I notice neither that Wikipedia page nor the general water fluoridation page cover water fluoridation's alleged effect on IQ, although that's the main recent claim I've seen conspiracy theorists make about it. (My impression, based on a desultory skim through a few of the studies they refer to: they're wrongly inferring causality from fairly weak observational studies that compare people in different regions with different levels of fluoride in the drinking water. These studies normally take place in less developed nations like India & China where the water is more likely to have naturally high levels of fluoride — often more than is added in the US — and other toxic chemicals that could readily confound the results.)