Irradiating the Mail: The Anthrax Attacks of 2001

Weeks after 9/11, the U.S. Postal Service scrambled to neutralize anthrax-laced letters. Irradiation had been used for decades to sterilize medical equipment, prepare food for human consumption, and artificially alter the color of gemstones. While both methods kill anthrax, neither was a clear winner when it came to irradiating the mail.