The type of irradiation they were talking about for the mail involved high-energy electrons and X-rays, which are generated by electrical means, and involve no radioactive materials. This reference discusses those methods as well as the cobalt gamma-ray concept.

I'm not sure how you can bombard mail with an electron beam without frying it, but I'm no expert. I think there is a place for all of these techniques.

As far as food irradiation goes, the only real obstacles (as usual) are psycho environmentalists. Even they have given up on the non-existent "radioactive food" canard, and have been concentrating on the "nutritional changes" and "substances" created in food when subjected to gamma rays. They ignore the fact that these changes are insignificant compared with the changes in food created by simply cooking it, or they toss if off by saying that the changes from radiation are "unknown" and "scary." All pretty feeble. Their last resort recently is the "danger" of transporting the radiation sources from the manufacturing site to the food irradiation site. Also pretty feeble.

I agree, once this is in place for mail, the resistance to using it for food will be greatly reduced, to our eventual benefit.