(KNBC) - Heavy marijuana use by teenagers is up 80 percent since 2008, according to a national survey released by The Partnership at Drugfree.org and the MetLife Foundation.
Nearly 10 percent of U.S. teens -- about 1.5 million youth -- smoked marijuana heavily, some 20 times in the past month, according to the Partnership Attitude Tracking Study, sponsored by MetLife Foundation.
- Past-month use of marijuana is up 42 percent
- Past-year use of marijuana is up 26 percent
- Lifetime use of marijuana is up 21 percent, which translates to 8 million teens