What Does Marijuana Do To Your Lungs?

Since tobacco smoking causes cancer, marijuana smoking must as well. Right? Wrong.

Marijuana decreases the risk of lung cancer. Marijuana does not cause chronic obstructive pulmonary disease (COPD). Thus, Pot is safer than cigarettes.

Professor emeritus of medicine at UCLA and one of the United States’ leading pulmonologists who has been studying weed and its effects on lungs for more than 30 years, Dr. Donald Tashkin once sought to prove pot causes lung cancer, but the evidence forced him to conclude that average weed smoking does not cause lung cancer or impair lung function:

“The smoke content of marijuana is very similar to that of tobacco. There is a higher concentrate of cancer-causing chemicals in marijuana tar, and it reaches the lungs before any other organ, so there is this idea that they are related in causing the same health issues of the lungs. But through my studies we failed to find any positive association [with cancer]. Instead, the association would be negative, between lung cancer and the use of marijuana. The likelihood is, that despite the fact that marijuana smoke contains carcinogens, we don’t see the same heightened risks of cancers that we see in tobacco.”

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Dr. Tashkin is not alone in his analysis. To investigate the association between cannabis smoking and lung cancer risk, data on 2,159 lung cancer cases and 2,985 controls were pooled from 6 case-control studies in the US, Canada, UK, and New Zealand within the International Lung Cancer Consortium. Results from the pooled analyses in 2014 provided little evidence for an increased risk of lung cancer among habitual or long-term cannabis smokers.

“I was opposed to legalization because I thought it would lead to increased use and that would lead to increased health effects. But at this point, I’d be in favor of legalization. I wouldn’t encourage anybody to smoke any substances. But I don’t think it should be stigmatized as an illegal substance. Tobacco smoking causes far more harm. And in terms of an intoxicant, alcohol causes far more harm.” – Dr. Tashkin

Dr. Tashkin also found that smoking marijuana, unlike smoking tobacco, does not cause COPD.

“Reasoning for this may be that marijuana is a potent anti-inflammatory and suppressive. But COPD is activated by tobacco smoke and other toxic substances. The other major impact of tobacco smoking on the lungs is the association between smoking tobacco and the development of destructive pulmonary disease, the third cause of death in America.”

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Again, his current findings echo results from previous research. In a large cross-sectional analysis of US adults aged 18 to 59 using data from two rounds of the National Health and Nutrition Examination Surveys (NHANES), researchers from Georgia’s Emory University found in 2015 that occasional and low cumulative marijuana use was not associated with adverse effects on pulmonary function.

Cumulative lifetime marijuana use, up to 20 joint-years, is not associated with adverse changes in spirometric [a person’s ability to exhale] measures of lung health. Although greater than 20 joint-years of cumulative marijuana exposure was associated with a twofold increased odds of a FEV1/FVC less than 70%, this was the result of an increase in FVC [forced vital capacity], rather than a disproportional decrease in FEV1 [forced expiratory volume]as is typically associated with obstructive lung diseases.



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