What the mail must go through

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.

The amount of radiation used to sterilize the mail is “overkill,” suggests Tumosa. He suspects that a better determination of just how much radiation is actually needed to kill anthrax could lead to a more mail-friendly process.

Washington, D.C., residents’ mail is sometimes mistakenly irradiated along with government mail. However, Tumosa says he’s less concerned about yellowed bank statements than, say, destroyed journals, computer disks, DNA specimens, and 35-millimeter slides destined for the Smithsonian Institution, the White House, the National Archives, and Congress.

Destructive irradiation is “creating a little bit of amnesia,” Tumosa says. “It’s part of history that’s being lost.”

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