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Study finds marijuana doesn't harm lung function

By Lindsey Tanner

Associated Press

LAST UPDATED: 12:50 p.m. HST, Jan 10, 2012

CHICAGO >> Smoking a joint once a week or a bit more apparently doesn't harm the lungs, suggests a 20-year study that bolsters evidence that marijuana doesn't do the kind of damage tobacco does.

The results, from one of the largest and longest studies on the health effects of marijuana, are hazier for heavy users — those who smoke two or more joints daily for several years. The data suggest that using marijuana that often might cause a decline in lung function, but there weren't enough heavy users among the 5,000 young adults in the study to draw firm conclusions.

Still, the authors recommended "caution and moderation when marijuana use is considered."

Marijuana is an illegal drug under federal law although some states allow its use for medical purposes.

The study by researchers at the University of California, San Francisco, and the University of Alabama at Birmingham was released Tuesday by the Journal of the American Medical Association.

The findings echo results in some smaller studies that showed while marijuana contains some of the same toxic chemicals as tobacco, it does not carry the same risks for lung disease.

It's not clear why that is so, but it's possible that the main active ingredient in marijuana, a chemical known as THC, makes the difference. THC causes the "high" that users feel. It also helps fight inflammation and may counteract the effects of more irritating chemicals in the drug, said Dr. Donald Tashkin, a marijuana researcher and an emeritus professor of medicine at the University of California, Los Angeles. Tashkin was not involved in the new study.

Study co-author Dr. Stefan Kertesz said there are other aspects of marijuana that may help explain the results.

Unlike cigarette smokers, marijuana users tend to breathe in deeply when they inhale a joint, which some researchers think might strengthen lung tissue. But the common lung function tests used in the study require the same kind of deep breathing that marijuana smokers are used to, so their good test results might partly reflect lots of practice, said Kertesz, a drug abuse researcher and preventive medicine specialist at the Alabama university.

The study authors analyzed data from participants in a 20-year federally funded health study in young adults that began in 1985. Their analysis was funded by the National Institute on Drug Abuse.

The study randomly enrolled 5,115 men and women aged 18 through 30 in four cities: Birmingham, Chicago, Oakland, Calif., and Minneapolis. Roughly equal numbers of blacks and whites took part, but no other minorities. Participants were periodically asked about recent marijuana or cigarette use and had several lung function tests during the study.

Overall, about 37 percent reported at least occasional marijuana use, and most users also reported having smoked cigarettes; 17 percent of participants said they'd smoked cigarettes but not marijuana. Those results are similar to national estimates.

On average, cigarette users smoked about 9 cigarettes daily, while average marijuana use was only a joint or two a few times a month — typical for U.S. marijuana users, Kertesz said.

The authors calculated the effects of tobacco and marijuana separately, both in people who used only one or the other, and in people who used both. They also considered other factors that could influence lung function, including air pollution in cities studied.

The analyses showed pot didn't appear to harm lung function, but cigarettes did. Cigarette smokers' test scores worsened steadily during the study. Smoking marijuana as often as one joint daily for seven years, or one joint weekly for 20 years was not linked with worse scores. Very few study participants smoked more often than that.

Like cigarette smokers, marijuana users can develop throat irritation and coughs, but the study didn't focus on those. It also didn't examine lung cancer, but other studies haven't found any definitive link between marijuana use and cancer.


For more information:

JAMA: http://jama.ama-assn.org

National Institute on Drug Abuse: http://www.nida.nih.gov

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al_kiqaeda wrote:
Make pot legal. It will decrease violent crimes by cartels just like the end of prohibition ended bootleg liquor related shooting. At worse there will be a wild rise in the shoplifting of Doritos and candybars.
on January 10,2012 | 12:00PM
Changalang wrote:
Not to mention solve the state's tax revenue shortage. THC for the masses over Meth any day.
on January 10,2012 | 03:25PM
hanabatadayz wrote:
now can we legalize it?..that's why hawaii is the meth capital of the world..meth ruined our state cuz marijuana became so expensive..legalize it and the price will go way down and there will be no more meth heads destroying families
on January 10,2012 | 12:04PM
FLIPTOP2 wrote:
Ya, just what we need. Any kind of a study supporting an illegal habit. Would guess those in the lead of the research are a bunch of pot smokin' liberals!!!
on January 10,2012 | 12:16PM
kainalu wrote:
I'll smoke to that!
on January 10,2012 | 12:23PM
aiea7 wrote:
this appears to be a stupid study, how can you compare the effects of a MJ user, once of twice a month compared to a regular cigarette smokers who smokes an average of 9 cigarettes a day. The cigarette smoker smokes about 400 times more cigarettes in the same time frame - of course the effect of the smoke is greater - common sense will tell you this. this must be pro MJ article. such a nonsensical study.
on January 10,2012 | 12:37PM
ya_think wrote:
on January 10,2012 | 01:11PM
Changalang wrote:
A true chronic chokes down two blunts before second breakfast. The study is skewed.
on January 10,2012 | 03:41PM
kalanik001 wrote:
Most if not all pot smokers cannot afford to smoke weed as if it were cigarettes. They'll smoke more as a social thing, not as an addiction or coping mechanism. The medicinal benefit of marijuana has been proven, whereas there is no benefit to moderate cigarette smoking.
on January 10,2012 | 03:52PM
Changalang wrote:
True; the grade A evidence shows the only verifiable outcome of cigarette smoking is an early death and a complicated path of various health complications that make the quality of life a pathetic journey to a sad ending plagued with suffering.
on January 10,2012 | 04:12PM
toomuchpilikia wrote:
Smoking a single cigarette once a week will probably not hurt your lungs either! How is government going to legislate how many doobies one can partake with?
on January 10,2012 | 01:12PM
Compassionate_Cat wrote:
Hey. Alcohol is a controlled substance. DUI, under age drinking, alcohol overdose, fights, drunken brawls, so this plant is nothing next to the chemical alternatives. What would have happened if they kept prohibition against alcohol and made this plant the natural alternative instead?
on January 10,2012 | 02:23PM
Changalang wrote:
I am sure this study did not fall short of volunteers.
on January 10,2012 | 02:13PM
Compassionate_Cat wrote:
Reduces swelling and improves lung function in addition to the other benefits that have been published in the past. It is time to decriminalize this plant that perhaps God has made for healing and relaxation. It is less harmful than alcohol and the only reason alcohol is legal is that it could not be controlled. Our prisons would be full of citizens who made alcohol and distributed that. We need to free our citizens held as criminals for use of this plant and hold only those who used weapons and resorted to violence. My Mom had a fatal cancer and she had comfort from the use of this plant before she died and we were so stressed trying to help her; that's wrong!
on January 10,2012 | 02:19PM
sloturle wrote:
ron paul 2012!
on January 10,2012 | 02:25PM
Changalang wrote:
If you guys get your stuff together, then you can win the Hawaii GOP nomination for Ron Paul and keep the message alive. Put down the bag of Doritos and get the crew registered for Hawaii GOP. :)
on January 10,2012 | 03:22PM
HD36 wrote:
Hawaii for Ron Paul Patriots at Meet Up
on January 10,2012 | 08:06PM
what about showing up to work?????? damage???? broken lives? how bout erectile dysfunction? broken lives, promises, your kids on weed? drink smoke and poke? teen age pregnancy? poverty innner city, and outer homesteads? middle america? your lungs? pu leze............how bout my class mates, still stuck in the 70's that never made the transition into reality? still living with mom and arguing over how much they eat, when they are unemployed and mom is on social security? double puh leze
on January 10,2012 | 04:01PM
kainalu wrote:
"Reefer Madness"? Is that you?
on January 10,2012 | 04:15PM
al_kiqaeda wrote:
I'm not even a smoker (weed or cigarettes) and I'm for legalization. Fact remains...meth is waaaaaay worse than pot and we can stem new meth users, kill cartels and all the deadly violence with marijuana legalization.
on January 11,2012 | 08:00AM
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