Though surveys have detected over 80 pharmacological compounds in US waterways--including painkillers, blood-pressure and heart medications, birth control pills, anti-fungal agents, Prozac, Viagra, anti-seizure medications, steroids, nicotine byproducts and antibiotics—whether this actually means anything is a mystery. "Little is definitively known," says the EPA, "regarding any real hazard posed by trace concentrations."
And like meep says, there's pretty much nothing that can be done about it since it's the usual "going through the human body" process that brings it into the water.