Law enforcement will collect two kinds of dangerous items on Saturday: guns and prescription drugs.

"Turn in a gun anonymously and receive a $50 food voucher for a local supermarket on the spot, no questions asked!" declares a Philadelphia Police Department announcement.

The firearms buyback will be held from 10 a.m. to noon at St. Joachim's Church Hall, 1527 Church Street, in Northeast Philadelphia. The Knorr Street Shop-Rite is sponsoring the event, along with the Philadelphia Police District Advisory Council.

Expired and unwanted medications pose threats both to abusers and the water supply.

That's why collections will be held from 10 a.m. to 2 p.m. Saturday at thousands of sites across the country, as part of the fourth National Prescription Drug Take-Back Day

In October, more than 188 tons of medications were collected nationwide, according to the federal Drug Enforcement Administration.

Supermarkets, churches, municipal buildings and police stations are among the places taking part, under police supervision.

To find a location near you, go to the Office of Diversion Control's drug collection site search and enter a zip code.

Never flush prescription drugs down a toilet unless accompanying information advises doing so, says the FDA. Most drugs can be disposed in household trash, but it's wise to put the pills into a sealed plastic bag filled with an unwanted substance such as coffee grounds or kitty litter, so children and trash pickers are less likely to be tempted.

But the safest way is to take advantage of the Take Back program, authorities say.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.