The FDA has authorized levels up to one kGy for fruits and vegetables, three kGy for poultry, 4.5 kGy for fresh meat and seven kGy for frozen meat. But the idea of exposing food to gamma rays does not sit right with many people. Opponents also claim that irradiation produces by-products such as benzene and formaldehyde. And there's some research indicating that irradiated food may cause cancer in children. Many opponents say that a better approach would be to focus on prevention of food contamination, starting at the farm or ranch.
Consumers prefer to have no filth on meat than to have filth sterilized by irradiation.
There is also evidence that bacteria could become immune to irradiation, in the same way that overuse of antibiotics seems to be breeding superbacteria. Scientists at Louisiana State University have found that one bacteria occurring in spoiled meat and animal feces, called D. radiodurans , can survive a radiation dose five times what the FDA has approved for beef. Irradiation can only be used on a limited range of disease sources, even accepting that poultry probably represents the single most significant source of salmonellosis . For irradiation to play a more prominent role in this area, there would have to be a massive investment in irradiation plants. The costs of this, and the treatment itself, would be borne by consumers.