Professor Philip Gschwend describes the “legacy of problems buried in our environment” that often arise as side effects of products — such as PCBs and catalytic converters — designed to solve already existing problems. His research group has developed inexpensive sheets of polyethylene that can be placed in mud or water to soak up chemicals and measure their availability as they move through the environment. But the real answer, he says, is to prevent such problems in the first place by involving environmental chemists at the outset of materials and chemicals design.