Study: Marijuana Smoke Exposure Not Linked To Poor Lung Health

Long-term exposure to cannabis smoke is not associated with adverse effects on pulmonary function, according to clinical data published in the journal Chronic Obstructive Pulmonary Diseases.

A team of investigators led by researchers at the Colorado School of Public Health assessed the relationship between marijuana use and respiratory function and symptoms in a cohort of 2,300 subjects ages 40 to 80, many of whom also smoked tobacco.

Authors reported, “Neither current nor former marijuana use was associated with increased risk of cough, wheeze, or chronic bronchitis when compared to never marijuana users after adjusting for covariates. … Current and former marijuana smokers had significantly higher FEV1 (forced expiratory volume) … when compared to never users. … Both current and former marijuana use was associated with significantly less quantitative emphysema … when compared to never users, even after adjusting for age, … current tobacco smoking pack years, and BMI. … In agreement with other published studies, we also did not find that marijuana use was associated with more obstructive lung disease.”

The long-term combined use of tobacco and cannabis also was not found to be associated with any additive adverse effects on the lungs. Authors concluded, “Among older adults with a history of tobacco use, marijuana use does not appear to increase risk for adverse lung function. … There may be no to little increased risk of marijuana use for a further increase in respiratory symptoms or adverse effects on lung function among those with a history of concomitant tobacco use.”

Prior longitudinal studies assessing the effects of long-term cannabis smoke exposure on lung function have similarly reported that subjects’ marijuana use history is not positively associated with increased incidences of chronic obstructive pulmonary disease (COPD), lung cancer, or with other significant detrimental effects on pulmonary function.

Full text of the study, “Marijuana use associations with pulmonary symptoms and function in tobacco smokers enrolled in the subpopulations and intermediate outcome measures in COPD Study (SPIROMICS),” appears online here.

12 thoughts

  1. Whoaaa, there Paul. Red flag in this study;

    “Marijuana has a similar chemical makeup, including toxins, as smoked tobacco, aside from approximately 60 cannabinoids in marijuana and nicotine in tobacco.”

    Clearly this statement is misleading from the get go. To begin, we all know that people who smoke tobacco aren’t harvesting it themselves and smoking it in a pipe; theyre buying tobacco in cigarette packs from stores with all kinds of horrific, toxic and addictive additives inside.

    Meanwhile whole plant marijuana is non toxic, and only contains trace toxins in the smoke, which would require such an intense amount of smoke in order to intoxicate someone that we would sooner axphyixiate from the marijuana smoke than be intoxicated by it.

    “Toxic,” by definition, has to lead to some reasonable quantity of consumption to cause intoxication or death. Death by axphixiation is not intoxication.

    I realize the study is testing marijuana’s effect on the lungs of tobacco smokers but there must be some accountability to explain the relatively vast difference in toxicity between marijuana and tobacco smoke during the introduction of this study.

    [Paul Armentano responds: Julian, in general, the smoke formed from the combustion of tobacco smoke and marijuana smoke contains several similarities, absent the activation of cannabinoids. See:

    Smoke from tobacco and cannabis contains many of the same carcinogens and tumor promoters [20, 21]. However, cannabis and tobacco have additional pharmacological activities, both receptor-dependent and independent, that result in different biological endpoints.]

    1. I think the bottom line is the ever-growing set of epidemiological studies, which keep on clearing the good name of cannabis.

    2. Thanks for the link Paul… a much more honest introduction in regards to cigarette tobacco vs. Marijuana smoke toxicity… even if it fails to specify the chemicals and byproducts from each method of consumption.. I’ll clarify:

      The synergy from the cannabinoids in a common hemp-papered joint (hence not the tobacco rolled blunt) creates harm reduction by metabolizing and attacking carcinogens as the marijuana smoke is introduced to the lungs. The better our brain and organs are stimulated to function, the better our bodies’ ability to attack, excrete and neutralize carcinogens and other toxins.

      On the other hand…

      Tobacco cigarette smoke compounds the toxicity of its combusted smoke. Ammonia, petroleum products and I suspect the withdrawal fatigue from our bodies’ relative inability to sustain or reproduce nicotine receptors as compared to cannabinoid receptors, all contribute to a depressed organ function and immune system.

      The original link actually discussed the kind of popular ways marijuana is smoked in a “filterless, rolled joint.”

      But just as we are careful to control the alternative substances consumed in a study involving tobacco and marijuana… (such as were they taking pills? Sleeping well? Healthy diet?)… it is irresponsible for us not to consider the quality of chemicals in the weed or tobacco consumed or even the rolling papers… (were they %100 hemp NORML curved papers? Or a Swisher-Sweet tobacco blunt? Was it tobacco smoke from a pipe? Or a filtered cigarette? And what other chemicals/carcinogens were in that cigarette?)

      If people were consuming nothing but the smoke itself, I’d give the study a B+. But without studying all the chemicals consumed, the introduction becomes a tool… a smokescreen for false equivalence, and fails to educate properly the quality, synergy and toxicity of what is being consumed and purchased.

  2. “Although we adjusted for tobacco use and excluded never tobacco smokers, it is still unclear if long-term heavy marijuana smoking results in significant risk of respiratory symptoms, lung obstruction, inflammation, or emphysema.”

    Although cannabis smoke won’t kill, the science here is still inconclusive on other types of lung damage or discomfort.

    Empirical observation says without a doubt smoke effects respiratory comfort in a negative fashion for a great number of individuals.

    In this regard eating cannabis will of course avoid this.

    1. That’s right. This is the important underlying point. As far as marijuana legalization is concerned, the debate over the risks of smoking is a paper tiger, because… “Brownies!”

  3. Studies like these are precisely why we need to lobby and demand our state legislators include quality third party whole plant marijuana testing for carcinogens, toxins, pesticides, molds and fungus into our state marijuana policies.

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