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What the mail must go through

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12:29pm, August 28, 2002

From Boston, Mass., at a meeting of the American Chemical Society

After last fall's anthrax attacks, the postal service began irradiating government mail.

The result: yellowed envelopes, shrunken address windows, and brittle paper. Even worse, the sterilization process destroyed some important objects and documents.

Charles Tumosa and his coworkers at the Smithsonian Center for Materials Research and Education in Suitland, Md., say there might be a better way. For their part, the researchers compared the chemical and physical properties of irradiated and nonirradiated materials. Although the investigators found minimal irradiation damage to inks, they observed that plastics had melted and that some paper was left too brittle to fold.

Recycled paper fared worst, and some scientific-journal pages stuck together into solid blocks. Tumosa notes that the irradiation process heats objects to temperatures higher than 130C.

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