There is no evidence that adding low levels of fluoride to community drinking water affects children's IQ or brain function later in life, according to a new study that tracked more than 10,000 people from their teen years through to old age. In many regions of the world, fluoride is added to water to improve communities' dental health: it's proven to strengthen teeth and reduce decay. The new study, which draws on longitudinal data from 10,317 high school seniors from 1957 to 2021, when