Flourine ions are easily liberated from their ionic partner. Sodiumflouride itself is listed as toxic waste by the EPA, and would normally be disposed of as such. It is a byproduct of the aluminum refinement process.
Needless to say, it goes into your tube of toothpaste. Convenient way to get rid of it, don't ya think?
So are chlorine ions. Have you ever dissolved table salt?
By the way, what's "flourine?" A by-product of grinding wheat?
(Once is a forgivable typo. More than that, by someone claiming to be giving us scientific information, and it's fair game.)
Stuff like this...
"Needless to say, [sodium fluoride] goes into your tube of toothpaste. Convenient way to get rid of it, don't ya think?"