It is not ionizing radiation, the primary hazard of microwave radiation is its heating effects on sensitive tissue that has poor blood circulation -- in particu

It is not ionizing radiation, the primary hazard of microwave radiation is its heating effects on sensitive tissue that has poor blood circulation -- in particular it has been implicated in the development of cataracts in the eye. So to a first approximation, the few milliseconds of 1000W output is really only as hazardous as a few minutes of the typical leakage you get with the door closed (somewhere on the order of 5 mW).