[mikeash]

This is a good example of the difference between "fear due to ignorance" and "fear can only come from ignorance". Perhaps there are reasons to think that heart arrhythmia is a potential effect of microwaves. Certainly there's an obvious and plausible mechanism, i.e. microwaves induce electric currents, the heart is sensitive to electric current, and the two could very well interfere.

However, this is the first I've heard of it. Which is not to discount it, but rather to point out that people fear microwaves for completely different reasons. I've never seen anyone say "it'll interfere with my heartbeat!" No, they think that they'll get brain cancer or something that makes little sense, and for which there is no real evidence.

Regarding Joe Bageant, I don't think that quote really contained any facts, so there isn't much to substantiate. Anyway, I'd rather learn about irradiating frogs than argue, so thank you for the link to the paper on that.

Edit: one big fat exception to not hearing about this is, of course, the common warning that people with pacemakers should stay away from microwaves. Which illustrates this in the opposite direction: while there's debate about how realistic the danger is, nobody thinks it's a crackpot idea, because it's fairly well founded.