For previous Star Tribune stories about the rise in synthetic drug use, go to lethaldose

• Retailers unsuccessfully tried to block a law on substances that mimic pot and LSD.

• Designer drugs can be purchased easily online, leading users to believe they are safer than street drugs. But the chemicals can be unpredictable --and disastrous.

• Synthetic drugs are widely sold as bath salts and incense. But lab tests reveal substances that can kill.