In Shanxi Province, China, children living in the endemic fluoride vil
lage of Sima (water supply F = 4.12 mg/L) located near Xiaoyi City had
average IQ (97.69) significantly lower (p < 0.02) than children livin
g to the north in the nonendemic village of Xinghua (F = 0.91 mg/L; av
erage IQ = 105.21). These differences were not associated with gender,
but the IQ scores were directly related to educational level of the p
arents.