One in three high school students reports riding with a driver who has been drinking, according to a new study from the University of Waterloo.

Researchers at the Propel Centre for Population Health Impact at Waterloo found that 35 per cent of students in Grades 9 to 12 reported riding in cars with drivers who consumed at least one drink within the previous hour.

The same study found that close to 20 per cent rode in cars with a driver who had used marijuana in the previous two hours.

“These numbers are concerning because Canadian youth are at higher risk of death from traffic injuries than any other age group,” said Leia Minaker, lead author on the paper and an assistant professor at Waterloo. “A significant proportion of car-crash deaths are related to alcohol and drug impairment.”

About nine per cent of students in Grades 11 and 12 — equating to around 66,600 teens — reported having driven within an hour of drinking. A total of 9.4 per cent said they had driven after using marijuana.

The study also discovered that boys were more likely to drive after drinking or using marijuana, but girls had higher odds of riding with drivers who had been drinking.

The study was published in Canadian Medical Association Journal Open.