CBS: Traces of anthrax in Dan Rather's office

CBS News anchor Dan Rather

NEW YORK (CNN) -- Preliminary testing found trace amounts of anthrax in CBS News anchor Dan Rather's anteroom and office areas, but Rather had shown no signs of exposure, CBS News announced Monday.

"There is no evidence of anthrax in the newsroom or anywhere else we tested," CBS News President Andrew Heyward said in a written statement released Monday afternoon. Final results of all samples were not completed, but "so far, so good," Heyward said.

The Centers for Disease Control and Prevention and New York health officials said it was safe to continue working in all parts of the building, the statement said.

"However, we obviously plan to do a thorough cleanup of the affected and adjacent areas over the next couple of nights, Heyward said in the statement. "As I've said before, don't be surprised to see cleanup personnel wearing protective gear; that's standard procedure."

Rather and an assistant -- who is taking antibiotics after contracting skin anthrax -- are still working in the areas where anthrax traces were discovered, the statement said.

Heyward also reassured CBS staffers that mail security procedures were in place. "You will not be receiving any letters or packages that have not already been screened," he wrote.