Also, to the best of my understanding, the only known risk to human safety of a microwave without proper shielding is injury due to the heating of human tissue.

Also, to the best of my understanding, the only known risk to human safety of a microwave without proper shielding is injury due to the heating of human tissue. Not like that's a good reason to ignore any potential health concerns, but I used to have the misconception that it was much more dangerous, e.g. could cause cancer, but, of course, ionizing radiation is much, much higher frequency.