My general sense: any health effects are likely to be weak at levels typically encountered, but I'm holding as plausible that thee may be some effects.
Microwave oven radio waves are non-ionizing 2.4 Ghz and I suspect they cause several health issues to any living organism exposed to them, even for a short time.
For some people, there's a risk on the outside as well. Pacemakers.
Less so these days, but still.
My understanding is that there's a possibility of creating induced current in the pacemaker. Which is to say, the non-ionizing radiation has an effect at a distance, albeit in a manufactured artifact, not (in this case) organic tissue.
It is not the 2.4Ghz radiation that causes the trouble with pacemakers. Its the plain old magnetic field generated by the inductive inrush from the giant coils that convert the power to feed to the magnetron tube in the microwave. Any large inductive load poses the same risk.
I'm getting slightly different information. The best "how do Microwaves interfere with pacemakers" info I could find was from The Straight Dope, which indicated that it was actually microwave leakage, not the coils themselves, which induced the current. And I'm aware that among the reasons you don't nuke metallic objects is because of the charges induced. Another source showing effects of various EMR frequencies indicated that induced currents were among the effects of microwave and other longer-wave radiation.
That said, other risks for pacemakers include store anti-theft devices, most of which are also inductive coils so far as I understand.
