Yeah. It’s not an entirely salient point. It does, however, underline the ubiquitous nature of fluorine.

The biggest source of Flourine in the environment is just the normal weathering of rocks that contain it. The biggest of the anthropogenic sources include brick production, phosphate fertiliser application and coal burning.

The minor amount added to drinking water really wouldn’t be the biggest issue if it was as toxic as it’s made out to be.