After a night of heavy drinking, everyone knows to question that one person driving about whether or not they’re drunk. But that’s not the case when you replace alcohol with marijuana, according to a new, rather unsurprising study, which found that too many male college students are getting in the car with a driver who’s hit the bong a few too many times.

“There seems to be a misconception that marijuana use it totally safe, but as an injury prevention researcher, I dispute that,” said lead author of the study Jennifer Whitehill, of the University of Massachusetts Amherst School of Public Health and Health Sciences, in a press release. Her research found that male underage college students were far more likely to get in a car after they used or the driver used marijuana. And although marijuana may be gaining in popularity among the U.S. population, that doesn’t mean it should be used prior to operating a vehicle.

In an episode of Discovery Channel’s Curiosity: Your Body on Drugs, four people, high on different illegal substances participated in different tasks, including a driving test, a furniture-building test, and an emergency response test. While the participant high on marijuana didn’t drive recklessly, his coordination was thrown off, resulting in slow driving, movements, and reactions. With drivers often find themselves in situations where defensive techniques are key to avoiding a crash, impaired judgment will only hinder their chances of survival.  

Whitehill’s study found that 44 percent of males and nine percent of females drove under the influence of marijuana, while 51 percent of males and 35 percent of females were passengers in a car with a high driver. “The issue of marijuana-impaired driving is particularly salient for young drivers, for whom the combination of inexperience and substance use elevates crash risk,” she said in the release. “If they are part of a culture that accepts the behavior, their risks increase at a predictable rate that we understand better now.”

A recent Columbia University study found that marijuana-related fatal car crashes tripled between 1999 and 2010. “Currently, one of nine drivers involved in fatal crashes would test positive for marijuana,” co-author of the study Dr. Guohua Li told HealthDay. Over the course of those 11 years, fatal crashes while under the influence rose from 16 percent of traffic deaths to 28 percent.

For the study, Whitehill and colleagues looked at an ongoing longitudinal study of about 338 18-year-old freshmen students at the University of Washington and University of Wisconsin, Madison. Overall, 30 percent of males and 13 percent of females said they had used marijuana over the past 28 days. The researchers proposed that public health campaigns should not only promote designating driving for those who drink alcohol, but also for those who use any kind of substance.