SAN FRANCISCO (CBS SF) — Twelve tons of unwanted or expired medicine was collected in Northern California and the Central Valley on Saturday, a day that was dedicated to proper disposal of prescription drugs, federal drug enforcement officials said Wednesday.

Saturday was the Drug Enforcement Administration’s 10th iteration of its Prescription Drug Take-Back Day, a national event. There were 169 collection sites manned by 108 different agencies that took in the 12 tons in the Central Valley and Northern California generally.

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More than 150 tons of prescription drugs have been collected since the event was introduced in 2010.

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Keeping unused or expired medicine in home cabinets makes these drugs susceptible to diversion, misuse and abuse, according to the DEA.

And the DEA reports that disposing of unused medications by flushing them down the toilet or simply throwing them in the trash both pose potential safety and health hazards.

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