Lung cancer and weed smoking

[Shaolin]

Context: Marijuana smoke contains many of the same constituents as tobacco smoke, but whether it has similar adverse effects on pulmonary function is unclear.

Objective: To analyze associations between marijuana (both current and lifetime exposure) and pulmonary function.

Design, Setting, and Participants: The Coronary Artery Risk Development in Young Adults (CARDIA) study, a longitudinal study collecting repeated measurements of pulmonary function and smoking over 20 years (March 26, 1985-August 19, 2006) in a cohort of 5115 men and women in 4 US cities. Mixed linear modeling was used to account for individual age-based trajectories of pulmonary function and other covariates including tobacco use, which was analyzed in parallel as a positive control. Lifetime exposure to marijuana joints was expressed in joint-years, with 1 joint-year of exposure equivalent to smoking 365 joints or filled pipe bowls.

Main Outcome Measures: Forced expiratory volume in the first second of expiration (FEV1) and forced vital capacity (FVC).

Results: Marijuana exposure was nearly as common as tobacco exposure but was mostly light (median, 2-3 episodes per month). Tobacco exposure, both current and lifetime, was linearly associated with lower FEV1 and FVC. In contrast, the association between marijuana exposure and pulmonary function was nonlinear (P < .001): at low levels of exposure, FEV1 increased by 13 mL/joint-year (95% CI, 6.4 to 20; P < .001) and FVC by 20 mL/joint-year (95% CI, 12 to 27; P < .001), but at higher levels of exposure, these associations leveled or even reversed. The slope for FEV1 was −2.2 mL/joint-year (95% CI, −4.6 to 0.3; P = .08) at more than 10 joint-years and −3.2 mL per marijuana smoking episode/mo (95% CI, −5.8 to −0.6; P = .02) at more than 20 episodes/mo. With very heavy marijuana use, the net association with FEV1 was not significantly different from baseline, and the net association with FVC remained significantly greater than baseline (eg, at 20 joint-years, 76 mL [95% CI, 34 to 117]; P < .001).

Conclusion Occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function.

Full study here and attached.

 

[corpus callosum]

Thanks for posting this Shaolin!

The paper is looking at lung function alone using spirometry; we cannot infer anything firm about about lung cancer incidence from this study.

Good to know that sensible use of marijuana doesnt appear to have a major effect on lung function though.:d

 

[a1pha]

Dr. Tashkin from UCLA had some interesting work in this area if you haven't already pulled his work.

http://www.lung.med.ucla.edu/faculty/tashkin.htm

 

[jamie]

I would like to know what kind of tobacco was used in the study..was it conventional adulterated tobacco or organic tobacco?

 

[a1pha]

I would like to know what kind of tobacco was used in the study..was it conventional adulterated tobacco or organic tobacco?

I don't believe medical doctors / scientists use words like organic in the same way as people shopping at the produce market. Any tobacco is, by definition, organic since it was derived from a living organism.

Also, it says in the study they used conventional cigs.

 

[SpartanII]

Conclusion Occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function.

I do know that from my experience, smoking weed daily for 15 years has caused me chest pain and reduced lung capacity. Not good. That's why nowadays I only vaporize it when I use it occasionally.