Iodine nutrition status among pregnant women before and after adjustment of salt iodine content in Hangzhou City

Objective To work out the suitable iodine content in iodized salt among general population in Enshi Autonomous prefecture,Hubei province by determination of the iodine content in salt.Methods The method of direct titration was used to determine the iodine content in salt samples collected from residents in natural villages sampled from four directions of east,west,south and north in each township which was sampled from five directions of east,west,south,north and center in each city(county) in Enshi Autonomous prefecture,and salt samples were collected in Hubei Salt Industry Group Co.,Limited.Enshi Branch in 2011.The method of three-days weighing was used to estimate the resident's daily per capita intake of iodized salt.The appropriate iodine content for general population in salt was worked out according to the iodine content in salt from households and enterprises in Enshi Autonomous prefecture,the amount of iodine loss in iodized salt,the amount of per capita daily intake of iodized salt and the national iodine nutrition monitoring results.Results The median of iodine content in salt from residents and the production enterprises in 2011 was 33.5 mg/kg and 34.7 mg/kg,respectively.The residents' per capita salt intake was 10.9 g,actual intake of iodine wss 335.0 μg/d.Iodine content in iodized salt was 20 mg/kg ±30％ for the general population,actual intake of iodine was 149.4-250.4 μg/d.Conclusions The residents iodine intake is higher in Enshi Autonomous prefecture.Considering the comprehensive factors,including food iodine,water iodine,and iodine cooking loss,that affect the intake of salt iodine,the appropriate iodine content in iodized salt is 20 mg/kg ± 30％ for the general population. Key words: Salt iodine; Intakes; Outcome assessment

Objective To explore the impact of iodine nutrition on 8 - 10 years old children after adjusting the iodine content in iodized salt in Hangzhou. Methods Twelve counties （ areas, cities ） were divided into urban, suburban and rural areas in Hangzhou. By population proportion survey （PPS）, every county（area, city） was divided into east, west, south, north and middle districts; one school was selected in each district; forty children （half male and half female） aged 8 - 10 years old in each school were selected; family salt and urine samples of each student were collected. The levels of salt and urinary iodine were measured by picrie sodium thiosulfate titrimetric （ GB 13025.7- 2012 ） and spectrophotometer method （WS/T 107-2006 ）, respectively. Results Two thousand seven hundred and twenty-five household salt samples were collected. The median of salt iodine, the iodized salt coverage rate, the qualification rate of iodized salt and the consumption rate of qualified iodized salt were 24.00 mg/kg, 4.35%（2 571/2 725）, 91.02%（2 340/2 57：1） and 85.87%（2 340/2 725）, respectively. The medians of salt iodine in urban, suburb and rural areas were 24.10, 22.12, 24.30 mg/kg, respectively. A total of 2 664 children urine samples were collected. The median of urinary iodine （MUI） of the children was 177.24 μg/L. The MUIs in urban, suburb and rural areas were 175.00, 178.55, 178.00 μg,/L, respectively; in male was 183.00μg/L and female was 170.50 μg/L. When non-iodized and unqualified iodized salt were taken, the differences of urinary iodine within groups were statistically significant in urban, suburb and rural areas（χ2 = 18.652, 14.686, all P 〈 0.05）. In rural area, the difference of urinary iodine of 8 - 10 years old children who ingested different types of iodized salt was statistically signifieant（χ2 = 39.07, P 〈 0.05）. Conclusion After adjustingthe iodine content of salt in Hangzhou, the iodine-nutritional status of 8 - 10 years old students is at a appropriate level. Key words: Children ; Iodine ; Salt

Objective To explore the impact of iodine nutrition on pregnant women after adjusting the iodine content in iodized salt in Hangzhou and provide a scientific basis for supplementation of iodine to pregnant women. Methods After adjusting the iodine content of salt from 2012 to 2014, proportional probability sampling method was used to select 300 families and 100 pregnant women from every county (area, city) of Hangzhou City, and the household salt and urine samples were collected to detect iodine. Results Totally 3 904, 3 900 and 3 900 samples of household salts were collected with the medians of salt iodine concentration of 23.77, 22.75 and 23.30 mg/kg of each year from 2012 to 2014, respectively. The qualified rate of iodized-salt was 95.87% (3 550/3 703), 97.04% (3 510/3 617) and 96.53% (3 564/3 692) and the consuming rate of qualified iodized salt was 90.92% (3 550/3 904), 90.01% (3 510/3 900) and 91.38% (3 564/3 900), respectively, from the year 2012 to 2014. Totally 1 300, 1 217 and 1 315 urine samples of pregnant women were collected and the median of urinary iodine (MUI) of each year from 2012 to 2014 was 119.90, 136.40 and 124.00 μg/L, respectively. Conclusion After adjusting the iodine content of salt in Hangzhou, the salt iodine consumption levels of pregnant women's family are stable, but the level of urinary iodine is low, which should be pay attention to. Key words: Pregnant women; Iodine; Salt; Urine

Objective To observe the implementation of national food safety standard for “Iodine Concentration in Edible Salt”（GB 26878-2011） and its effectiveness on iodine nutritional status of key populations. Methods Information of iodine concentration in edible iodized salt of various provinces （autonomous regions and municipalities, including Xinjiang Production and Construction Corps） was collected using Baidu Searching Engine through the establishment of key words. Sal t samples were collected in Tianjin City and Aksu Region of Xinjiang , and the salt iodine concentration in both places was 30 mg/kg. In Tianjin, Hongqiao, Tanggu and Hangu, Beichen were selected as representatives of the downtown areas, the coastal areas and the suburbs, respectively and counties of Baodi and Ji were iodine deficiency areas in history. Sampling work was carried out from August 2012 to March 2013 in Tianjin. In Aksu, Yatuoer Township and Charqi Town in Baicheng County, Aotebeixi and Aketuohai Townships in Wushen County were chosen as iodine deficiency areas, and the survey was carried out from January＆amp;nbsp;to September 2013 . Random urine samples of school-age children （ 8 - 10 years old ） , pregnant women and lactating women were collected; urinary iodine was measured following the Method for Determination of Iodine in Urine by As3＋-Ce4＋ Catalytic Spectrophotometry（WS/T 107-2006） and iodine in edible iodized salt was measured following the General Test Method in Salt Industry Determination of Iodideion （ GB/T 13025 . 7-1999 ） . Results Fourteen of the provinces（autonomous regions and municipalities, including the Corps of Xinjiang） chose 25 mg/kg as their iodine concentration in edible iodized salt and 13 provinces chose 30 mg/kg. Besides, there were another 5 provinces providing 30 mg/kg particularly for pregnant women and lactating women while 25 mg/kg for other populations. In Tianjin, the medians of iodine concentration in edible iodized salt were ranged from 24.4 - 32.1 mg/kg in retail stores and 26.4 mg/kg at households. The household coverage rate of iodized salt and the proportion of households using adequately iodized salt were 78.5%（168/214） and 62.6%（134/214）, respectively. The median ranges of urinary iodine were 178.2 - 183.9 μg/L in school children, 124.3 - 130.9 μg/L in pregnant women and 72.7 - 109.5 μg/L in lactating women. In Aksu, the medians of iodine concentration in edible iodized salt were 27.1 and 26.5 mg/kg in retail stores and households, respectively. The household coverage rate of iodized salt and the proportion of households using adequately iodized salt were 100.0% （363/363） and 98.9%（359/363）, respectively. The median ranges of urinary iodine were 174.8 - 293.0, 154.9 - 230.0 and 135.8 - 239.3 μg/L among school children, pregnant women and lactating women, respectively. The median of iodine concentration in a special edible iodized salt sample reached 49.1 mg/kg, and qualified rate was 0（0/11） in Aksu. Conclusions All provinces , municipalities and autonomous regions （ including the Corps of Xingjiang ） in China have adjusted the iodine content in edible iodized salt in accordance with GB 26878-2011. However, in Tianjin the household iodine concentration in edible salt is lower than the local standards; the household coverage rate of iodized salt and the proportion of households using adequately iodized salt are lower than the national standards; pregnant women and lactating women are at risk of mild iodine deficiency. Key words: Iodized salt; Urinary iodine; Children; Pregnant women; Lactating women

Objective To understand the status of iodine nutrition of children aged 8-10 years and pregnant women in Shizuishan City. Methods In 2017, five sampling districts were divided into east, west, south, north and middle districts in three counties (Dawukou District, Huinong District and Pingluo County) of Shizuishan City, one township (town, street) was selected in each district, one primary school was selected in each township (town, street), 40 children aged 8-10 years were selected in each primary school, and 20 pregnant women were selected in each township (town, street). In Dawukou District and Huinong District of Shizuishan City, 50 g of edible salt and 10 ml of urine samples were collected from the homes of children and pregnant women; in Pingluo County 50 g of edible salt samples were collected from the homes of children and pregnant women. Iodine in edible iodized salt was measured by redox titration and urinary iodine content was measured by arsenic-cerium catalytic spectrophotometer. Results A total of 900 edible salt samples were collected, the median iodine content in salt was 24.50 mg/kg, the coverage rate of iodized salt was 97.67% (879/900), the qualified rate of iodized salt was 86.92% (764/879), and the edible rate of qualified iodized salt was 84.89% (764/900). A total of 400 urine samples of children were tested, the median urinary iodine was 213 μg/L. There was statistically significant difference in urinary iodine among children between Dawukou District and Huinong District (the median urinary iodine was 246 and 194 μg/L, respectively, Z=-4.827, P 0.05). A total of 200 urine samples of pregnant women were tested, and the median urinary iodine was 173 μg/L. There were no significant differences in urinary iodine content between pregnant women in different counties(districts), and between pregnant women at different pregnancy stages (P > 0.05). Conclusion The iodine nutrition status of the children aged 8-10 years and pregnant women in Shizuishan City is generally at the appropriate level. Key words: Iodine; Deficiency diseases; Nutritional status; Salts; Urine

Objective To analyze the characteristics of urinary iodine and edible iodized salt,and to provide suitable iodine concentration in iodized salt.Methods Sample testing was carried out to detect iodine concentration in marketed salt and child urine before salt iodization (1994).After salt iodization (2001-2010),sample testing was carried out to detect salt iodine level in manufacture,market(2001-2010) and resident household(1997-2010).Urine of children aged 8 to 10 were sampled by PPS method from 1997 to 2005.In 2009,urinary iodine of 20 children was determined in each of 5 schools,which were sampled from 5 counties located at North,South,East,West and center of Chongqing.Based on the urinary iodine and salt iodine levels before salt iodization,the relationship of urinary iodine and consumption of iodized salt was calculated.Suitable iodine concentration in iodized salt was put forward.x2 test and trend analyze approach(F-test) were used for statistical analysis.Results Before salt iodization,salt iodine level was not tested in 204 edible salt samples; the median of urinary iodine was 53.14 μg/L in 1374 children.After salt iodization,form 2001 to 2010,the average iodine levels in manufacture and wholesale salt were between 29.72-36.25 mg/kg and 30.65-36.13 mg/kg,respectively,both of them decreased significantly(F =35.35,140.59,all P ＜ 0.01),and show a downward trend.Batch quality passing rate of industry iodized salt was 100％ except in 2001,which was 92.86％.Batch quality passing rate of market iodized salt were between 88.68％-99.77％,specifically in 2001 (88.68％),in 2002(92.57％) and in 2003 (96.22％).There was no significant difference in other years (all P ＞ 0.05).The median of urinary iodine were between 238.80-328.00 μg/L,more than 35％ fall into ＞ 300 μg/L; while salt iodine increased 1 mg/kg,urinary iodine increased 5.51 μg/L-7.40 μg/L; The medium of urinary iodine of children were between 140.05-383.00 μg/L in 40 counties or districts in 2009.Reducing the iodine concentration in edible iodized salt to 20 mg/kg,the median of urinary iodine can be kept at 163.34 μg/L to 201.14 μg/L.Conclusions Iodine in iodized salt is above sufficient in Chongqing.Salt iodine should be reduced to 20 mg/kg,which will meet various population's need. Key words: Iodine; Salts; Urine

Objective To understand the level of urinary iodine of schoolchildren and salt iodine content of their families in a primary school and to analysis influence between salt iodine content and urinary iodine level in Haimen City,Jiangsu Province.Methods A cross-sectional study was conducted in a primary school of Haimen City in 2012.With the method of stratified cluster sampling,all students aged 9 ～ 12 were extracted in grades 3-5,urine samples and salt samples of their family were collected.Urinary iodine and salt iodine were determined according to ＂Method for Determination of Iodine in Urine by As3＋-Ce4＋ Catalytic Spectrophotometry＂ （WS/T 107-2006） and ＂Direct Titration of Universal Test method in Salt Industry＂ （GB/T 13025.7-1999）.Results Totally,452 students from grades 3-5,including 233 boys and 219 girls were selected by cluster-stratified sampling.The median of children＆#39;s urinary iodine was 231.90 μg/L,while the median of boys and girls was 235.40 and 222.60 μg/L,respectively.The median of urinary iodine of 9,10,11 and 12 year old students was 253.65,195.70,236.40 and 241.70 μg/L,respectively.The proportion of less than 100 μg/L and ≥300 μg/L was 7.7% （35/452） and 27.7% （125/452）,respectively.There were no significant differences between different gender and age students.Among the 452 salt samples collected the median of salt iodine was 27.50 mg/kg.The coverage rate of iodized salt,the qualified rate of iodized salt and the intake rate of qualified iodized salt were 98.9% （447/452）,95.1% （425/447） and 94.0% （425/452）,respectively.After consumptionn of non-iodized salt （〈 5 mg/kg）,unqualified iodized salt（5 ～ 〈 20 mg/kg or 〉 50 mg/kg） or qualified iodized salt [（35 ± 15）mg/kg],the median of urinary iodine of children was 177.30,211.95 and 232.90 μg/L,respectively.Correlation analysis showed that there was no relationship between iodine content of salt and urinary iodine level of schoolchildren （r =0.085,P 〉 0.05）.Conclusions Current nutritional level of schoolchildren in Haimen City is higher than the appropriate amount.Household salt iodine content of edible salt does not affect urinary iodine level of the children significantly. Key words: Cross-sectional study; Children; Urinary iodine; Salt iodine

Objective To explore the iodine status of pregnant women after 17 years of salt iodization in rural areas of Shijiazhuang City. Methods Probability proportionate to size sampling was employed in which 30 towns were selected from the 211 towns in the rural areas of Shijiazhuang City. In each town selected, 40 pregnant women were randomly selected to collect their spot urine samples, edible salt samples and drinking water samples from their households to measure iodine content. The iodine content of salt was determined quantitatively using a titration method (GB/T 13025.7-2012). The urinary iodine content was determined using the method of ammonium persulfate digestion arsenic cerium catalytic spectrophotometry (WS/T 107-2006). The iodine content in drinking water was determined by the method of standard test for drinking water. Results A total of 1 200 salt samples was collected from the pregnant women's households in 30 towns, with the overall median iodine content being 27.2 mg/kg. The median salt iodine content in 30 towns varied from 23.4 to 32.6 mg/kg. A total of 478 water samples were collected, with a median of 5.3 μg/L. The median urinary iodine content (UIC) of 1 200 pregnant women in 30 towns was 146.4 μg/L. The median UIC in the first (≤13 weeks), second (14 ~ 26 weeks) and third (≥27 weeks) trimesters was 166.3, 145.1 and 133.5 μg/L, respectively. The median UIC in the first trimester was significantly higher than that in the third trimester (Mann-Whitney Test, U = 18 265, P 0.05). Conclusion Under the current universal salt iodization, the pregnant women's iodine intake could almost meet their requirement in the rural areas of Shijiazhuang City, however, mild iodine deficiency has existed in the third trimester. Alternative measures of iodine supplement could be implemented. Key words: Iodine deficiency; Salts; Iodine nutrition; Pregnant women; Survey

Objective To understand the condition of iodine deficiency disorders,and the iodine nutritional status of population before adjustment of iodine level in edible salt in Liaoning Province.Methods Thirty countries （cites,districts） which were divided into coastal,inland,city,rural areas according to location and population characteristics were sampled by population probability sampling method in the whole province; one township （town,street office） was sampled from each country （city,district）; one village （neighborhood） and one school were chosen from each township（town,street office）.Forty children aged 8-10 were selected from each school to measure their thyroid volumes and household salt samples were collected to detect their iodine content; fourteen of those 40 children were selected to detect their urinary iodine content.In each village （neighborhood）,five drinking water samples were collected in the east,the west,the south,the north and the center positions.Two tap water samples were collected to detect their iodine content if the water supply was centralized.Around each school; three townships were selected,in each township,random urine samples were collected from 5 pregnant women and 5 lactating women to detect their iodine content.Thyroid volume was examined by ultrasound method; the salt iodine was tested by the method of direct titration; iodine content of urine and drinking water was tested by arsenic cerium catalytic spectrophotometry.Results Totally one thousand two hundred and nineteen children aged 8-10 were examined; twenty-nine children were diagnosed goiter,and the goiter rate was 2.4%（national standards：〈 5%）.One thousand two hundred and nineteen edible salt samples were tested,and the median salt iodine level was 30.1 mg/kg.The iodized salt coverage rate was 99.3%（1 211/1 219）,and the consumption rate of qualified iodized salt was 97.9%（1 194/1 219）.Four hundred and eighty urine samples were tested,and the median urinary iodine level was 189.0 μg/L（suitable content of salt iodine was 100-199 μg/L） ; urinary iodine 〈 20 μg/L accounted for 0.6%（3/480）.Ninety-nine drinking water samples were selected,and the average iodine content of the drinking water was （5.9 ± 5.7）μg/L.Four hundred and fifty-one urine samples of pregnant women and four hundred and fifty urine samples of lactating women were selected,and the median urinary iodine level of pregnant women and lactating women was 163.2,151.0 μg/L（suitable contents of urinary iodine in pregnant women and lactating women were 150-249 μg/L,〉 100 μg/L）.The median urinary iodine of pregnant women was 135.4 μg/L in coastal city,138.0 μg/L in coastal rural,168.0 μg/L in inland city,171.1 μg/L in inland rural.The difference of urinary iodine between coastal region and inland region was significant（H =14.287 6,P 〈 0.05）.Conclusions The iodine nutrition conditions of pregnant women,lactating women and children are adequate in Liaoning Province,but the iodine nutritional status is insufficient in pregnant women from the coastal areas. Key words: Thyroid; Urine; Salts; Iodine; Monitoring

Objective To study the intake of iodine and iodine nutritional status of adults and provide a scientific basis for choosing appropriate salt iodine content in the region. Methods By using multi stage random sampling method, according to the four corners of 4 directions, 4 non water iodine counties or districts were selected from Nankai District, Jixian County, Dagang District and Hangu District. Totally 1 to 4 administrative villages were selected (neighborhood committees) from each district or county as the survey points. Ten to 15 households were selected from each survey points. All the members more than 18 years old of each household were investigated(excluding pregnant and lactating women). Of the 225 households, 404 people, salt iodine of the family, urinary iodine and water iodine were detected. The questionnaire survey was used to investigate the daily salt intake of residents per capita. The daily intake of iodine was calculated by the method of dietary frequency. Salt iodine content was detected by direct titration method; iodine in water was detected by cerium sulfate catalytic spectrophotometry; urinary iodine was detected by arsenic cerium catalytic spectrophotometry. Results A total of 24 drinking water samples were tested, the median water iodine was 8.0 μg/L. A total of 225 salt samples and 404 urine samples were tested, the medians of family salt and urinary iodine were 23.30 mg/kg and 149.0 μg/L, respectively. Investigation was done on salt intake and dietary intake of 393 people, the per capita consumption of salt intake was (11.45 ± 5.70) g/d. Salt supplied 148.75 μg/d iodine and food supplied 82.47 μg/d iodine. The total contribution rate of iodized salt to the total iodine intake was 68.99% (193.18/280.00) in the population of iodized salt consumer. The value of urinary iodine and iodine intake were correlated (r = 0.170,P < 0.05). Conclusions The adult iodine nutrition in Tianjin city is in the appropriate level. Iodized salt is the main source of iodine intake for adults, so salt iodine is a indispensable iodine nutrition source for adults. Key words: Adult; Iodine; Salts; Food

Objective To understand the dynamic conditions after reaching the stage goal of elimination of iodine deficiency disorders (IDD) in Wenzhou, and to provide a scientific basis for prevention and treatment of IDD. Methods Three counties that the annual consumption rate of qualified iodized salt < 80% in 2014 and had the prevalence of endemic cretinism in history, Cangnan, Taishun and Yongjia, were selected as high risk monitoring areas. Three townships were selected in each area, and two primary schools were selected from each township, and 40 children urine samples were collected in each school (half male and half female) and the age of children were 8 -10 years old. And near the location of these primary schools, we randomly selected 10 pregnant women in each village, and estimated the urinary iodine level and salt iodine concentration, respectively. The examination of thyroid by B ultrasound was performed in children by provincial professionals. Urinary iodine was determined using the arsenic cerium catalytic spectrophotometric method (GB/T 13025.7-2012). Salt iodine was determined by direct titration. Results Endemic cretinism case was not found in this survey, total goiter rate of 8 -10 years old children was 2.04% (16/783). The median of urinary iodine was 116.1 and 108.2 μg/L, respectively, in 8 -10 years old children and pregnant women. Iodized salt coverage rate was 90.48% (171/189), the intaking rate of qualified iodized salt was 84.66%(160/189). The concentration of pregnant women urinary iodine and salt iodine was positively correlated(r = 0.54,P < 0.05). Conclusions Children's iodine nutrition is in the appropriate level, but pregnant women are in iodine definciency in Wenzhou City. Key words: Iodine deficiency disorders; Goiter rate; Iodine; Salts; Urine iodine

Objective To study the effect of different iodine nutrition on thyroid function in adult and pregnant women. Methods A random sampling method was used to select healthy adult and pregnant woman from the communities of coastal city, coastal rural and inland rural areas in Liaoning Province. Drinking water, urine and salt samples were collected to measured urinary iodine（UI）, salt iodine（SI） and water iodine content. Fasting venous blood was collected to measured thyroid stimulate hormone （TSH）, freethyroxine （FT4）, free triiodothyronine （FT3）, thyroglobulin antibody （TgAb） and thyroid peroxidase antibody （TPOAb） with the method of immunoassay chemical luminescence. Results A total of 150 salt samples were collected, means of SI was （30.1 ± 6.0）mg/kg. A total of 72 pregnant woman and 271 adults were investigated in iodized salt supplied regions, median UI of pregnant woman and adults were 176.3, 203.2 μg/L. Iodine nutrition of pregnant women and coastal region aduhs was in an adequate level. Means of SI of inland adults （244.4 μg/L） was higher than appropriate level but not reached the excessive level. FT4 of the adults （11.7 pmol/L） and pregnant women（ 10.7 pmol/L） in inland regions were slightly higher than that of coastal city, rural adults （11.2, 8.6 pmol/L） and pregnant women （10.9, 9.6 pmol/L）. TSH, FT3 and FT4 were not statistically different between regions （all P 〈 0.05）. But UI, FT4 and FT3 levels of pregnant women（176.3μg/L, 9.5 pmol/L, 4.3 pmol/L） were significantly lower than that of the adults （203.2 μg/L, 11.3 pmol/L, 4.7 pmol/L, all P 〈 0.05）, Hypothyroxinemia（4.4%, 10/173） was higher than that of the inland adults （2.0%, 2/98, P 〈 0.05）. And all hypothyroxinemia were found in women of childbearing age. Hypothyroxinemiaprevalence of pregnant women （ 16.7 %, 12/72 ） was higher than that of adults （4.4%, 12/271, P 〈 0.05）, The prevalence of hypothyroidism, hyperthyroidism and subclinical hyperthyroidism between the 3 regions adults and pregnant women were not statistically different （all P 〉 0.05）. Conclusions Under appropriate supply conditions of iodized salt, iodine nutrition and thyroid function are closely related. Pregnant women and women of childbearing age are at risk of iodine deficiency. The thyroid function of these people should be strengthen detect. Key words: Iodine; Thyroid function; Pregnant women; Adult

Objective To master the status of iodine content in drinking water and iodine nutritional status of population before and after the salt iodine concentration reduction in 2012 in Meizhou City, and to provide a scientific basis for safety assessment of salt iodine content after adjustment of the policy. Methods Using stratified random sampling method, drinking water samples were collected, and iodide content was measured by cerous sulfate catalytic spectrophotometry. Urine samples of children aged 8 - 10 were collected, in which the iodide content was quantitatively tested by arsenic cerium catalytic spectrophotometry. Samples of household edible salt were collected to determine iodine content by direct titration in 2012 before (September 2011), and after the salt iodine concentration reduction (September 2012 and September 2013). Results A total of 422 water samples were measured, the median iodine content of water was 2.4 μg/L. The water iodine median was 2.1 μg/L in centralized water supply (n = 163), and 2.9 μg/L in decentralized water supply (n = 259), the difference was statistically significant (U = - 2.526,P < 0.05). Totally 800 and 803 urine samples of children aged 8 - 10 were collected in 2011 and 2012, median urinary iodine was 216.5 and 207.5 μg/L, respectively, which were higher than that in 2013 (n = 807, 190.0 μg/L, χ2 = 17.040, 24.868, all P < 0.05). Urinary iodine ≥300 μg/L ratio was significantly decreased (2013 than 2011 and 2012, 19.3% (156/807) vs. 26.5% (212/800) and 24.5% (197/803), χ2 = 6.363, 11.695, all P < 0.05), and urinary iodine < 100 μg/L rose in the proportion (2013 than 2011, 18.0% vs. 13.5%, χ2 = 6.045,P < 0.05). A total of 2 410 household salt samples were tested, and the coverage rate of iodized salt, iodized salt qualified rate, the consumption rate of qualified iodized salt were all higher than 98.8%. Totally 800, 803 and 807 salt samples were collected in 2011, 2012 and 2013, the salt iodine medians were 31.0, 27.7 and 25.4 mg/kg, respectively, the difference between the salt iodine medians was statistically significant (H = 91.422,P < 0.05). Conclusions Iodine excess risk is significantly decreased, and the level of iodine nutritional status of the city's population is appropriate after the salt iodine concentration reduction in 2012. The salt iodine concentration adjusted is suitable and safe. Key words: Drinking; Urine; Salts; Iodine

Objective s To understand current situation in national prevention and control of iodine deficiency disorders (IDD), and to evaluate the progress in eliminating IDD in 31 provinces and Xinjiang Production and Construction Corps (Corps) in China. Methods In 2011, 30 units were sampled in each of 31 provinces and Corps in China based on the sampling method of Probability Proportional to Size. After excluding townships of water iodine level higher than 150 μg/L, 1 primary school was chosen in each unit, by the randomized sampling method, 40 students in each school were sampled for examining their thyroid volume, among them, 12 students were tested for their urinary iodine level and for their household salt iodine level and per capital daily salt intake. Near the location of these primary schools, 3 townships were chosen, 5 pregnant women and 5 lactating women in each township were sampled to test their urinary iodine level. Besides, 1 water sample was sampled according to the location in each village (east, west, south, north, and middle) in non-central water supplying villages, and 2 tap water samples in central water supplying villages. The ultrasound was used to detect goiter size according to the diagnostic criteria for endemic goiter; As3+-Ce4+ catalytic spectrophotometry using ammonium per sulfate digestion (WS/T 107-2006) was used to test the urinary iodine level; the testing method recommended by the National Iodine Deficiency Disorders Reference Lab was applied to test the water iodine level, the direct titration method among the generic methods of iodide testing for salt production industry (GB/T 13025.7-1999) was used to determine the salt iodine level; and the arbitration method was adopted for quantitative determination in case of well salt or special salts and the salt intake was estimated based on three-day weighed food record. Evaluation standards are as follows: urinary iodine level of children: deficient is the median of urinary iodine (MUI) less than 100 μg/L, adequate is MUI at 100-199 μg/L, more than adequate is MUI at 200-299 μg/L, and excessive is MUI equal to or greater than 300 μg/L; salt iodine: definition of qualified iodized salt is (35 ± 15) mg/kg; non-iodized salt (GB 5461-2000) is iodine less than 5 mg/kg; definition of unqualified iodized salt is iodine between 5-< 20 mg/kg or higher than 50 mg/kg. The total population of the sixth national census was used for statistical data correction. Results Among 31 provinces and Corps, children's goiter rate was 2.4%, which was obviously lower than the IDD elimination standard at the national level (< 5%); the national iodized salt coverage rate was 98.0% and the consumption rate of qualified iodized salt was 95.3%, both figures had achieved the national standard (the iodized salt coverage should be greater than 95% and the consumption rate of qualified iodized salt greater than 90%). The median of salt iodine was at 30.2 mg/kg; the MUI of children, pregnant women and lactating women was 238.6, 184.4 and 174.4 μg/L, respectively. Urinary iodine of children was higher than adequate level, of both pregnant women and lactating women were at adequate level. The surveillance results of water iodine in 25 provinces revealed that the median was at 5.6 μg/L; the salt intake surveillance results among students' households in 24 provinces and the Corps revealed that the daily intake was 10.1 g per person a day. Conclusions National IDD prevention and control strategy integrated with universal salt iodization as a key measure has achieved remarkable impacts. IDD has been eliminated at the national level. Key words: Iodine; Deficiency disorders; Children; Women; Urinary; Salts; Epidemic studies

Objective To analyze the survey results of iodine nutritional level among women of childbearing age, pregnant, lactating women and infants before and after the adjustment of iodine concentration in salt of Zibo City, in order to provide a scientific basis for reasonable iodine supplement. Methods The iodine content in the residents' edible salt samples was determined in 2011 and 2015. Four groups of target populations including women of childbearing age, pregnant, lactating women and infants from 7 districts and towns of Zibo were investigated to test their urinary iodine level in 2011 and 2015. The monitoring results of the two years were compared and analyzed. Results A total of 2 100 and 2 160 residents edible salt were monitored in 2011 and 2015, and the median of salt iodine were 30.2 and 22.7 mg/kg, there was statistically significant difference in the constitute of salt iodine level between the two years (χ2= 141.90, P < 0.01). A total of 354, 402, 403, 362 urine samples of women of childbearing age, pregnant, lactating women and infants' were detected and the median urinary iodine were 161.80, 127.20, 138.80, 147.10 μg/L in 2011, and 350, 706, 350 and 352 of the corresponding target population's urine samples were detected and the median urinary iodine were 127.80, 129.95, 70.20 and 152.35 μg/L in 2015. Conclusions The salt iodine median has reduced and the urinary iodine in childbearing age women and infant is in the appropriate level, while it is insufficient in the pregnant women and lactating women after the adjustment of iodized salt concentration in Zibo. It is necessary to promote health education and instruct pregnant women and lactating women to supplement iodine, additionally, surveillance of the iodine nutrition status of the targeted populations should be strengthened. Key words: Iodine; Nutrition; Surveillance; Salts