Smoking Marijuana Can Increase the Risk of Cancer

[Erik von Nein]

According to Rajinder Singh and his team at Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine and Karolinska Institute, Sweden, smoking 3-4 cannabis cigarettes is the same as smoking 20 tobacco cigarettes.

Marijuana Damages DNA And May Cause Cancer, New Test Reveals

ScienceDaily (June 15, 2009) — Using a highly sensitive new test, scientists in Europe are reporting "convincing evidence" that marijuana smoke damages the genetic material DNA in ways that could increase the risk of cancer.

Researchers note that 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.

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.

The scientists describe development and use of a modified mass spectrometry method that showed clear indications that marijuana smoke damages DNA.

“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.”

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.

"In conclusion, 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 article states. "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."

Journal reference:

1. Singh et al. 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, 2009; 22 (6): 1181 DOI: 10.1021/tx900106y

Adapted from materials provided by American Chemical Society.

Pretty significant amount.. Though, the study mostly focuses on the damage acetaldehyde can do.

I'd assume, though, the ingesting marijuana would lessen the impacts.

Fixed your spelling.

[General Zod]

So. . .3-4 marijuana joints is equivalent to 20 cigarettes? I'd be curious to see a study comparing how many people smoke 3-4 joints a day vs how many smoke 20 cigarettes a day, personally. (Also, can somebody fix that title? It's an eyesore when they spell marijuana properly in the article several times.).

[Executor32]

Also, tobacco cigarettes are almost always filtered, while cannabis one are almost never. I would think that would make a significant difference by itself.

[FireNexus]

I'm assuming these joints are of equivalent mass to a cigarette? Approximately 1-1.25 grams. If that's the case, I can guarantee you that, Snoop Dogg notwithstanding, there are few marijuana smokers who ingest that amount. Besides that, it focuses only on acetaldehyde without any mention of tobacco specific nitrosamines. Those, AFAIK, are responsible for the bulk of tobacco's cancer causing properties.

[Erik von Nein]

Yes, I know that few marijuana users smoke more than 3 joints a day, it was just an equivalent amount they used. Also, Nexus, they did mention the amount of compounds in cigarettes, and how many of them are carcinogens. Besides which, that is fairly irrelevant to the article's main point, which is that there is a not-insignificant increased risk of cancer while smoking marijuana.

Filtering marijuana smoke would cut down on particulate matter inhalation, in all likelihood. The amount which it would might be something you could guesstimate off of the amount by which tobacco cigarettes cut down on particulate matter.

[Erik von Nein]

*sigh* And before it gets brought up, no I'm not in favor of keeping marijuana banned.

[KlavoHunter]

How does this study stack up against other studies which have shown that marijuana successfully shrinks cancerous tumors?

[Erik von Nein]

It's possible that other chemicals do have positive effects on existing tumors and acetaldehyde only causes problems in the lungs. Do you happen to have links to these studies?

[Broomstick]

How does this study stack up against other studies which have shown that marijuana successfully shrinks cancerous tumors?

A lot of the chemotherapy drugs that are used to shrink tumors are, themselves, carcinogenic and can lead to additional cancers years later. Therefore, it would seem that a substance can both shrink tumors AND cause cancers at the same time.

[Surlethe]

I'm assuming these joints are of equivalent mass to a cigarette? Approximately 1-1.25 grams. If that's the case, I can guarantee you that, Snoop Dogg notwithstanding, there are few marijuana smokers who ingest that amount. Besides that, it focuses only on acetaldehyde without any mention of tobacco specific nitrosamines. Those, AFAIK, are responsible for the bulk of tobacco's cancer causing properties.

Can you point me to the research supporting your AFAIK?

[Pablo Sanchez]

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.

By "damage" are they talking about the cellular damage that leads to cancer, or about the damage that would cause bronchitis, COPD, and so on? It isn't clear to me from this paragraph. That said, I wouldn't be surprised that smoking joints is more injurious to health than cigarettes; as people have said, they're unfiltered and the smoke is deeply inhaled and held for a long time. Of course, smoking 20 cigarettes a day (one pack) is pretty common while 1 joint is sufficient to get a normal person high for hours; 3-4 joints every day would be, I think, evidence of a serious dependency.

[Erik von Nein]

I assume they mean damage to cancer-suppressing genes and genes that regulate DNA repair enzymes. Proto-oncogenes.

[Shroom Man 777]

Inhaling smoke of any kind, from burning matter of any kind, is never healthy. I'm sure you can get cancer from inhaling multiple sticks of burning paper, of equivalent amounts to tobacco or cannabis, just as well.

[PainRack]

Inhaling smoke of any kind, from burning matter of any kind, is never healthy. I'm sure you can get cancer from inhaling multiple sticks of burning paper, of equivalent amounts to tobacco or cannabis, just as well.

Not really. Lung Cancer was relatively new despite the high dosage of smoke inhalation amongst various groups such who burnt heavy coal or peat.

[PainRack]

How does this study stack up against other studies which have shown that marijuana successfully shrinks cancerous tumors?

Which ones are they?

[General Zod]

Inhaling smoke of any kind, from burning matter of any kind, is never healthy. I'm sure you can get cancer from inhaling multiple sticks of burning paper, of equivalent amounts to tobacco or cannabis, just as well.

Not really. Lung Cancer was relatively new despite the high dosage of smoke inhalation amongst various groups such who burnt heavy coal or peat.

Relatively new or relatively undocumented?

[jcow79]

If marijuana were to become legalized is it likely the tobacco industry would jump on it to add to their product line? Would we see a lot of the harmful substances added to cigarettes also added to marijuana essentially creating a more harmful and addictive product than cigarettes and marijuana are already? It seems to me any industry would have motivation to make marijuana AS addictive as cigarettes so that people ARE smoking a pack a day or at least more than just 1 a day. Would Marlboro's new product be Niccojuana?

[General Zod]

If marijuana were to become legalized is it likely the tobacco industry would jump on it to add to their product line? Would we see a lot of the harmful substances added to cigarettes also added to marijuana essentially creating a more harmful and addictive product than cigarettes and marijuana are already? It seems to me any industry would have motivation to make marijuana AS addictive as cigarettes so that people ARE smoking a pack a day or at least more than just 1 a day. Would Marlboro's new product be Niccojuana?

Why would the tobacco industry jump on it? It's doesn't have anywhere near the capacity for physical addiction the way tobacco does, it requires significantly different facilities for growing (read: massive dollars to invest in a risky product) and even if it were legalized there's still a massive stigma associated with marijuana that doesn't exist to nearly the same degree for tobacco.

[jcow79]

Why would the tobacco industry jump on it? It's doesn't have anywhere near the capacity for physical addiction the way tobacco does,...

That's what I'm getting at. Wouldn't there be incentive to MAKE marijuana as addictive by blending it with tobacco in an attempt to bring both the marijuana and tobacco users under one product?

it requires significantly different facilities for growing (read: massive dollars to invest in a risky product)...

Isn't marijuana A LOT easier to grow than tobacco? I admit to knowing very little about agriculture. I have no idea the relative yields of a typical marijuana crop vs. a typical tobacco crop but even a casual Google search seems to indicate marijuana is pretty simple to produce. A legalized marijuana would likely have certain federal standards to adhere to so it wouldn't be your cousin Jimmy's basement grown blend, but when you consider the profits being estimated from legalizing marijuana I would think any major industry might consider selling the product.

and even if it were legalized there's still a massive stigma associated with marijuana that doesn't exist to nearly the same degree for tobacco.

As far as stigma goes, we're talking about an industry that is well versed in peddling a largely demonized product. Wouldn't they be well suited to 'rebrand' marijuana?

[General Zod]

That's what I'm getting at. Wouldn't there be incentive to MAKE marijuana as addictive by blending it with tobacco in an attempt to bring both the marijuana and tobacco users under one product?

What makes you think there wouldn't be regulations in place against doing just that? Especially with the recent powers the FDA received over the tobacco industry?

Isn't marijuana A LOT easier to grow than tobacco? I admit to knowing very little about agriculture. I have no idea the relative yields of a typical marijuana crop vs. a typical tobacco crop but even a casual Google search seems to indicate marijuana is pretty simple to produce. A legalized marijuana would likely have certain federal standards to adhere to so it wouldn't be your cousin Jimmy's basement grown blend, but when you consider the profits being estimated from legalizing marijuana I would think any major industry might consider selling the product.

In small amounts, yes. Growing large amounts of high quality plants in anything but tropical environments require specialized hydroponics, greenhouses, lots of electricity and employees. In other words it's not cheap.

As far as stigma goes, we're talking about an industry that is well versed in peddling a largely demonized product. Wouldn't they be well suited to 'rebrand' marijuana?

Marijuana has the problem of being seen as a gateway drug and lots of soccer moms railing against it, which is largely false but still persists regardless. No such bones about tobacco, even if it's become less popular in the last few years.

[FireNexus]

I'm assuming these joints are of equivalent mass to a cigarette? Approximately 1-1.25 grams. If that's the case, I can guarantee you that, Snoop Dogg notwithstanding, there are few marijuana smokers who ingest that amount. Besides that, it focuses only on acetaldehyde without any mention of tobacco specific nitrosamines. Those, AFAIK, are responsible for the bulk of tobacco's cancer causing properties.

Can you point me to the research supporting your AFAIK?

This is the best I can find in a couple of minutes, and it admittedly doesn't indicate "the bulk" so I'll be happy to concede that point.

Abstract of the study by Stephen S. Hecht

Abstract: DESCRIPTION (provided by applicant): Tobacco-specific nitrosamines are among the most important carcinogens in tobacco products. Extensive analytical studies, carried out in the U.S. and internationally, clearly document the presence in tobacco products of substantial quantities of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), as well as several related compounds. The carcinogenic activities of NNK and NNN in laboratory animals are well-established. These data, together with considerable biochemical evidence from studies with rodent and human tissues, support the prominent role of tobacco-specific nitrosamines as major causative factors for a number of tobacco-related cancers including lung, oral cavity, esophagus, and pancreas. Metabolism and DNA adduct formation are critical factors in the mechanisms of carcinogenesis by NNK, its major metabolite 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanol (NNAL), and NNN. Our goal is to understand these processes and use this knowledge as a basis for developing practical strategies for prevention of tobacco-induced cancer. Our overall hypothesis is that cancer susceptibility relates to carcinogen dose as well as the balance between carcinogen metabolic activation and detoxification. Our specific aims are: 1. Carry out a comprehensive analysis, using liquid chromatography-electrospray ionization-mass spectrometry, of DNA adduct formation and persistence in rats chronically treated with NNK, NNAL, and NNN, and extend these studies to humans. This research builds on our recent structural characterization of pyridyloxobutyl DNA adducts of NNK and NNAL. 2. Determine the levels and persistence of formaldehyde-derived cross-linked and hydroxymethyl DNA adducts in rats treated with NNK, NNAL, and N-nitrosodimethylamine. We have recently shown, for the first time, that the metabolic activation of N-nitrosomethyl carcinogens leads to formation of these formaldehyde-DNA adducts in vitro. 3. Develop methods to determine the balance of metabolic activation and detoxification of NNK in humans. This is critical to an understanding of NNK metabolism as an indicator of cancer susceptibility. 4. Assess the endogenous formation of NNK in smokers, snuff-dippers, and people who use nicotine replacement therapy. This aim extends our observation that 2'-hydroxylation of nicotine leads directly to the precursor of NNK. 5. Develop mass spectrometry methods to analyze nicotine, cotinine, and total NNAL in human toenails, as a biomarker of tobacco smoke exposure. Better biomarkers of chronic tobacco smoke exposure are needed, particularly for studies of environmental tobacco smoke exposure and cancer. The results of these studies will provide exciting new data on mechanisms of nitrosamine carcinogenesis in laboratory animals and humans, and will lead to practical methods to test the hypothesis that human uptake, metabolic activation and detoxification of tobacco-specific nitrosamines are related to cancer susceptibility in humans.

Emphasis mine.

[wolveraptor]

Anyone who smokes marijuana, or does any recreational drug, daily already has dependence problems. That said, you can at least minimize the risks by using a vaporizer or ingesting it instead.

[Simon_Jester]

I'm beginning to suspect that within the next fifty years, everything will be shown to cause cancer, and half of everything will be shown to cure it.

Part of the problem is that even good scientific studies are typically done to a 95% confidence standard... which means that 5% of them are false positives. And any positive result of the form "X causes cancer!" is likely to make the news. So an unknown and difficult-to-estimate percentage of cases where the general public hears "X causes cancer!" will be false alarms.

To suppress the risk of false positives you need multiple studies of the same thing, and you need intellectually honest reporting of the negative results as well as the positive ones.

[Akkleptos]

I'm beginning to suspect that within the next fifty years, everything will be shown to cause cancer, and half of everything will be shown to cure it.

As my father (a surgeon) told me once:

"LIVING causes cancer"

Meaning pretty much everything we eat, drink, inhale, or even do can pottentially trigger the abnormal cell growth that can in turn become cancer. Hell, even wearing a necktie can potentially cause skin cancer by repeated bruising!

[Erik von Nein]

Oie.

Yes, many things can cause cancer, it's the risk level that's important.

Anyway, the article has a journal link if you're curious about their methodology.