Survey on excessive iodine in drinking water and its geographical distribution in Hebei Province / 中国地方病学杂志

ABSTRACT

Objective To investigate the geographical distribution of excessive iodine in drinking water and to demarc aI|e the excessive iodine regions in Hebei Province.Methods In 173 counties of Hebei Province, town was surveyed as an elementary unit.Five villages were sampled according to the direction of east,west, south,north,center in every town.If the water sources were more than 5 in a village,water was sampled according to the direction ofeast,west, south,north, center, respectively;If the water sources were less than 5 in a village, all were sampledIf the village used water of cental supply,only one sample wag collected.Arsenic-cerium catalysis was used to determine the iodine concentration of drinking water.Results Two thousands and forty-nine towns were investigated and 19 352 water samples were determined in Hebei Province.One hundred and seventy- two towns were confirmed to be excessive iodine areas,where the range of water iodine Wag 0.1～2840.4μg/L The water 8amDle with 18 358 had a water iodine median less than 150.0μg/L The areas with water iodine median less than 150.0μg/L,in between 150.0μg/L and less than 300.0μg/L,and equal to or more than 300.0 μg/L accounted for 94.86%,2.92%and 2.22%,respectively.There were 110 towns with water iodine median being between 150.0μg/L and iess than 300.0 μg/L and 62 towns with water iodine median equal to or more than 300 gμ/L.Exeessive iodine towns distributed in 33 counties of 6 cities involving 5 854 960 residents in'Hebei Provmce. MOBt of the water sources with excessive iodine Cangzhou were deep wells and there was a positive correlation between we depth and water iodine concentration (r=0.430,P<0.01), while they were shallow wells in Handan, Xingtai.Hengshui,and no correlation was found between well depth and water iodine concentration(r=-0.060,-0.119.-0.121,P>0.05).Conclusions Six cities have excessive iodine water resotlrees in Hebei Province, mostly in Handan.xingtai,Hengshui and Cangzhou Cities,which all are low-lying land.The water with excessive iodine is hypogene,and the towns with excessive iodine water distributein patchy or spot pattern.