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Advisory Council on the Misuse of Drugs, U.K., 2002

The Classification of Cannabis
Under the Misuse of Dugs Act 1971

Commissioned by the British Home Office in October of 2001. Submitted in March, 2002.

Il testo completo (pdf)

Cannabis Arrests:
The number of cannabis offences (as persons found guilty, cautioned, given a fiscal offence, or dealt with by compounding) rose from 15,388 in 1981 to 99,140 in 1998 before falling to 88,548 in 1999. Over 90 per cent of such recorded cannabis offences in 1999 were for ‘unlawful possession’. Offences related to heroin and amphetamines in 1999 were 12,760 and 12,102 (respectively). (P.5, para. 3.6, Advisory Council on the Misuse of Drugs, U.K., 2002)

Addiction:
No individuals are reported to the Northern Ireland Addicts Index as having problematic cannabis use. (P.5 para. 3.8, Advisory Council on the Misuse of Drugs, U.K., 2002)

Fertility:
The effects of cannabis on fertility, however, are unclear. (P.6, para. 4.3.4, Advisory Council on the Misuse of Drugs, U.K., 2002)

Criminality/Risk-Taking Behaviour/Violence:
Cannabis differs from alcohol, however, in one major respect: it seems not to increase risk-taking behaviour. This may explain why it appears to play a smaller role than alcohol in road traffic accidents. Cannabis intoxication tends to produce relaxation and social withdrawal rather than the aggressive and disinhibited behaviour commonly found under the influence of alcohol. This means that cannabis rarely contributes to violence either to others or to oneself, whereas alcohol use is a major factor in deliberate self-harm, domestic accidents and violence. (P.7, para.4.3.6, Advisory Council on the Misuse of Drugs, U.K., 2002)

As discussed in paragraph 4.3.6, cannabis use does not commonly produce the mental states leading to violence to others; but the illegal market does contribute to violence in some parts of our cities. (P.10, para. 4.7.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

Anxiety:
Acute cannabis intoxication can also lead to panic attacks, paranoia and confused feelings that drive users to seek medical help. These effects are generally short lived and usually respond to reassurance or a minor tranquilliser. (P.7, para. 4.3.7, Advisory Council on the Misuse of Drugs, U.K., 2002)

Cancer/Health:
Indeed, smoking cannabis may be more dangerous than tobacco since it has a higher concentration of certain carcinogens. However, there are factors with smoked cannabis that may mitigate this risk. In general cannabis users smoke fewer cigarettes per day than tobacco smokers and most give up in their 30s, so limiting the long-term exposure that we now know is the critical factor in cigarette-induced lung cancer. (P.7, para.4.4.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

Preliminary studies of lung function in regular cannabis smokers have not found a major cause for concern in the majority, but some severe cases of lung damage have been reported in young very heavy users. (P.7, para. 4.4.2, Advisory Council on the Misuse of Drugs, U.K., 2002)

The occasional use of cannabis is only rarely associated with significant problems in otherwise healthy individuals. Impaired psychomotor performance and, uncommonly, acute psychotic states are the most important. They are, however, self-limiting and (usually) readily managed. These harmful effects of cannabis, however, are very substantially less than those associated with similar use of other drugs, such as amphetamines, which (like cannabis) are currently classified as Class B. (P.11, para. 5.2, Advisory Council on the Misuse of Drugs, U.K., 2002)

Cardiovascular:
Cannabis also produces an increase in heart rate. Maximum increases in heart rate occur within 15 to 30 minutes of inhalation, and remain raised for two hours or more. Tolerance to the cardiovascular effects of cannabis occurs with repeated use. (P.6, para. 4.3.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

The cardiovascular actions of cannabis are similar to the effects of exercise, and probably do not constitute a significant risk in healthy adolescents and young adults. (P.6, para. 4.3.3, Advisory Council on the Misuse of Drugs, U.K., 2002)

Cannabis has been reported to produce modest bronchodilator effects (opening of the airways) but can worsen asthma. (P.6, para.4.3.4, Advisory Council on the Misuse of Drugs, U.K., 2002)

Unlike sedative intoxicants such as alcohol, cannabis does not cause respiratory depression or suppress the gag reflex even when extremely intoxicated. Moreover, the fact that cannabis is usually smoked means that the effects are almost immediate and once inhalation stops they begin to subside. (P.6-7, para. 4.3.5, Advisory Council on the Misuse of Drugs, U.K., 2002)

Addiction/Dependence:
It is possible to rank the risks of dependence of abused drugs with heroin and crack cocaine the worst and cannabis generally at, or near, the bottom (and well below nicotine and alcohol). Nevertheless, repeated cannabis use does lead to a significant proportion of regular users becoming dependent although the severity of their dependence is generally not such as to lead to criminal behaviour. (P.8, para. 4.4.5, Advisory Council on the Misuse of Drugs, U.K., 2002)

The epidemiological evidence demonstrates that cannabis use, especially amongst adolescents and young adults, is substantial. The apparent and ready availability of cannabis is, however, disproportionate to the relatively small numbers of people seeking help from drug treatment agencies for cannabis misuse. The high use of cannabis is not associated with major health problems for the individual or society. (P.11, para. 5.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

Regular heavy use of cannabis can result in dependence, but its dependence potential is substantially less than that of other Class B drugs such as amphetamines or, indeed, that of tobacco or alcohol. (P.11, para. 5.4, Advisory Council on the Misuse of Drugs, U.K., 2002)

Mental Illness:
The other main concern about the chronic use of cannabis is whether it can lead to mental illness (especially schizophrenia). Although debated for well over a century, no clear causal link has been demonstrated. (P.8, para. 4.4.6, Advisory Council on the Misuse of Drugs, U.K., 2002)

Brain Damage:
There is no evidence that cannabis causes structural brain damage in man. Neither radiological studies nor post mortem examinations have revealed atrophy or other causes for concern. (P.8, para. 4.4.8, Advisory Council on the Misuse of Drugs, U.K., 2002)

Pregnancy:
Tobacco smoking and alcohol use are significant causes of harm to the unborn child. A small proportion of women use cannabis during pregnancy and the birth weights of their babies are lower than expected. This is probably due to the effects of carbon monoxide in the smoke of cannabis cigarettes as similar findings are well established for tobacco smoking in pregnancy. (P.9, para. 4.5.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

Taken together this data suggest that cannabis use in pregnancy is not safe but that it is probably no more dangerous to the foetus than either alcohol or tobacco. Pregnant women should continue to be warned to avoid all these substances. (P.9, para. 4.5.3, Advisory Council on the Misuse of Drugs, U.K., 2002)

Gateway Theory:
Even if the gateway theory is correct, it cannot be a particularly wide gate as the majority of cannabis users never move on to Class A drugs. (P.9, para. 4.6.2, Advisory Council on the Misuse of Drugs, U.K., 2002)

Interestingly, other studies have found that the use of alcohol and tobacco in early teens (and especially in pre-adolescents) appears to be associated with the later use of many drugs including cannabis. In all these studies there is a distinct possibility that the driving factor in the misuse of drugs is the personality and/or peer group of the subject rather than the drug itself. (P.9, para. 4.6.3, Advisory Council on the Misuse of Drugs, U.K., 2002) It is not possible to state, with certainty, whether or not cannabis use predisposes to dependence on Class A drugs such as heroin or crack cocaine. Nevertheless the risks (if any) are small and less than those associated with the use of tobacco or alcohol. (P.11, para.5.5, Advisory Council on the Misuse of Drugs, U.K., 2002)

Cannabis and Driving: Cannabis appears not to make as major a contribution to road traffic or other accidents as alcohol. (P.10, para. 4.7.1, Advisory Council on the Misuse of Drugs, U.K., 2002)

HIV/AIDS Transmission: Injecting a drug is one of the most important causes of the spread of blood borne infections such as HIV or hepatitis. Unlike many drugs (opiates, stimulants, benzodiazepines and barbiturates) cannabis is not used by injection and so is free of these risks. (P.10, para. 4.7.2, Advisory Council on the Misuse of Drugs, U.K., 2002)

Conclusion:
Cannabis, however, is less harmful than other substances (amphetamines, barbiturates, codeine-like compounds) within Class B of Schedule 2 to the Misuse of Drugs Act 1971. The continuing juxtaposition of cannabis with these more harmful Class B drugs erroneously (and dangerously) suggests that their harmful effects are equivalent. This may lead to the belief, amongst cannabis users, that if they have had no harmful effects from cannabis then other Class B substances will be equally safe. (P.12, para. 6.2, Advisory Council on the Misuse of Drugs, U.K., 2002)

The Council therefore recommends the reclassification of all cannabis preparations to Class C under the Misuse of Drugs Act 1971. (P.12, para. 6.3, Advisory Council on the Misuse of Drugs, U.K., 2002)