(BIRMINGHAM, Ala.) — Occasionally puffing the magic dragon does not appear to have long-term adverse effects on lung function, according to new research published in the Journal of the American Medical Association.
Researchers from the University of Alabama at Birmingham and University of California at San Francisco analyzed marijuana and tobacco use among 5,000 black and white men from the national database CARDIA (Coronary Artery Risk Development in Young Adults study), which was intended to determine heart disease risk factors over a 20-year period.
Measuring participants’ lung function for air flow and lung volume five times throughout the study period, the researchers found that cigarette smokers saw lung function worsen throughout the 20-year period, but marijuana smokers did not. Only the heaviest pot smokers (more than 20 joints per month) showed decreased lung function throughout the study.
But, cautioned Dr. Stefan Kertesz, assistant professor of medicine at the University of Alabama at Birmingham and principle investigator on the study, the research should not be viewed as a green light to spark up.
Among the study participants, the average pot smoker lit up two to three times per month. The average tobacco user smoked eight cigarettes per day.
Those who smoked less than the heaviest actually saw a slight increase in air flow and lung function. But otherwise, researchers actually saw a slight increase in lung function among marijuana users.
While an adult male blows out about 4 liters of air in one second, those who occasionally smoked weed could blow out those 4 liters, plus another 50 milliliters — about one-seventh of a soda can. Kertesz said that the enhanced lung capacity could be due to the extended and heavy inhalations done while smoking marijuana rather than any beneficial effect.
Marijuana is the most commonly used illegal drug in the U.S. About 16.7 million Americans 12 and older reported using marijuana at least once in the month prior to a survey conducted in 2009 by the National Survey on Drug Use and Health. Still, the debate goes on as to whether pot should be legalized. So far, 16 states have legalized the substance for medical use to curb symptoms in patients with pain, AIDS, cancer and several other conditions.
As an institute on studying drug abuse, the National Institute of Drug Abuse noted that the results should not overshadow other established harmful effects of marijuana, such as adverse effects on cognition, potential for psychosis or panic during intoxication and the risk of addiction, which occurs in nine percent of users.
Some health experts have questioned whether the study’s findings are conclusive. Robert MacCoun, professor of public policy and law at University of California at Berkeley, said that while the study was carefully conducted, the results are purely correlational.
Experts agreed that the study does not provide evidence that marijuana smoking is healthy for the lungs, but that marijuana is indeed a complex substance.
“I think what is most striking about the results is that we are so accustomed to studies emphasizing, and sometimes exaggerating, how dangerous marijuana is for users’ health,” said MacCoun. “So this study is a cautionary note that we still have a lot to learn about this complex psychoactive plant.”
Copyright 2012 ABC News Radio