Pubdate: Sat, 03 Nov 2001
Source: New Scientist (UK)
Copyright: New Scientist, RBI Limited 2001
Contact:  http://www.newscientist.com/
Details: http://www.mapinc.org/media/294
Bookmark: http://www.mapinc.org/pot.htm (Cannabis)

SANITY AT LAST

Whatever The Dangers Of Cannabis, Draconian Laws Make No Sense

IS CANNABIS more - or less - harmful than its legalised cousins 
alcohol and nicotine? Last week, bang on cue, this hoary old question 
surfaced yet again as the British government signalled its intent to 
relax the laws on cannabis possession, and join what is becoming an 
almost global trend.

Other countries have already taken steps towards decriminalising 
possession, but nobody expected the same from Britain (see p 12). The 
admission that cannabis is not as harmful as heroin and cocaine goes 
against everything it's been saying for years. It also leaves the US, 
which is sticking to this hardline position, increasingly isolated.

But not quite alone. One of the strongest attacks on Britain's U-turn 
came from the nation's bestknown neuroscientist, Susan 
Greenfield-Oxford pharmacologist, TV presenter and now a member of 
the House of Lords. In a thundering broadside in a daily paper, 
Greenfield blasted liberal campaigners who seek to play down the 
evidence that cannabis permanently damages the brain. It's good to 
see scientists of Greenfield's standing voicing strong opinions on 
public issues. However, having reported on the science of cannabis 
for many years, we have to disagree with her conclusions.

To take just one example, she points out that some 7000 milligrams of 
alcohol are needed to achieve intoxication, whereas for cannabis the 
figure is just 0.3 milligrams: cannabis is far more potent and hence 
far more dangerous, she reasons. But what this really means is that 
you have to have 20,000 times as much alcohol coursing through your 
veins before you feel the effects. By then your liver is having to 
work overtime. Alcohol certainly lacks cannabis's ability to act on 
brain receptors in a potent and specific manner: that is one reason 
why booze can be so deadly.

A number of cannabis users do develop a serious dependency problem. 
And in excess the drug can lead to poor concentration, even bouts of 
paranoia. But permanent brain damage? A few lab studies have, it's 
true, reported that cannabis-like substances can harm nerve cells 
cultured in the test tube. But such cultures are notoriously fragile, 
and other studies have found no signs of brain damage in animals 
given doses far higher than those needed to produce intoxication in 
humans.

And even if they hadn't, it wouldn't matter - at least not as far as 
changing the laws on cannabis go. The evidence from other countries 
is that more relaxed laws do not lead to more youngsters using the 
drug. Wherever cannabis lies in the league table of harmful 
substances, there seems little point in imprisoning people for 
possessing small amounts unless this is likely to make the drug less 
popular. And all the signs are that it doesn't.
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MAP posted-by: Josh