After 70 years of uninterrupted use in Grand Rapids U.S.A  there are no people unexpectedly dying from chemical poisoning ,or suffering from mental illness. And a city like that would be the best place to do any tests 
And I bet the anti fluoride/vaccine lobby has gone through everybodys medical history to find any fault That they can shout from the rooftops and say, see we told you so. fluoride is this and causes this at .7 PPM 
But as usual what do we hear ,,,Nothing 
So really all the negative comment is just unproven scaremongering 

It says a lot for there arguments, when not one quality medical or dental institution says fluoride is any danger at .7 PPM