Study Shows Marijuana Does Not Impair Lung Function

**Red Team** · 11 Jan 12,, 15:04

Marijuana Smoking Does Not Harm Lungs, Study Finds - NYTimes.com

Marijuana Smoking Does Not Harm Lungs, Study Finds
By ANAHAD O'CONNOR

Jim Wilson/The New York Times
Investigating the medical effects of marijuana.
A large new government study has found that smoking marijuana on a regular basis, even over many years, does not impair lung function.

Marijuana, the country’s most widely used illicit drug, has become increasingly popular and less stigmatized in recent years, particularly among young adults. One government report released in December found that one out of 15 high school students now smokes marijuana nearly every day, a growth fueled in part by the spread of medicinal marijuana, which is legal in 16 states. With its use rising, questions about the drug’s long-term medical consequences have garnered more attention.

The new research is one of the most extensive looks to date at whether long-term marijuana use causes pulmonary damage, and specifically whether its impact on the lungs is as harmful as smoking cigarettes. The researchers followed more than 5,000 people over two decades and found that regularly smoking marijuana — the equivalent of up to a joint a day over seven years — did not impair performance on a lung function test. The test, a measure of pulmonary obstruction that looks at the amount of air a person can force out in one second after taking a deep breath, is typically worsened by smoking tobacco.

In something of a twist, the researchers found that compared to nonsmokers, marijuana users performed slightly better on the lung function test, though the improvement was minuscule. “Even with this tiny increase in airflow, I have to admit that I really doubt that there’s any real increase in lung health,” said Dr. Stefan Kertesz, an associate professor at the University of Alabama at Birmingham school of medicine and an author of the study. The finding may merely reflect marijuana smokers’ years of “training” in taking deep inhalations and holding the smoke, the researchers said.

In the near term, smoking marijuana irritates the airways and can cause coughing, and public health advocates stress that it causes impairment that reduces attention, lowers motivation and heightens the risk of accidents. Over days or weeks, chronic use can lead to problems with learning and memory. But whether smoking marijuana sets off the type of pulmonary changes that lead to lasting damage like chronic obstructive pulmonary disease, a leading cause of death among Americans, was not entirely clear.

Earlier research suggested that the impact of marijuana smoke, which contains some of the same noxious chemicals as tobacco, was not as harmful to lung function as cigarette smoke. But many of the studies were carried out over relatively short periods and contained hundreds, not thousands, of subjects.

In the new study, which was published in The Journal of the American Medical Association and financed by the National Institutes of Health, roughly 5,100 men and women in four cities – Oakland, Calif.; Chicago; Minneapolis; and Birmingham – were interviewed and given lung function tests repeatedly over 20 years. They were on average about age 25 at the start, and more than half smoked marijuana, cigarettes or both.

The researchers found that for marijuana smokers, an exposure of up to seven “joint years” — with one joint-year equivalent to smoking 365 joints or filled pipes, or an average of one joint a day for seven years — did not worsen pulmonary function. Dr. Kertesz noted that with heavier marijuana use, described as 10 joint-years of exposure or more, lung function did begin to decline. And for a person who smokes both marijuana and cigarettes, “the net effect is going to be continued loss of lung function.”

Dr. Donald Tashkin, a pulmonologist at the University of California, Los Angeles, who has studied marijuana for over 30 years and was not involved in the study, said it confirmed findings from several other studies showing “that essentially there is no significant relationship between marijuana exposure and impairment in lung function.” He said one reason marijuana smoke may not be as harmful as tobacco smoke, despite containing similar noxious ingredients, may be the fact that its active ingredient, THC, has anti-inflammatory effects.

“We don’t know for sure,” he said, “but a very reasonable possibility is that THC may actually interfere with the development of chronic obstructive pulmonary disease.”

Dr. Tashkin said he and his colleagues had found in their own research — unexpectedly — that even smoking up to three joints a day did not appear to cause a decrease in lung function. “I think that the bottom line is that there does not appear to be any negative impact on lung function of marijuana smoking,” he said, “and that therefore marijuana is not a risk factor for the development of C.O.P.D. Tobacco smoking is the most important risk factor for C.O.P.D.”

This is sure to be a major pro-legalization talking point, and possibly the tobacco industry's worst nightmare.

**HKDan** · 12 Jan 12,, 00:53

I was in Michigan last spring, visiting some family and was amazed to discover that since allowing medical marijuana, basically what appears to have evolved from that situation was tacit decriminalization. My cousin in Ann Arbor tells me that if a cop were to catch you walking down the street smoking a joint, its a minor fine. His brother, who lives in East Lansing showed me a couple of blocks that were once basically abandoned commercial properties, now pot dispensaries. Both of them support legalization and I have to admit I do too. The war on drugs is a disaster. Legalize, regulate, and tax.

**rickshaw92** · 12 Jan 12,, 01:02

Legalize, regulate, and tax.

And pass the bong!

**mustavaris** · 12 Jan 12,, 04:24

Criminalization of cannabis is a mistake, giving hard sentences for smoking/possession.. that is pure insanity.

**Tanker** · 12 Jan 12,, 04:34

Originally Posted by mustavaris

Criminalization of cannabis is a mistake, giving hard sentences for smoking/possession.. that is pure insanity.

Many states are walking away from jail time now unless its distribution weight or packaged for distribution. A friend of mine was saying that his roommate was stopped and found to have 3 joints on him the trooper took the weed crushed them into the pavement and gave him a desk ticket for 400$. I laughed.

But then again I laugh at idiots who snap their arms off skateboarding on handrails, people who get rode rash when their "endo" goes south and they get dragged by their own bike or the car that was behind them, or idiots who climb out of their 40,000$ pick-up truck and ride the roof until they hit a bump, fall off and they truck hits a pole and folds it into tinfoil....

**TopHatter** · 12 Jan 12,, 04:51

Some interesting tidbits in there

...government report released in December found that one out of 15 high school students now smokes marijuana nearly every day, [It's a good thing that pot is "harmless" because for young people at that stage in life, things like reduced attention, lower motivation, heightened risk of accidents, not to mention problems with learning and memory are issues to be very concerned about]. Over days or weeks, chronic use can lead to problems with learning and memory. a growth fueled in part by the spread of medicinal marijuana, which is legal in 16 states. With its use rising, questions about the drug’s long-term medical consequences have garnered more attention. [Why bother? It's harmless, right?]

In the near term, smoking marijuana irritates the airways and can cause coughing, and public health advocates stress that it causes impairment that reduces attention, lowers motivation and heightens the risk of accidents. Over days or weeks, chronic use can lead to problems with learning and memory. [Aw crap!] But whether smoking marijuana sets off the type of pulmonary changes that lead to lasting damage like chronic obstructive pulmonary disease, a leading cause of death among Americans, was not entirely clear.

**HKDan** · 12 Jan 12,, 05:08

TH,

I am not of the opinion that smoking grass is entirely harmless, nor that teenagers(or anyone else for that matter) should be receiving that message. However, I do feel that the body of evidence showing that there is a great deal of difference in harmful effects between marijuana and say, crystal meth, does indicate that it should be controlled more in the same manner as alcohol or tobacco.

**Red Team** · 12 Jan 12,, 06:20

Again as with any other drug or body altering substance, there will be undesirable short and long term effects on the body, which must be made known to the general public if it were to be legalized. In this case, same rules should apply in terms of DWI, legal age to procure, etc. But ultimately, regulation is the best answer not criminalization. Instead, spending more of our resources going after the more dangerous stuff would be much more benefitial overall.

Not to mention the myriad other uses of cannabis: 15 Fascinating Facts About Hemp

**USSWisconsin** · 12 Jan 12,, 08:13

I agree, treat it like alcohol, in the past there was concern about not beng able to prove someone was under the influence - this is history - it is easily proven now.
For adults, we don't need to be a nanny state - putting someone in prison for using marijauna - that is just wrong. Instead we should tax them when they buy it, arrest them for driving under the influence or providing it to minors. I don't see chemicals like meth, coke or heroin in the same light - there are plenty of bodies to demonstrate how dangerous that stuff is (and not from accidents while under the influence - but from direct overdose). Coffee and tobacco are just as addictive, adults need to be responsible for their actions - including the use of marijauna. We don't need them in our prisons for having a bag of plant material.

**bigross86** · 12 Jan 12,, 08:16

Smoking weed extremely frequently, just like hitting the bottle every day or smoking a pack of smokes every day can cause problems, yes. But having a beer at night with your mates or a good Scotch when you get home from work? No one has a problem with that.

**Chogy** · 12 Jan 12,, 13:57

You guys would be OK with your airline pilot smoking weed? Just checking...

Here's the problem with the "pilot on dope" scenario... with alcohol, there are rules, such as "8 or 12 hours bottle to throttle" and a very specific blood alcohol maximum prior to operation. So let's say weed is now OK. The airlines create a policy - "24 hours minimum between bong and boeing." (<-- Hey, that's mildly funny!) You've got Captain Rasta who really enjoys his weed. He blazes up the morning of his flight. Now, how can you prove he was under the influence when he insists it's been more than 24 hours? There's no quick and easy way to determine blood THC, AFAIK, and unlike alcohol, the effects are hugely different between people, and metabolization is also very different.

**USSWisconsin** · 12 Jan 12,, 14:26

Originally Posted by Chogy

You guys would be OK with your airline pilot smoking weed? Just checking...

Here's the problem with the "pilot on dope" scenario... with alcohol, there are rules, such as "8 or 12 hours bottle to throttle" and a very specific blood alcohol maximum prior to operation. So let's say weed is now OK. The airlines create a policy - "24 hours minimum between bong and boeing." (<-- Hey, that's mildly funny!) You've got Captain Rasta who really enjoys his weed. He blazes up the morning of his flight. Now, how can you prove he was under the influence when he insists it's been more than 24 hours? There's no quick and easy way to determine blood THC, AFAIK, and unlike alcohol, the effects are hugely different between people, and metabolization is also very different.

But modern urine tests do determine the level. It takes about 150 ng/ml to see effects, the testing threshold is 50 ng/ml (5 ng/ml with gas chromotography) - were most people feel no effects at 100 ng/ml. So if capt rasta pees and show's a level of 300 ng/ml - then he's buzzed. At 5 ng/ ml this means its been about 2 weeks since light use or perhaps two months since heavy use.

The argument you are stating is based on old info. I have to go through this testing regularly. It lasts much longers since its oil based. Airline pilots might be able enjoy it on a long vacation, but not on weekends...

**Chogy** · 12 Jan 12,, 14:35

The argument you are stating is based on old info. I have to go through this testing regularly.

OK, I learned something new today. I had no idea urine metabolites were proportional to effects. The only problem I see then is time. Doing a pee test is going to cause the flight to be grossly delayed or cancelled, based upon a nervous passenger's suspicions.

I think what would actually happen is the industry (FAA et al) would simply say "MJ is legal now? Oh, OK, but part 121 pilots may not partake, ever." They already do this for 98% of legally prescribed pharmaceuticals out there.

**USSWisconsin** · 12 Jan 12,, 16:17

Originally Posted by Chogy

OK, I learned something new today. I had no idea urine metabolites were proportional to effects. The only problem I see then is time. Doing a pee test is going to cause the flight to be grossly delayed or cancelled, based upon a nervous passenger's suspicions.

I think what would actually happen is the industry (FAA et al) would simply say "MJ is legal now? Oh, OK, but part 121 pilots may not partake, ever." They already do this for 98% of legally prescribed pharmaceuticals out there.

I suspect many jobs would totally prohibit the use - and test to enforce. I would also think that getting gov't welfare or unemployment benifits should require tests - so we don't subsidize people who are unable to work due to self intoxication - a medical prescription would be another case - but if I am on powerful drugs, then being an airline pilot should not be a "right" available to me. Driving under the influence of 5ng/ml is the same as driving sober - but with 500 ng/ml its a very different story. Just like alcohol the tolerence and noticable effects vary, but we are able to set limits - someone with 0.005% BA isn't drunk, someone with 0.5 would be very drunk. An interesting contrast, the 100 times the dose - the effects, for THC - the person is in no physical danger of OD, but with alcohol, they may be dead already.

**HKDan** · 12 Jan 12,, 23:59

Originally Posted by Chogy

I think what would actually happen is the industry (FAA et al) would simply say "MJ is legal now? Oh, OK, but part 121 pilots may not partake, ever." They already do this for 98% of legally prescribed pharmaceuticals out there.

I see this as quite reasonable. If you want to be a pilot, you can't do this.