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Not All Smoke is Created Equal: Cannabis Smoke and the Lung Cancer Paradox

January 7, 2019 in General News

Not All Smoke is Created Equal

Decades of scientific research and clinical trials have indisputably established that smoking cigarettes is associated with the progression of several cancers, including, but not limited to, liver, bladder, kidney and lung cancer 1. While smoke is generally harmful to the lungs when inhaled, comprehensive studies have demonstrated vastly different chemical compositions between smoke from tobacco, wood, plastic and even cannabis combustion 2,3. If not all smoke is created equal; it begs the question as to whether or not all smoke is equally harmful to our health. If there is indeed variation, then how bad is smoking cannabis for you compared to smoking cigarettes?

Tobacco Smoke & Cannabis Smoke Affect Lung Health Differently

Epidemiological studies investigating tobacco smokers and cannabis smokers tell two very different stories. The effect of tobacco smoke on lung health are very well known and established in the literature. However, the same cannot be said at all when it comes to cannabis smoke and lung health. Most studies turn up inconclusive evidence when trying to establish a link between lung disease and exposure to cannabis smoke, even habitual, long-term use 3–5. Other studies have even shown certain lung functions improving while even more have confirmed the presence of several deadly chemicals in the smoke. As far as cannabis smoke, unlike tobacco smoke, the jury is still out as for how deadly or dangerous it really is in the long run.

Cigarettes Are Still Deadly

Several decades of high-quality, large-scale cohort studies and retrospective analyses have established without a reasonable doubt that cigarette smoke causes cancer. Despite being considered the leading cause of preventable disease worldwide, it is estimated over 1.1 billion people used tobacco globally in 2015 6,7. Major long term health complications of tobacco smoking include the biggest killers of them all: coronary heart disease, cancer, and chronic obstructive pulmonary disease (COPD) 8.

People are Smoking Less Overall

Nevertheless, studies are showing overall tobacco use in adults has been declining over the years, a 9. Once glamorized in society, the appeal of cigarette smoking has since gone up in smoke after evidence-based, educational quit smoking campaigns began changing public perception (pummeling the public with ads of smokers talking like robots out of a hole in their neck turned out to be pretty effective at getting the message across). Interestingly enough, the mental health community, particularly those suffering with opiate addiction and taking methadone have taken to cigarette smoking as a form of replacement therapy; while individuals with mental health are only reported to constitute about a quarter of the population, it’s estimated they comprise of 40% of all smokers 10,11.

Smoking Cannabis & Lung Health: Inconclusive to Intriguing

Curiously enough, other studies have paradoxically shown exposure to cannabis smoke can actually improve lung function, such as an increase in forced vital capacity (an important measure of lung function), temporary vasodilatation (opening up of the airways), and even immediate reversal of exercise-induced asthma 12–14.

smoking cannabis


Cannabis Smoke Still Contains Harmful Chemicals

This author would like to point out that further large scale, epidemiological studies show a correlation between marijuana and lung cancer doesn’t mean it can be ruled out. It can be safely said that smoking cannabis is safer than smoking tobacco at this point, however, many toxic chemicals such as “ammonia, hydrogen cyanide, nitric oxide, and aromatic amines” are still found in cannabis smoke and chronic exposure is known to cause bronchitis 15,16.

Why the Discrepancy?

The true reason cannabis smoke doesn’t cause the level of harm one would expect given the toxicology profile of the smoke is a mystery. Some hypothesize it has to do with the bronchodilating and anti-inflammatory effect cannabis has that may prevent damage caused by toxins in the smoke 12. New studies indicating anti-tumorgenic/anti-cancer effects caused by cannabis may also play a role in mitigating long term damage and cancer formation 17. The truth is, we don’t really know and we should keep looking to try and figure it out.


Why Smoke Your Medicine At All?

The modern age allows for cannabis to consumed in a variety of ways outside of simply combusting the flower and smoking it. Edibles, vaporization, transdermal technology and sublingual formulations have all become available. Are there potential benefits to actually smoking cannabis? Turns out, there may be. The rapid onset of effects, especially anti-emetic effects makes smoked cannabis a preference for chemotherapy patients who otherwise must deal with severe nausea that makes synthetic cannabinoid pills or even edibles, difficult to swallow and keep down 18. Other advantages conferred by smoking cannabis that have been reported include: the ability for self-titration with the smoked marijuana and the benefits allowed by the “entourage effect” 18.

Clearing the Smoke

For far too long, the term “smoking” has carried with it far too many assumptions that do not take into account what in fact is being smoked. While smoke itself may not be good for the lungs, the composition of the smoke and it’s source is truly important in discerning just how damaging it may be and what, if any, benefits there may be for utilizing this method of administration for cannabis. Presently, chemotherapy patients seem to be one of the groups that benefit the most from smoking cannabis. As far as tobacco smoke, there’s hardly any physician that would ever advocate for such a thing.


No Smoke, No Fire: Cannabis Vaporization as a Closing Thought

Vaporizing cannabis (as well as nicotine) is a new trend that has begun to skyrocket to epic proportions. This new method of administration requires even further research, however, preliminary findings do suggest it may be a healthier option than smoking 19. In the end, patients must find the best medical option that works for them. Currently, vaporization may offer the same instant relief, especially to patients who can’t keep down food or water due to nausea. While rigorous long-term studies are required to assess cancer risk in heavy, regular cannabis smokers, several large studies have yet failed to establish a link. Vaporization seems to eliminate many risks even further.


So while smoking may be “bad” for you overall, the real story is much more nuanced and if we know one thing for sure, it’s that tobacco smoke and cannabis smoke are nowhere near equally harmful, especially in the short term where cannabis use has actually shown to have more beneficial effects. Hopefully future studies will help further clarify any and all potential pathophysiology of lung disease as it relates to cannabis smoke in the long run.















by Gaurav Dubey (M.S. Biotechnology),
Clinical Researcher Pediatric Cardiothoracic Surgery, Rush Medical Center,
Active Cannabis Blogger (The Medical Cannabis Community, Green Flower Media, Bloom, MCC)
Co-Founder & President Karmik, LLC

Works Cited

  1. Jacob, L., Freyn, M., Kalder, M., Dinas, K. & Kostev, K. Impact of tobacco smoking on the risk of developing 25 different cancers in the UK: a retrospective study of 422,010 patients followed for up to 30 years. Oncotarget 9, 17420–17429 (2018).
  2. Pryor, W. A. Biological effects of cigarette smoke, wood smoke, and the smoke from plastics: the use of electron spin resonance. Free Radic. Biol. Med. 13, 659–676 (1992).
  3. Robert Melamede. Cannabis and tobacco smoke are not equally carcinogenic. Harm. Reduct. J. 2, 21 (2005).
  4. Huang, Y.-H. J. et al. An epidemiologic review of marijuana and cancer: an update. Cancer Epidemiol. Biomark. Prev. Publ. Am. Assoc. Cancer Res. Cosponsored Am. Soc. Prev. Oncol. 24, 15–31 (2015).
  5. Zhang, L. R. et al. Cannabis smoking and lung cancer risk: Pooled analysis in the International Lung Cancer Consortium. Int. J. Cancer J. Int. Cancer 136, 894–903 (2015).
  6. Samet, J. M. Tobacco smoking: the leading cause of preventable disease worldwide. Thorac. Surg. Clin. 23, 103–112 (2013).
  7. WHO | Prevalence of tobacco smoking.
  8. Bonnie, R. J. et al. The Effects of Tobacco Use on Health. (National Academies Press (US), 2015).
  9. Mendez, D. & Warner, K. E. Adult Cigarette Smoking Prevalence: Declining as Expected (Not as Desired). Am. J. Public Health 94, 251–252 (2004).
  10. Cooperman, N. A., Richter, K. P., Bernstein, S. L., Steinberg, M. L. & Williams, J. M. Determining Smoking Cessation Related Information, Motivation, and Behavioral Skills among Opiate Dependent Smokers in Methadone Treatment. Subst. Use Misuse 50, 566–581 (2015).
  11. Santhosh, L. et al. From the sidelines to the frontline: how the Substance Abuse and Mental Health Services Administration embraced smoking cessation. Am. J. Public Health 104, 796–802 (2014).
  12. Ribeiro, L. I. & Ind, P. W. Effect of cannabis smoking on lung function and respiratory symptoms: a structured literature review. NPJ Prim. Care Respir. Med. 26, 16071 (2016).
  13. Tashkin, D. P., Shapiro, B. J., Lee, Y. E. & Harper, C. E. Effects of smoked marijuana in experimentally induced asthma. Am. Rev. Respir. Dis. 112, 377–386 (1975).
  14. Tetrault, J. M. et al. Effects of Marijuana Smoking on Pulmonary Function and Respiratory Complications: A Systematic Review. Arch. Intern. Med. 167, 221–228 (2007).
  15. Repp, K. Marijuana and health: a comprehensive review of 20years of research. 58
  16. Sachs, J., McGlade, E. & Yurgelun-Todd, D. Safety and Toxicology of Cannabinoids. Neurotherapeutics 12, 735–746 (2015).
  17. Chakravarti, B., Ravi, J. & Ganju, R. K. Cannabinoids as therapeutic agents in cancer: current status and future implications. Oncotarget 5, 5852–5872 (2014).
  18. Parker, L. A., Rock, E. M. & Limebeer, C. L. Regulation of nausea and vomiting by cannabinoids. Br. J. Pharmacol. 163, 1411–1422 (2011).
  19. Loflin, M. & Earleywine, M. No smoke, no fire: What the initial literature suggests regarding vapourized cannabis and respiratory risk. Can. J. Respir. Ther. CJRT Rev. Can. Thérapie Respir. RCTR 51, 7–9 (2015).


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