(Related: “Cocaine, Spices, Hormones Found in Drinking Water.”)

But what's puzzling is where the drug is coming from. Fluoxetine is thought to enter waterways after it passes through the body and is excreted in urine. And pill users who dispose of unused pills down the sink could be adding to the problem. Wastewater treatment plants generally don't filter out the chemical.



But near Presque Isle State Park in Lake Erie, where the water samples containing fluoxetine were found, "there's no particular fallout. We don't have a direct sewage outfall located anywhere near the beaches," Mauro said. That means the fluoxetine is likely spread out all over the lake, he added.



Mauro and colleagues presented their work Monday at the