March 20, 2000 (Baltimore) -- Chronic marijuana smoking may lead to emphysema, a serious disorder in which areas of lung tissue are destroyed and replaced with cysts, according to a paper published in this month's issue of the journal Thorax.
In the paper, Martin Johnson, MD, of the department of respiratory medicine at Glasgow (Scotland) Royal Infirmary, and colleagues discuss the cases of four men who regularly smoked marijuana but did not smoke much tobacco, and who developed emphysema in the upper areas of their lungs. "Our cases are of particular interest, not just because of their young age, but also because of the unusual pattern of emphysema and the relatively low level of exposure to tobacco smoke compared with that more commonly associated with emphysema," Johnson writes.
The men ranged in age from 27 to 46. The 27-year-old had smoked several pipes full of marijuana daily for several years, while the other men smoked from two joints per week to three per day. Tobacco use, which is commonly associated with the development of lung cancer and emphysema, was minimal among all three men. All of them developed the cysts, called bullae, in the upper areas of their lungs, but not in the middle or lower areas.
The researchers were unable to show that marijuana smoking is a cause of emphysema, but demonstrated that it may play an additive role in the development of bullae. "There is a public perception that marijuana smoking has little adverse effect on physical health. ... We hope that our case reports will stimulate further study into ... potential lung toxicity," Johnson writes.
Jag Khalsa, PhD, a neuropharmacologist with the Center on AIDS and Medical Consequences of Drug Abuse with the National Institute on Drug Abuse, reviewed the paper for WebMD. "There have been anecdotal reports of the development of these kinds of conditions in chronic marijuana users, and I'm not surprised by these findings," he says. "The idea that people who smoke marijuana don't smoke as much as those who smoke cigarettes and are therefore not at risk of health consequences is erroneous." Because pot smokers try to keep the smoke in their lungs longer, and because marijuana is smoked unfiltered, a few joints may be as harmful as a much larger number of tobacco cigarettes, he says.
In an interview with WebMD, Christopher Gallagher, MD, clinical assistant professor at the University of Pennsylvania Cancer Center, says: "In our clinic we have encountered several young marijuana smokers with no history of tobacco smoking or other significant risk factors who were diagnosed with lung cancer or other ... cancers. It's certainly reasonable to suspect there could be an association with the development of emphysema." Though more study is needed, he says, "for the recreational user with a full life expectancy, the potentially harmful effects of marijuana smoking are a legitimate concern."
- Experts believe that chronic use of marijuana could lead to the development of emphysema, a disorder of the lungs in which tissue is replaced with cysts.
- Four young men who smoked pot but used only limited amounts of tobacco developed the cysts, or bullae, in the upper areas of their lungs.
- Smoking marijuana can be detrimental to your health, even if it is not used as often as cigarettes, because it is smoked unfiltered and people hold the smoke in their lungs longer.