Generally speaking, microwave radiation is only harmful if the radiation can somehow seep out of the unit. There are many different types of waves of energy, and the waves that emit when microwaving food are just like radio waves or X-rays but much different in terms of the energy output. Obviously, radiation from microwaving is harmful, and you need only look at how searingly hot these waves are when preparing food. But the good news is that these radiation waves cannot be transmitted to you. All the radiation is contained inside of the oven and immediately dissipates once the oven stops and is cleared. But yes, radiation inside microwaves is very harmful to anything not being melted.