The trouble with modern plastics is that they seem to be as immortal as they are useful. Plastic garbage bags litter Italy; Florida's discarded containers clog Bahama beaches. Each year one Kansas plant makes enough cellophane to wrap the earth with a 15-inch band 40 times; most of it becomes enduring garbage. Even getting rid of plastics can be dangerous. When polyvinyls like Saran Wrap are burned, they produce corrosive hydrochloric acid.
The obvious need, a plastic that decomposes naturally, may soon become a reality. An international team of scientists, led by University of...