Unfortunately, old medication often goes straight down the toilet or the sink, but the problem is sewage wastewater treatment plants aren't equipped to filter out drugs so they wind up in our waterways.
US Environmental Protection Agency (EPA) studies have found pharmaceuticals present not only in waterways, but also in aquatic creatures. Minute levels have also been found in drinking water. In addition to antibiotics and steroids, over 100 different Pharmaceuticals and Personal Care Products as Pollutants (PPCPs) had been identified by 2007 in environmental samples and drinking water.
Not a lot is known about the environmental and human health impact of the presence of pharmaceuticals in waterways as more research is needed; but it's a disturbing situation.
How to dispose of old medication
It's important not to flush prescription drugs down the toilet or drain unless information accompanying the medication specifically states you can do so.
Probably the best first course of action is to contact your local pharmacy and ask them if they have a drug take-back program as these initiatives are becoming increasingly common. Pharmacies that do will ensure the medications are disposed of in the proper manner; usually via incineration.
Another point of contact is your local council's waste department as they may offer a drop-off facility for old medications or may be able to direct you to a service that does.
Failing all that, the general advice is to dispose of the medications in your household trash, but to take some special safety precautions by take the medications out of their original containers and placing them into another airtight container, mixed in with something undesirable - such as used kitty litter or other substances equally as unappealing. It's not ideal as the drugs can contaminate the soil when landfilled and possibly contaminate groundwater; but that's really the only other option and according to authorities; the "lesser of the evils".
While some disposal programs incinerate old medications, do not attempt to incinerate medications at home as this can be just as environmentally damaging as landfill disposal and hazardous to your health, due to the gases produced. Medicine disposal programs use special incinerators that burn at very high temperatures.
Green Living Tips.com