Study: Cannabis smoke not associated with serious pulmonary risk

By Paul Armentano,

Cannabis smoke poses only nominal pulmonary risks compared to those associated with tobacco smoke, reports a literature review to be published in the Annals of the American Thoracic Society. Its author, Donald P. Tashkin, MD, emeritus professor of medicine and medical director of the Pulmonary Function Laboratory at the David Geffen School of Medicine at UCLA conducted US-government sponsored studies of marijuana and lung function for over 30 years.

“Dr. Tashkin found that regular smoking of marijuana by itself causes visible and microscopic injury to the large airways that is consistently associated with an increased likelihood of symptoms of chronic bronchitis that subside after cessation of use,” explains the American Thoracic Society news website. “He also found that the evidence does not indicate that habitual use of marijuana leads to significant abnormalities in lung function when assessed either cross-sectionally or longitudinally, except for possible increases in lung volumes and modest increases in airway resistance of unclear clinical significance.”

“[F]indings from a limited number of well-designed epidemiological studies do not suggest an increased risk for the development of either lung or upper airway cancer from light or moderate use, although evidence is mixed concerning possible carcinogenic risks of heavy, long-term use,” notes Dr. Tashkin. “In summary, the accumulated weight of evidence implies far lower risks for pulmonary complications of even regular heavy use of marijuana compared to the grave pulmonary consequences of tobacco.”

In addition, the review found no clear link between marijuana use and the development of COPD or lower respiratory tract infections. The full paper will be released in June, 2013.

Presenters at the annual meeting of the American Academy for Cancer Research in May, 2013, reported that subjects who regularly inhale cannabis smoke have no greater risk of lung cancer than do those who do so occasionally or not at all, based on six case-control studies involving over 5,000 subjects (2,159 cases and 2,985 controls) from around the world that were conducted between 1999 and 2012.

Clinical data published in the Journal of the American Medical Association (JAMA) last year reported that subjects’ exposure to moderate levels of cannabis smoke, even over the long-term, is not associated with significant adverse effects on pulmonary function.

Vaporizers, which heat marijuana to a point where cannabinoid vapors form, but below the point of combustion, reduce subjects’ intake of potentially hazardous combustible compounds. In several clinical trials, investigators have concluded that vaporization is a “safe and effective” cannabinoid delivery mode that “does not result in exposure to combustion gases.” Researchers also report that vaporization results in higher plasma concentrations of THC compared to smoked cannabis. — West Coast Leaf News Service

Leave a Reply




You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>