Comparing marijuana and tobacco smoke

Q: How do the pulmonary effects of smoking marijuana compare to those of tobacco?

A: Although smoking tobacco is legal, its harmful effects are well-known. There is much documented evidence of its role in the development of COPD, lung cancer, heart disease, as well as other cancers and diseases. But what about smoking marijuana; is it just as harmful as smoking tobacco? With the new emphasis on the Canadian government legalizing marijuana for both recreational and medicinal purposes, some members of the public may have questions regarding the safety of smoking marijuana. Education in this matter is extremely important because, with legalization, there may be misconceptions about the safety of marijuana.

Why does this misconception exist? With the growing use of marijuana for medical purposes, there are many of those who are under the impression that smoking marijuana poses little or no health risk. However, this is not true. Medically, cannabis has been used for a variety of therapeutic purposes, such as nausea and vomiting due to chemotherapy, spasticity due to multiple sclerosis or paraplegia, as well as chronic, neuropathic and cancer pain (Health Canada, 2007, 2013; Whiting et al., 2015). However, despite these benefits, many people fail to recognize the adverse effects and drug interactions that need to be taken into consideration.

Marijuana smoke and tobacco smoke share similar properties and contain many of the same compounds and carcinogens (Gates, Jaffe, & Copeland, 2014; Ribeiro et al., 2016). Additionally, when cannabis is smoked, the user tends to inhale deeper, hold their breath longer (Gates et al., 2014; Ribeiro et al., 2016). Consequently, people who smoke marijuana and/or tobacco often present with similar respiratory symptoms, such as coughing, wheezing, shortness of breath, increased sputum production, increased risk of infection, chronic bronchitis, the development of lung bullae, and more (American Thoracic Society, 2013; Government of Canada, 2017; Ribeiro et al., 2016).

In addition to the pulmonary risks, there are systemic risks to smoking marijuana. In the short term, it can impair cognitive function, increase sleepiness, anxiety, blood pressure, heart rate, among other things (Government of Canada, 2017). In the long-term, smoking marijuana may cause harm to a person’s memory, ability to concentrate and overall intelligence (Government of Canada, 2017).

Other methods of inhalation are not guaranteed to be less harmful. Some people may choose to consume cannabis through vaporizers, electronic cigarettes (e-cigarettes) or hookahs to avoid inhaling smoke. However, these products all contain similar chemicals and carcinogens as tobacco (Petrasko, 2017). At this time, further studies are required before other methods of inhalation can be considered safe (American Thoracic Society, 2013). For more information, see this article

Smoking marijuana for medical purposes carries the same risks as it does for recreational purposes. To mitigate these risks, it is recommended that those who require medical cannabis use formulations such as oral tablets or buccal sprays in place of inhalation.

Unfortunately, the quantity of evidence regarding marijuana use pales in comparison to that of tobacco use. Additionally, there are many caveats to much of the existing studies due to the many variables involved with smoking cannabis, as there is much variety in strength of marijuana, quantity of marijuana in a joint, reproducibility, etc. (Ribeiro et al., 2016). At this point in time, we can say with reasonable certainty that the health risks associated with smoking marijuana are comparable to those of tobacco smoking. With the legalization of marijuana in Canada on the horizon, education of the general public with regards to these health risks is essential.

 

The author acknowledges the help of Jennifer Butler and Naomi Wolfe, BScPharm Candidates 2018 from the University of Manitoba, for their contributions to this article.

 

References:

American Thoracic Society. (2013). Smoking Marijuana and the Lungs. American Journal of Respiratory and Critical Care Medicine187, 5–6.

Gates, P., Jaffe, A., & Copeland, J. (2014). Cannabis smoking and respiratory health: Consideration of the literature. Respirology19(5), 655–662. https://doi.org/10.1111/resp.12298

Government of Canada. (2017). Health effects of cannabisHealth Canada. Retrieved from www.ncbi.nlm.nih.gov/pubmed/24176069

Health Canada. (2007). Consumer Information – Cannabis. Retrieved from http://www.hc-sc.gc.ca/dhp-mps/alt_formats/pdf/marihuana/info/cons-eng.pdf

Health Canada. (2013). Information for Health Care Professionals: Cannabis (marihuana, marijuana) and the cannabinoidsEthics (Vol. 9). Retrieved from http://www.hc-sc.gc.ca/dhp-mps/alt_formats/pdf/marihuana/med/infoprof-eng.pdf

Petrasko, K. L. (2017). Ask the Experts: Cigars, e-cigarettes and hookahs vs. cigarettes. Retrieved May 12, 2017, from http://www.canadianhealthcarenetwork.ca/pharmacists/discussions/the-experts/tobacco-addiction/ask-the-experts-cigars-e-cigarettes-and-hookahs-vs-cigarettes-39161

Ribeiro, L. I., Ind, P. W., Atakan, Z., Beutler, J. A., Marderosian, A. H., Forti, M. Di, … Mukherjee, J. (2016). Effect of cannabis smoking on lung function and respiratory symptoms: a structured literature review. Npj Primary Care Respiratory Medicine26(August), 16071. https://doi.org/10.1038/npjpcrm.2016.71

Whiting, P. F., Wolff, R. F., Deshpande, S., Di Nisio, M., Duffy, S., Hernandez, A. V, … Kleijnen, J. (2015). Cannabinoids for Medical Use: A Systematic Review and Meta-analysis. Jama313(24), 2456–2473. https://doi.org/10.1001/jama.2015.6358


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