Study Reveals Serum Fluoride Lowers Children's Intelligence Quotient  This study was conducted to assess the relationship between serum fluoride and children’s IQ. Animal studies show that brain fluoride levels increase with increasing exposure to fluoride. Human studies have indicated an association between high levels of drinking-water fluoride and lower intelligence. The results indicated that fluoride in drinking water was highly correlated with serum fluoride, and higher fluoride exposure will affect intelligence among children.