When the "spice" products first went on the market about nine years ago, they had certain advantages to pot, especially for young users: They weren't illegal, they were easy to get and they didn't turn up in drug tests. But of course they also hadn't been used enough for people to understand the potential risks. In 2010, more than 11,000 American emergency room visits were tied to synthetic cannabinoids (to be fair, regular pot generated nearly 40 times that many). European countries started cracking down. The Drug Enforcement Agency followed suit, listing as Schedule I controlled substances five of the compounds, which can be an order of magnitude more potent than THC, the cannabinoid in marijuana, depending on how they bind to the brain's cannabinoid receptors. Even now, as labels of the stuff explicitly state that they're not for human consumption (i.e., an incense), reporters have found clerks who recommend smoking it.