Six Philadelphia police districts will get drop boxes where residents can safely dispose of unwanted prescription drugs under a pilot program announced Wednesday.

More than 100 drop boxes have already been installed in suburban counties.

Prescription drugs can pollute water systems if dumped down drains and unused medicines - particularly powerful pain killers - can be abused if they fall into the wrong hands. Nearly half of the 650 people who died of overdoses in Philadelphia in 2014 had prescription opioids in their system.

Philadelphia District Attorney Seth Williams, whose office is leading the program, said the drop boxes will be available at:

- First District, 24th and Wolf Streets, South Philadelphia;

- 15th District, Harbison Avenue and Levick Street, Mayfair;

- 19th District, 61st and Thompson Streets, West Philadelphia;

- 22nd District, 17th Street and Montgomery Avenue, North Philadelphia;

- 25th District, 3901 Whitaker Ave., North Philadelphia;

- and the 35th District, North Broad and Champlost Streets, Ogontz.

The program will be expanded to every police district if it is found to be successful, officials said.

Outside Philadelphia, drop boxes have been installed in recent years at many municipal police departments and other locations, with a total of 104 boxes in the Pennsylvania suburban counties and 12 in the New Jersey suburbs.

To locate a box, go to www.americanmedicinechest.com.