Feeding of irradiated beef to rats

Irradiated and nonirradiated beef were added to the diet of rats in amounts equal to 35% of the solids fed for a period up to two years. A four-generation reproduction study was conducted simultaneously. No adverse effects were demonstrated, as evidenced by growth, hematologic change, food efficiency, reproduction, mortality, or gross and microscopic pathology. It is felt that the somewhat higher incidence of mammary fibroadenomas and adenomas than reported by some other workers is a reflection of age and strain differences rather than diet.