NASHVILLE, TN - Data from police, drug treatment centers and hospitals shows an apparent decline in synthetic drugs in Tennessee after a law was passed banning most of the substances.

Tennessee Poison Center director Dr. John Benitez says cases are still being reported in emergency rooms across the state, but the number this year has dropped substantially.

Rep. Mike Sparks, R-Smyrna, told The Tennessean that the law has worked, "but we can't let our guard down."

Synthetic drugs began showing up in 2010. They were sold in small packets and labeled "not for human consumption," but people ingested them anyway.

Many users ended up in emergency rooms.

Tennessee lawmakers responded by passing legislation that not only banned the substances, but allowed local authorities to shut down businesses selling the packets.