But our days of wasting human waste may be numbered, if Kathleen Smith of the US Geological Survey has anything to say about it. She's leading a new research program that's examining the feasibility of extracting precious metals from sewage. As Smith will explain Tuesday at a press conference at the annual meeting of the American Chemical Society, recovering metals from waste could reduce the need for environmentally-destructive mining programs, and make biosolids a safer source of fertilizer to boot.

"There are metals everywhere," Smith said in a statement. "If you can get rid of some of the nuisance metals that currently limit how much of these biosolids we can use on fields and forests, and at the same time recover valuable metals and other elements, that's a win-win."