I remember reading that there was a deal made to get rid of the large amount of man-made by-product of some manufacturing process (?) ~ fluoride, by selling the idea of health benefits of adding it to public water supplies. There was no place for this company to dispose of their huge amount of fluoride. Don’t have the source, but I remember reading it online somewhere. I use toothpaste without fluoride now. Tom’s of Maine.
I use Thom's of Maine too - and other tooth powders - they've brought powders back...I use the ones with myrrh = an ancient and efficient germ killer - there's a reason it was so highly valued 2000 years ago.