5 Answers

Stay at least an arm’s length away from the front of an operating oven. Never should anyone, and especially children, stand gazing into, or directly against an operating microwave oven.

Arms length I would think.. Wikipedia states:  Microwave ovens are not harmful or deadly (unless dropped from a great height...), and neither is the food heated by them.

this site is anti-microwave: 

http://www.health-science.com/microwave_hazards.html

I no longer use mine. They are not safe.

Microwave energy from ovens are generally not considered hazardous unless the equipment is damaged, compromising the door seal or exposing internal components.  

If you have to use them always put the food in glass and cover the food with glass lid never use plastic and as Pamela said dont stand to close or look at them and certianlty dont let children near them