High anxieties

What the WHO doesn't want you to know about cannabis

Health officials in Geneva have suppressed the publication of a politically sensitive analysis that confirms what ageing hippies have known for decades: cannabis is safer than alcohol or tobacco.

According to a document leaked to New Scientist, the analysis concludes not only that the amount of dope smoked worldwide does less harm to public health than drink and cigarettes, but that the same is likely to hold true even if people consumed dope on the same scale as these legal substances.

The comparison was due to appear in a report on the harmful effects of cannabis published last December by the WHO. But it was ditched at the last minute following a long and intense dispute between WHO officials, the cannabis experts who drafted the report and a group of external advisers.

As the WHO's first report on cannabis for 15 years, the document had been eagerly awaited by doctors and specialists in drug abuse. The official explanation for excluding the comparison of dope with legal substances is that "the reliability and public health significance of such comparisons are doubtful". However, insiders say the comparison was scientifically sound and that the WHO caved in to political pressure. It is understood that advisers from the US National Institute on Drug Abuse and the UN International Drug Control Programme warned the WHO that it would play into the hands of groups campaigning to legalise marijuana.

One member of the expert panel which drafted the report, says: "In the eyes of some, any such comparison is tantamount to an argument for marijuana legalisation." Another member, Billy Martin of the Medical College of Virginia in Richmond, says that some WHO officials "went nuts" when they saw the draft report.

The leaked version of the excluded section states that the reason for making the comparisons was "not to promote one drug over another but rather to minimise the double standards that have operated in appraising the health effects of cannabis". Nevertheless, in most of the comparisons it makes between cannabis and alcohol, the illegal drug comes out better--or at least on a par--with the legal one.

The report concludes, for example, that "in developed societies cannabis appears to play little role in injuries caused by violence, as does alcohol". It also says that while the evidence for fetal alcohol syndrome is "good", the evidence that cannabis can harm fetal development is "far from conclusive".

Cannabis also fared better in five out of seven comparisons of long-term damage to health. For example, the report says that while heavy consumption of either drug can lead to dependence, only alcohol produces a "well defined withdrawal syndrome". And while heavy drinking leads to cirrhosis, severe brain injury and a much increased risk of accidents and suicide, the report concludes that there is only "suggestive evidence that chronic cannabis use may produce subtle defects in cognitive functioning".

Two comparisons were more equivocal. The report says that both heavy drinking and marijuana smoking can produce symptoms of psychosis in susceptible people. And, it says, there is evidence that chronic cannabis smoking "may be a contributory cause of cancers of the aerodigestive tract".

From New Scientist, 21 February 1998