(CBS) Teens haven't stopped smoking - they've just put down the cigarette and picked up a joint.
That's according to a new study, which found that more high school seniors are smoking marijuana than tobacco. In 2010, 21.4 percent of seniors said they had toked pot within the past 30 days, while 19.2 percent said they had lit up cigarettes.
And marijuana wasn't the only drug that saw a jump in use, according to a written statement issued by the University of Michigan, which conducted the study. Teens' use of Ecstasy increased, apparently because of declining concerns over the dangers posed by the drug.
Why are more kids getting high?
One possibility is that teens may not view marijuana as a dangerous drug, according to the study's authors. "Fewer teens have shown disapproval of marijuana use over the past two or three years," the study stated.
But one bad behavior of teens actually went down: drinking. The level of alcohol use among high school seniors hit its lowest level since the annual study's 1975 inception, and the percentage of seniors who reported binge drinking - consuming five or more drinks in a row - dipped to its lowest level since 1999.
There was no significant increase in the number of teens using narcotics other than heroin, and heroin use increased only a small amount, but researchers said it's unclear if use is actually growing.