Washington ? It’s time to pooper-scoop your leftover medicine.

Mixing cough syrup, Vicodin or Lipitor with cat litter is the new advice on getting rid of unused medications. Preferably used cat litter.

It’s a compromise, better for the environment than flushing – and one that renders dangerous medicines too yucky to try if children, pets or drug abusers stumble through the trash.

A government experiment is about to send that advice straight to thousands of patients who use potent painkillers, sleeping pills and other controlled substances.

Why? Prescription drug abuse is on the rise, and research suggests more than half of people who misuse those drugs get them for free from a friend or relative. In other words, having leftovers in the medicine cabinet is a risky idea. Anyone visiting your house could swipe them.

So 6,300 pharmacies around the country have signed up for a pilot project with the Substance Abuse and Mental Health Services Administration. When patients fill prescriptions for a list of abuse-prone medicines, from Ambien to Vicodin, the pharmacist also will hand over a flier urging them to take the cat-litter step if they don’t wind up using all their pills.

Not a cat owner? Old coffee grounds work, or doggie doo, even sawdust. Just seal the meds and the, er, goop in a plastic bag before tossing in the trash.

“We don’t want to assert that this is a panacea for the larger problem,” says SAMHSA’s Dr. H. Westley Clark. “It just provides them with a caveat that these are not things you can just lay around.”

But the concern isn’t only about controlled substances. How to best dispose of any medicine, whether prescription or over-the-counter, is a growing issue.

Unfortunately, “we don’t have a silver bullet,” says Joe Starinchak of the U.S. Fish and Wildlife Service.

No one knows just how many unused drugs Americans dump each year, or how many are hoarded because patients simply don’t know what to do with them or that they should dispose of them.

Once, patients were told to flush old drugs down the toilet. No more – do not flush unless you have one of the few prescriptions that the Food and Drug Administration specifically labels for flushing.

That’s because antibiotics, hormones and other drugs are being found in waterways, raising worrisome questions about potential health and environmental effects. Already, studies have linked hormone exposure to fish abnormalities. Germs exposed to antibiotics in the environment may become more drug-resistant.

Some communities set aside “take-back” days to return leftover doses to pharmacies or other collection sites for hazardous-waste incineration. The Environmental Protection Agency recently funded a novel pilot program by the University of Maine to see whether consumers would mail back unused drugs – a program that local officials estimate could cull up to 1.5 tons of medications.

But it’s not clear whether incineration is better for the environment than the slow seepage from a landfill, cautions the Fish and Wildlife Service’s Starinchak.

Starinchak calls the yucky-bag disposal method interim advice – the top recommendation until more research can determine the best way to balance the human health, environmental and legal issues.

So early next year, Fish and Wildlife will team with the American Pharmacists Association for a larger campaign called SMARxT Disposal. The campaign will spread this latest advice through even more drugstores, to purchasers of all types of medicine.