Emphysema more common among marijuana smokers than cigarette smokers

A recent study found that marijuana smokers are more likely to have airway inflammation and emphysema than cigarette smokers, which may be due to the way that marijuana smoke enters the lungs.

The study, published in Radiology, was conducted by researchers from the University of Ottawa in Ottawa, Canada. According to researchers, marijuana use continues to grow in popularity, however little is still known about the substance’s effects on the lungs. For their investigation, researchers sought to determine how smoking marijuana effects the lungs compared to smoking tobacco, and not smoking at all.

Researchers analyzed chest computerized tomography (CT) findings in 56 marijuana smokers, 57 nonsmokers, and 33 tobacco-only smokers. Results showed that 75 percent of the marijuana smokers had emphysema, a lung disease which makes breathing difficult. Surprisingly, emphysema was less prevalent among the tobacco-only group, affecting 67 percent of them. In contrast, only five percent of non-smokers had emphysema.

In addition, airway inflammation was more common among marijuana smokers than tobacco-only smokers as well as gynecomastia. According to the study, gynecomastia leads to enlarged male breast tissue due to a hormonal imbalance. The condition was found in 38 percent of the marijuana smokers, 11 percent of the tobacco-only smokers, and 16 percent of the nonsmokers.

According to the study’s authors, these results may be because marijuana smoke is unfiltered, while tobacco smoke is usually filtered. In addition, marijuana is usually smoked with a full inhalation, which may cause more damage to the lungs.

Similar results were found when participants were broken into age-matched subgroups. These results, researchers concluded, indicate that marijuana smoke may be more harmful to lungs than tobacco smoke.

“The fact that our marijuana smokers—some of whom also smoked tobacco—had additional findings of airway inflammation/chronic bronchitis suggests that marijuana has additional synergistic effects on the lungs above tobacco,” said Gisselle Revah, MD, a cardiothoracic radiologist and assistant professor at the University of Ottawa.