More than one quarter of high school seniors drive after using alcohol or marijuana, or ride with someone who has, according to a new study published in the American Journal of Public Health. Researchers from the University of Michigan found that 28 percent of respondents to a survey have operated a motor vehicle after using an illegal substance in the past two weeks. They also found that the number of teens driving after smoking marijuana has increased over the past three years.
"It's a big deal […] the sheer numbers," Patrick O'Malley, one of the study's authors, told NBC News. "It has been increasing steadily and looking down the road, it seems likely to get worse. We are concerned. He noted that the questionnaires did not ask the teens about the amount that they smoked. As there is no comparable DUI standard, O'Malley said that it is difficult to determine how much marijuana is too much.
"We don't have any good degree of impairment," O'Malley said to the source. "It's almost impossible to say what the level of marijuana in your system is."
According to the survey, the percentage of teens who reported smoking marijuana before driving increased from 10 in 2008 to 12 in 2011. Males are more likely to drink and drive than females, but there was no gender difference of those who rode with drivers who had used illegal substances.