New and important research done in Mexico with 300 mother-children couples illustrates that fluoride exposure potentially has an even stronger impact on our children before they are born. Fluoride exposure was measured based on the fluoride levels in the urine of the mothers and children over a 12 year period. This study shows average values for urinary fluoride in the mothers and children of 0.90 mg/L and 0.82 mg/L, respectively (Read an article about the study by CNN here).
Another study – done by the University of Guanajuato in 2015 – tested the fluoride levels in urine of people living in communities in the Independence Watershed region. This study has shown much higher fluoride levels in the urine of adults, measuring as high as 5.09 mg/L.
The conclusion from the current study in Environmental Health Perspectives is that every 0.5 mg/L increase in fluoride exposure leads to a drop in a score on intelligence tests.