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Monday, 11 November, 2002, 22:23 GMT
Cannabis smoke 'worse' than tobacco
Many people think smoking cannabis is safe
Smoking pure cannabis is more harmful to lungs than tobacco, a health charity is warning.

A study by the British Lung Foundation found that just three cannabis joints a day cause the same damage as 20 cigarettes.

It is vital that people are fully aware of the dangers so they can make an educated decision and know the damage they may be causing

Dr Mark Britton
And when cannabis and tobacco are smoked together, the effects are dramatically worse.

Evidence shows that tar from cannabis cigarettes contains 50% more cancer causing carcinogens than tobacco.

Dr Mark Britton, chairman of the British Lung Foundation, said: "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.

"It is vital that people are fully aware of the dangers so they can make an educated decision and know the damage they may be causing."

Dr Britton emphasised that the British Lung Foundation report - called A Smoking Gun? - was "not about the moral rights and wrongs of cannabis".

But, he said, they simply wanted to make sure people were completely clear about the respiratory health risks involved.


Surveys carried out earlier this year showed that 79% of children believed that cannabis was 'safe'.

Only 2% understood correctly that there are health risks associated with smoking the drug.

The British Lung Foundation report also shows that the health dangers of cannabis have substantially increased since the 1960s.

That means that clinical studies carried out in the sixties and seventies may well underestimate the ill effects of smoking the drug.

This is due to increased amounts of THC - or delta-9 tetrahydrocannabinol, the major active chemical compound - in the cannabis consumed today.

Pleasure receptors

In the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and thereby influences the activity of those cells.

Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement.

Dame Helena Shovelton, chief executive of the British Lung Foundation, said: "Puff and inhalation volume with cannabis is up to four times higher than with tobacco - in other words you inhale deeper and hold your breath with the smoke for longer before exhaling.

"This result in more poisonous carbon monoxide and tar entering into the lungs."

The British Lung Foundation is calling for the government to implement a public health education on the health risks of cannabis.

The charity will also be pushing for further research into cannabis and the lungs and its potential link with the development of chronic obstructive pulmonary disease.

Read a selection of your comments on this subject.

As a secondary school teacher, I constantly have to correct the almost universal misconception amongst teenagers that smoking cannabis is harmless, or at least much safer than tobacco-smoking. This report will perhaps change the behaviour of a few, to whom health risks are a significant factor in their recreational drug use.
Andy Bolton, UK

Almost everything is bad for your health if taken in excess. How big a killer would stress be if we didn't have alcohol, tobacco and hash?
Andy, Egypt

Relatively few pot smokers smoke every day

Andrew Nason, USA
Yes, marijuana does contain cancer causing carcinogens. However, look at statistics regarding amount of use. Most cigarette smokers smoke a pack a day, while relatively few pot smokers smoke every day, and even less smoke three joints a day. Further, much of the tar (over 90%) can be filtered out through the use of water filtration, and it can be double filtered to remove close to all of the tar. Another thing is that pot is not physically addictive, while nicotine is. So smoking three joints one day doesn't mean that the body will require three joints the next day. When someone smokes a pack of cigarettes in a day, chances are they will do the same thing the next day, because they are addicted.
Andrew Nason, USA

Was this research published in a peer-reviewed medical journal somewhere? I didn't see a reference. That's not a guarantee that the research is good, but it's a reasonable way for non-experts like me to gauge the study's quality.
John Kelsey, USA

This report has elements which are as expected as they are unexpected. After a cigarette is re-rolled with cannabis, it is smoked filterless. So is it surprising that the effect of smoking three joints with no filter is as harmful as smoking 20 filtered cigarettes?? Not to me, I'm afraid...
Paul, netherlands

Inhaling smouldering plant material is apparently not what lungs are good at.

Name Here
Thank you for including this article on cannabis smoking on your website. Public education is a very effective modifier of human behaviour. Inhaling combustion products from smouldering plant material is apparently not what lungs are good at. That anyone would assume otherwise suggests to me a considerable degree of denial.
bob collens, Canada

I'm surprised how rarely mentioned are the alternatives to smoking hash or grass. Treated like any other cooking ingredient (dried) it can be added to everything from pizza to brown bread and biscuits. Smoking isn't very comfortable but eating can be yummy. In moderation, just a pinch, see package for details.
Norman Conquest, US

Just because we have other things which are bad for you legalised, doesn't mean that we should make cannabis legal - it has often been said that if cigarettes and alcohol had been discovered in a more recent age, they would have been criminalised. It's too late for them, but not too late to stop people harming themselves and others whilst under the influence of weed. People are trying to help us, what's wrong with their advice? Chill out, people...
Sonia Aherne-Conroy, UK

I think most cannabis smokers are well aware of the risks. I, for one, would welcome decriminalization and taxing. I don't have a problem paying for the associated health problems from smoking. Perhaps the politicians should look at the statistics for abuse suffered from alcohol. I've never seen someone high on pot abuse someone. Too much work!
E. Butler-Henderson, Canada

I can't help being suspicious of reports against cannabis; who funded it?

Tom, UK
According to the UK Government's website for death certificates, alcohol, cigarettes and sugar kill tens of thousands every year. Heroin and aspirin/paracetamol both kill 800 a year and cannabis has gone up to seven, which is still less than nut allergies. I can't help being suspicious of reports against cannabis; who funded it? Cannabis is not a big killer - high street fast food retailers and pubs that encourage binge drinking - they are the real murderers. But they make money so who cares?
Tom, UK

It is a report that makes for worrying reading. I'm not sure that people will believe the basic message though, or heed it even if they do.
Ross Little, England

I always thought that smoking cannabis was safer than tobacco, so it's a bit of a shock. I'm grateful for this research.
Az, London, UK

We could put these health warnings on the packet cannabis is sold in, as we already do with tobacco. But only if we legalise the market.
Brian Milner, UK

We should have a policy of protecting the health of cannabis users

Simon Donovan, Britaine
Anyone who smokes cannabis regularly should realise that it is harmful to the respiratory system; nevertheless millions will continue to use it as cannabis acts as a stress buster. Cannabis can be synthesised into a harmless spray which can achieve the same affects as smoking a joint. The problem is that the development and sale of sprays would require the (shock horror) legalisation and licensing of cannabis. We should have a policy of protecting the health of cannabis users rather than the absolute failed policies of attempting to criminalise us.
Simon Donovan, Britain

None of this is news. The increased health risks caused by inhaling more and for longer have been talked about for years. I think the government should be pressing tobacco companies to control what kinds of chemicals are added to tobacco, rather than try to continuously rule our lives.
Mike Dunn, UK

I'm sure it is bad for you, you never see an athletic hash smoker breaking any records! But then again so is bacon, sex, beer and all things good!
Phil, England

People knew the government advice was wrong

David M, UK
This study should have been done and made public 30 years ago. From the ignorant public information films and anti-drug campaigns people who smoked cannabis knew the government advice was wrong (smoking weed will not turn you into Zammo from Grange Hill) but they've had no other source of information so have assumed it's safer than it is. At least cannabis smokers could judge the risk for themselves (as do the millions of drinkers and cigarette smokers in the UK).
David M, UK

At least cannabis is typically additive-free. Compare that to the amount of rubbish the tobacco companies put in cigarettes - saltpetre, flavour enhancers, preservatives, and so on. Most users will simply not smoke three joints of pure grass in a day! And cannabis users tend to share. And most importantly, THC is far less addictive than nicotine.
Ben Godwin, UK

People who smoke will suffer more illness in older age and like tobacco smokers, place a disproportionate strain on health services - so they should pay more to cover this cost. Cannabis should be taxed heavily like tobacco. Such a shame the government prefers to subcontract distribution to the criminal fraternity, and do so tax free!!
J Halstead, UK

The BBC's Gill Higgins
"Pro-cannabis campaigners are worried"
Dame Helena Shovelton, British Lung Foundation
"People smoke cannabis differently"
See also:

11 Nov 02 | Health
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05 Nov 02 | Health
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07 Jan 02 | Health
21 Mar 00 | Medical notes
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