Pubdate: Mon, 11 Nov 2002
Source: New Scientist (UK Web)
Copyright: New Scientist, RBI Limited 2002
Contact:  http://www.newscientist.com/
Details: http://www.mapinc.org/media/294
Note: The British Lung Foundation report is on line as a .pdf file at 
http://www.lunguk.org/news/a_smoking_gun.pdf

CANNABIS SMOKING 'MORE HARMFUL' THAN TOBACCO

Smoking pure marijuana is at least as harmful to lungs as smoking tobacco, 
a report from the British Lung Foundation concludes.

And in some key ways, it may be more dangerous.

For example, the BLF's review of previous research highlights that just 
three marijuana joints a day causes the same damage to the lung's airways 
as 20 cigarettes, mainly because of the way joints are smoked.

Individually, cannabis and tobacco produce the same constituents and 
quantities of chemicals known to be toxic to respiratory tissue, other than 
nicotine, the report says. But when cannabis and tobacco are smoked 
together, the health effects are worse.

"These statistics will come as a surprise to many people, especially those 
who choose to smoke cannabis rather than tobacco in the belief it is safer 
for them," says Mark Britton, chairman of the BLF. A UK survey conducted 
earlier in 2002 found that 79 per cent of children believed cannabis to be 
'safe'.

Deep Breath

A key finding highlighted by the review of 90 published papers is that the 
amount of smoke taken into the lungs is two thirds larger if cannabis is 
being smoked.

The smoke is also taken one third deeper into the lungs - and that smoke is 
held an average of four times longer before being exhaled.

"You inhale deeper and hold your breath with the smoke for longer before 
exhaling.

This results in more poisonous carbon dioxide and tar entering into the 
lungs," says Helena Shovelton, BLF's chief executive.

Other points in the report include:

* Tar from cannabis cigarettes contains up to 50 per cent higher 
concentrations of carcinogens benzathracenes and benzpyrenes than tobacco smoke

* THC, the primary psychoactive ingredient of cannabis, decreases the 
function of immune system cells that help protect the lungs from infection

* The average cannabis cigarette smoked in the 1960s contained about 10 
milligrams of tetrahydrocanabinol (THC), the primary psychoactive 
ingredient. Today, it may contain 150 mg.

"This means that the modern cannabis smoker may be exposed to greater doses 
of THC than in the 1960s or 1970s," says the report. "This in turn means 
that studies investigating the long-term effects of smoking cannabis have 
to be interpreted cautiously."

Mouth Spray

Cannabis is the most widely consumed illegal drug in the UK. In 2000, 
almost 45 per cent of 16 to 29 year olds in the UK said they had used 
cannabis at some point.

"We are not making any policy recommendations. The aim of this report is to 
try to inform the public that if you do choose to smoke cannabis, be aware 
of the health risks," says a BLF spokeswoman.

Cannabis-based medicines could be prescribed for medical use in the UK as 
early as 2003, following the recent success of final-stage trials.

But medicinal cannabis is supplied through a mouth spray or in tablet form.

"We have always been keen to find additional ways of administering cannabis 
as a medicine," says Nina Booth-Clibborn of the UK's Medicinal Cannabis 
Research Foundation. "It did seem that smoking would not be the best way."

Lyndon Pugh, editor of pro-cannabis magazine CC Newz, is not impressed by 
the report: "These allegations have been made before countless times.  Lot 
of things are dangerous, like driving."
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MAP posted-by: Alex