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Deborah Leader, RN

Study Finds Periodic Pot Smoking Doesn't Harm Lungs

By January 11, 2012

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In the largest study ever conducted about the effects of marijuana on the lungs, researchers found that periodic pot smoking is not harmful to lung capacity.

The study, published in the Journal of the American Medical Association (JAMA) found that even those who smoked a joint a day for seven years, or once a week for 20 years had no decline in lung capacity.

The debate about the harmful effects of marijuana to the lungs has been going on for years. In fact, people with COPD who smoke pot have written to me expressing their concerns about previous studies. Study results have been contradictory at best -- some suggesting no harmful effects on the lungs, some suggesting adverse effects, and even others suggesting that it actually improved lung function.

Researchers conducting the new study knew the harmful effects of tobacco smoking on the lungs, but, wanted to clear the air once and for all about whether or not marijuana produced similar, deleterious effects.

The study took multiple lung function measurements in over 5,100 pot-smoking men and women during a 20-year study period. What they found surprised even them -- that some people who smoke pot may actually see a slight improvement in lung function.

Dr. Donald Tashkin, professor of medicine at UCLA has studied the relationship between smoking marijuana and lung function for over 3 decades. He believes the study confirms what other research has also concluded:

"This is a well-done study involving more subjects than in the past. The public should take away it's a confirmatory study, but larger and longer than previous studies demonstrating, once again, that smoking marijuana does not impair lung function, unlike tobacco."

Researchers warn, however, that this is not a green light for lighting up. Dr. Taskin states:

"We're only talking about one end point. We're not looking at lung cancer, chronic bronchitis symptoms. We are not looking at other effects, behavioral effects. We are looking at lung function."

How do you feel about these results? Do you think people will smoke more pot as a result of this study? Will study results give people the wrong message? What about other adverse effects of smoking pot? Share your comments below.

January 12, 2012 at 12:06 am
(1) kookykathy says:

So,they say: “We’re only talking about one end point. We’re not looking at lung cancer, chronic bronchitis symptoms. We are not looking at other effects, behavioral effects. We are looking at lung function.” So, does this mean that smoking pot does not impair lung function, but can, in fact, improve lung function in lungs that have been impaired and/or not been impaired? Yeah, right.

January 12, 2012 at 10:44 am
(2) malcolm kyle says:

1) Tobacco is cancer causing largely because it delivers specific carcinogens such as NNK and NNAL that are not present in cannabis. Not all “tar” is created equal, and tobacco has some of the most carcinogenic types of tar known to science, whereas cannabis does not.


2) Cannabis (marijuana) use is associated with a DECREASE in several types of cancer… potentially even providing a protective effect against tobacco and alcohol related cancer development.

Donald Tashkin, a UCLA researcher whose work is funded by NIDA, did a case-control study comparing 1,200 patients with lung, head and neck cancers to a matched group with no cancer. Even the heaviest marijuana smokers had no increased risk of cancer, and had somewhat lower cancer risk than non-smokers (tobacco smokers had a 20-fold increased lung cancer risk). Tashkin D. Marijuana Use and Lung Cancer: Results of a Case-Control Study. American Thoracic Society International Conference. May 23, 2006.

Researchers at the Kaiser-Permanente HMO, funded by NIDA, followed 65,000 patients for nearly a decade, comparing cancer rates among non-smokers, tobacco smokers, and marijuana smokers. Tobacco smokers had massively higher rates of lung cancer and other cancers. Marijuana smokers who didn’t also use tobacco had no increase in risk of tobacco-related cancers or of cancer risk overall. In fact their rates of lung and most other cancers were slightly lower than non-smokers, though the difference did not reach statistical significance. Sidney, S. et al. Marijuana Use and Cancer Incidence (California, United States). Cancer Causes and Control. Vol. 8. Sept. 1997, p. 722-728.

January 19, 2012 at 12:36 pm
(3) EvilPoet says:

The alternative to smoking cannabis is ingesting it. Which is what I do. I vaporizing it but only rarely and in extreme cases where I do not feel I can wait for the pain relief from the medibles (cannabis infused edibles) that I make to kick in. Overall, I have found that ingesting it via food is far more effective in reducing the pain of my RA and removes any fear that I have in putting things into my lungs. I know they say it is safer to vaporize but why choose the lessor of two evils when there is a third choice that is completely safe.

January 21, 2012 at 10:03 am
(4) COPD sufferer says:

I also choose to ingest my cannabis. It is an alternative that is much less harmful to people who suffer from COPD and chronic pain from arthiritis and migranes. Getting enough rest and walking also help.

January 23, 2012 at 9:19 am
(5) Mrs T says:

Dang, guess I should of been getting high all these years! I find this unbelievable, why not spend some money on research that actually may help those who suffer!

I’ll bet those 5,100 + pot smokers were more than happy to be able to participate in this research study. I’m sure pot smokers will see this as a “free for all” and “why not it won’t harm me!”

It says “We are not looking at other effects, behavioral effects. We are looking at lung function.” We all know there is a whole lot more to this than meets the eye. I’m all for the medical use of marijuana, as it can make a real difference in a terminally ill patient. But, hey lets looks into all the aspects and what this type of study real says.

February 1, 2012 at 11:48 am
(6) Marcy says:

I would think there might be some increase in those who have not smoked because they feared more damage from doing so.

September 27, 2012 at 9:57 pm
(7) jere says:

I have copd and smoke pot, tome it seems to make you cough deeper an helpremove the mucos that cloggs your lungs . itend to beath easer

September 29, 2012 at 6:37 pm
(8) Brandon says:

I have COPD and smoke marijuana regularly. Will this lead to worsening of my COPD?

September 30, 2012 at 6:04 pm
(9) copd says:

The thing about this study, it does not tell us the effects of pot smoking on the lungs of people with COPD, only those with normal lung function at the beginning of the study. I would definitely monitor your spirometry tests to see if they are getting worse and discuss this with your doctor.

December 17, 2012 at 10:49 pm
(10) stands2reason says:

There’s no good reason to smoke it, use a vaporizer instead.

August 20, 2013 at 3:30 am
(11) trx program says:

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