For and against: Cannabis control: costs outweigh the benefits * For * Against

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Abstract
High costs of control noted decades ago Perhaps doctors have often led the search for less harmful drug policies because the premier axiom of medicine is “first, do no harm.” In 1893 Britain's Indian Hemp Drugs Commission concluded that excessive use of cannabis was uncommon and that moderate use produced practically no ill effects. In 1926, Sir Humphrey Rolleston, then president of the Royal College of Physicians, chaired a committee that recommended against criminalising opiates.2 Similarly, Dr W C Woodward, counsel to the American Medical Association, testified in Congress in 1937 to the lack of evidence justifying criminalisation of cannabis3 and several other commissions in Britain, Canada, and the United States have come to similar conclusions.4 In 1972, an American presidential commission concluded that marijuana “does not warrant” the harmful consequences of “criminal stigma and threat of incarceration.”5 In 1978, President Carter told Congress that “penalties against the use of a drug should not be more damaging to an individual than the use of a drug itself; and where they are they should be changed. Nowhere is this more clear than in the laws against the possession of marijuana.”6 Unfortunately, little has changed since President Carter uttered these words. The UK Police Foundation's review of cannabis policy in 2000 was the most recent senior international committee to reach the same verdict: “Our conclusion is that the present law on cannabis produces more harm than it prevents.”7 Health risks of cannabis The pro-cannabis lobby conveniently overlooks the serious health effects of cannabis, pointing to its safety record in comparison with other illicit and legal drugs, such as tobacco and alcohol. The lobby would have us believe that cannabis never killed anyone. It is true that cannabis is relatively safe in overdose compared with heroin, but it is far from harmless in the longer term, particularly for heavy or regular users. The World Health Organization has concluded that cannabis, when smoked, is twice as carcinogenic as tobacco.1 It causes carcinoma of the lungs, larynx, mouth, and oesophagus as well as other chronic pulmonary diseases,2 with evidence of a dose-response relation.3 These carcinomas appear earlier than cancers that are purely the result of tobacco smoking. Cannabis increases the risk of death in people with heart disease.4 Furthermore, cannabis is now 10 times as pure as it was 20 years ago, which points to potentially greater health risks than earlier research has identified.5 In vulnerable individuals, cannabis precipitates schizophrenia and other psychotic disorders and worsens their course. 2 6 It is worth remembering that about 15% of schizophrenic patients commit suicide. This is not to mention other clear adverse psychological effects of cannabis, including depression, anxiety, and violent behaviour.6 Cannabis has up to 60 psychoactive ingredients, so it is hardly surprising that it is bad for the mental health of many vulnerable people. Apart from death, cannabis also causes dependence in about 10% of users and in 50-90% of regular users.2 The number of cannabis users seeking specialist help has doubled in the past 10 years, accounting for 10% of attendances at drug treatment clinics in the United Kingdom.7 This is likely to be an under-representation, as most clinics tend to be geared more towards helping users of opiates. Also included among the risks are impairment of cognitive function, reduced academic achievement, teratogenic effects, immunosuppression, impaired fertility, and increased promiscuity and sexually transmitted diseases in regular users. 2 5 6 8 As Henry has recently pointed out “it is perilous for the voice of science to be drowned out by campaigners for legalisation who are dismissive of the mounting evidence on dependence and harm.”9 The effect of cannabis intoxication on cognitive and motor functions is another aspect of the harm it does. Research on the adverse effects of cannabis in vehicle accidents is complicated by confounding factors such as alcohol intoxication, although in one UK study of fatal road accidents, no alcohol was detected in the bodies of 80% of people found positive for cannabis at necropsy.10 It is now recognised that the separate effects of alcohol and cannabis on psychomotor impairment and driving performance are approximately additive.2 And yet because of the absence of a roadside test equivalent to the breathalyser for alcohol, cannabis is much more difficult for the police to detect accurately. All of this points to appreciable social, health, and economic hazards of cannabis.