Smoking marijuana causes more damage to the lungs than tobacco

Smoking marijuana causes more damage to the lungs than tobacco

In a recent radiology In a journal study, chest computed tomography (CT) researchers report that the lungs of marijuana smokers have more significant levels of respiratory inflammatory markers and emphysema than those of tobacco-only smokers.

Learn: Chest CT results in marijuana smokers. Photo credit: PIJITRA PHOMKHAM / Shutterstock.com

The health effects of smoking marijuana

Marijuana is the world's most widely used psychoactive drug, with global consumption continuing to increase following decriminalization and/or legalization in many countries. In Canada, for example, 20% of people over the age of 15 reported using marijuana in the last three months. Similarly, nearly 13% of adults in the United States have reported marijuana use in the past year.

Although marijuana is the second most commonly smoked substance worldwide after tobacco, it can be consumed in a variety of other ways, including vaporization and ingestion. Compared to smoking tobacco, smoking marijuana often involves inhaling larger amounts of smoke for longer periods of time. Additionally, marijuana is often smoked without a filter.

Like tobacco smoke, marijuana smoke is made up of various carcinogens and chemicals that can cause respiratory illnesses. In fact, several studies have confirmed that smoking marijuana can lead to respiratory symptoms such as coughing, sputum production, and wheezing, all of which are also commonly reported in tobacco smokers. The presence of these symptoms has been found to alter pulmonary function tests in marijuana smokers, indicating the likely presence of respiratory inflammation in these individuals.

Assessing the Effects of Marijuana Smoke by CT Imaging

In addition to pulmonary function tests, CT lung imaging can also provide important information about the effects of marijuana smoking on the lungs.

To this end, researchers in the current study compared chest CT studies of 56 marijuana smokers, 57 non-smokers and 33 tobacco-only smokers conducted between October 2005 and July 2020 in Ottawa, Canada. All patients included in the current study were matched for age and gender.

Importantly, due to the retrospective nature of this study, researchers were limited in their ability to quantify daily marijuana use among patients. In fact, only 28 of the 56 patients had reported their daily marijuana consumption, which averaged 1.85 grams per day. Fifty of the 56 marijuana smokers also smoked tobacco.

Compared to nonsmokers, CT findings for marijuana smokers showed different rates of emphysema, bronchial thickening, bronchiectasis, mucoid impactions, and centrilobular nodules, all of which are CT markers of airway inflammation. Gynecomastia was also reported in 38% of marijuana patients compared to 16% of non-smokers.

When comparing CT results between marijuana and tobacco smokers, researchers reported differences in bronchial thickening, bronchiectasis, and mucoid impaction. Additionally, higher emphysema rates of 93% were observed among age-matched marijuana smokers and 67% among tobacco-only smokers, respectively. No differences were observed when comparing the incidence of centrilobular nodules between marijuana and tobacco-only smokers; However, this may be due to the high rate of tobacco smokers who also smoked marijuana.

Paraseptal emphysema has also been found more frequently in marijuana smokers than in the lungs of tobacco-only smokers. Conversely, centrilobular emphysema has been visualized primarily in the lungs of tobacco smokers.

Future outlook

Larger cohort studies are needed in the future to confirm the CT findings in this study and to elucidate possible pathogenic mechanisms responsible for the effects of marijuana smoke on lung injury. Additionally, because most of the marijuana smokers in this study also smoked tobacco, it is difficult to determine whether the CT findings reported in this study are due to marijuana smoke or whether they represent synergistic effects of marijuana and tobacco smoke on the lungs.

Reference:

• Murtha, A., Sathiadoss, P., Salameh, J., et al. (2022). Thorax-CT-Ergebnisse bei Marihuana-Rauchern. Radiologie. doi:10.1148/radiol.212611.

.