Senate received 383 cases of suspicious mail in 2011
Terrance Gainer, the Senate Sergeant at Arms and Doorkeeper, announced the figure during budget testimony. There have as of yet been no injuries in the 10 years since the attacks, the Washington Examiner reports.
"(The Senate Post Office intercepted mail) addressed to senators with the intent to disrupt Senate business," Gainer said, according to the Washington Examiner.
All internal and incoming mail is searched and scrubbed of contaminants before it is delivered, with more than 300,000 items tested in 2011. There were 18.4 million pieces of mail delivered to Senate offices last year.
According to the Centers for Disease Control and Prevention, anthrax was deliberately spread through the postal service in 2001 when letters were mailed that contained anthrax powder. The anthrax spores infected 22 people in all, with five deaths. Anthrax is caused by the spore-forming Bacillus anthracis bacterium that can infect through the skin, lungs or digestive system. Anthrax can be spread by handling products from infected animals, breathing in anthrax spores from infected animal products or by eating undercooked meat from infected animals.