The USPS warned that a number of products could be adversely affected, such as seeds, photographic film, biological samples, food, medicines, and electronic equipment. In the process of irradiation, mail is exposed to extreme heat. Paper is weakened and may appear to have been aged, with discoloration (e.g., yellowing), and brittleness. Pages may break, crumble, or fuse to other pages. Documents bound with glue may have loose pages. The printing on pages may be distorted or offset onto adjacent pages. If tape is affixed to address labels, the address may be illegible.
Irradiations effects on paper caused some alarm in the philatelic world, which sends large numbers of rare postage stamps and covers through the mail. A number of auction houses stopped sending material through the mail, and Linns Stamp News regularly featured reports on stamps and covers that had been ruined by irradiation.
Although at one time the USPS expected to irradiate all mail, it later scaled back to just treating mail sent to government offices, including all mail directed to the White House, Congress, and the Library of Congress.