Researchers from the University of Alberta in Canada have found that cannabis smoke contains 110 potentially toxic chemicals. Although less than cigarettes, they say their research should serve as a warning for the potential adverse health effects of cannabis smoke.

For the study, Robert Nishida, a post-doctoral fellow at the university, and his team used a ‘smoking machine’.  Behaving much like human smoking, it was used to receive human-like volume samples of both tobacco and cannabis smoke from cigarettes and joints. As the machine inhaled the smoke, it entered a large bag where the lab’s aerosol instruments then measured for size, concentration, and chemical properties of particles.

All in all, the researchers identified 536 chemicals in cannabis smoke. Of those, 110 are known to be toxic. While some cause cancer, others are known to cause mutations, and others harm the development of unborn children. Meanwhile, the team found 173 toxic chemicals in tobacco smoke, of which 69 overlapped with those in cannabis.

On average, they said that particles in cannabis smoke tend to be 29% larger than those from tobacco; something could impact where they are deposited in a smoker’s respiratory tract.

“It’s not out of line to say there’s potential health effects of marijuana smoke,” says Nishida. “Tobacco cigarettes have been studied for decades, and even with tobacco, I don’t think the picture is fully there. The body of research for marijuana smoke is not even remotely comparable.”

Although both tobacco and cannabis smoke hold the potential to harm the body, Nishida said that researchers still need to develop a better understanding of smoking before conclusions can be made. In the case of cannabis, this includes how it functions according to different puff profiles, joint designs, cannabis strains, and how its chemicals spread in the body.