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The Ontario Lung Association (OLA) has announced a funding commitment of $50,000 to study the effects of combusted (smoked) cannabis on the immune system. The study is being led by Dr. Jeremy Hirota at the Firestone Institute for Respiratory Health at St. Joseph’s Healthcare Hamilton. Dr. Hirota is the Canada Research Chair in Respiratory Mucosal Immunology and Assistant Professor in the Department of Medicine at McMaster University.

The cannabis study is based on Dr. Hirota’s previous work, which has shown striking similarities between the effects of tobacco and cannabis smoke (see The similarities suggest that cannabis smoke may also have a similar, detrimental effect on the immune system as tobacco smoke.

“There is a long history that shows tobacco smoking is associated with increased respiratory tract infections,” noted Dr. Hirota. “Tobacco smoke can decrease the antiviral processes of our lungs.”

When it comes to smoking cannabis, many scientists and clinicians believe there may be immune consequences similar to that of smoking tobacco.

“But that’s an unknown,” commented Dr. Hirota, who explained that research on cannabis has historically been very difficult due to restrictions on the controlled substance. This has left an enormous knowledge gap in medicinal and recreational cannabis use, particularly in the areas of respirology, but also in areas of mental health, addiction, and pain research.

Recreational use of cannabis has been expected to rise following its legalization in October 2018. In Ontario, the first storefronts legally allowed to sell cannabis opened their doors on April 1, 2019, increasing the accessibility of cannabis in the province. Previously, the only legal cannabis sales in Ontario were from the online Ontario Cannabis Store.

The OLA grant will allow researchers to test various cannabis strains, as the chemical composition of cannabis varies widely between different strains.

The two main active compounds found in cannabis are THC (the main psychoactive component) and CBD (thought to have pain relieving properties). Canadian law requires distributors to list the amount of THC and CBD in each product, though there are also more than 100 other cannabinoid compounds found in cannabis, in smaller quantities.

Initial grant work was done cooperatively with the Centre for Medicinal Cannabis Research at St. Joe’s West 5th Campus, which studies cannabis objectively as a therapeutic agent, including its risks and benefits.

The announcement was made at the OLA’s Breathe! Bash on March 28, 2019, an evening to celebrate and create breathing breakthroughs. The event brought together researchers, donors, and other stakeholders. Researchers discussed their goals and progress on existing projects.

Two other cannabis research grants were announced at the OLA event. These grants will support research related to the effects of recreational cannabis on obstructive sleep apnea, and help determine whether smoking cannabis affects diagnostic breathing tests.

“Cannabis is a very polarizing topic, but as scientists we should approach things with data, with experiments to test hypotheses, and then based on the data make an informed decision,” commented Dr. Hirota.

According to George Habib, President and CEO of the OLA, “The results of these projects will ensure that healthcare providers and the public have the evidence they need to better inform the decisions they make on behalf of their patients or themselves around the use of cannabis.”

Dr. Hirota was also the past recipient of an OLA grant that recently concluded. The grant supported research that was looking for ways to improve the effectiveness of current medications for Chronic Obstructive Pulmonary Disease (COPD), as its trajectory is increasing with an aging population.

By conducting research on potential public health issues stemming from the legalization of cannabis, Dr. Hirota’s lab is committed to tackling new challenges in respiratory health.



The Firestone Institute for Respiratory Health (FIRH) conducts groundbreaking basic, clinical, and translational research on complex airway diseases, such as asthma, COPD, IPF, and others. FIRH is the proud partnership of St. Joseph’s Healthcare Hamilton and McMaster University, which has been helping Canadians breathe better for over 40 years. Learn more about FIRH here.


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