Smoking marijuana can be worse for your lungs than smoking cigarettes

Smoking marijuana can be worse for your lungs than smoking cigarettes

Smoking marijuana can be worse for your lungs than smoking cigarettes

Smoking marijuana can be worse for your lungs than smoking cigarettes

Airway inflammation and emphysema are more common in marijuana smokers than in cigarette smokers, a new study has found.

Emphysema is more common in marijuana smokers than in cigarette smokers

Airway inflammation and emphysema are more common in marijuana smokers than in cigarette smokers, according to new research. The researchers said the difference may be due to the way marijuana is smoked and the fact that marijuana smoke enters the lungs unfiltered. The research study was published on November 15 in RadiologyJournal of the Radiological Society of North America (RSNA).

Marijuana is the most commonly smoked substance after tobacco and one of the most widely used psychoactive substances in the world. Amid the legalization of recreational marijuana in Canada and many states in the US, its use has increased significantly in recent years. With increasing use, there is an urgent need for information on the effects of marijuana on the lungs, something that is currently lacking.

“Smoking marijuana is suggested to deposit four times more particles in the lungs than the average tobacco cigarette.” — Giselle Revah, MD

“We know what cigarettes do to the lungs,” said study author Giselle Revah, MD, a cardiothoracic radiologist and assistant professor at the University of Ottawa in Ottawa, Canada. “There are well-researched and established findings of cigarette smoking on the lungs. We know very little about marijuana.”

To learn more, Dr. Revah and colleagues compared the chest CT results of 56 marijuana smokers with those of 57 nonsmoking controls and 33 smokers who only smoked tobacco.

Three-quarters of marijuana smokers had emphysema, a lung disease that causes difficulty breathing, compared to 67% of smokers who only smoke tobacco. Only 5% of non-smokers had emphysema. Paraseptal emphysema, which damages the tiny ducts that connect to the air sacs in the lungs, was the predominant subtype of emphysema in marijuana smokers compared to the tobacco-only group.

Airway changes in marijuana and tobacco smokers

Airway changes in a 66-year-old marijuana and tobacco smoker. Axial (A) and (B) contrast-enhanced coronal CT images show cylindrical bronchiectasis and bronchial wall thickening (arrowheads) in multiple lung lobes bilaterally in the background of paraseptal (arrows) and centrilobular emphysema. Credit: Radiological Society of North America

Airway inflammation was also more common in marijuana smokers than in non-smokers and tobacco-only smokers. The same was true for gynecomastia, a condition of enlarged male breast tissue due to hormone imbalance. Gynecomastia was found in 38% of marijuana smokers, compared to only 11% of tobacco-only smokers and 16% of controls.

The researchers found similar results among age-matched subgroups, where rates of emphysema and airway inflammation were again higher in marijuana smokers than in tobacco-only smokers.

There was no difference in coronary artery calcification between age-matched marijuana and tobacco-only groups.

According to Dr. Revah, the results were surprising, especially considering that the patients in the tobacco-only group had a long history of smoking.

Pulmonary emphysema in marijuana and tobacco smokers

Pulmonary emphysema in (A, B) marijuana smokers and (C, D) tobacco smokers. (A) Axial and (B) coronal CT images in a 44-year-old marijuana smoker show paraseptal emphysema (arrowheads) in the bilateral upper lobes. (C) Axial and (D) coronal CT images in a 66-year-old female tobacco smoker with centrilobular emphysema represented by areas of centrilobular lucency (arrowheads). Credit: Radiological Society of North America

“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 compared to tobacco,” she said. “Furthermore, our results were still significant when we compared age-matched groups, including younger patients who smoked marijuana and who likely had less lifetime exposure to cigarette smoke.”

According to the CDC, 48.2 million people, or about 18% of Americans, used marijuana at least once in 2019.

There are probably several factors that contribute to the differences between the two groups. Marijuana is smoked unfiltered, Dr. Revah noted, while tobacco cigarettes are typically smoked with a filter. This causes more particles to enter the respiratory tract than smoking marijuana.

In addition, marijuana is inhaled with a longer breath hold and puff volume than tobacco smoke.

“Smoking marijuana is suggested to deposit four times more particles in the lungs than the average tobacco cigarette,” said Dr. Revah. “These particles probably irritate the airways.”

The higher incidence of emphysema may also be due to the way marijuana is smoked. A full inhalation with a continuous Valsalva maneuver, an attempt to exhale with a closed airway, can lead to trauma and changes in the peripheral air space.

More research is needed, Dr. Revah said, with larger groups of people and more data on how much and how often people smoke. Future research could also look at the impact of different inhalation techniques, such as a bong, joint or pipe.

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

See more about this research Emphysema is more common in marijuana smokers than in cigarette smokers.

Reference: “Chest CT Findings in Marijuana Smokers” By Luke Murtha, Paul Sathiadoss, Jean-Paul Salameh, Matthew DF Mcinnes, and Giselle Revah, 15 Nov 2022. Radiology.
DOI: 10.1148/radiol.212611



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