The Effects Of Fluoride And Aluminum Exposure On Children’s Intelligence, Dental Fluorosis In Endemic Fluorosis Areas

This project was carried out to investigate the explicit dose-response relationsbetween urine fluoride concentration and dental fluorosis as well as intelligencequotient in drinking water type of endemic fluorosis areas. Additionally, theassociations of the combined high fluoride and aluminum exposure with children’sintelligence and dental fluorosis were investigated in drinking tea type of endemicfluorosis areas.882children aged from7to14were randomly recruited from foursites in Hulunbuir City, of which387children belong to control group,260childrenbelong to the type of drinking water group and325children belong to the type ofdrinking tea group. Intelligence was assessed using Combined Raven Test-The Ruralin China while dental fluorosis was diagnosed with Dean’s index. F-ion was detectedusing F-ion selective electrode and Al-ion was detected using ICP-OES. Multiple linerregression model was used to evaluate the dose-response relation between children’sintelligence and urine fluoride, as well as urine aluminum. CMH test for trend wasused to evaluate the association between dental fluorosis and urine fluoride and thecorrelation of dental fluorosis with IQ scores. In drinking water type of endemicfluorosis areas, the prevalence rate of dental fluorosis was49.61%. There was adose–response relationship between urine fluoride and dental fluorosis (P<0.0001).Urine fluoride was inversely associated with IQ in the multiple linear regressionmodel (P<0.0001). Each increase in1mg/L of urine fluoride was associated with0.642-point decrease in IQ scores. Although the percentage of children with IQ≤89was much higher, numbers of children with IQ≤89did not have significant differencesamong normal, very mild and mild group of dental fluorosis (P=0.748). In drinkingtea type of endemic fluorosis areas, the prevalence rate of dental fluorosis was46.38%. The proportation between urine fluoride and dental fluorosis appears to have nostatistical significance (χ2=0.9511, P=0.3294). Urine fluoride and aluminum were notassociated with IQ scores in the multiple linear regression model (P>0.05) either. Withthe aggravation of dental fluorosis, the percentage of children with IQ≤89got larger,but this tendency did not have statistical significance among normal, very mild andmild group of dental fluorosis (P=0.65). Our study suggested that low levels offluoride exposure in drinking water was inversely associated with children’sintelligence and dental health and confirmed the dose–response relationships betweenurine fluoride and IQ scores as well as dental fluorosis. In the type of drinking teaareas, there was no statistical significance in the relation of dental fluorosis and urinefluoride, and also the association between IQ scores and urine fluoride and aluminum.