As of October 17th, 2018 cannabis will be legal in Canada.
The Canadian Lung Association aspires to a future free of lung disease. Prevention is one key element that could help us towards this future. We caution the public against smoking cannabis recreationally because of the risks it may pose to lung health.
There are still many unknowns about cannabis and its long-term effects on lung health, but we do know that the inhalation of smoke is harmful to lung health as the combustion of materials releases toxins and carcinogens. These are released regardless of the source – whether it is burning wood, tobacco or cannabis. Knowledge about the long-term effects of cannabis smoke is still limited but early research studies have demonstrated harm that can lead to chronic bronchitis.[i] Other studies suggest that frequent and heavy cannabis smoking is associated with cough, sputum production, wheezing and a decline in lung function. [ii][iii] Smoking of cannabis by people who also smoke tobacco is of particular concern, as there is evidence that tobacco and cannabis act synergistically to increase the risk of respiratory issues and chronic obstructive pulmonary disease (COPD).[iv]
Second-hand cannabis smoke contains many of the same toxins and chemicals found in directly inhaled cannabis smoke. [v] More research on the health effects of second-hand cannabis smoke is needed. Until this issue is addressed, the Canadian Lung Association remains concerned about the potential harmful effects – especially among vulnerable populations, such as children and youth. If you chose to smoke cannabis, do not smoke it in areas where children or youth are present.
The Canadian Lung Association has developed a list of recommendations, such as dedicated funding for research, advocating for regulations in advertising and public education. Until we know more, we strongly advise Canadians to avoid smoking cannabis recreationally.
If you choose to use cannabis recreationally, please use Canada’s Lower-Risk Cannabis Use Guidelines: https://www.camh.ca/-/media/files/pdfs---reports-and-books---research/canadas-lower-risk-guidelines-cannabis-pdf.pdf
For more information about our position and our policy recommendations, please visit lung.ca/cannabis.
[ii] Hancox, R. J., Shin, H. H., Gray, A. R., Poulton, R., & Sears, M. R. (2015). Effects of quitting cannabis on respiratory symptoms. European Respiratory Journal, 46(1), 80–87.
[iii] Pletcher, M. J., Vittinghoff, E., Kalhan, R., Richman, J. and others. (2012). Association between marijuana exposure and pulmonary function over 20 years. JAMA. 307: 173-18
[iv] Tan WC, Lo C, Jong A, Xing L, Fitzgerald MJ, Vollmer WM, Buist SA, Sin DD; Vancouver Burden of Obstructive Lung Disease (BOLD) Research Group. Marijuana and chronic obstructive lung disease: a population-based study. CMAJ 2009;180:814-20.
[v] Moir D, Rickert WS, Levasseur G, et al. A comparison of mainstream and sidestream marijuana and tobacco cigarette smoke produced under two machine smoking conditions. Chem Res Toxicol. 2008;21(2):494-502. doi:10.1021/tx700275p.