A Canadian study reported in JAMA Pediatrics (Journal of the American Medical Association). They discovered a positive correlation between maternal levels of fluoride associated with typical fluoridated water supplies and lower average IQs in their children. (Close to 5 IQ points on average.)
https://jamanetwork.com/journals/jamaped...erm=081919
Similar results have been seen in other studies.
I'm still not 100% convinced, at least in part since many other factors could be influencing these children's intellectual development. But the study did try to correct for most of the known ones.
What's more, when they graph the results, they don't get a nice line showing IQ a function of fluoridation levels. What they got was a dust, a fairly random looking non-linear collection of points with lots of IQ variability at all fluoridation levels. It took some aggressive statistics to tease a correlation out of it. (Which makes me skeptical in principle.)
https://jamanetwork.com/journals/jamaped...erm=081919
Similar results have been seen in other studies.
I'm still not 100% convinced, at least in part since many other factors could be influencing these children's intellectual development. But the study did try to correct for most of the known ones.
What's more, when they graph the results, they don't get a nice line showing IQ a function of fluoridation levels. What they got was a dust, a fairly random looking non-linear collection of points with lots of IQ variability at all fluoridation levels. It took some aggressive statistics to tease a correlation out of it. (Which makes me skeptical in principle.)