What’s the best way to throw away leftover, expired medicines? Once the answer was “flush ‘em” to ensure that children and animals couldn’t stumble on the drugs and be poisoned. Now scientists are increasingly warning not to flush drugs. Antibiotics, hormones, and other medicines are being found in waterways, raising worrisome questions about potential health and environmental effects.

“So what the heck do you do with it? This is not black and white,” Georgetown University pharmacology chairman Kenneth Dretchen said with a sigh.

Seniors are the largest single consumer group for medicine. So it stands to reason that they are also that group with the latgest amount of leftovers.

The children of seniors are also faced with the problem of what to do with unused medicines when their parent pass away.

No one knows just how many unused drugs are dumped each year or how many are hoarded because patients don’t realize the drugs have expired or simply don’t know what to do with them. It’s a question that arises each fall as pharmacy groups launch annual “clean out your medicine cabinet” campaigns.

A special program in one city a few years ago encouraged residents to turn in unused medicines and collected hundreds of pounds in a week, said Ted Tong, director of the Arizona Poison Information Center.

Individual patients aside, one study estimated the nation’s nursing homes discard anywhere from $73 million to $378 million worth of drugs a year. Some are incinerated, but many are flushed.

Australia has collected more than 760 tons of medicines since starting a program in 1998 that encourages consumers there to return unwanted drugs to pharmacies so they can be incinerated. Canada has a similar program.

The U.S. Environmental Protection Agency is studying whether to develop formal recommendations for what to do with old drugs.

“The age-old wisdom of flushing medication down the toilet ... is probably the least desirable of all the alternatives,” Christian Daughton of the EPA’s Las Vegas laboratory wrote in an overview of the issue, published in a scientific journal last spring.

In fact, a new contraceptive, a vaginal ring, actually comes with do-not-flush instructions because it still contains estrogen after it’s been used. Women are instructed to wrap the NuvaRing in an accompanying foil patch and put it in a trash can out of reach of children and pets &Mac247; the idea being that landfill disposal slows drug seepage.

At issue are the “pharmaceutical and personal care pollutants” that defy traditional wastewater treatment. Long a concern abroad, they made headlines in the United States when the U.S. Geological Survey found traces of dozens &Mac247; painkillers, estrogen, antidepressants, blood-pressure medicines in water samples from 30 states.

Long-term effects aren’t known, but scientists worry that exposure to even tiny amounts might cause some harm, at least ecologically. Studies have linked hormone exposure to reproductive side effects in fish, for example, and environmental exposure to antibiotics may encourage development of drug-resistant germs.

Chemicals get into water in myriad ways. There’s runoff from farms or factories. Indeed, the World Health Organization is pushing for a major decrease in farmers’ antibiotic use. Topical chemicals like insect repellent are bathed off. Then there’s excretion.

But disposal is starting to get more attention. The Food and Drug Administration is reevaluating its policy for which drugs need the environmental assessments that can spark disposal instructions.

For individual patients, officials offer some disposal advice:

• Take all of a prescribed medicine so there aren’t leftovers, unless there’s a specific reason to quit, like a bad side effect.
• Trash is better than sewer, with precautions in case children or animals get into it, Tong said. He advises breaking up capsules and crushing tablets, then putting the remains back in the original container with its child-resistant cap. Tape it up and double-bag it before tossing.
• Alternatively, check if local household hazardous-waste collection programs, “where you’re supposed to take motor oil and batteries“ accept expired medicines.
• The FDA suggests asking if pharmacies will take back expired drugs, as is common in Canada and Australia. Pharmacies have programs to incinerate or otherwise dispose of inventory they can’t sell, but the industry couldn’t say how many would accept consumers’ leftovers too.