Correlation between prevalence of dental fluorosis and soil chemical elements in endemic fluorosis areas

Objective To explore the correlation between chemical elements in soil and dental fluorosis and to provide a scientific basis for prevention of endemic fluorosis.Methods In 2011,using cluster sampling,totally 38 of 55 townships (towns) in Fengjie and Wushan Counties were selected as investigation spots.Dental fluorosis of children aged 8 to 12 were examined with Dean index in all individuals from the sampled townships (towns).We also detected the content of fluorine(F),zinc(Zn),copper(Cu),iodine(I),selenium(Se),cadmium (Cd),chromium (Cr),arsenic (As),nickel (Ni),mercury (Hg) and lead (Pb) in topsoil of sampled townships (towns).Using Spearman rank correlation analysis the correlation between dental fluorosis prevalence and the content of chemical elements in the topsoil of selected townships (towns) was analyzed.Results Children's dental fluorosis prevalence was positively correlated with surface soil F and Cd content in Wushan County,but negatively correlated with the content of Cu,Zn and Se,and the correlation coefficients were 1.0000,0.9053,-0.6617,-0.7353 and-0.5143,respectively (P ＜ 0.05).Children's dental fluorosis detection rate was also positively correlated with the surface soil content of F and Cd in Fengjie County,but also negatively correlated with the content of Cu,Zn and Se,and the correlation coefficients were 0.9959,0.9298,-0.5728,-0.8308 and-0.6533,respectively(P ＜0.05).Conclusions The relationship between detection rate of children's dental fluorosis and the content of F,Cd,Cu,Zn and Se in topsoil was positively or negatively correlated in Fengjie and Wushan Counties.And the relationship between these elements and endemic fluorosis should be further studied. Key words: Fluorosis, dental; Soil; Elements; Ecology