From what I've read, non-ionizing EM radiation is harmless. There is little evidence that it causes any health issues. This is also the consensus here on Skeptics, that's the case in mobile phone related questions and microwave related questions.
So let's assume that cooking food with non-ionizing radation is safe.
Which leads to my question:
Does eating food which was exposed to ionizing EM radiation pose a health risk? The DNA material found in that food would most likely be seriously damaged, but does that even matter? Human food is in essence a dead organism. A dead DNA will not be active, it will not reproduce nor generate any proteins even when damaged. In the worst case scenario, we'd just eat a dead cancerous cell.
At least that's my theory. Enlighten me!
This also leads to a highly related sub-question: Is eating dead cancerous cells dangerous?
Possible answers that refute my theory:
Eating dead cancerous cells is dangerous.
Ionizing radiation has some dangerous effects beyond crippling the DNA of the food.
The DNA is still somewhat active, even in a dead organism.