Purpose: To heat food.
Issue: As well as putting forth electric fields their digital control panel when sitting idle, because these units generalte HUGE magnetic and electric fields when in operation. The cook setting does not seem to matter in these measurements.
Better Option: Microwave ovens, no matter how convenient, should be avoided. There is no safe space in the kitchen when using a microwave (see below). Because of their faraday cage design, a mirowave is a good place to store sensitive electronics (unplug the microwave) to keep them safe from a solar flare or EMP. It is better to use a toaster oven or gas oven.
Recently, a colleague and I were at a course and staying in a hotel room. I had my test instruments with me and we took background levels of the magnetic and electric fields in the room. Then we turned on the microwave and took more readings. There was NO PLACE in that hotel room where we could get far enough away from the microwave oven so that the readings returned to the backgound level. The readings at the front of the oven (yes, with the door closed) were higher than the scale the meter could read (at least 100x the background level).