Added fluoride is done at safe levels. But some natural water sources have TOO MuCH fluoride which is unsafe. https://en.wikipedia.org/wiki/Fluoride_toxicity#Bo

Added fluoride is done at safe levels. But some natural water sources have TOO MuCH fluoride which is unsafe. https://en.wikipedia.org/wiki/Fluoride_toxicity#Bones https://en.wikipedia.org/wiki/Fluoride_toxicity#Bones