The gamma rays emitted are very short wavelengths, similar to ultraviolet light and microwaves. The Co gamma energy penetrates the food and its packaging but most of the energy simply passes through the food, similar to the way microwaves pass through food, leaving no residue. The small amount of energy that does not pass through the food is negligible and is retained as heat. Food irradiation does not replace proper food handling. Therefore, the handling of foods processed by irradiation should be governed by the same food safety precautions as all other foods.
Irradiation does cause changes in food, all of which have been found to be benign.
More than 40 years of multi species, multi generational animal studies have shown no toxic effects in eating irradiated foods. Irradiation produces so little change in food that it is difficult to design a test to determine whether a food has been irradiated. Food irradiation has the longest history, more then 40 years, of scientific research and testing of any food technology before approval. Named products are used for clarification and ease of discussion only and are not necessarily endorsed or promoted by the University of California Cooperative Extension.