‘Tens of thousands of letters may contain anthrax'

Tens of thousands of letters mailed around the US could have picked up trace amounts of anthrax while passing through a contaminated postal centre, the nation’s top anthrax investigator has said.

Faced with mounting - yet circumstantial - evidence that a 94-year-old Connecticut woman died from cross-contamination in October, the question is of how big a problem the possibly contaminated mail poses.