Think Twice Before Puffing: Why Smoking Marijuana Might Be More Harmful To Lungs Than Tobacco, New Evidence

With cannabis being set free from a decades-long stigma and its recreational and medical use more widespread, the question arises: is smoking weed dangerous?

While it is scientifically proven that smoking tobacco harms nearly every organ of the human body, researchers are divided on marijuana smoking.

Is Marijuana More Harmful To Lungs Than Tobacco?

Most recent evidence that cannabis is even more harmful to the lungs than tobacco comes from researchers at the University of Ottawa and The Ottawa Hospital reported Medical News Today. 

Research Findings

Published in the journal Radiology, the Canadian research suggests that cannabis smokers are more prone to emphysema and airway diseases than cigarette smokers.

The researchers studied chest computerized tomography (CT) examinations of 56 marijuana smokers, 57 non-smokers and 33 tobacco-only of the same age and gender. Cannabis smokers showed higher rates of paraseptal emphysema and airway inflammatory changes, including bronchiectasis, bronchial wall thickening and mucoid impaction, to name a few.

"I can tell if someone is a heavy or a long-time cigarette smoker when I look at a CT scan," said lead author Dr. Giselle Revah, a cardiothoracic radiologist at Ottawa Hospital in Canada and assistant professor of radiation oncology and medical physics at the University of Ottawa. "With marijuana being the second most inhaled substance after tobacco, I started wondering: What does marijuana inhalation look like on a CT scan? Would I be able to tell if someone was a marijuana smoker, is it different from cigarette smoke?"

While tobacco-only smokers also showed signs of emphysema, a lung condition that causes shortness of breath, marijuana smokers seem to be at higher risk of developing the disease, according to a retrospective case-control study conducted between 2005 and 2020.

"93% of the marijuana smokers had emphysema rather than 67% of the tobacco-only smokers," Revah said, adding that "more robust research before we can make sweeping conclusions" is needed.

What Exactly Is Emphysema?

Also known as a "disease of the small air sacs in the lungs," whose walls get damaged resulting in small holes in the lung, emphysema reduces the surface area available for gas exchange - oxygen and carbon dioxide, Revah continued.

But why such a discrepancy between tobacco and marijuana smokers?

Revah explained that particulates that reach the airways and stay deposited in the lungs during marijuana inhalation are "airway irritants," causing inflammation followed by mucus buildup in the airways and bronchial wall thickening and possible irreversible enlargement of the airways.

"The way marijuana is inhaled compared to tobacco with longer breath hold [and] higher puff volume may lead to microtrauma to the airspaces causing little holes (emphysema)," she said.

Who Is Advocating The Opposite?

Interestingly, a growing body of researchers is trying to prove quite the opposite.

In fact, a 2012 study published in the journal American Review of Respiratory Disease showed that cannabis use does not negatively affect the lungs. Instead, certain cannabinoids found within cannabis — namely tetrahydrocannabinol, commonly known as THC, may actually act as a bronchodilator, reducing respiratory obstruction and increasing airflow to the lungs. Those who smoked cannabis displayed better lung function than their peers who did not.  

Researchers in Britain even conducted a case study involving a lung cancer patient and cannabis extracts.

According to that study, an elderly lung cancer patient (in her 80s), who refused to pursue 'conventional' cancer treatments, self-administered cannabis extracts on a daily basis (2-3 times daily) over the course of two and a half years, unknown to her clinicians.

"Serial imaging shows that her cancer reduced in size progressively from 41 mm to 10 mm over a period of 2.5 years," the authors stated.

Photo: Courtesy of Amritanshu Sikdar on Unsplash