With the legality of marijuana, more people are smoking sticky bud—and one way in which it’s frequently enjoyed is in combination with tobacco. Now, researchers are beginning to look at what negative health effects this stimulatingly dank mixture of plants may have.
According to a research presented at the annual Radiological Society of North America (RSNA) meeting in Chicago, smoking weed in combination with tobacco may increase the risk of damage to lung air sacs—though an announcement about the study's results says nothing about cancer.
Jessie Kang, MD, from Dalhousie University in Halifax, Nova Scotia, Canada and co-author of the study said that the research was ultimately inspired because little is known about the long term effects of marijuana, let alone how the body responds to a combination of inhaled plant matter.
To determine the impact, Kang and her team examined chest CT images of four patient groups: nonsmokers, cigarette smokers, marijuana smokers, and those who use both. “Marijuana smoker” was defined as someone who had smoked actual cannabis leaf at least four times a month for at least two years. Those who ingested marijuana baked goods or used THC products such as edible candies, aerosol sprays, and vape oils were excluded from the study.
“The mean number of marijuana smoking years was less than compared to cigarette smokers and combined marijuana and cigarette smokers,” Kang added. “However, marijuana that is smoked is often unfiltered, which can potentially lead to more damaging particles entering the airways and lungs.”
All groups were compared to nonsmokers—and those who smoked both were found to be 12 times more likely to have centrilobular emphysema, which can lead to difficulty breathing, coughing, and other respiratory symptoms. Combined marijuana and cigarette smokers were also three to four times more likely to have airway wall thickening, increasing their risk of infections due to scarring.
When looking at those who smoked marijuana only and cigarettes only, bronchial wall thickening was not as significant. The same was true for rates of centrilobular emphysema, signaling that there may be a uniquely negative effect from the combination of the two smokes.
Despite the results, Kang was careful to not make any firm conclusions, given the lack of causal evidence. She hopes her study will bring attention to the possible negatives of smoking weed and spur researchers to develop larger long-term studies, including those that look into a possible link to lung cancer.
“There is a common public misconception that marijuana smoking is not harmful,” Kang said. “More research needs to be done in this area, so the public can make an informed decision on their recreational usage of marijuana.”
Chad is an award-winning writer and editor with over 15 years of experience working in media. He has a decade-long professional background in healthcare, working as a writer and in public relations.