Carpet & Flooring Main Reservoirs Of THC: Researchers' Advice On How To Protect Children From Exposure

THC, or tetrahydrocannabinol, which is the main psychoactive ingredient in cannabis can linger in the environment for extended periods, causing unintended exposure long after smoking has stopped, a new study has shown.

A group of scientists from the U of T Engineering lab led by Professor Arthur Chan (ChemE) looked at how THC behaves and transforms after being released in an indoor environment.

“We began our research on tetrahydrocannabinol (THC), which is the psychoactive part of cannabis that causes intoxication because when we looked at second- and third-hand smoke, we started to see how much involuntary exposure happens,” said Amirashkan Askari, a ChemE Ph.D. candidate in Chan’s lab, who is co-author of the study with Chan and Professor Frank Wania (Physical and Environmental Sciences, ChemE).

A general opinion is that secondhand smoke is less harmful than firsthand smoke, but earlier research established that exhaled smoke contains hundreds of toxic and carcinogenic chemicals.

“Any type of smoking, whether it is tobacco or cannabis, leaves behind a suite of pollutants that can remain in homes,” says Chan.

Why Is Cannabis Not An Exemption?

Considering that the chemical structure of THC is large and complex, it tends to hold onto surfaces resulting in third-hand exposure, Askari explained.

“There are a lot of surfaces indoors — tables, chairs and floors. When you calculate the ratio of surfaces to volume, it is quite elevated compared to the outdoors,” he continued. “So, when a pollutant is emitted, it always has the chance to migrate from air to surfaces."

Children In Danger

The exposure analysis utilized a model that considered the exposure level of an adult and a toddler to THC from a burning cannabis joint emitted into the air for one hour daily, according to the University of Toronto Engineering News.

“Involuntary exposure to pollutants starts to become more important when we consider infants and children who reside in homes where this smoking takes place," Askari said. “Children tend to touch surfaces more than adults as they crawl or play; they are also known to frequently put their hands or objects in their mouths.” 

The study found that carpet and flooring materials were significant reservoirs of THC.

How To Mitigate Health Risks?

Askari said the best way to avoid involuntary exposure to THC is to stop smoking marijuana.

“When it comes to improving indoor air quality, the best way to degrade air pollutants is to shut down the source,” he said.

But for those who want to keep using cannabis responsibly, he said air purifier units can be a solution.

“If our aim is to suppress it [involuntary exposure to THC], we found the most effective measures were strategies that target the air particles directly,” Askari added. “So, if you have an air purifier unit that filters particulate matter from the air, that will reduce that exposure significantly.”

Photo: Beniznga edit of images by Picsea and  Elsa Olofsson on Unsplash