A poster warns of the effects of the drug known as 'Spice' at the Naval Hospital in San Diego. The Navy has investigated more than 700 sailors and Marines this year for smoking the "synthetic" marijuana.  (Associated Press)

A poster warns of the effects of the drug known as 'Spice' at the Naval Hospital in San Diego. The Navy has investigated more than 700 sailors and Marines this year for smoking the "synthetic" marijuana. (Associated Press)