For over a decade, synthetic “herbal incense” designed to mimic the effects of cannabis has gained popularity due to the fact it’s been buyable in-store, and doesn’t show up on drug tests. It’s dangerous because synthetic cannabanoids have the potential to be much more potent than their organic counterparts. In addition, their non-regulation leaves much unknown about potential negative effects.

The reason volatile ‘analogs’ (like various versions of herbal incense) even exist, is cannabis prohibition. If the federal government doesn’t make serious amendments to drug policy, significant demand for herbal incense will remain.

(http://www.ladybud.com/2014/06/02/inside-the-issue-synthetic-marijuana-aka-herbal-incense/)