WASHINGTON – The Federal Reserve reported Thursday that about 20 pieces of mail tested positive for traces of anthrax in an initial screening.
The tainted mail was discovered as part of routine mail testing by the Fed in a mobile trailer stationed in a courtyard at the Federal Reserve's main buildings in downtown Washington. The test results were preliminary.
The mail did not contain powderlike substances or handwritten addresses. Such preliminary tests often are inaccurate and further tests are being conducted.
"The affected mail was routine commercial and business mail and did not have any of the characteristics identified by the FBI as suspicious," the Fed said in a statement.
The Fed did not have information on where the mail originated or where it had been processed. All mail addressed to the federal government is irradiated to kill any possible anthrax, but even the presence of dead spores could produce an initial positive reading.
Some of the mail was addressed to Fed Chairman Alan Greenspan as well as other officials, Fed spokesman David Skidmore said.
Skidmore said the 20 pieces of mail were "fairly recent" with postmarks of April or May.
Swabs that produced the positive readings will be sent to a laboratory for additional testing.
"There is a very real possibility this could have been traces on some piece of equipment," U.S. Postal Inspector Daniel L. Mihalko said. "Until the very detailed culture tests come back, we'll have to wait and see. It could be mail that rubbed against something at an outside location."
He said none of the letters was similar to the threatening notes sent last year to media organizations and Capitol Hill.
"The source of the possible contamination is not known," the Fed said. "Subsequent tests of mailroom surfaces and mail distribution points within the board's buildings have all been negative."
The Fed stopped distributed mail to its buildings on Tuesday. However, the secure mail facility is continuing to receive mail.
The Fed also had positive initial test readings for a batch of mail received in December. However extensive follow-up tests never found any new letters containing anthrax.