Smoking marijuana is not associated with chronic obstructive pulmonary disease, or COPD, according to a newly released study.
Researchers from the University of California, Los Angeles examined participants who smoke or have smoked tobacco cigarettes, and divided them into three groups: current, former or never pot smokers.
The authors of the study said that limited “data are available regarding marijuana smoking’s impact on development or progression of chronic obstructive pulmonary disease (COPD) in middle-aged or older adults with a variable history of tobacco cigarette smoking.”
“We compared [current marijuana smokers], [former marijuana smokers] and [never marijuana smokers], and those with varying amounts of lifetime marijuana use. Mixed effects linear regression models were used to analyze changes in spirometry, symptoms, health status and radiographic metrics; zero-inflated negative binomial models were used for exacerbation rates,” the research team wrote.
Most participants were followed for four years or more, according to the researchers, who wrote that “incident COPD, respiratory symptoms, health status, radiographic extent of emphysema or air trapping, and total or severe exacerbations were not different between [current marijuana smokers] or [former marijuana smokers] versus [never marijuana smokers] or between those with any lifetime amount of marijuana use versus [never marijuana smokers].”
In their concluding analysis, the researchers wrote: “In a cohort of ever-tobacco smokers of ≥20 pack-years with established COPD or at risk of developing COPD followed over an average of more than 4 years, a history of current and/or former smoking of marijuana of any cumulative lifetime amount was not found to be associated with a significantly deleterious impact on progression of COPD. Among ever-tobacco smokers in the same cohort without COPD at enrollment, self-reported current and/or former concomitant marijuana smoking, including heavy marijuana smoking, was not found to be associated with an increased risk of subsequently developing COPD. However, in view of our study’s limitations and of previously published findings that conflict with our results, additional studies with a larger sample size and longer duration of follow-up that are specifically designed to evaluate this issue are needed for a better understanding of potential long-term effects of marijuana smoking in persons with or at risk of developing COPD.”
NORML’s Deputy Director Paul Armentano touted the findings from the UCLA study, which was published this month in Chronic Obstructive Pulmonary Diseases.
“These results are consistent with decades worth of data finding that cannabis smoke exposure is not associated with the same sort of deleterious pulmonary impact as is tobacco smoke exposure,” Armentano said. “They should be reassuring to cannabis consumers and to health professionals alike, and they should help to guide future policies with respect to the crafting of evidence-based public health messages and associated regulations.”
NORML noted that the findings “are consistent with those of prior studies concluding that cannabis inhalation, even long-term, is not positively associated with COPD, lung cancer, or irreversible airway damage,” and added that “the use of vaporization technology, which heats herbal cannabis to a set temperature below the point of combustion, is associated with reduced exposure to toxic gasses and has been identified as a ‘safe and effective’ cannabis delivery device in clinical trial settings.”
In one of the studies cited by NORML, researchers from Great Britain in 2018 said that the “available literature fails to support an association between cannabis smoke exposure and the onset of COPD, emphysema, lung cancer, shortness of breath, or irreversible airway damage,” although they did “identify a link between marijuana inhalation and more frequent cough, sputum production, wheezing, and chronic bronchitis – though they acknowledged that these symptoms largely cease upon quitting.”
“The long-term respiratory effects of cannabis differ from traditional smoking,” the researchers wrote, as quoted by NORML. “[C]annabis smoking does not appear to be carcinogenic.”