The Effects Of Endemic Fluorosis On Children's Intelligence Development And Oxidative Stress

Objectives:To study the effects of endemic fluorosis on intelligence development of children , and explore the role of free radical and oxidative stress in the damage of fluorosis children's intelligence development.Methods:Four investigated primary schools were selected respectively from slight, medium, severe fluorosis groups and control group in Xinhua county of Hunan province, and twenty children were sampled randomly as objectives in grade 5 of every primary school. The seriousness of dental fluorosis was examined by Dean's method and intelligence level was evaluated by CRT-RC in these sampled children. The morning Urine was collected and venous blood was draw from the objectives who were on an empty stomach in the morning. Fluoride content in urine was measured by fluoride ion selection electrode method. MDA content was measured by TBA chromatometry method. SOD activity was determined by xanthine oxidase method. GSH-PX activity and GSH content were determined by DTNB method. NO content was measured by nitrate reductase method. ANOVA of randomized block design was applied to analyze the difference of urinary fluoride content, children's intelligence level and the level of lipid peroxidation, antioxidase and antioxidant in serum among different disease areas and among different disease degree groups.Results:The more serious children's dental fluorosis was, the higher fluoride content in urine was (P<0.01). The difference of children's IQ was statistically significant among the different disease degree groups (P<0.01), and the children's IQ tended to decrease with seriousness of dental fluorosis. There was a negative correlation between children's IQ and urinary fluoride content (P<0.01). In the abilities of cognition discerning and analogical comparison, the difference wasn't statistically significant among the different disease degree groups (P>0.05), but the difference was significant in the abilities of comparative inference, serial relationship and abstract inference(P<0.05).Excess fluoride in children with endemic fluorosis increased the level of NO and MDA (p<0.05), and decreased the content of GSH and the activities of SOD and GSH-PX (p<0.05) in serum. A negative correlation was observed between the children's IQ and the content of MDA (p<0.01), and the content of MDA showed negative correlations with the abilities of comparative inference, serial relationship and abstract inference (P<0.05). The children's IQ showed positive correlations with the activity of SOD and the content of GSH. There was a positive correlation between the capacity of abstract inference and the activity of SOD (P<0.05), and the abilities of comparative inference and serial relationship demonstrated positive correlations with the content of GSH (P<0.05). The children's IQ and the score of every cell showed negative correlations with the content of NO (P<0.05).Conclusions:1. Endemic fluorosis may cause significant damage in children's intelligence development, especially in the capacity of abstract inference.2. Excess fluoride in fluorosis children may increase the level of free radical, decrease the activities of antioxidase and the content of antioxidant, and promote lipid peroxidation.3. Free radical and oxidative stress may play a important role in the damage of fluorosis children's intelligence development.