The Drug Enforcement Administration (DEA) has collected a total of two million pounds of unused prescription medications during its five National Prescription Drug Take-Back Days, the agency announced Thursday. During the latest Take-Back Day on September 29, almost half a million pounds of drugs was collected, the Associated Press reports.

The drug collection initiative, which took place over the past two years, was a collaboration between the DEA and state and local law enforcement. People were urged to empty their medicine cabinets, kitchen drawers and bedside tables of prescription drugs that were expired or no longer needed, and bring them to one of thousands of designated disposal sites around the nation.

According to the National Survey on Drug Use and Health, in 2011 more than six million Americans used prescription drugs nonmedically in the past month.