An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »


Mail Irradiation

Radiation Facts

  • Irradiated mail is passed through a high energy beam of electrons or x-rays.
  • Irradiation sterilizes mail; it does not make mail radioactive.
  • Mail irradiation can damage plastics and make paper brittle.

Mail irradiation is a technique that is used on mail addressed to certain government agencies to ensure that packages and letters do not contain harmful bacteria. Postal workers that use mail irradiation equipment are kept safe by strict controls throughout the process.

On this page:

About Mail Irradiation

Irradiating mail can make it dry, brittle or discolored.

In October 2001, the infectious disease anthrax was found in mail sent to several news agencies and the offices of two United States Senators. Anthrax is a species of bacteria (scientific name: Bacillus anthracis) that forms spores, which when inhaled, can make people sick. It is very rare that you would come in contact with anthrax during normal daily activities. However, after the anthrax mailings in 2001, the U.S. Postal Service began to irradiate mail addressed to certain government agencies. This was done with help from the Federal Bureau of Investigation (FBI) and public health experts.

During the irradiation process, mail must pass through a high energy beam of ionizing radiation in order to kill harmful bacteria. The beam penetrates deep into the mail to destroy viruses and bacteria—like anthrax. Mail irradiation can also be used on thicker postal materials like letter trays and packages.

The ionizing radiation used in the mail irradiation process can cause chemical changes in paper. The mail might come out brittle and discolored, looking and smelling like it has been baked in an oven. Irradiation also might turn plastics brown and warp CD cases or other plastic storage containers. Even though it causes physical changes, irradiating mail does not make the mail radioactive.

Radiation levels are closely monitored at mail irradiation facilities to ensure that workers are safe. The facilities have thick concrete or lead lined walls to shield employees and visitors from radiation.

Top of Page

What You Can Do

There are no radiation concerns with handling irradiated mail. Irradiation does not make the mail radioactive.

Top of Page

Top of Page