Is Marijuana more harmful than cigarette smoking?

We are aware of what smoking does to the lungs. The effects of smoking on the lungs have been widely studied and proven. When it comes to marijuana, we know very little.

The second most popular substance smoked after tobacco is marijuana, one of the most extensively used psychoactive compounds in the world. Due to the legalization of recreational marijuana in many U.S. states and Canada in recent years, its use has surged. There is an urgent need for an understanding of marijuana’s effects on the lungs, which is something that is currently lacking due to its rising use.

Dr. Giselle Revah, M.D., a cardiothoracic radiologist and assistant professor at the University of Ottawa in Ottawa, Canada and associates compared the chest CT findings of 56 marijuana smokers with those of 57 non-smokers controls and 33 tobacco-only smokers to learn more.

Compared to 67% of tobacco-only smokers, 75% of marijuana smokers had emphysema, a lung condition that makes breathing difficult. Emphysema only affected 5% of non-smokers. The most common emphysema subtype in marijuana users compared to the tobacco-only group was paraseptal emphysema, which affects the small ducts that connect to the air sacs in the lungs.

Inflammation of the airways and gynecomastia, enlarged male breast tissue brought on by an imbalance in hormones, were also more prevalent among marijuana smokers than in non-smokers and tobacco-only smokers. In comparison to 11% of tobacco-only smokers and 16% of controls, gynecomastia was discovered in 38% of marijuana smokers.

Even in subgroups of the same age, the rates of emphysema and inflammation of the airways were again higher in the marijuana smokers than in the tobacco-only smokers.

Age-matched marijuana and tobacco-only groups did not differ in terms of coronary artery calcification.

Considering that the patients in the tobacco-only group had a long history of smoking, Dr. Revah said the results were unexpected.

“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,” she explained. “In addition, our results were still significant when we compared the non-age-matched groups, including younger patients who smoked marijuana and who presumably had less lifetime exposure to cigarette smoke.”

Multiple causes are most likely responsible for the discrepancies between the two groups. Dr. Revah pointed out that tobacco cigarettes are typically filtered, whereas marijuana is smoked unfiltered. As a result, marijuana smoking causes more particles to enter the airways.

In addition, compared to tobacco smoke, marijuana smoke requires a longer breath hold and larger puff volume.

“It has been suggested that smoking a marijuana joint deposits four times more particulates in the lung than an average tobacco cigarette,” Dr. Revah added. “These particulates are likely airway irritants.”

Emphysema prevalence may also be influenced by marijuana smoking habits. An attempt to breathe out while doing a sustained Valsalva maneuver may result in damage and changes to the peripheral airways.

Dr. Revah said that there needs to be more research with bigger groups of people and more information about how much and how often people smoke. Future studies might also examine the effects of various inhalation methods, such as using a bong, a joint, or a pipe.

Dr. Revah commented, “it would be interesting to see if the inhalation method makes a difference.”

Source: Radiological Society of North America

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