Reefer Badness

March 24th, 2007 by Ben Goldacre in bad science, drurrrgs, references, statistics | 51 Comments »

Ben Goldacre
Saturday March 24, 2007
The Guardian

The more I see of the world [looks pensively out of window] the more it strikes me that people seem to want more science, rather than less, and to deploy it in odd ways: to abrogate responsibility; to validate a hunch; to render a political or cultural prejudice in deceptively objective terms. Because you can prove anything with science, as long as you cherry pick the data and keep one eye half closed.

The Independent last Sunday ran a front page splash: “Cannabis – An Apology” was the headline. “In 1997, this newspaper launched a campaign to decriminalise the drug. If only we had known then what we can reveal today…Record numbers of teenagers are requiring drug treatment as a result of smoking skunk, the highly potent cannabis strain that is 25 times stronger than resin sold a decade ago.” Twice, in this story, cannabis is 25 times stronger than it was a decade ago. For Rosie Boycott, in her melodramatic recantation, skunk is “30 times stronger“. In one inside feature the strength issue is briefly downgraded to a “can”. It’s even referenced. “The Forensic Science Service says that in the early Nineties cannabis would contain around 1 per cent tetrahydrocannabidinol (THC), the mind-altering compound, but can now have up to 25 per cent.”

Well I’ve got the Forensic Science Service data right here in front of me, and the earlier data from the Laboratory of the Government Chemist, the United Nations Drug Control Program, and the European Union’s Monitoring Centre for Drugs and Drug Addiction. I happen to think that people are very well able to make their own minds up about important social issues when given true facts.

The Laboratory of the Government Chemist data goes from 1975 to 1989. Resin pootles around between 6% and 10% THC, herbal between 4% and 6%, with no clear trend.

The Forensic Science Service data then takes over to produce the more modern figures, showing not much change in resin, and domestically produced indoor herbal cannabis doubling in potency to around 12% or 14%. (2003-5 data in table under references).

The rising trend of cannabis potency is gradual, fairly unspectacular, and driven largely by the increased availability of intensively UK grown indoor herbal cannabis.

If you were in the mood, you could argue that intensive indoor cultivation of a plant that is very easy to cultivate outdoors is the cannabis industry’s reaction to the illegality itself. It is dangerous to import in large amounts. It is dangerous to be caught growing a field of it. So perhaps it makes more sense to grow it intensively indoors, producing a more concentrated product. There is little incentive, on the other hand, to produce a perversely strong skunk product for the mass market, since most people tend not to pay any more for unusually strong skunk.

There is, of course, exceptionally strong cannabis to be found in some parts of the UK market today: but there always has been. The United Nations Drug Control Program has detailed vintage data for the UK online. In 1975 the LGC analysed 50 seized samples of herbal cannabis: 10 were from Thailand, with an average potency of 7.8%, and the highest was 17%. In 1975 they analysed 11 samples of seized cannabis resin, 6 from morocco, average strength 9%, with a range from 4% to 16%.

To get their scare figure, The Independent have compared the worst cannabis from the past with the best cannabis of today. But you could have cooked the books in exactly the same way 30 years ago if you’d wanted: in 1975 the weakest herbal cannabis analysed was 0.2%; in 1978 the strongest herbal cannabis was 12%. Oh my god: in just 3 years herbal cannabis has become 60 times stronger.

And in fact, what’s most amazing is that this scare isn’t new. In the US, in the mid 1980s, during Reagan’s “war on drugs”, it was claimed that cannabis was 14 times stronger than in 1970, which rather sets you thinking. If it was 14 times stronger in 1986 than in 1970, and it’s 25 times stronger today than the beginning of the 1990s, does that mean it is now, in fact, 350 times stronger than 1970?

That’s not even a crystal in a plant pot. That’s impossible. That would require more THC to be present in the plant than the total volume of space taken up by the plant itself. That would require matter to be condensed. If I was a physics-minded branding manager, I would suggest Quark Gluon Plasma as the most appropriate street name for this substance: and I look forward to reading about the scare in the Independent tomorrow.


United Nations Drug Control Program (quoting Laboratory of the Govt Chemist):

European Union Monitoring Centre for Drugs and Drug Addiction (quoting and graphing Forensic Science Service data):

UK Advisory Council on the Misuse of Drugs Act 2005 Review of Cannabis for Home Office (more recent UK THC potency tabulated up to 2005) :

Also worth reading is the broader coverage of the issues around these figures from the excellent Transform Drug Policy Foundation Blog:

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51 Responses

  1. CUtech said,

    July 29, 2010 at 5:13 pm

    An(n) amusing observation:

    Ann Druryan

    If she and her late husband are the slackjaws, I’m headed over to the LHC to get some of that Quark Gluon Plasma out of their black holes.