Diffuse Security Threats: Technologies for Mail Sanitization Exist, but Challenges Remain, Report to Congressional Requesters [open pdf - 2MB]
The attacks of September 11, 2001, and recent anthrax exposures have heightened long-standing concerns about the proliferation of biological weapons and the United States' ability to quickly respond to such incidents. The United States must identify technologies to protect against biological weapons, such as anthrax, without harming humans. Ionizing radiation has emerged as the leading current technology for mail sanitization. However, ionizing radiation may have adverse effects on mailed material, and it may not be applicable to some types of parcels, boxes, and large packages. In addition, applying ionizing radiation in a mail-processing environment requires radiation and biohazard precautions, such as shielding the radiation source and wearing protective gear.
Government Accountability Office (GAO): http://www.gao.gov/