Because science is evolving and changing always. I don't love flouride, I have done actual research into the topic and determined that since plenty of peer reviewed scientific research over decades have demonstrated its effectiveness and shown that there's no correlation to it being dangerous that the .7 MG in the water is a non issues. That the 100 of millions of people who have drank said water for decades with no issues. You people are so willfully ignorant that all you can do is cherry pick, be incredulous, and then straw man you can't present any real evidence nor can you comprehend what even the scientific method is let alone how actual data and experiment works. People like you all are the kids in science who blew of science in school because "i don't need to know this in real life.... I am the big brain smarter and my indivisible sky daddy and muh holy book has all answers."