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, 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.