Most of the world's plastics are made from hydrocarbons, specifically oil and petroleum products that take hundreds of years to disintegrate once they are thrown away. However, there are indications that tomorrow's plastics will be made from materials that are more quickly and completely biodegradable than oil-based plastics. Plastics of this sort may one day be discarded in backyard compost piles.

During the 1980s, compostable bags made of polyethylene plus starch first came upon the market. These early biodegradable bags caused disappointment when it was discovered they did not totally degrade, but left polyethylene residues that were invisible to the naked eye and difficult to find by normal chemical analysis. Soil scientists expressed concern that the polyethylene fragments might accumulate in soils and hinder both microbial and plant growth. The test of true biodegradability, they argued, is whether in a composting environment 100 percent of the carbon...