Yes! Apparently some communities have to remove it from the water first because the naturally occurring levels are too high in modern times now that people brush with it.
I actually have Fluorosis stains on my front teeth. I had no idea what caused that before. I’ve had it for a very long time. It’s just a cosmetic symptom so I’m not worried about it. Something like 25% of the population have staining on teeth from Fluorosis and it’s how the communities can tell when Fluoride levels need to be adjusted in water.
Fluoride levels in water used to be much higher but as society got better at brushing their teeth, it wasn’t needed as much.