Marijuana Damages DNA and May Cause Cancer

By chillinwill · Jun 15, 2009 · ·
  1. chillinwill
    A lot of studies have shown marijuana is not good for you. It can fry the brain and contribute to psychosis. The latest one finds "convincing evidence" that marijuana smoke damages the genetic material DNA in ways that could increase the risk of cancer.

    Toxic substances in tobacco smoke can damage DNA and increase the risk of lung and other cancers. However, there has been uncertainty over whether marijuana smoke has the same effect.

    Scientists are especially concerned about the toxicity of acetaldehyde, present in both tobacco and marijuana. However, it has been difficult to measure DNA damage from acetaldehyde with conventional tests.

    Using a highly sensitive new method called modified mass spectrometry, Rajinder Singh at the University of Leicester and colleagues found the data they sought, they report in the June 15 issue of Chemical Research in Toxicology, a journal of the American Chemical Society.

    "These results provide evidence for the DNA damaging potential of cannabis [marijuana] smoke, implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development," the researchers write. "The data obtained from this study suggesting the DNA damaging potential of cannabis smoke highlight the need for stringent regulation of the consumption of cannabis cigarettes, thus limiting the development of adverse health effects such as cancer."

    Earlier this year, a separate study found evidence that adolescents and young adults who smoked a lot of marijuana are more likely than non-users to have disrupted brain development. Research in 2007 found pot smokers have on average a 41 percent increased risk of developing psychotic disorders later in life.

    The study was funded by the European Union Network of Excellence, the Medical Research Council and other groups.

    By LiveScience Staff
    Sat Jun 13, 12:01 pm ET

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  1. Nature Boy
    Yowza! You always have to be sceptical of a marijuana article that starts out by saying 'it can fry the brain'. Well, by whichever criteria frying of the brain is set under, I'm sure American Idol does the same thing yet no-one's highlighting its need for stringent regulation.
  2. nibble
    The conclusion of this study, or at least the articles conclusion seems to be implying that cannabis itself is what is "causing" cancer. Acetaldehyde is a combustion product of cannabis, tobacco and any burning plant matter, cannabis doesn't have to be smoked and any negatives due to carcinogenic compounds being generated during combustion would be eliminated via other methods including vaporisation.

    People inhale acetaldehyde as soon as they step outside, in fact it is also a metabolic product of ethanol. You have to measure actual harm, DNA damage is of course a primary marker for carcinogenicity but you can't study that in isolation and conclude the substance definitely will cause future cancer. It's not all about about acetaldehyde, studies have shown that despite the theoretical damage cannabis smoke would do it doesn't appear to be anywhere near as bad as that of tobacco.
  3. psyche
    This myth doesn't seem to die easily. Yes, cannabis smoke might have compounds which are mutagenic or teratogenic, but wider studies have found no link between cannabis smoke and cancer. Maybe because of THC's anti-cancer effect, maybe because of some other reason.
  4. Mike177

    SWIM has been studying biology at a major state university, but has not taken many classes and is not an authority on the subject by any means. At least not yet. So please correct SWIM if SWIM is mistaken, SWIM knows there are a lot of knowledgeable SWIY's on this board.

    So if a substance damages DNA (a mutagen), it must be a carcinogen... right? wrong. Without getting too far into it, there are several kinds of DNA mutations that occur every day. Some are not as bad as others, and our cells have several "check points" when reproducing to correct any mistakes in DNA. If the DNA cannot be repaired the cell self-destructs and does not undergo mitosis (cell division). To allude to the conclusion that because a substance is a mutagen that it is a carcinogen is just not true and misleading. Could a substance in cannabis have a carcinogenic effect? It sure could but SWIM will wait for the evidence, until then SWIM thinks he put his money on the test of time.

    SWIM is unfamiliar with the current methods, but has conducted the Ames tests at a lab at his university. It is important to read the entire article carefully. Remember the whole saccharin scare? Around 1977 the US and Canada banned saccharin based on a study linking saccharine to bladder cancer in rants. If SWIM recalls, they were pumping massive amounts of the substance, IV into rats every day for quite a while. (sketchy on details) and what did ya know! some of the rats had bladder cancer! So I suppose that means that if SWIM puts a few grams of Sweet n' low in his morning coffee he is doomed for cancer! As many know, this study turned out to be extremely flawed. Anyone remember that government study that concluded that MDMA created "holes" (not holes, but doesn't that sound scary!) in your brain..... many SWIY's know how credible that turned out to be.

    Is repeated, daily, long-term use of marijuana good for long term cognitive function.... No, SWIM imagines its not. But the statement above is quite misleading. Unfortunately if you tell that to your average Joe (why not Joe the plumber), they may believe it. "WHAT!? A STUDY!? THAT CAN'T BE FALSE. ITS A 'STUDY' AFTER ALL"

    Another issue is explaining a correlation. Does Marijuana usage lead to increased risk for developing psychotic disorders? Or do those who are at high risk for developing psychotic disorders self medicate with marijuana?

    When looking at the link SWIM failed to find any link or mention of a published article in a peer reviewed journal, or data regarding any research at all. Words are cheap, a good reliable study is not. To SWIM, unless some compelling peer-reviewed articles come out, these claims are just as credible as the DEA in providing accurate information.

    Sorry if SWIM ranted a bit, his pet cat has been up for 24 hours with his face in a book popping dextroampetamine and is mentally clouded, tiered, and a little energetic.

    SWIM hopes that post was coherent!
  5. EscapeDummy

    You hit the nail on its ugly, grotesque head. Correlation, not causation. Conditions such as insomnia and other sleeping disorders often are the backbone of worse mental problems. Those with insomnia tend to watch lots of late night TV. Would a legitimate researcher conclude that late-night TV indeed induces mental problems? Not if he didn't want to be ridiculed to all hell, and lose all credibility.

    Seriously people, go to It's basically the National Enquirer (a trashy tabloid) of science websites. I don't know how these guys are still in business. Most of their articles at the very least spread misinformation; at the worst, they deliberately weasel in lies and untruths to spin their stories. Most of the "research articles" they print are re-interpreted and usually don't follow the scientific method, or have a sample size far too small, or do something else which is simply stupid. The "marijuana can fry your brain" statement, as others have remarked, is entirely unsubstantiated.
  6. Mike177
    It's funny you mentioned that correlation does not equal causation... One of the reasons SWIM was up all night was so SWIM could study psychological research designs. :)

    I have only read that one article, so I don't feel that I can't denounce it fairly...... but I would be reluctant to call it..... science.... That's not fair, its at least bad science. Can I not find it, or do they not cite a single source, journal article, or anything to back up their claims?
  7. Euthanatos93420
    The science for prohibiting marijuana is good but not for evolution?

    Fucking puritans can't tell a political agenda from the taxes they pay.
  8. corvardus
    SWIM has uploaded the original PDF file from the research cited in the LiveScience article. SWIM has not even read it yet, so can't comment.

    SWIM will not be pleased if it is a simple case of 1) Burning Plant Matter 2) Die from cancer.

    The article has been uploaded here

    SWIM is rolling his eyes at this article. SWIM has cut down to the minimum the waffling, but this is the essence.

    So in other words any typical human exposure to Acetaldehyde by the very fact of living is most likely already past tolerance levels meaning that any consumption of cannabis is going to have negligible additional risk than what we already achieve by simply living in a 1st world country. Good we got that out of the way.... Also SWIM has attempted to find how much acetaldehyde is present in the average cannabis cigarette, SWIM can't seem to find that data, in this article.

    So we have 60 chemicals classed as carcinogens for cigarettes, out of those how many of those are polycyclic aromatic hydrocarbons?

    Having a quick check of the literature... There are 10 poly cyclic aromatic hydrocarbons in tobacco, meaning 20 polycyclic aromatic hydrocarbons in Cannabis smoke. What about the other 40 carcinogenic chemicals from tobacco? No one mentions those. /snort. (I'll see if SWIM can get full text of that one later)

    Also this might give you a laugh:

    LOL so this guy started smoking 20 cannabis cigarettes per day when he was 11. God I wish I had that much spending money at that age! Good parenting there.

    This article screams of a PhD thesis, and whilst the technical science behind it is sound it oozes, nay drips of naivity.

    So what can we get from this piece of "research". Acetaldehyde that is found in fruits, vegetables, cooked meats, environmental polution, acetic acid (and its metabolites), metabolites of alcohol has been found to increase the risk of cancer.

    So the data obtained from this study suggests the DNA damaging potential of the 5-a-day fruit consuming advertisements made by the UK government is mistaken. The study highlights the consumption of fruit, meats and vegetables highlight the stringent regulation of the consumption of those materials.

    That is about as much credence as you can give this article. Hardly "convincing" evidence with so many variables. In the scientific arena all it does is confirm that Cannabis, a plant based material will, upon incomplete combustion give off acetaldehyde, which has been found to be a carcinogenic substance.

    Therefore, the vaporisation of cannabis is perfectly OK and so, therefore, should not require "stringent" regulation.
  9. chillinwill
    'Cannabis alters human DNA' -- new study

    A new study published by University of Leicester researchers has found "convincing evidence" that cannabis smoke damages DNA in ways that could potentially increase the risk of cancer development in humans.

    Using a newly developed highly sensitive liquid chromatography-tandem mass spectrometry method, the University of Leicester scientists found clear indication that cannabis smoke damages DNA, under laboratory conditions.

    They have now published the findings in the journal Chemical Research in Toxicology1.

    The research was carried out by Rajinder Singh, Jatinderpal Sandhu, Balvinder Kaur, Tina Juren, William P. Steward, Dan Segerback and Peter B. Farmer from the Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine and Karolinska Institute, Sweden.

    Raj Singh said: "Parts of the plant Cannabis sativa, also known as marijuana, ganja, and various street names, are commonly smoked as a recreational drug, although its use for such purposes is illegal in many countries.

    "There have been many studies on the toxicity of tobacco smoke. It is known that tobacco smoke contains 4000 chemicals of which 60 are classed as carcinogens. Cannabis in contrast has not been so well studied. It is less combustible than tobacco and is often mixed with tobacco in use. Cannabis smoke contains 400 compounds including 60 cannabinoids. However, because of its lower combustibility it contains 50% more carcinogenic polycyclic aromatic hydrocarbons including naphthalene, benzanthracene, and benzopyrene, than tobacco smoke."

    Writing in the journal Chemical Research in Toxicology, the scientists describe the development of a mass spectrometry method that provides a clear indication that cannabis smoke damages DNA, under laboratory conditions.

    The authors added: "It is well known that toxic substances in tobacco smoke can damage DNA and increase the risk of lung and other cancers. Scientists were unsure though whether cannabis smoke would have the same effect. Our research has focused on the toxicity of acetaldehyde, which is present in both tobacco and cannabis."

    The researchers add that the ability of cannabis smoke to damage DNA has significant human health implications especially as users tend to inhale more deeply than cigarette smokers, which increases respiratory burden. "The smoking of 3-4 cannabis cigarettes a day is associated with the same degree of damage to bronchial mucus membranes as 20 or more tobacco cigarettes a day," the team adds.

    "These results provide evidence for the DNA damaging potential of cannabis smoke," the researchers conclude, "implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development."


    The study was funded by the European Union Network of Excellence ECNIS, the Medical Research Council and Cancer Research UK.

    1. Rajinder Singh, Jatinderpal Sandhu, Balvinder Kaur, Tina Juren, William P. Steward, Dan Segerback and Peter B. Farmer (2009) Evaluation of the DNA Damaging Potential of Cannabis Cigarette Smoke by the Determination of Acetaldehyde Derived N2-Ethyl-2′-deoxyguanosine Adducts. Chemical Research in Toxicology, 22, 1181-1188.

    June 16, 2009
  10. Waffa
    LMAO, i specially love when they slip in facts like "A case of metastatic lung cancer was reported in a 27 year old man who smoked 20 cannabis cigarettes per day for 16 years" - they cant be serious right?

    This is so ridiculous in SO many way's that it's hard to comment.
    In best case i can see that cannabis MUST be supper safe if u start to smoke (really hard) when u are 11 years old and after 16 years you are still not dead.
    Simple conclusion by most simple people:" Does that mean that if you smoke 20 times less, its 20 times safer ... that means smoking entire one joint every day in your life starting from 11 years old... you still live happily? Let's legalize it, it's safe"

    not that i would make so simple conclusions but yeah.. this fact about person who started to smoke when he was 11 is no way less stupid.
  11. Free Will-E
    It's studies like this that put everyday people whom are on the fence about marijuana on the wrong side. All that the government has left is skewed studies and sensationalist propaganda. The masses are waking up, and progressing in the right direction, and these control freaks are getting desperate.
  12. Quagsign
    If it IS true. All I have to say is this:


  13. shivakiva2112
    I didn't read through this entire thread, but what I did notice was that the article failed to mention that acetaldehyde is the primary metabolite of alcohol in the body. Anyone who has ever experienced a hangover has had mild acetaldehyde poisoning.

    It is almost comical but actually kind of sad that these scientists are making public statements of the kind in this article. This is some of the worst science I have read and probably the most clearly influenced by federal dollars. These guys couldn't suck government dick any harder.
  14. EscapeDummy
    I feel like... we should do something about this. Email the site, calling them out on the flawed science?
  15. Greenport
    They're worried about acetaldehyde from tobacco and marijuana?!?!

    News flash: People drink alcohol (aka ethanol) all the time, and what is the oxidation product of ethanol. Anyone know? It's ^ acetaldehyde. The body further metabolizes it to acetic acid (but that's unrelated.) This is a study regarding the composition of tobacco and marijuana smoke. It states that the marijuana smoke tested contained 1200 micrograms of acetaldehyde.

    So now, they're worried about the levels of acetaldehyde found in the smoke when certainly drinking alcohol causes the body to create the compound in amounts much higher than a measly 1200 micrograms...that makes no sense.

    Combine that with the fact that THC has anti-cancer effects and finds medical use for this reason, and with the fact that it states data from potentially incorrect studies, and the fact that the title states marijuana may fry the brain, and you see just how propaganduous and infactual this article really is.

    I would say write the author and tell him how much misinformation his/her story contains, but (omgz!) it isn't listed! The author is 'LiveScience Staff' so it isn't even credited to a single person...
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