Dear Wordminstrel: On a Colgate University site, I found this: Seaweeds use vanadium bromoperoxidase, in the oxidation of bromide, as a defense mechanism against predators.

How much seaweed do you have to eat?

I went back and was not able to find out what value bromide would have associated with a toothpaste.
I found a site about aphthrous stomatitis, but the author was a real kook. I was involved in early dental fluoride programs fifty years ago. Sadly the same crowd of nuts that were against it then have been reincarnated and still using the same stupid sick arguments Let's not have a thread about that!.