Naturally occurring or from aluminum and steel processing slag? May make a meaningful difference.

Back in the 1950's-60's, teeth of American Indian tribes were studied by the American Dental Association and found to be in a particularly healthy condition, and it was attributed at the time to the fact that their ground water contained a meaningful amount of fluoride. Based on this, the metal processing industry used this finding to justify the disposal of metal processing run off environmentally containing "fluoride," promoting the adding of "Fluoride" to municipal water supplies, and prevailing upon FDA to approve its use in formulations by toothpaste manufacturers under the guise of promoting healthy teeth in the populace at large. Detection of fluoride in ground water vs. being present as a matter of municipal fluoro-fortification of water would be obfuscated.

Costly waste disposal floated under the guise of "heath" promotion. What a concept!

Consider arsenic for instance. Organic arsenic is present in soil everywhere. It is generally not toxic to humans. Inorganic arsenic by contrast is extremely toxic to humans. It may be that organically bound fluoride as might be present in the water where the Indian tribes lived that was studied by ADA is beneficial to teeth maintenance, but the fluoride generated from metal processing is of a different type that results in deleterious health effects, but the concept of "fluoridation" has been normalized in public policy for American society for over 60 years.