Objective To investigate the daily total fluoride intake in relating to the prevalence of skeletal fluorosis in two villages in Jiangsu Province,in order to provide the scientific evidences for the control and prevention of endemic fluorosis.Methods Adults sampled from a high-fluoride Village,Wamiao,and a low-fluoride Village,Xinhuai,were surveyed in this study according to the fluoride concentration in their household shallow well.The average daily total fluoride intake from difierent sources and the skeletal fluorosis were investigated in each subject.Then the subjects from two villages were allocated into five subgroups(＜2.00,2.00～,3.00～,4.00～,≥5.00 mg/d),the relation fluoride intake and prevalence of osteofluorosis was analyzed.Results The prevalence of skeletal fluorosis in Wamiao Village was 31.06%(41/132),but no skeletal fluorosis case(0/35)was found in Xinhuai Village.According to the daily total fluoride intake,subjects with higher daily total fluoride intake tended to associated with a higher prevalence of skeletal fluorosis in a significant dose-response relationship(regression equation:y=2.624-6.855x+3.424x2:r=0.997).The benchmark dose lower limitation of daily total fluoride intake with 95% confidencewas 2.50 mg/d calculated according to this dose-response relationship,the reference dose(RfD)was 2.50 mg/d.In Wamiao Village a significant difference was also found between daily total fluoride intake in 41 subjects[(5.09±1.20)mg/d]with X-ray detectable skeletal fluorosis and in 91 subjects[(3.08±1.12)mg/d]without X-ray detectable skeletal fluorosis(t=-9.32,P＜0.01).Conclusions These findings indicate that the daily total fluoride intake has a significant dose-response relationship with the prevalence of skeletal fluorosis in an endemic fluorosis area associated with high-fluoride drinking water;and the RfD in this study was lower than that in the national standard of"Chinese hygienic standard for daily total fluoride intake(WS/T 87-1996)"(3.50 mg/d).