Regardless of whether fluoride is a serious risk or not, it seems ridiculous to take a topical drug systemically. Fluoride works by inorganic reactions with the teeth themselves. There's no benefit to flooding the whole body with it. It's reasonable to be suspicious of water fluoridation when the same benefit can be achieved with fluoridated toothpastes, which deliver the fluoride only where it's needed.
"Systemic fluorides can also give topical protection because ingested fluoride is present in saliva, which continually bathes the teeth providing a reservoir of fluoride that can be incorporated into the tooth surface to prevent decay."
It also says fluoride ingested during teeth-formation is incorporated into the teeth.
As someone who grew up on well water with no fluoride in it I can confirm that my teeth are looking fine after all these years of regular dental checkups and twice daily tooth-brushing.
Fluoride occurs naturally (in varying concentrations) in water. Water with high natural concentrations is how we found out fluoride prevents tooth decay in the first place.
