add up after prolonged exposure. The USGS study conducted several years ago shows water with high levels of these drugs have had an adverse affect on wildlife, especially fish and frogs. There is a phenomenon known as the feminization of fish and frogs caused by prolonged exposure to female hormones. Never, ever flush your unused drugs. Waste water treatment plants are not designed to remove these drugs from water that is discharged into lakes and streams. Always take unused drugs to a chemical collection or hazardous waste collection event.