Due to the recent anthrax mail issues, some mail will be treated with radiation, in the form of electron beams from accelerators. The radiation will kill the anthrax, even in boxes. A company, SureBeam headquartered in San Diego, California, has been contracted by the US Postal Service to do the mail irradiations. They are a leading provider of electron beam and x-ray food safety systems and services for the food industry. Other sources of radiation may also be used in the future to kill anthrax.
SureBeam is part of Titan Technologies, and also does Medical Product Sterilization. It is important to note that the irradiation does not cause the mail to become radioactive. The irradiation will not cause any risk to mail carriers or the public. It just kills the bacteria on it. There is some possible problems that may result from the irradiation, including fogged film, sterilization of yeasts, and possible damage to some electronics and magnetic media.