Marijuana Not Linked To Lung Cancer

This doesn't mean cynically (and uselessly) ignoring a study because it's hard to find people who smoke weed past middle age, either: you have to consider the methodology as it is, not as you'd like it to be, and try to understand what the study means in practice.

Does this not mean the study is rather incomplete?
 
Does this not mean the study is rather incomplete?

If you can't understand even the one single sentence you quoted, which itself answers the question you just asked, how am I to respond to you in a manner that you will understand? The key phrase is "what the study means in practice".

Keep in mind that people who stop smoking tobacco before middle age still experience some increased risk of cancer. This should be a hint: the study is fine. A reasonable, measured criticism would be that it does not adequately assess the risk of marijuana smoking to people beyond middle age. It rather obviously is a good assessment* of the risk of marijuana smoking in people below middle age, which is what it measures. There is no clear reason, unless you can provide one (you can't), that these effects cannot be measured separately, and in fact it is common to perform studies on a single age-cohort.

*I haven't read it. sekio seems to think it's okay, which is good enough for me.
 
That was rhetoric, merely a stimulant for conversation.

I value opinions just like every human being.

Tobacco didn’t have these types of age categories in it’s studies... I see no reason why the middle age thing was even applied. Does the population of weed smokers also not have increased risk for cancers for a period of time of withdrawing from smoking?

*I* in fact did read the studies... I wouldn’t say they seem incomplete without me reading them... Which they in fact do.

Sekio actually was helping me prove a valid point which you made as well as I did: That the plants did in fact only become as radioactive as the soil they grow in...

I consistently said from the get-go that both plants are indeed creating some of the same byproducts of burning...

I did state that many of the “tar” theories that many stoners use is rather inconsistent. A little weed with a lot of tar is in fact no safer than a lot of tobacco with a little tar...

Most of this is stuff that has and is set in stone already. Smoking plant material is quite universal in byproducts besides active constituents.

You can burn a random tree and come to some if not most of the same carcinogenic hydrocarbons being made...
 
The answer is "all of them", because tar is not a precisely defined term, and what definition is used depends on the precise aim of the research in question. It makes more sense, if the object of concern is carcinogenicity, to compare the levels of specific compounds. However, keep reading.

http://www.ukcia.org/research/ComparisonOfSmoke.pdf

Marijuana has significantly higher levels of compounds which present no carcinogenicity concern, such as ammonia and cyanide, though these are recognizable buzzword chemicals that are often reported in the media. The major nitrosamines are obviously below detection limits in marijuana smoke.

The important table is Table 9: certain of these polycyclic aromatic hydrocarbons, such as benzo[a]pyrene, are extremely potent carcinogens because their metabolites readily intercalate with DNA and interfere with transcription. A good description of this mechanism is given on the Wikipedia page for benzo[a]pyrene:

http://en.wikipedia.org/wiki/Benzo(a)pyrene

In general, marijuana seems to be roughly at parity with tobacco on the content of PAHs in mainstream smoke, maybe slightly lower.

Now the caveat: these numbers, as it is commonly reported, are per cigarette. The importance of this fact cannot be overstated, and explains to a great degree the large discrepancy in many studies regarding the content of marijuana smoke. The size of a cigarette is largely standardized; the size of a joint is up to the smoker. In some older studies on cannabis, the size of a cigarette used is... two grams:

http://pubs.acs.org/doi/abs/10.1021/ac60366a048?journalCode=ancham

Even at my highest rate of usage, I didn't smoke two grams of weed in a week, much less in a single joint. In the study I've linked, the typical size of a cigarette is 0.775 grams.

Note also that the method of smoking influences the content of smoke. In particular, it is suggested that the "extreme" condition applies more to marijuana smoking than tobacco smoking.

This post is a reminder to make sure you understand the methodology of a study, not just the conclusions. This doesn't mean cynically (and uselessly) ignoring a study because it's hard to find people who smoke weed past middle age, either: you have to consider the methodology as it is, not as you'd like it to be, and try to understand what the study means in practice.

According to the information in that chart which Sekio had posted, are the cigarettes (for marijuana and tobacco) the same size? According to that chart which Sekio had posted, a marijuana cigarette has 8 times the tar of a tobacco cigarette. But is that chart talking about a marijuana cigarette which is larger than a tobacco cigarette, the same size, smaller, etc?

The variables in that study may explain why a lot of this information is very contradictory.

The amount of a specific substance may be a variable which may result in different results for different studies. It's always important to know the variables in a study when coming up with a conclusion for what the study says.
 
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According to the information in that chart which Sekio had posted, are the cigarettes (for marijuana and tobacco) the same size? According to that chart which Sekio had posted, a marijuana cigarette has 8 times the tar of a tobacco cigarette. But is that chart talking about a marijuana cigarette which is larger than a tobacco cigarette, the same size, smaller, etc?

Dude, actually read the stuff I post and maybe you'll learn something. That chart compared 700mg cannabis joints to 700mg cigarettes.
 
You should actually be able to be warned for posting misinformation that goes this far. Just accept the facts and don't argue based on your "common sense", use some actual facts of your own to argue against.

and no, smoke is not smoke. smoke is not just 1 element. smoke is what stuff turns to when vaporized and incinerated. So by definition weed smoke and tobacco smoke are completely different.
It's not equally as poisonous (you were WRONG) and it's not always going to be cancerous no matter how much you like to say it.

It is cancerous. Even those studies which said that "marijuana smoke does not cause cancer, and marijuana smokers have less of a risk for cancers, etc", have noted that marijuana smokers get precancerous growths in their bodies. The only reason those studies claim that marijuana smokers don't get cancer is because they didn't spend more time on those studies. The studies were not long-term. Even those studies hinted at marijuana smoke's carcinogenic effects.
 
It is cancerous. Even those studies which said that "marijuana smoke does not cause cancer, and marijuana smokers have less of a risk for cancers, etc", have noted that marijuana smokers get precancerous growths in their bodies. The only reason those studies claim that marijuana smokers don't get cancer is because they didn't spend more time on those studies. The studies were not long-term. Even those studies hinted at marijuana smoke's carcinogenic effects.

This is simply not true. You've been told time and again that it's not true, yet you keep saying this.

Is there any point in keeping this thread open, other than to allow you to have your own personal dartboard here on this forum?

Again, here is the abstract which this thread is based on:

Ann Am Thorac Soc. 2013 Jun;10(3):239-47. doi: 10.1513/AnnalsATS.201212-127FR.

Effects of marijuana smoking on the lung.

Tashkin DP.

1 Division of Pulmonary and Critical Care Medicine, David Geffen School of
Medicine, University of California at Los Angeles, Los Angeles, California.

Regular smoking of marijuana by itself causes visible and microscopic injury to
the large airways that is consistently associated with an increased likelihood of
symptoms of chronic bronchitis that subside after cessation of use. On the other
hand, habitual use of marijuana alone does not appear to lead to significant
abnormalities in lung function when assessed either cross-sectionally or
longitudinally
, except for possible increases in lung volumes and modest
increases in airway resistance of unclear clinical significance. Therefore, no
clear link to chronic obstructive pulmonary disease has been established.
Although marijuana smoke contains a number of carcinogens and cocarcinogens,
findings from a limited number of well-designed epidemiological studies do not
suggest an increased risk for the development of either lung or upper airway
cancer from light or moderate use, although evidence is mixed concerning possible
carcinogenic risks of heavy, long-term use. Although regular marijuana smoking
leads to bronchial epithelial ciliary loss and impairs the microbicidal function
of alveolar macrophages, evidence is inconclusive regarding possible associated
risks for lower respiratory tract infection. Several case reports have implicated
marijuana smoking as an etiologic factor in pneumothorax/pneumomediastinum and
bullous lung disease, although evidence of a possible causal link from
epidemiologic studies is lacking. In summary, the accumulated weight of evidence
implies far lower risks for pulmonary complications of even regular heavy use of
marijuana compared with the grave pulmonary consequences of tobacco.

PMID: 23802821 [PubMed - in process]

What is a longitudinal study? What is a well-designed epidemiological study? It's certainly not something that only involves a brief period of observation, as you claim. The full text of this paper is trapped behind a paywall, but as I've shown in previous posts, these studies involved tens of thousands of patients observed over multiple decades.

Again, nobody is saying that marijuana smoke does not contain carcinogens. We're simply saying that when looking for increased incidence of cancer in cannabis smokers, we have not found it. Do what you want with that data, but don't distort it.

It would be an immense help if someone here would link to the full text of this paper, especially since it's probably taxpayer-funded.
 
This is simply not true. You've been told time and again that it's not true, yet you keep saying this.

Is there any point in keeping this thread open, other than to allow you to have your own personal dartboard here on this forum?

Again, here is the abstract which this thread is based on:



What is a longitudinal study? What is a well-designed epidemiological study? It's certainly not something that only involves a brief period of observation, as you claim. The full text of this paper is trapped behind a paywall, but as I've shown in previous posts, these studies involved tens of thousands of patients observed over multiple decades.

Again, nobody is saying that marijuana smoke does not contain carcinogens. We're simply saying that when looking for increased incidence of cancer in cannabis smokers, we have not found it. Do what you want with that data, but don't distort it.

It would be an immense help if someone here would link to the full text of this paper, especially since it's probably taxpayer-funded.

It also says this.

evidence is mixed concerning possible
carcinogenic risks of heavy, long-term use.
This study did not rule out the possibility that long-term marijuana smoking can lead to cancers. Of course, since marijuana smoke contains carcinogens, then there's no question that people have gotten cancer from it. This study just didn't find any direct evidence. But it did acknowledge that marijuana smoke is carcinogenic.
 
That comma in the quote of yours indicates that they didn't rule out for HEAVY and LONG TERM use not HEAVY or LONG TERM. Evidence suggests it does not occur for long term and not heavy.

Anyway this is the stupidest thread I've seen in a while.
 
This study did not rule out the possibility that long-term marijuana smoking can lead to cancers.

It doesn't rule out any possibility. It can't. All it can do is present evidence and posit a conclusion.

Of course, since marijuana smoke contains carcinogens, then there's no question that people have gotten cancer from it. This study just didn't find any direct evidence. But it did acknowledge that marijuana smoke is carcinogenic.

We're going in circles. Again and again and again.

When you compare the population of marijuana smokers to the population of non-smokers, the incidence of respiratory cancers is about the same.

Again:

When you compare the population of marijuana smokers to the population of non-smokers, the incidence of respiratory cancers is about the same.
 
It doesn't rule out any possibility. It can't. All it can do is present evidence and posit a conclusion.
We're going in circles. Again and again and again.

When you compare the population of marijuana smokers to the population of non-smokers, the incidence of respiratory cancers is about the same.

Again:

When you compare the population of marijuana smokers to the population of non-smokers, the incidence of respiratory cancers is about the same.

That's exactly what i'm trying to say. Since that study didn't rule out the possibility that long-term pot smoking may cause cancers, people shouldn't read that study and think, "marijuana has a zero percent chance of causing cancers, nobody has ever gotten cancer from pot". It's inconclusive.
 
It's inconclusive.

Science is always somewhat inconclusive. But that doesn't preclude the formulation of reasonable conclusions. These must always be open-ended, as more research is always indicated.

For the record, I don't smoke weed any more because it really brutalizes my lungs. I recommend that everyone explore alternate means of ingestion.
 
Science is always somewhat inconclusive. But that doesn't preclude the formulation of reasonable conclusions. These must always be open-ended, as more research is always indicated.

For the record, I don't smoke weed any more because it really brutalizes my lungs. I recommend that everyone explore alternate means of ingestion.

What exactly happened to your lungs?
 
What exactly happened to your lungs?

Every time I smoke blunts they tend to get sore. Smoking out of pipes or bongs is a bit smoother, but they begin to hurt after a couple of days too. I used to tolerate the soreness, but then I started running every day, and I now prefer to have my respiratory system in as good a shape as possible.
 
That's exactly what i'm trying to say. Since that study didn't rule out the possibility that long-term pot smoking may cause cancers, people shouldn't read that study and think, "marijuana has a zero percent chance of causing cancers, nobody has ever gotten cancer from pot". It's inconclusive.
Do you realize the amount of funding and accolades that would be available to a scientist who successfully demonstrated a risk of lung cancer from marijuana usage? The tone of your posts has been to suggest that academia has somehow chosen to specifically ignore the risks of cannabis smoking, despite years of funding, investigation, incentive, great public health concern, and -- you may be surprised to hear this -- a not entirely uncommon conservative tenor among academics.

The thing about carcinogenesis is that it's not binary. There are a whole lot of things that cause cancer, to a great or small extent, be they charred food, sunlight, radon, fireplaces, certain viruses, tomatoes, or as we all know, alcohol and cigarettes.

The other thing you should realize is that the carcinogenic potential of cigarettes is huge, like, unmissably huge. A cigarette smoker has a relative risk of lung cancer about 1500% higher than a non-smoker. That's not a typo: I mean to say sixteen times higher. While the body of knowledge we've accumulated with respect to cannabis is much smaller than what we know about tobacco, we do know enough that it is all but certain that the carcinogenic potential of cannabis is way smaller than tobacco!

There is just no way that cannabis smokers are sixteen times as likely to get lung cancer as non-smokers and it is somehow slipping under the radar of multiple well-designed longitudinal studies. This is why, while there is certainly a gap in our knowledge relating to a the possibility of a lower odds ratio of lung cancer for cannabis smokers, the fact that all these studies fail to link marijuana to lung cancer means approximately this: marijuana smoking is unlikely to become a leading cause of death.

I'd estimate that the real odds ratio for primary malignant neoplasms of the lung related to being a moderate consumer of cannabis is less than 2. That, by itself, is a big deal, it is a piece of valuable knowledge relevant to harm-reduction, and it is most certainly a justification that these studies should be news.

EDIT: To give you an idea of just how huge the impact of tobacco on lung cancer is, consider that before cigarette smoking became widespread, the first real book on lung cancer began like this:


Today, lung cancer is the most common terminal cancer in the world bar none.
 
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I'd estimate that the real odds ratio for primary malignant neoplasms of the lung related to being a moderate consumer of cannabis is less than 2. That, by itself, is a big deal, it is a piece of valuable knowledge relevant to harm-reduction, and it is most certainly a justification that these studies should be news.

Odds ratio is actually less than 1! Meaning (lol) weed smokers are less likely to develop lung cancer than non-smokers.

The Los Angeles County Cancer Surveillance program provided Tashkin's team with the names of 1,209 L.A. residents aged 59 or younger with cancer (611 lung, 403 oral/pharyngeal, 90 laryngeal, 108 esophageal). Interviewers collected extensive lifetime histories of marijuana, tobacco, alcohol and other drug use, and data on diet, occupational exposures, family history of cancer, and various "socio-demographic factors." Exposure to marijuana was measured in joint years (joints per day x 365). Controls were found based on age, gender and neighborhood. Among them, 46% had never used marijuana, 31% had used less than one joint year, 12% had used 10-30 j-yrs, 2% had used 30-60 j-yrs, and 3% had used for more than 60 j-yrs. Tashkin controlled for tobacco use and calculated the relative risk of marijuana use resulting in lung and upper airwaves cancers. All the odds ratios turned out to be less than one (one being equal to the control group's chances)! Compared with subjects who had used less than one joint year, the estimated odds ratios for lung cancer were .78; for 1-10 j-yrs, .74; for 10-30 j-yrs, .85 for 30-60 j-yrs; and 0.81 for more than 60 j-yrs. The estimated odds ratios for oral/pharyngeal cancers were 0.92 for 1-10 j-yrs; 0.89 for 10-30 j-yrs; 0.81 for 30-60 j-yrs; and 1.0 for more than 60 j-yrs. "Similar, though less precise results were obtained for the other cancer sites," Tashkin reported. "We found absolutely no suggestion of a dose response." The data on tobacco use, as expected, revealed "a very potent effect and a clear dose-response relationship -a 21-fold greater risk of developing lung cancer if you smoke more than two packs a day." Similarly high odds obtained for oral/pharyngeal cancer, laryngeal cancer and esophageal cancer. "So, in summary" Tashkin concluded, "we failed to observe a positive association of marijuana use and other potential confounders."

http://www.bluelight.ru/vb/threads/209988-Study-Smoking-Marijuana-Does-Not-Cause-Lung-Cancer
 
Every time I smoke blunts they tend to get sore. Smoking out of pipes or bongs is a bit smoother, but they begin to hurt after a couple of days too. I used to tolerate the soreness, but then I started running every day, and I now prefer to have my respiratory system in as good a shape as possible.

Smoking blunts is going to have effects on your lungs for 40+ years. The reason smoking weed alone makes it sore is the harshness combined with the expectorant activity. I think you wouldn't have had this problem if you had never smoked blunts, and I feel the same about myself.

Of course this is just random ideas with no evidence, but I think it fits. Trust me breathing in blunt smoke and weed smoke are very different. Breathing in rolling paper smoke by itself and blunt are very different. As soon as there's a touch of tobacco in there I can tell and it leaves my lungs producing extra mucus and feeling tender for days. Weed doesn't do this at all even if I smoke a shitload of joints constantly. There's no equivalent, weed doesn't do the same thing that tobacco does slower, it's just different. However I won't deny it might feel the same for you. For me, my lungs are sensitive and the difference is easy to tell both instantly (as soon as I breathe that nasty shit in) and long term (weeks later I still have that tobacco cough every once in awhile)

To the guys talking about tar: stop circle jerking and talk about the purpose of the thread, the cancer. Marijuana tar is pretty much healthy. Tobacco tar is pretty much an accumulating toxin.
 
35020830_zps04eeef2b.jpg

All that's needed to sum up this thread is this picture.

Maeijuana smoke, just like any other burning of a plant, produces benzene. Benzene is cancerous therefore smoke is cancerous.

Marijuana is not a special circumstance. By smoking marijuana you're inhaling benzene and, again, benzene is cancerous. Therefore, smoking marijuana is cancerous. Period.
 
[going around in circles]

So why isn't a higher incidence of cancer observed? Nobody claims marijuana makes you invincible to cancer.

By the same token, we shouldn't breathe oxygen, because oxygen can convert compounds to peroxy compounds, and peroxy compounds are reactive and explosive, so breathing air will destroy your lungs through oxidation, turning them into contact explosives.

[edit]
Ann Am Thorac Soc. 2013 Jun;10(3):239-47. doi: 10.1513/AnnalsATS.201212-127FR.
Effects of marijuana smoking on the lung.
Tashkin DP.

[...] habitual use of marijuana alone does not appear to lead to significant abnormalities in lung function when assessed either cross-sectionally or longitudinally, except for possible increases in lung volumes and modest increases in airway resistance of unclear clinical significance. Therefore, no clear link to chronic obstructive pulmonary disease has been established. Although marijuana smoke contains a number of carcinogens and cocarcinogens, findings from a limited number of well-designed epidemiological studies do not suggest an increased risk for the development of either lung or upper airway cancer from light or moderate use, although evidence is mixed concerning possible carcinogenic risks of heavy, long-term use. [...] In summary, the accumulated weight of evidence implies far lower risks for pulmonary complications of even regular heavy use of marijuana compared with the grave pulmonary consequences of tobacco.
 
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All that's needed to sum up this thread is this picture.

Maeijuana smoke, just like any other burning of a plant, produces benzene. Benzene is cancerous therefore smoke is cancerous.

Marijuana is not a special circumstance. By smoking marijuana you're inhaling benzene and, again, benzene is cancerous. Therefore, smoking marijuana is cancerous. Period.

Stop acting like you know it all punk. All the last 3 pages worth of posts are worth something, except your's.

Btw, marijuana smoke is not the same as benzene. Just as air is not the same as oxygen. Just as water is not the same as face-melting steam.
 
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