A Plastic That Decays

Hundreds of thousands of years from now, the most persistent signs of man's present civilization could be masses of well-preserved plastic bottles, containers, bags and wrappings. That is because plastics resist natural processes of decay almost indefinitely. To make the material go away when it is thrown away, scientists in Germany have developed a type of plastic that disintegrates when exposed to the ultraviolet rays in sunlight. But it has a hitch: the sun does not distinguish between unopened plastic containers and discards.

Now the British have come up with a better solution. The big packaging firm of Coloroll, Ltd., is producing plastic bags that will decompose naturally in five years. The secret: addition of clean, dry starch to plastic polymers. "By putting in the starch," explains Inventor Gerald J.C. Griffin, a teacher of plastics technology at Brunei University, "we are adding carbon, hydrogen and oxygen. The bags will act as a carbon source for soil bacteria, breaking down into humus and carbon dioxide." Griffin's process, which can be used for most plastic products, has a powerful appeal beyond reducing long-lived litter. Because starch costs much less than polymer plastics, the process saves money --up to $4.50 per 1,000 bags right now.

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