therefore, on the basis of the scientific evidence which we have collected, we recommend that cannabis and its derivatives should continue to be controlled drugs.