Why is Fluoride a toxin?

Answer 1

All things are toxic at a sufficiently high dose or if the exposure is at a sufficiently high dose rate. Even water is toxic and people have died by drinking too much water too fast.

At the normal exposures one gets to fluoride it is not toxic (and even significantly helps teeth resist tooth decay). However one exception to this is very young children should never be allowed to brush their teeth with a toothpaste containing fluoride as they tend to swallow the toothpaste instead of spitting it out and toothpaste tends to taste like candy so some very young children also eat it, there have been cases where such children have reached toxic doses of fluoride (especially in areas where the drinking water also contains fluoride either naturally or via artificial fluoridation).