Using alcohol leads to unsafe driving and compromised relationships with peers, while using marijuana harms relationships with authority figures, U.S. teens said in a survey.

“Our most serious finding was that people who reported drinking alcohol were much more likely to report driving unsafely as a direct effect of use,” said lead author Joseph J. Palamar of New York University Langone Medical Center’s Department of Population Health.

“That doesn’t mean that using marijuana and driving is safe, but people perceive alcohol to have a more negative effect on driving,” Palamar told Reuters Health by phone.

He and his team analyzed responses in nationally representative surveys of high school seniors between 2007 and 2011.

Most participants were 18 years old, and they answered questions about their history of alcohol and marijuana use and whether either substance had caused any of 15 problems, including hurting relationships with parents, significant others, friends or teachers, emotional instability, reduced energy and unsafe driving.

Nearly 97 percent of the students reported having ever consumed alcohol and 60 percent said they had used marijuana.

Compared to marijuana users, alcohol users reported more regrettable behavior, more unsafe driving and less emotional stability, according to the results in The American Journal of Drug and Alcohol Abuse.

Almost a quarter of kids who used only alcohol said it caused them to behave in ways they later regretted, compared to six percent of those who only used marijuana.

More marijuana users reported becoming involved with others who were a “bad influence” and tied the drug to having less energy, worse school performance and damaged relationships with supervisors or teachers.

Alcohol users reported more harm to relationships with peers, as opposed to superiors.

That may have to do with the illegality of the substances, Palamar said. While using either one is illegal for a high school senior, alcohol is an ubiquitous part of pop culture and society at large, whereas kids who smoke pot are more readily pinpointed as "outsiders," he said.

“Alcohol is pushed on us by society,” he said. “You can’t watch a sporting event without having alcohol.”

Most people think of marijuana as less dangerous, but Palamar stressed that the kids in this study were not asked to compare the dangers of alcohol and marijuana.

“I compared them, but the students didn’t,” he said.

Research that does compare the two head to head tends to get it wrong, according to drug policy expert Jonathan P. Caulkins of Carnegie Mellon University Heinz College in Pittsburgh.

“The breakthrough here and what I’m glad to see is they didn’t fall into that trap,” Caulkins told Reuters Health.

“The gestalt and conventional wisdom has been to say that marijuana is safer, and that’s primarily because marijuana has lower risk of leading to death,” he said.

Both substances are unhealthy, particularly for teens, and the two separate substances shouldn’t be compared he said.

“Parents can’t control their behavior, but to the extent they can, they should try to keep (kids) away from both,” Caulkins said.

The surveys were done before recreational marijuana had been legalized in Colorado and Washington, and the results may be different in those states today, Palamar noted.