A Reasearch Of Finding Out The Suitable Iodine Concentration Cut Point To Stop Supplying Iodized Salt In Areas Where Water Iodine Is Excess

With the popularity of salt iodization measures, iodine deficiency conditions have been greatly improved. At the same time, damage caused by iodine excess have begun to attract attention. Due to iodine distribution in the geographical there is a big difference, high water content of iodine in some areas may cause periodate problems. Therefore, understanding the high water iodine water iodine changes, the iodine status of the population with high water iodine intake, the existence of the problem of excessive water iodine levels in which to meet the population iodine nutritional needs and thus does not require the supply of iodized salt. In order to avoid the people in areas of high water iodine harmed by periodate, it is a problem need to solve urgently.Objective:To grasp the water iodine concentration and distribution changes in those high iodine water areas. To evaluate the iodine nutrition level of women and children living in high water iodine(where drinking water iodine concentration is between 10～150 μg/L);to find out the iodine nutrition change of these people after deducting the amount of iodized salt supply to them; to explore the suitable range of water iodine concentration to stop supplying iodized salt in high iodine water areas and keep residents’iodine nutrition level normally.Methods:Combining the rural drinking water monitoring system, sampling the water plants of the rural drinking water monitoring points’ finished water and peripheral water in the wet and dry seasons. Using the national water iodine deficiency disease reference laboratory detection methods to detect the water iodine concentration.. The region that haven’t stopped supplying iodized salt were chosen to be the study sites. In the epidemiological survey research,331children aged 8～10 and women aged in 177 families were chosen to be target people. Before the household survey, a simple baseline survey was implemented which include questionnaires and a collection of morning urine samples of target people. The amount of three days’ slat intake and Soy sauce, sweet oil intake for the target people were done by a door-to-door survey. And a 24-hour urine survey for two days were also done at the survey. While the urine contents in the morning urine,24-hour urine, salt, soy sauce, sweet oil were measured(GB/13025.7-2010, WS/T107-2006, WS302-2008).To survey the Urinary iodine excretion, salt consumption and 24-hour urine output, to calculate the iodine intake. Combining the median urinary iodine and the survey iodine intake of target people to find out the suitable water iodine concentration to stop supply iodized salt.Results:There were 448 and 449water plants were monitored in the dry and wet season, the medians of water iodine concentration of the finished water and peripheral water were 16.1 μg/L,16.05μg/L,16.8μg/L、 16.8μg/L. There was statistical significant between the water iodine levels (P<0.05). But there was no statistical significant between the finished water and peripheral water (P>0.05). There was statistical significant between the different areas (P＜0.05).There was statistical significant difference that the water iodine concentration of Fengxian, Peixian, Suining country were higher than the other areas in this survey (P<0.05). In the epidemiological survey research,331 target people were got a special investigation. At the 10～50μg/L、50.01～100μg/L、100.01～150μg/L water iodine group, the environmental source of iodine of the school-age children were 83.9 μg/d、83.4 μ g/d、166.0μg/d, while the women were 223.3 μg/d、218.9 μg/d、 332.9 μg/d.The soy sauce intake of school-age children, women were 0.37g/d,0.47g/d,while the sweet oil intake were 3.65g/d,4.56g/d.The iodine concentration of the Hengxin, Haitian shengchou, Haitian laochou soy sauce were 745.3ng/g,60.76 ng/g,60.91 ng/g. The iodine concentration of the Henxin, Didixian, Wantong sweet oil were 475.57 ng/g,202.04 ng/g,92.35 ng/g. The medians of morning urine,the secondary day, the third day were 310.5 μg/L,290 μg/L,285 μg/L. There was no statistical significant between the medians of urinary iodine concentration of women and children (P>0.05).And there was no statistical significant among the different batches (P>0.05) The iodine intake had high-positive correlation relation with the content of water iodine((P＜0.05)Conclusive:The same batch of the peripheral water of iodine can replace the finished water, there were significant difference among the different batches. Water iodine content of 10 to 150μg/L range of areas, in the case of non-stop for iodized salt condition, iodine nutrition is desirable or slightly iodine excess levels. The suitable stopping iodized salt water iodine cut-off point might be 100 ug/L. The evaluable of iodine nutrition of people, "environmental source of iodine" is more intuitive than the urinary iodine level and it also can avoid the impact of factors such as time. Iodine content of the soy sauce, sweet oil can’t be cause iodine excess.