From this NYS website:
Why Not Flush?
* Flushed medications can get into our lakes, rivers and streams
Pharmaceuticals enter our wastewater from a variety of sources including the flushing of unused medications. A nationwide study done in 1999 and 2000 by the United States Geological Survey (USGS) found low levels of drugs such as antibiotics, hormones, contraceptives and steroids in 80% of the rivers and streams tested.
* Fish and other aquatic wildlife are being adversely affected
A number of studies have shown impacts on aquatic life. For example, male fish have been feminized (produced eggs) when exposed to hormones (birth control pills). Other drugs, such as anti-depressants and beta-blockers, reduce fertility or affect spawning in certain aquatic organisms.
* Drug-resistant bacteria might develop
Long-term exposure to low levels of antibiotics might result in the evolution of, or selection for, drug-resistant microbes and bacteria.
Before placing in the trash, follow these steps:
* To avoid accidental or intentional misuse of drugs, treat medications (liquids and pills) by adding water and then salt, ashes, dirt, cat litter, coffee grounds, or another undesirable substance.
* Hide all medications in an outer container, such as sealable bag, box or plastic tub to prevent discovery and removal from the trash. Seal the container with strong tape.
* Dispose of drugs as close to your trash collection day as possible to avoid misuse and/or misdirection.
* Do not conceal discarded drugs in food to prevent consumption by scavenging humans, pets or wildlife.
Note: Be careful in handling medications. Some drugs can cause harm if handled by people other than those to whom they were prescribed. Also, avoid crushing pills as some medications can be harmful in powder form.