Objective To find out fluorine content in drinking water in Yi County,and to provide ascientific basis for prevention of endemic fluorosis and children's dental caries.Methods According to FluorideDistribution Survey Program in Drinking Water of Hebei Province,an administrative village was taken as a unit,one drinking water sample was randomly collected from every village with centralized water supply.For villages withdecentralized water supply,five drinking water samples were randomly collected according to directions (east,west,south,north and centre) if there were more than five water sources in the village;samples from all the water sourceswere collected if there were less than five.Fluorine content was determined with drinking water standard testmethods (GB/T 5750.2-2006).Analysis and comparison of fluoride content in drinking water of different landscapes,water types and different well depth were carried out.Results The range of water fluoride content was 0.00-18.39 mg/L,and water fluorine median was 0.24 mg/L in 1 024 water samples in 27 towns in the county.Watersamples of 490,505 and 29 copies were collected in the hills,plains and mountains,and water fluorine medianwas 0.26,0.22 and 0.21 mg/L,respectively.Concerning water fluorine content in drinking water,mountains werehigher than hills and plains (x2 =71.71,17.74,all P ＜ 0.01).There was no significant difference between waterfluoride content in hills and plains (x2 =2.48,P ＞ 0.05).Water samples of 742,228 and 54 copies were collected,respectively,in household well water,tap water and mountain spring water,and water fluoride median was 0.22,0.24 and 0.33 mg/L,respectively.Concerning water fluoridation content in drinking water,spring water were higherthan tap water and household well water (x2 =53.16,50.85,all P ＜ 0.01).There was no significant differencebetween water fluoridation content in tap water and household well water (x2 =2.97,P ＞ 0.05).Water samples of583 and 441 copies were collected,respectively,in well depth ＜ 40 m and well depth ≥40 m,and water fluoride median was 0.24 and 0.23 mg/L,respectively,and there was no significant difference between water fluoridation content in the well depth ＜ 40 m and the well depth ≥40 m (Hc =0.17,P ＞ 0.05).Conclusions Fluoride content of drinking water in Yi County is not high,endemic fluorosis disease does not occur.

Objective To find out the iodine content in drinking water in Yi County,and to provide a scientific basis for prevention of iodine deficiency disorders.Methods An administrative village was taken as a unit in Yi County,Hebei Province.One drinking water sample was randomly selected from each village with centralized water supply.For villages with decentralized water supply,five drinking water samples were randomly selected according to directions (east,west,south,north and center) if there were more than five water sources in the village ; all the water source samples were taken if there were less than five water sources.Water iodine content of all of the water samples was tested; geomorphological feature,water type and well depth were surveyed.Water iodine content was determined through arsenic cerium catalytic spectrophotometric method.Results The range of water iodine content was 0.00-18.39 μg/L,and water iodine median was 2.08 μg/L in 1 024 water samples in the county.Water samples of 490,505 and 29 copies were collected in the hills,plains and mountains,and water iodine median was 1.74,2.26,3.15 μg/L,respectively.Concerning water iodine medians in drinking water,mountains were less than hills and plains(x2 =37.36,34.25,all P＜ 0.01),hills were less than (x2=15.27,P ＜ 0.01).Water samples of 742,228,54 copies were collected,respectively,in household well water,tap water and mountain spring water,and water iodine median was 2.08,2.24 and 0.73 μg/L,respectively.There was no significant difference between the water iodine median in tap water and household well water (x2 =2.97,P ＞ 0.05),and the iodine in mountain spring water was less than that of tap water and household well water (x2 =38.23,43.82,P ＜ 0.01).Water samples of 583 and 441 copies were collected,respectively,in the well depth ＜ 40 m and well depth ≥40 m,and water iodine median was 1.81 and 2.24 μg/L,respectively,and there was no significant difference between the water iodine median in the well depth ＜ 40 m and well depth ≥40 m(x2 =2.32,P ＞ 0.05).Conclusions Residents iodine content of drinking water in Yi County is lower; the natural environment is seriously iodine deficiency,and iodine supplementation should be strengthened.