Study: Weed May Hurt Smokers More Than Cigarettes Alone

According to a recent study, smoking weed while also smoking tobacco may worsen respiratory system damage.

“There’s a public perception that marijuana is safer than tobacco, and this study raises concern this may not be true,” said lead study author Dr. Giselle Revah, an assistant professor in the department of radiology at the University of Ottawa in Ontario.

“The American Lung Association says the only thing that should go into your lungs is clean air, so if you’re inhaling anything, it could potentially be toxic to your lungs,” she said.

Small, Early Research

The preliminary study, which was published on Tuesday in Radiology, a publication of the Radiological Society of North America, compared computed tomography (CT) lung scans of 33 heavy cigarette smokers with 56 people who smoked marijuana and tobacco.

As controls, scans from 57 additional nonsmokers without a history of lung disease, chemotherapy, or other lung damage were used.

In the study, about 75% of cannabis and tobacco smokers also had emphysema, which affects the small airways and damages the lungs’ air sacs. According to her, only 5% of nonsmokers had emphysema, compared to approximately 67% of tobacco-only smokers.

Even though an 8 percentage point difference between smokers of tobacco and only tobacco may not seem like a lot, Revah said it was significant.

“It suggests that marijuana has additional effects on the lungs than tobacco alone,” Revah said. “Is it the combination of the marijuana and tobacco that makes more holes in the lungs and airway inflammation or just the marijuana itself?”

Another concern was the age of the marijuana smokers — many were much younger than 50, she said.

“These patients presumably had less lifetime exposure to smoke, except they’re even sicker than those who are heavy tobacco smokers and have been doing it longer,” Revah said. “We just don’t know if it’s a synergistic effect between the marijuana and the tobacco versus the marijuana alone.”

Irreversible damage?

Airway damage from smoking can quickly become permanent, she said.

“Airway inflammation early on is reversible,” she said. “When I see mucus and thickening of the airways, if you stop the exposure that should improve. But sometimes that can lead to dilatation of the airways and when it’s dilated, then it’s irreversible.”

Revah pointed out some restrictions on the study. It was tiny. The amount of marijuana smoked or the method of inhalation—bong, blunt, or joint—were not well known.

However, Revah noted that there are several distinctions between the ways that marijuana and tobacco are smoked that might offer information for additional research. For instance, while weed is often smoked without a filter, tobacco is usually.

If you’re smoking an unfiltered joint, let’s say, more particulates will reach the airways, get deposited and become irritants, which is why you see the mucus and the inflammation,” she said.

In addition, she said that tobacco smokers quickly exhale, while marijuana smokers often inhale and hold their breath to maximize the high.

“People usually have a longer breath hold and a higher puff volume, so they are holding in the larger volume of smoke for a longer period of time,” she said. “That could lead to micro-trauma of those airspaces. These are all questions for future research.”

There’s more “research”

This isn’t the first study to find lung damage from inhaling weed.

A 2021 study found teens are about twice as likely to report “wheezing or whistling” in the chest after vaping marijuana than after smoking cigarettes or using e-cigarettes.

“I often am approached by both parents and teens who believe vaping cannabis is ‘OK’ and better than smoking (a joint, blunt, doobie etc.),” Carol Boyd, founding director of the Center for the Study of Drugs, Alcohol, Smoking & Health at the University of Michigan in Ann Arbor told CNN in a prior interview.

“And so, they ask, ‘Vaping is safe — right?’ My reaction: ‘You are fooling yourself. We know that inhaling hot tobacco/cannabis smoke into your lungs is unhealthy and can cause bronchitis or life-threatening breathing problems,” said Boyd, who is also professor emerita in the department of health behavior and biological sciences at the University of Michigan’s School of Nursing.

“And yet, you seem to believe that heating chemicals (including carcinogens) into a vapor and inhaling them is healthy? My answer is, ‘No, it is not a healthy behavior,’ ” she said.

What do you think about these studies? Let us know in the comments!