I can tell you of one adult guy who went to Germany with no cavities, lived there for two years, and came back with several cavities. Not, like, a couple cavities, but several. Germany doesn't flouridate their tap water.

That guy was me, and now whenever I hear fucknuts complaining about flouride in tap water in the US, I stick 'em in the mental "dumb-asses not worth listening to" bin.

I don't think the claim is that it's deadly; I believe the concern it's that there's little to no proven benefits when used topically and at least a few proven detriments when ingested. I haven't done much reading on the subject, so I'm not sure.

Regardless of the veracity of the aforementioned claims, I believe it's immoral for a government to add unnecessary chemicals to public water supply.