There was a study comparing test scores of children from a more poor neighborhood that had city water with fluoride and test scores of children from a rich neighborhood that had its own water system and didn’t add fluoride to the water. To nobody’s surprise, the rich kids tended to score higher on tests and those publishing the study claimed that it was the lack of fluoride in the rich kids’ water that helped them score higher, instead of the inherent food and home security and additional parental support that comes from wealth.