Lifetime Marijuana Smoking Not Tied to Permanent Lung Damage

While a recent study published in the Annals of the American Thoracic Society (ATS) highlighted an association between recent marijuana smoking and airway inflammation, moderate lifetime use was not linked to changes in lung function.

Researchers at Emory University analyzed data from a 2007-2010 National Health and Nutrition Examination Survey (NHANES) involving recent and extended marijuana use as well as determined lung function through forced vital capacity (FVC) and forced expiratory volume (FEV1).

In doing so, the investigators found that for every day the lifetime smoker smoked the month prior, they did not experience a decrease in their FEV1 (0.002% ± 0.04%, P=0.9). However, they did note an increase in their mean predicted FVC (0.13% ± 0.03%, P<0.01) and decrease in their average FEV1/FVC (-0.1% ± 0.04%, P<0.01).

Jordan A. Kempker, MD, MSc, a clinical research fellow in the Division of Pulmonary and Critical Care Medicine at Emory University School of Medicine and the study’s lead author, said, "Furthermore, smoking marijuana seems to increase symptoms of respiratory irritation, such as bronchitis, and our study was inconclusive about whether those effects are permanent. We also did not study the association of marijuana smoking with the development of cancer.”

“Lifetime marijuana use up to 20 joint-years is not associated with adverse changes in spirometric measures of lung health. While > 20 joint-years of marijuana exposure was associated with a two-fold increased odds of a FEV1/FVC < 70%, this was the result of an increase in FVC rather than the disproportionate decrease in FEV1 seen with obstructive lung diseases,” the authors concluded.