JAMA: Long-Term Exposure To Cannabis Smoke Is Not Associated With Adverse Effects On Pulmonary Function

Exposure to cannabis smoke, even over the long-term, is not associated with adverse effects on pulmonary function. That’s the conclusion of a major clinical trial published today in the prestigious Journal of the American Medical Association (JAMA).

Investigators at the University of California, San Francisco analyzed the association between marijuana exposure and pulmonary function over a 20 year period in a cohort of 5,115 men and women in four US cities.

Predictably, researchers “confirmed the expected reductions in FEV1 (forced expiratory volume in the first second of expiration) and FVC (forced vital capacity)” in tobacco smokers. By contrast, “Marijuana use was associated with higher FEV1 and FVC at the low levels of exposure typical for most marijuana users. With up to 7 joint-years of lifetime exposure (eg, 1 joint/d for 7 years or 1 joint/wk for 49 years), we found no evidence that increasing exposure to marijuana adversely affects pulmonary function.”

The study concludes, “Our findings suggest that occasional use of marijuana … may not be associated with adverse consequences on pulmonary function.”

To those familiar with the science of cannabis, JAMA’s findings should come as no great surprise. They are consistent with previous findings reporting no significant decrease in pulmonary function associated with moderate cannabis smoke exposure. For instance, according to a 2007 literature review conducted by researchers at the Yale University School of Medicine and published in the Archives of Internal Medicine (and summarized by NORML here), cannabis smoke exposure is not associated airflow obstruction (emphysema), as measured by airway hyperreactivity, forced expiratory volume, or other measures.

Further, in 2006, the results of the largest case-controlled study ever to investigate the respiratory effects of marijuana smoking reported that cannabis use was not associated with lung-related cancers, even among subjects who reported smoking more than 22,000 joints over their lifetime. (Read NORML’s summary of this study here.)

“We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use,” the study’s lead researcher, Dr. Donald Tashkin of the University of California at Los Angeles stated. “What we found instead was no association at all, and even a suggestion of some protective effect” among marijuana smokers who had lower incidences of cancer compared to non-users.

A previous 1997 retrospective cohort study consisting of 64,855 examinees in the Kaiser Permanente multiphasic health checkup in San Francisco and Oakland also reported, “[E]ver- and current use of marijuana were not associated with increased risk of cancer … of the following sites: colorectal, lung, melanoma, prostate, breast, cervix.”

Separate studies of cannabis smoke and pulmonary function have indicated that chronic exposure may be associated with an increased risk of certain respiratory complications, including cough, bronchitis, phlegm. However, the ingestion of cannabis via alternative methods such as edibles, liquid tinctures, or via vaporization — a process whereby the plant’s cannabinoids are heated to the point of vaporization but below the point of combustion –- virtually eliminates consumers’ exposure to such unwanted risk factors and has been determined to be a ‘safe and effective’ method of ingestion in clinical trial settings.

Marijuana may up heart attack, stroke risk-if you smoke 2-9 Oz. a week

This from NORML Podcaster Russ Belville at the NORML Daily Audio Stash blog…

Marijuana may up heart attack, stroke risk: study | Health | Reuters
WASHINGTON (Reuters) – Heavy marijuana use can boost blood levels of a particular protein, perhaps raising a person’s risk of a heart attack or stroke, U.S. government researchers said on Tuesday.

Levels of a protein called apolipoprotein C-III were found to be 30 percent higher in the marijuana users compared to the others. This protein is involved in the body’s metabolism of triglycerides — a type of fat found in the blood — and higher levels cause increased levels of triglycerides.

High levels of triglycerides can contribute to hardening of the arteries or thickening of the artery walls, raising the risk of stroke, heart attack and heart disease.

The study did not look at whether the heavy marijuana users actually had heart disease.

The marijuana users in the study averaged smoking 78 to 350 marijuana cigarettes per week, based on self-reported drug history, the researchers said.

The researchers said the active ingredient in marijuana, known as THC, seems to overstimulate marijuana receptors in the liver, leading to overproduction of the protein. [They] said higher levels of the protein in marijuana users could raise future risk for cardiac abnormalities, blood flow problems, heart attack and stroke.

A U.S. group supporting legal sales and regulation of marijuana disputed the findings. Marijuana Policy Project spokesman Bruce Mirken said, for example, the study involved people who were extremely heavy users.

“I think the low end was 78 joints a week. That’s 10 or 11 joints a day,” Mirken said in a telephone interview.

“We’re talking about people who are stoned all the time. We’re talking about the marijuana equivalent of the guy in the alley clutching a bottle of cheap wine. If you do anything to that level of excess, it might well have some untoward effects, whether it’s marijuana or wine or broccoli,” Mirken added.

“Even if you take this finding at face value, it’s not at all clear that it has any relevance to the real world because there is still no data showing higher rates of mortality among marijuana smokers. If this was a significant cause of cardiovascular disease, where are the bodies?”

Mirken’s right. 78 to 350 joints a week? That’s 11 to 50 joints per day. Let’s see, the government-rolled joints weigh in at about ¾ gram each (you do know there are official US Federal Government joints, right?), but the folks I know roll them a bit bigger (even to the ridiculous cubit-sized 70-gram models). However, most researchers seem happy with the ¾ gram model, so let’s do the math:

Low-end = 11 joints/day = 11 x 0.75g = 8.25g/day = about 2 ounces / week
High-end = 50 joints/day = 50 x 0.75g = 37.5g/day = over 9 ounces / week

So if you are consuming daily enough cannabis to equal about one-half to two-and-one-half pounds per month, then you might run an increased risk of stroke, heart attack, and heart disease. Personally, I’m thinking that at $300 per ounce, you’re more likely to run the risk of bankruptcy!

Yet still, note that the study doesn’t check to see if the heavy marijuana users actually do have heart disease. The research done on the health effects of even heavy marijuana smokers show little if any difference between cannabis users and their non-using counterparts, and some studies even show a benefit from cannabis in treating hypertension.

However, overeating, drinking alcohol, and smoking tobacco are proven to have deleterious effects on the heart and on health. I doubt we’re going to see any major effort to arrest the users of those substances, though.