13th January 2022
By Roland Sebestyén
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A new study shows that there has been a rise in the number of drivers treated in trauma centres following a collision since recreational cannabis use was legalised in Canada.

While other studies argue that cannabis legalisation hasn’t resulted in more death or injuries on the roads in the United States, a paper published in The New England Journal of Medicine found slightly worrying data from Canada.

According to researchers, a significantly higher number of drivers in trauma centres were found to have consumed substances linked to THC -the chemical compound that causes the ‘high’ largely associated with cannabis – than before legalisation.

The researchers assessed data of “moderately injured” motorists at four trauma centres in British Columbia between 2013 and 2020.

Subjects were placed in three different groups: those with a THC level greater than 0; a THC level of at least 2 ng per millilitre (Canadian legal limit); and a THC level of at least 5 ng per millilitre.

The secondary outcomes were a THC level of at least 2.5 ng per millilitre plus a blood alcohol level of at least 0.05%; a blood alcohol level greater than 0; and a blood alcohol level of at least 0.08%.

In the study, researchers analysed the blood samples of 4339 drivers (3550 before legalisation and 789 after legalisation).

The results are somewhat telling: before cannabis legalisation, a THC level greater than 0 was detected in 9.2% of drivers, a THC level of at least 2 ng per millilitre in 3.8%, and a THC level of at least 5 ng per millilitre in 1.1%.

After legalisation, however, the numbers increased heavily as the values were 17.9%, 8.6%, and 3.5%, respectively.

They also found that the most affected groups were those identify themselves as male and were aged over 50.

The researchers concluded: “After cannabis legalisation, the prevalence of moderately injured drivers with a THC level of at least 2 ng per millilitre in participating British Columbia trauma centres more than doubled.

“The increase was largest among older drivers and male drivers.”

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