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In October, the deadly bacterium anthrax was found in mail
sent to various news agencies, and to offices of the U.S.
Congress. As a precaution, the U.S. Postal Service, with assistance
from FBI and national public health experts, began irradiating
mail to kill any potentially present anthrax spores.
Is my mail is being irradiated?
Currently only mail to the White House, Congressional
offices, and federal government offices in the 202-205 Zip
Code exchanges is being irradiated. Irradiation is taking
place at facilities in Ohio and New Jersey.
What technology is being used to irradiate the mail?
The Postal Service has selected electron beam technology
to sterilize mail one half inch thick or less. Some powerful
x-ray devices may also be used for certain types of packages.
How does irradiation kill anthrax?
Irradiation kills anthrax by shattering its DNA and other
cellular components. The process for irradiating mail is
the same process used to sterilize medical equipment.
During irradiation, an intense stream of electrons (or
x-rays) strikes the mail and any anthrax spores it may contain.
The radiation dose is very high, about 56 kilograys
of radiation, which is approximately 2 million times more
than a chest x-ray.
Does mail that has been irradiated become radioactive?
No. The process is roughly analogous to shining a flashlight
on the mail - when the flashlight is turned off, mail does
not glow, or radiate back the light it received.
Are there changes to the mail after it has been irradiated?
Yes. Irradiating mail at such high intensity creates new
compounds, which can result in a different look, feel, and
even smell. The potential health effects of these changes
is unknown. Because of the intensity of the beam, mail often
looks yellowed, and can become brittle. Book bindings may
become brittle, and plastic may be discolored. Seeds, plants
or other biological material will be sterile, and photographic
film will be useless. Items such as gem stones may be altered,
and computer disks, CDs, and some electronic equipment (like
personal digital assistants) may be damaged.
Have people complained of health problems from irradiated
mail?
Some postal and federal workers have complained of skin
irritation and respiratory problems associated with exposure
to irradiated mail. However, there are no established health
effects from the mail, and investigations into a these complaints
are ongoing.
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