While a controversy still swirls as to who masterminded the attacks, a recent research study proves more accurate on the cost of facility cleanups. The 2001 anthrax mailings resulted in $320 million in expenditures aimed at ensuring government and private facilities were free of the deadly bacteria, according to an analysis just published. The anthrax-tainted letters addressed to Congressional offices and media organizations killed five people and sickened 17. The attacks have also spurred copycat incidents over the years.

After reviewing U.S. Government Accountability Office information and other material, experts at Concordia University in Montreal determined the mailings resulted in follow-up detection efforts in 26 structures and cleansing operations in seven, including two mail service centers that required an expensive decontamination treatment, the Center for Infectious Disease Research and Policy reported. In addition, six business facilities required cleaning.