LOS ANGELES (AP) -- The state of California has a warning for its 36 million residents: Do not flush pharmaceuticals down the toilet or drain, or they may end up in a river near you.

Or, it turns out, even in the drinking water.

State and local officials are teaming with the U.S. Environmental Protection Agency for a "No Drugs Down the Drain Week," starting with events Oct. 2. The program recommends that drugs be dropped at special collection sites or tossed in the trash.

The event comes less than two weeks after The Associated Press published an investigative report about the dangers of flushing millions of pounds of unused pharmaceuticals annually by the American health care industry and consumers. The ongoing AP investigation has revealed that tests show the drinking water supplies of at least 46 million Americans contain minute concentrations of pharmaceuticals, including antibiotics, anti-convulsants and mood stabilizers.

Researchers have found evidence that even extremely diluted concentrations of pharmaceutical residues harm fish, frogs and other aquatic species in the wild. Related research reports that human cells fail to grow normally in the lab when exposed to trace concentrations of certain drugs.

The AP first reported on the pharmaceutical contamination issue in March.

The awareness week is part of a bill sponsored by Sen. Joe Simitian that funds pilot projects allowing consumers to drop off old prescriptions at retailers and public facilities.

"I think the public will step up, if they're told how to dispose of drugs the right way," Simitian said. "If you want people to do the right thing, make it easy for them to do it."

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.