Nearly 11,500 people were hospitalized last year after taking synthetic drugs meant to imitate marijuana, a new federal report finds. A third of those sent to the ER were kids ages 12 to 17, while 35% were 18- to 24-year-olds. Some 59% of the cases among those aged 12 to 29 involved no other substances, unlike in most drug abuse hospitalizations. The synthetic substances include Spice and K2, which are labeled as herbal incense and advertised as a legal marijuana substitute, USA Today notes. In comparison, 461,028 people went to the ER in 2010 after using marijuana itself.