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Comparison undesirable: the health risks of alcohol and cannabis

Franjo Grotenhermen

It is not appreciated by people who defend the current legal status of cannabis to compare the dangers of legal and illegal drugs, especially those of alcohol and cannabis. It is too obvious that alcohol is a more dangerous drug than cannabis.

Recently, Professor Wayne Hall of the Center for the Study of Adolescent Substance Abuse at the University of Queensland in Australia published an article in a medical journal entitled: "Robin Room and Cannabis Policy: Dangerous Comparisons." It was a festschrift in honor of Professor Robin Room, a companion of Professor Hall. Together, the two had compared the dangers of cannabis with those of other legal and illegal drugs on behalf of the World Health Organization (WHO) some 20 years ago. The WHO wanted to publish a report on the dangers of cannabis use and had invited leading scientists from around the world to contribute from their field of research, for example on the potential for dependence, the effects of cannabis smoking on the respiratory tract, or risks to road traffic. This report was published in 1997, but the contribution of Professors Hall and Room on their drug comparison is missing. Professor Hall now explained the reason for this unusual process.

He had become a member of the WHO expert group on the health effects of cannabis use in 1993. The working group first met in Geneva in November 1993. The plan was for WHO to publish the expert reviews and a consensus summary of all the reviews. Wayne Hall was to contribute to several chapters, one of which was to compare the health effects of cannabis with those of alcohol, tobacco, and opiates. The head of the expert group, Professor Harold Kalant from Canada, suggested Robin Room as co-author for this chapter. The two experts set to work. They not only compared the health effects of the four drugs, but ended their chapter by considering what would happen to the negative health effects of cannabis if the drug were legalized.

They found that the negative health effects of cannabis use in the context of "current patterns of use" were much lower than those of alcohol and tobacco. One of the ways they explained this was that there were far fewer regular cannabis users than users of alcohol and tobacco, according to global policy at the time. However, they also pointed out that even if cannabis were legalized, it was unlikely that cannabis would cause greater harm than alcohol because cannabis did not cause liver damage and other gastrointestinal disorders, it did not cause fatal overdoses, it did not damage the nervous system as much as alcohol, and it had a lower significance for traffic accidents compared to alcohol.

After discussion with other experts made it clear that these passages were controversial, Hall and Room, in a revised version, emphasized the uncertainties in predicting health risks of cannabis if legalized.

In 1995, the working group met again and produced the consensus abridged version of the report. This contained, as planned, summaries of all the reports, including the chapter comparing harms from the use of alcohol, cannabis, opiates, and tobacco. Finally, in late 1997, about two years late, the World Health Organization published the abridged version of the report, but this time without the comparison of legal and illegal drugs. The WHO argued that this comparison had been "more speculative than scientific" because drug users use combinations of different drugs, making it difficult to attribute adverse effects to specific drugs. In addition, the "quantitative risks of cannabis use are largely unknown because reliable epidemiological studies are lacking."

Wayne Hall writes in his current article that he only learned later that there were some individuals who used their influence to prevent the publication of the chapter on the "dangerous" drug comparison, including representatives of the United Nations Drug Control Program (UNDCP) and representatives of the United States.

In 1998, this suppressed chapter became the subject of an article in New Scientist entitled "Big fears: what WHO doesn't want you to know about cannabis." In 1999, the head of the then working group, Professor Kalant, published a book that included full versions of all the chapters for the WHO overview on cannabis, including the chapter comparing the dangers of cannabis, alcohol, tobacco and opiates.

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