Smoking cannabis may be tougher on lungs than cigarettes, study shows
While marijuana legalization in some U.S. states and Canada may send a message that weed is harmless, that’s not necessarily so, according to a new study that found lung damage was more common in cannabis smokers than tobacco users.
Research into marijuana’s impact on the lungs is just getting started because weed wasn’t legal in many places until recently, but early indications show that it could do serious damage.
“The main message is that it may not be as safe as people think it is, and we need more information,” said study co-author Dr. Giselle Revah, a cardiothoracic radiologist and assistant professor at the University of Ottawa in Canada.
In the study, researchers compared chest CT results from 56 cannabis smokers, including some who also used tobacco, with 33 who smoked only tobacco and 57 nonsmokers.
Roughly 75% of the weed smokers had emphysema compared to 67% of the tobacco-only smokers and 5% of nonsmokers.
The chief type of emphysema found in marijuana smokers was paraseptal, which damages tiny ducts connecting air sacs in the lungs. Pot smokers also had more airway inflammation.
In emphysema, toxins deposited in small air sacs of the lungs that are responsible for the exchange of oxygen and carbon dioxide create irreversible holes.
“Early on patients may not have any symptoms, but over time as that emphysema progresses, then patients will start to have symptoms: coughing, wheezing, difficulty breathing,” Revah said.
Tobacco cigarettes are often filtered, while marijuana is typically smoked without filters. As a result, more particles may be deposited in the airways, she said. Weed smokers also tend to take a bigger puff and hold it in longer before exhaling.
Determining marijuana’s impact on emphysema rates will require larger studies, Revah said.
Cannabis edibles shouldn’t cause any lung damage, she said, but its effects on other parts of the body hasn’t been studied.
The findings were recently published in Radiology.