Smoke without fire? Scaremongering by the British Lung Foundation over cannabis vs tobacco

June 11, 2012

The BLF is an admirable charity that promotes lung health and supports those affected by lung disease. Unfortunately, last week they produced a press release promoting unfounded claims about the harms of cannabis to the lungs. These claims were uncritically parroted from this press release as ‘news’ by the BBC, Channel 4, Sky, the Independent, Telegraph, Metro, Evening Standard, the Huffington Post and more.

The BLF, who wish to promote awareness of “the serious, even fatal impact [cannabis] can have on the lungs”, managed to hit the headlines with a survey about public attitudes to cannabis commissioned alongside their new report reviewing existing evidence. Surveys, with their (often unsupported) appearance of objectivity, are a popular way for groups, commercial or otherwise, to win press attention. It has worked for them before – the Daily Mail has a ten-year old article archived online reporting a virtually identical story of BLF “research” apparently showing that the dangers of cannabis are underestimated, and worse than tobacco. Then, as now, the BLF received news coverage as if they had made a breakthrough just through publishing a survey and a report of evidence. Confusingly, whilst this is the BLF’s second special report on cannabis, they have never dedicated a special report to tobacco, which causes the vast majority of lung cancer deaths and many other lung conditions.

This time around, the BBC, whose science coverage usually deserves praise, rehashed the first lines of the BLF’s press release, writing “88% [of the public] incorrectly thought tobacco cigarettes were more harmful than cannabis ones – when the risk of lung cancer is actually 20 times higher”. In this sentence, as in almost every news article I have seen on the subject, almost 9 in 10 of the public are condescended to as being mistaken, but where is the evidence for this assertion that tobacco is so much kinder to the lungs than cannabis? Could the public perhaps be wiser about drug harms than the BLF and the media? I had a closer look at the BLF’s report to check their evidence.

The BLF’s report itself references a great deal of scientific evidence, but it seems to be an attempt to collect evidence that supports their predetermined opinion that cannabis harms the lungs, rather than exploring the evidence to find out what the balance of findings really suggests. When the evidence they found was mixed, they came to firm conclusions that the most alarming interpretation of the most alarming evidence was true. This is most striking in the case of the lung cancer claim that tops the press release, that a cannabis joint is 20 times as carcinogenic as a cigarette. This is an old chestnut, listed amongst Wikipedia’s list of popular drug myths. But that didn’t stop Kenneth Gibson of the Scottish National Party lodging a motion (look for S4M-03197) in the Scottish Parliament last week on 8th June endorsing the BLF’s claims and recommendations.

This claim about the 20-fold cancer risk is prominent in the introductory ‘background’ information section of the BLF’s report. Here it assures the reader that the evidence explored in the report (section 3.2) shows this. But the report contradicts itself: Section 3.2 on cancer actually very reasonably says that “studies in human populations have yielded conflicting evidence on the subject: some suggest there is a link between smoking cannabis and lung cancer while others don’t [3 references]. It’s worth noting that these studies are of limited value as they looked at relatively small numbers of people and didn’t take into consideration the quantity of cannabis smoked or the effects of smoking a mixture of tobacco and cannabis. In addition, some previous evidence suggests that THC may have anti-carcinogenic effects”.

Having explained, with directions to three references, that the evidence is mixed and inconclusive, the report’s writer(s) disappointingly then give a long and overgenerous account of one of the three papers referenced, a 2008 study by Aldington (a thorough scientific rebuttal of which can be found here). They then dubiously interpret the study as suggesting that a joint is as carcinogenic as 20 cigarettes. Christopher Snowdon has written a blog post on just why this interpretation is wrong. Do the BLF at least give other evidence an airing? After considering Aldington’s paper, a much smaller account is given of another of their references, which says cannabis increases lung cancer risk 2.4 times, and they do not write anything about their third reference, which found no link to lung cancer. This last study, by Hashibe et. al., looked at more people’s cannabis use over a longer time, and so has a claim to be the most valid. Why did the BLF reference three studies then largely ignore the findings of two?

We cannot doubt the BLF’s worthy intentions to help us all look after our lungs, and indeed there are harm-reduction messages that should be heard about cannabis smoke, specifically that if you must use the drug despite the risks, rolling with tobacco may increase risk of harms, and that using a cannabis vaporiser instead of smoking it may decrease harms.

The BLF’s lack of care with the evidence, and the media’s lack of care in fact-checking, could have the opposite effect from their good intentions. Public confidence in science as a means of getting to the truth can only be harmed when the BBC reports “experts” mistakenly declaring that what 88% of us apparently think about cannabis is wrong. What’s more, if the BLF’s misguided information is believed, people could actually be put at greater risk of lung cancer, for example by cutting down on the cannabis in their joints and padding them out with more tobacco, or by making parents relatively more relaxed about finding out that their teenagers smoking cigarettes every day than finding out that they smoke the occasional joint.

(Apologies for low res image).

What can be done? The ISCD contacted the BBC on the 6th of June, but as yet the BBC have not replied or removed the inaccuracies although they have now included an alternative opinion on the subject from Peter Reynolds of Clear. The Metro, on the other hand, can be thoroughly commended for their prompt and prominent publication of critical responses to their article from me and other readers. We will pursue further corrections, firstly by contacting editors directly, and if that fails, through the PCC. I will update readers of this blog on any progress.

The ISCD’s aim is for ordinary people, without scientific expertise, to be able to find reliable information about the effects and risks of drugs. With thousands of voices clamouring to be heard, each offering conflicting views, it’s a huge challenge. As I write, the BLF’s claim about cannabis cigarettes being more carcinogenic than tobacco ones has already found its way onto Wikipedia’s information about cannabis harms, so Wikipedia currently reports, on different pages, the same claim as an evidenced fact and as a popular myth. Though I trust it won’t be there long, this shows how easily misinformation can gain the stamp of truth. The ISCD website,, should help individuals who are looking for evidence-based information. Our drugs information page on cannabis provides scientifically evidenced information on the drug and its effects and harms. For information on the specific connection between cannabis and cancer, see Cancer Research UK’s balanced information.

We gave the BLF the opportunity to address the inaccuracies and inconsistencies of their report which they declined, thus missing an important opportunity to address the very real harms of smoking. Public health organisations are to be commended for trying to help the general public make better choices.  Unfortunately in this case, the choice made was to confuse rather than inform.

39 Responses to “Smoke without fire? Scaremongering by the British Lung Foundation over cannabis vs tobacco”

  1. A Quiet Man Says:

    thank you for this information . as a parent of 2 young teenagers i do need to understand this and you have been straight and honest with the facts. thanks again doc

    • Iain Says:

      tobacco used WITH cannabis in joints , and what about the chemicals used to process readymade cigarettes tobacco and their carcinogenic properties

  2. Dear David – excellent post, just what’s needed to counteract this rubbish. BLF has been knowingly pulling this trick since 2002. I wrote a critique of similar arguments in 2002, when I was director of Action on Smoking and Health – it is preserved here: . We gave ave them the opportunity to change course then, and they declined. Not sure why they qualify to be a charity. What purpose is served by this. Good luck with the corrections… that’s important work. Clive

  3. Peter Reynolds Says:

    I think the really critical thing David is that the BLF claimed that its report had been subject to “…external, independent peer review, in order to ensure that it reflects the current evidence in as accurate and balanced way as possible.”

    This is self-evident nonsense. I have asked it to publish details of this review but had no response as yet. If it fails to support this claim then the BLF is as thoroughly discredited as is possible and one would expect mayhem if not resignations from the trustees.

    The report is based on prejudice against cannabis and cannabis users. It is a disgrace and the individual who wrote it, whose name I will not repeat, should be ashamed of himself.

    As you would expect, CLEAR is already in the process of submitting several PCC complaints. I would caution against any optimism about them though. The publishers will claim that all they were doing was reporting what the BLF had said and did so accurately.

    This is my letter to Dame Helena Shovelton, chief executive of the BLF:

  4. dan8richeson Says:

    It’s too bad that the prohibitionists have squandered their credibility long ago. They are preaching to their own choir. Even if this were true how does it compare to the damage done by the prohibitionist thugs who have turned the lives of cannabis users upside down and even killed them and/or their loved ones?

    The laws regarding cannabis were born on the wings of lies and pampered by propaganda such that now the tightly held belief systems are going to have to reckon with the desire of all humanity to live with dignity, free from the oppressive tyranny that ignorance and bigotry have spawned.

  5. I’ve been a huge fan of your commitment to evidence based drug policy for a long time, but only just found your blog. You are an inspiration to people like me who know that drug policy is not based on evidence but on a smorgasbord of different pressures and influences. Let’s make the biggest pressure on policy makers be from those who want sensible decisions to be made that will benefit individuals and society!

    I look forward to reading your input in the future, and to checking out your back-catalogue of information!

    – Craig Keeble

  6. focusonpeace Says:

    The voice of reason and wisdom

  7. Rob Chapman Says:

    It is good to see that even respected services such as the BLF are being called to account regarding the (mis)information they provide. Australia also has a worryingly high rate of cannabis consumers who mix tobacco with cannabis (called spin here). For those who use cannabis, from a health perspective this is a bad practice . As a worker in the A & D sector, I appreciate the clarity that is being brought to bear on this issue .

  8. […] neuropsühhofarmakoloogia professor ja endine Ühendkuningriigi uimastinõunik David Nutt oma blogis ning Ühendkuningriigi kanepi legaliseerimise aktivistide ühendus UKCIA oma […]

  9. Matt Wall Says:

    Good work David!

  10. Michael Says:

    It’s called a vaporizer.

    how incompetent are people when they don’t even bother to advertise a product that can allow someone to smoke without inhaling tar to all smokers (not just weed users).

    Plus, check out the other studies and the peer reviews on studies like this one.
    The negative effects of smoking are so much worse than for marijuana that smoking cannabis is completely trivial in comparison to smoking tobacco.
    I mean,
    they put over 3 thousand extra chemicals in cigarettes and we wonder why they cause cancer while cannabis doesn’t.

    In fact,
    2 separate studies found that cannabis actually slows down tumor growth in the lungs.
    It’s funny that none of these anti-cannabis studies can ever replicate their results from causation theory to this.
    That’s because they leave out variables on purpose and tailor the data to get the outcome they desire to support their agenda like they always have.

    The big indicator that there is a bias behind any given study to do with cannabis is when they are trying to justify putting drug addicts in prison.
    No matter what the health effects are,
    nothing justifies putting people who are sick with addictions in prison.
    That is charging the victim and that is what makes a law unjust to begin with let alone the fact that it’s excessive punishment under cruel and unusual.
    Anyone who supports this is a monster hands down.
    I’ve heard from girls that were raped and not able to report it because of the fear of being killed, people attempt suicide over this law, mentally ill people charged over and over again when they are known to self-medicate, young kids be able to get drugs at the drop of a hat due to the lack of a legal age limit, hundreds of thousands of people being brutally murdered by drug cartels when we could take this out of the hands of organized crime, etc.

    Stop supporting bad policy that has never once been effective in the 60+ years that it’s been in effect.
    Also, the dealers are the criminals,
    not the drug addicts.
    If you cared about helping them..
    you wouldn’t be trying to ruin their lives even more by putting them in jail.

    • ColinB Says:

      1) Vaporizors are less effective and produce a totally different effect to either a joint (with tobacco) OR a water pipe (without) and is not my extremely informed opinion a viable / credible alternative.

      2) Suggest that you confine your coomments and accusations of incompetence to subject areas where you have at least some expertise.


      Aged 53 – smoking grass for 35 years, recently recovering from (HPV) oral cancer and looking to reduce ongoing risks or a reoccurence through eliminating tobacco use.

      • From Admin (not David);-
        Hi Colin, glad to hear you’re recovering from that cancer, and hope you do successfully manage to eliminate your tobacco use. I’m not to clear on what your objection is to the article. David and the ISCD are experts on drug science, we’re not experts on your subjective opinion on vaporisers. If you personally don’t like them, that’s fine, we don’t mind! The article very cautiously suggests that they may be helpful for those seeking to reduce the harms they face. Also, many cannabis users DO find them to be a credible and viable alternative. Scientific research has shown them (at least the ones tested) to effectively deliver the active ingredients of cannabis. (e.g Indeed they have been used for this purpose in research as it is possible to calibrate a dose more consistently. Perhaps you tried a poor quality one? I think that unfortunately the best are very pricey.
        I’m sorry that you don’t think David has the necessary expertise to comment on cannabis. I think a few people might disagree. He can only comment from a scientifically-minded rather than a users perspective, which I suppose is a small limitation, but he never tries to pretend otherwise.

  11. Adam Says:

    I can’t understand why the British people don’t want to increase this country’s revenue, the same sort of coffee shop culture as Holland, even if it “only” generated £2 BILLION(!!!) a year extra revenue to the country, it would pay for so many positive things, it would be better than the national lottery! I have no faith in the government because they appear to be morons. If they can’t figure work out the simple economics then I’m amazed we aren’t already in total financial disarray…….
    Cannabis has never killed anyone, and we can’t work out a way to accept that some people would rather use cannabis than easily lethal, highly addictive and damaging alcohol.
    I’m sick of banging my head against a brick wall. I’m leaving for any one of the many countries with politicians that work with and for the people rather than for themselves. Shame on those politicians that used to smoke, loved that feeling of freeing the mind and relaxing the body, taking a moment in the chaos to stop and take a little bit of time out for themselves and others, and then they became politicians and sold their souls and their integrity to the devil. It’s the worst type of dishonesty, “Do as I say not as I do” I can understand ignorance, but knowing the truth and still saying nothing, that’s simply disgusting. No wonder we don’t trust a word from their mouths.
    I feel the British public are so bored of listening to spin, and never really knowing who is actually telling the truth anymore, it needs someone above the rhetoric to come out in support, a national treasure. I personally think Prof. Nutt already fits the bill, but I think the last great trustworthy person untainted and honest in the eyes of the public is Stephen Fry. Perhaps a special QI episode on the subject of cannabis is called for? Surely Alan Davies can’t say no after this

    Decriminalisation because it works, Holland rents out prison space to Belgium and earns £2.5Billion from cannabis tourism. Surely that says it all?

  12. Rick Simpsonite Says:

    “Medical Cannabis and its effect on human health”

    Rick Simpson’s “Run from the cure”

    These 2 films will astonish you, cannabis kills cancer and many other diseases.
    Watch them while you still can…

  13. Rick Simpsonite Says:

    “Medical Cannabis and its effect on human health”

  14. […] writing that post, I ran across a blog post dated June 16, 2012, from Dr David Nutt, neuropsychopharmacologist, professor, author and former […]

  15. Rick Simpsonite Says:

    Dr Robert Melamede Phd UCCS
    is recording groundbreaking research based on (Rick Simpsons) cannabis oil hi strength cannabiniods and the endocannabinoid system, as found in all vertebrates. Just look at this current study involving very aggressive squamous cell carcinoma on the scalp. The cancer is being drawn out of the skin, killed and then dropping off before healing of fresh skin begins (not for kids/the squeemish!)

    Other current studies are here

  16. Rick Simpsonite Says:

    Dear Prof Nutt, I notice that the blf has now (prob because of global reaction) moved the article on thier website so when anyone clicks on your paragraph 1 link they cannot find the article, now you would have to actively search for it. I believe they’re running scared of the truth coming out. This is just like when President GHW Bush cancelled the us federal cannabis program in the 1980’s stating that “people might get the wrong idea that cannabis is actually medicinally beneficial” The truth is in 1977 George Herbert Walker Bush left his position as director of the CIA and was appointed as director of Eli Lilly Pharmaceuticals by Dan Qualye’s father & family who along with Bush are major shareholders in Lilly. Then in 1982 Omni Magazine & other sources report that Eli Lilly, Abbot Labs, Pfizer, Smith, Kline & French and other drug companies would lose HUNDREDS OF MILLIONS TO BILLIONS OF DOLLARS annually if cannabis were legal in the US alone. Now, do you really think that the “powers that be” want us to cure ourselves free of charge??????

    It’s time to wake up and start questioning instead of merely accepting…

  17. Sugel Says:

    “But then why do the studies show that those that have smoked pot seem to be protected from lung cancer, including head and neck? The THC must be getting there!” Please read this: “Under the conditions of these 2-year gavage studies, there was no evidence of carcinogenic activity* of 1–trans–delta9–tetrahydrocannabinol in male or female F344/N rats administered 12.5, 25, or 50 mg/kg.” This is good. “There was equivocal evidence of carcinogenic activity of THC in male and female B6C3F1 mice based on the increased incidences of thyroid gland follicular cell adenomas in the 125 mg/kg groups. ” This is bad. The higher the dose of THC, the higher the risk of Thyroid cancer in labratory animals. The next step is obviously seeing where the safe THC administration levels are going to be. Also: “The incidences of mammary gland fibroadenomas and uterine stromal polyps were decreased in dosed groups of female rats, as were the incidences of pancreatic adenomas, pituitary gland adenomas, and interstitial cell adenomas of the testis in dosed male rats, and liver neoplasms in male and female mice. These decreases were likely related to lower body weights in dosed animals. ” This is a good thing, but they cannot pin point if THC was related to this, or lower body weights during the study. Either way, as said, the higher doses of THC in Lab Animals caused higher incidences of Thyroid Cancer.

  18. […] This complex issue recently hit the headlines when the British Lung Foundation released a study suggesting that the cancer risks of cannabis had been underestimated, although this has been questioned by some experts including Professor David Nutt. […]

  19. gold account Says:

    Also, people often mix cannabis with tobacco. There is strong evidence that smoking tobacco causes lung cancer and chronic lung disease. This makes it difficult to isolate whether health problems are specifically caused by cannabis or tobacco, says the report.

    • Iain Says:

      what about the carcinogenic properties of chemicals used to process the tobacco , is there any research there ?
      and why was cannabis made illegal ?
      wasnt it a NEWSPAPER owner that decided it was ? using his papers to push the idea ?
      because hemp makes better paper than his timber based paper which he heavily invested in !

  20. EyesWide Open Says:

    watch “run from the cure”

  21. Michael the simple peasant. Says:

    Just wanted to say that I am a high school drop out (left highschool in year 8), and daily cannabis smoker (of course all my “problems” should be blamed on cannabis) and even my bullshit meter went into overdrive when reading the BLF claims. I have even had “experts” tell me that I would be better off returning to drinking (I am a former alcoholic) than smoking cannabis, and no I am not kidding.

  22. Reblogged this on Cannabis seed blog and commented:
    well said

  23. stephen brophy Says:

    cannabinoids in cannabis are good for every one, i do not smoke but like to read, the goverment are not telling the truth about drugs at all! thanks to professor nutt we have someone telling it as it is, thank you and keep up your good work.

  24. Mark Hamilton Says:

    I have smoked cigarettes since i was 17 now 52 i smoked cannibis for 25 yrs i also have copd i gave up cannibis since learning about my copd but not ciggarettes but now i think i should give up the fags which do me no good and go back to the cannibis which medically done me wonders much of what i got out of cannibis i would normally be getting a prescription for from my gp. SINCE GIVING up cannibis i have returned to my gp.i think it has been going on to long that poeple think cannibis is a bad drug when in my opinion is not poeple get brainwashed.. yes anything in excess is not good. But poeple have to use there own commonsense. Alcohol ruins far more lives if alcohol was a new thing then without any doubt it would be banned. If we went like amsterdam the goverment would get the taxes the police would save money and not waste there time on menial cannibis offences.perhaps next time i vote i will vote libdem who want to decrimilise cannibis i beleve.

  25. linda brady Says:

    after seeing my mum on oxygen with copd through smoking just 12 cigarettes a day I would say to everyone throw them in the bin my mum died 2 yrs ago having to depend on oxygen 24 hrs a day in the end not nice to see someone go through this

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