More police departments across the country are adopting drop boxes for expired or unused prescription medication since pharmacies are often not allowed to take back certain drugs.

The programs have existed for some time, but in the past five years more organizations and take-back days have sprouted.

The National Association of Drug Diversion Investigators has been providing grants for the past four years for police departments to purchase the drop-off boxes, according to USA Today.

It also raises funds for 100 boxes each year to distribute to departments, which apply online, and has distributed 400 to date.

Since police departments often confiscate drugs, they meet the requirements to apply for the drop boxes. The first requirement is to be in a location that is accessible to the public. The second is that the department much already have a means of disposing the drugs, which exists in regions where officers confiscate drugs.

Pharmacies are not allowed to take back controlled substances like pain relievers and stimulants, and the only other way to dispose of them has been through take-back days by the Drug Enforcement Agency in certain areas.

The boxes are the best solution, thus far, for preventing the pills from getting into the wrong hands, or from being flushed down the toilet.

"We've seen an increase of our officers taking drugs off the street from people, and (the drugs) aren't theirs at all or they're being abused," said Cmdr. Geoff Huff of the Ames, Iowa, police department.

Officials said flushing the drugs is the worst thing to do since they may end up in the drinking water supply.

But the federal government and DEA are exploring more options to ensure safe disposal of these drugs.

If approved, the new rules would allow options like mail-back programs and expand the existing take-back and drop-box programs.