Comment by Beretta_Vexee

In fact, many countries even have a maximum permissible limit for fluoride in tap and bottled water.

In France, for example, the limit is 1.5 mg/L in tap water. https://www.anses.fr/en/system/files/NUT2007sa0315q.pdf

Supplementation mainly concerns iodine for non-marine salts. Sea salt naturally contains iodine and fluorine. Salt from salt mines contains much less. For this reason, iodine deficiency was relatively common in the Alps until the beginning of the twentieth century.

To my knowledge, there is no debate or controversy on the subject. Endemic goiters are exceedingly rare and are linked to behavioral and eating disorders.