Objective To investigate the iodine nutritional status in the populations of Guizhou Province after implementation of a new standard of salt iodine and to provide a basis in formulating strategy for control of iodine deficiency disorders.Methods In 2011 and 2014,30 units were sampled in Guizhou Province using the sampling method of Probability Proportional to Size.One primary school was chosen in each unit,by the randomized sampling method,40 or 50 students in each school were sampled for examining their urinary iodine level and for testing their household salt iodine level;12 and 50 children were chosen before and after the adjustment,respectively,for testing their urinary iodine level;near the location of the primary school,1 township was chosen,15-20 pregnant women in each township were sampled to test their urinary iodine level.Results Totally 1215 salt samples were collected before adjustment,the median of salt iodine was 32.2 mg/kg;consumption rate of qualified salt was 96.63％;totally 364 urine samples of 8-10 children were collected,the median of urinary iodine (MUI)of children was 308.9 μg/L;450 urine samples of pregnant women were sampled,and their MUI was 216.5 μg/L,among these,121 below 150 μg/L,the proportion was 26.9％.Totally 1 538 salt samples were collected after the adjustment,the median of salt iodine was 26.6 mg/kg;consumption rate of qualified salt was 96.40％;totally 1538urinary samples of 8-10 children were collected,the MUI of children was 218.3 μg/L;and 601 urinary samples of pregnant women were collected,the MUI was 175.1μg/L,among these,241 below 150 μg/L,the proportion was 40.1％.As can be seen from the results,the percentage of sample below 150 μg/L after the adjustment was increased to 13.2％ compared to that before the adjustment,the difference was statistically significant (x2 =19.89,P ＜0.01).Conclusion After implementation of a new standard of salt iodine in Guizhou Province,the iodine nutrition is suitable in residents,but the iodine nutrition of pregnant women is in a trend of declining,which should be noticed.

Objective To investigate the content and changes of fluoride in corn and pepper, to evaluate the effect of prevention and control measures, and to provide a basis for adjusting the prevention and control strategy. Methods In 2013, according to the different directions of east, west, south, north and center, 5 townships were selected from each coal-burning-borne endemic fluorosis areas in all 23 counties (cities, districts), and 3 villages was randomly selected from each township. Household samples of corn and dried pepper in 10 households were collected to detect fluorine content. The results of 14 counties were compared with the 2007 survey data. Results A total of 884 and 3379 samples of corn and pepper were collected, and the median fluorine content was 1.26 and 9.15 mg/kg, the range was 0.50~254.59 mg/kg and 0.50~3701.88 mg/kg, respectively. Compared with the survey data of 2007, the median fluoride content of corn of 14 counties decreased by nearly 50%, and the median amount of pepper was reduced by more than 80%. The differences were statistically significant (mg/kg:corn 1.36 vs 2.63, dried pepper 9.70 vs 55.31, Z = 3.28, 9.13, P<0.05). Conclusion The fluoride content of corn and pepper in Guizhou Province is significantly lower, but it is still relatively high in some coal-burning-borne fluorosis counties (cities, districts).

Objective To apply hydride generation atomic fluorescence spectrophotometry (HG-AFS method) in urinary arsenic detection,and to provide a better,newer and more convenient detection method for quantitative analysis of urinary arsenic.Methods According to the Guide to Develop Biological Sample Inspection Method(WS/T 68-1996) and Guide for Establishing Occupational Health Standards-part 5:Determination Methods in Biological Materials (GB/T 210.5-2008),HG-AFS method was established to detect arsenic content in urine after modification of the method for sample pretreatment,and to verify the linear range of standard curve and linearity,detection limit,precision,accuracy,stability of the sample,and to compare the experimental results of HG-AFS method with those of standard methods of WS/T 28-1996 and Determination of Arsenic in Urine by Cyanide Generation Atomic Fluorescence Method (WS/T 474-2015).Results The HG-AFS method linear range was from 0-100 μg/L,the correlation coefficient r =0.999 9,the detection limit was 0.07 μg/L,the precision was 1.96％-3.97％,and the recovery rate was 95.1％-105.0％.There was no statistical significance between HG-AFS method,the standard of WS/T 28-1996 or WS/T 474-2015 methods (t =1.539,0.353,all P ＞ 0.05).Conclusion The new method is superior to the current detection method owing to its low detection limit,high precision,good accuracy,and wide linear range.

Objective To investigate the prevalence of dental fluorosis in children aged 8-12 in coalburning-borne endemic fluorosis areas in 23 counties in Guizhou Province,and to evaluate the effects of prevention and control measures.Methods In 2014,five towns were selected according to their location of the east,the south,the west,the north and the center of the 23 counties,one primary school in each town was chosen.All the students aged 8-12 in each school were selected,according to the Diagnosis of Dental Fluorosis (WS/T 208-2011),dental fluorosis was examined.At the same time,the detection rate of dental fluorosis of children aged 8-12 was investigated in 23 counties in 2000 and 2007.Analysis and comparison of the data in 2000,2007 and 2014 were done.Results The total detectable rate of dental fluorosis of children aged 8-12 was 32.31％ (5 803/17 962).The detection rate of 3 counties was lower than 15％,12 counties ranged from 15％ to 30％ and 8 counties more than 30％.Very light,mild,moderate,and severe cases of dental fluorosis cases accounted for 48.39％ (2 808/5 803),30.43％ (1 766/5 803),15.16％ (880/5 803) and 6.01％ (349/5 803).Male and female children's overall detection rate was 33.05％ (3 083/9 329) and 31.51％ (2 720/8 633),the difference was statistically significant (x2=4.86,P ＜ 0.05).The detection rates of dental fluorosis of children aged 8,9,10,11 and 12 were 17.79％ (224/1 259),26.02％ (871/3 348),30.28％ (1 255/4 144),34.07％ (1 595/4 682) and 41.02％ (1 858/4 529),indicating that the detection rate increased with age (x2 =345.78,P ＜ 0.01).After longitudinal comparison of the detection rates of dental fluorosis of children aged 8-12 in 2000,2007 and 2014,we found that 17 counties were gradually decreased (all P ＜ 0.05) except Xiuwen,Weining,Qianxi,Qingzhen,Liuzhi and Xixiu (x2 =0.84,4.19,3.67,5.03,1.98,2.37,all P ＞ 0.05).The ratio of dental fluorosis detection rate ＜ 15％,15％-30％ and ＞ 30％ was accounted for 21.74％ (25/115),32.17％ (37/115) and 46.09％ (53/115),respectively,in the 115 villages.Conclusion The detection rate of dental fluorosis of children aged 8-12 in coal-burning-borne endemic fluorosis areas is significantly dropped,and the comprehensive prevention and control effect is gradually apparent.

Objective To survey on fluorosis awareness of children aged 8 - 12 in coal-burning type endemic fluorosis in key diseased districts of Guizhou Province, and to provide a basis for school health education. Methods In 2014, five towns were selected according to five locations as east, south, west, north and center of 23 key diseased districts of Guizhou Province, one complete primary school in each town was chosen to survey on fluorosis awareness of all the children aged 8 - 12. At the same time, datas of fluorosis knowledge awareness of 23 counties in 2010 were collected and compared with the results of this survey. Results In 2014, the students awareness knowledge on endemic fluorosis was 84.21% (247518/293940). The awareness of 9 counties was higher than 90%, 5 counties ranged from 80% to 90%, and 9 counties lower than 80%. Compared with 2010 (awareness:96.58%), 21.74%(5/23) of the counties with increased awareness, and 78.26%(18/23) of the counties with decreased awareness. In overall qustionnaines object, the awareness rates of fluorosis prevention, correct use of coal-fired stoves, correct maintenance method of coal-fired stoves, method of avoid soot pollution food were 81.91% (48154/58788), 83.72%(82026/97980), 85.11%(66709/78384), and 86.12%(50629/58788), respectively. The awareness rates of children aged 8, 9, 10, 11 and 12 were 80.47%(32359/40215), 83.36%(52581/63075), 85.04%(53882/63360), 84.79% (53328/ 62895), and 85.98% (55368/64395), respectively, the differences were statistically significant (χ2=658.93, P<0.01). The awareness rates of male and female students were 84.35%(128802/152700) and 84.05%(118716/141240), respectively , the difference was not statistically significant (χ2= 3.64, P>0.05).Conclusions The awareness rate of children aged 8 - 12 in key diseased districts of Guizhou Province is decreased. Work on school health education should be continued, to consolidate control outcomes.

Objective To investigate the usage of the stoves in the severe endemic areas of coal burning fluorosis, sum up experience timely, find problems and adjust strategy for making prevention and control measures. Methods In 23 counties of Guizhou Province in the severe endemic areas of coal burning fluorosis, a town was selected according to the east, west, south, north and center positions, three villages were selected from each town, and 20 families were selected from each village;household stoves and usage were investigated in 2013. And the data of 14 conties was compared with the survey results of 2007. Results A total of 6 916 families from 341 villages in 115 towns of the 23 counties were investigated. Average utilization rate of coal-fired furnace and electric cooker was relatively high, which was 91.34%(6 317/6 916) and 92.93%(6 427/6 916), respectively. Utilization rate of coal stove, firewood oven, gas stove and liquefied gas stove oven was 7.75% (536/6 916)-21.56%(1 491/6 916). The correct utilization rate of coal-fired furnace was 92.80%(5 862/6 317). The correct utilization rate of coal stove was 66.80%(839/1 256); 92.93%(6 427/6 916)of the families used electric cooker year around. Totally 89.82%(5 674/6 317) of the farmers used iron stove in winter. Compared with those of 2007, in 14 of the counties; the differences of coal-fired furnace, coal stove, firewood oven, electric cooker, gas stove, and liquefied gas stove utilization rate were statistically significant (χ2= 888.35, 6 210.71, 165.54, 9 194.29, 36.98, 729.76, all P<0.05). Conclusion After positive and effective comprehensive treatment for many years, great c hanges have taken place in energy structure, clean energy is widely used, the correct utilization rate of coal-fired stoves is increased, and indoor fluorine pollution caused by coal-burning is under control.

Objective To analyze the Sichuan salt detection ability and the network running situation in different centers for disease control (CDC) laboratories of Guizhou Province,and to provide reliable laboratory quality assurance for iodine deficiency disorders prevention.Methods The examination results of external quality assessment (EQA) were collected in 2012-2016,and the relative error between Sichuan salt and the given reference value was analyzed.The results of Sichuan salt from all laboratories were evaluated in Guizhou Province.Results In 2012-2016,the feedback rate and qualified rate were all 100.00％ of the provincial and 7 municipal laboratories.The range was 0-4.53％ of relative error at provincial level,and the average relative error was 1.46％-5.28％ at prefecture level.At the county level,the feedback rate was 100.00％,and the qualified rate went from 63.64％ in 2012 up to 100.00％ in 2016,the average relative error was 1.65％-12.12％.Conclusions The testing ability at provincial and prefecture level laboratories is relatively stable.The testing ability at the county level laboratories has been significantly improved through national laboratory network operation and sustained technical training,and they could provide reliable laboratory quality in prevention of iodine deficiency disorders.

Guizhou had the most serious coal-burning-borne fluorosis areas and was the first implemented province-wide comprehensive control measures in 2010.Through sustainable comprehensive prevention and control measures,the utilization rate of household coal resources in the disease affected areas had been effectively reduced.We improved the structure of domestic energy sources,made significant progress in energy conservation and emission reduction,and significantly improved air pollution.The concept of health and hygiene had been deeply rooted in the hearts of the people.The transformation of citizens' knowledge,trust and conduct gradually took shape,and the comprehensive prevention and control measures achieved remarkable results.

Objective To understand the thyroid stimulating hormone (TSH) level of neonates and iodine nutritional status of pregnant women and children in Guizhou Province.Metheds From 2016 to 2017,a city (district,county) in government location in Guizhou Province was selected as the urban survey site,and a county (city,district) whose economy was relatively backward and farther from the city (prefecture) in government location was selected as the rural survey site.In each survey site,300 salt samples were collected for determination of salt iodine;300 blood samples in the heel of neonates after birth 72 hours were taken for measurement of TSH.The Wodd Health Organization,United Nations International Children's Emergency Fund,and the International Committee for the Control of Iodine Deficiency (WHO/UNICEF/ICCIDD) recommend that when the proportion of neonates (TSH levels ＞ 5 mU/L) is ＜ 3％,the area is non-iodine-deficient.In other words,the 97th percentile (P97) value should be ≤5 mU/L.The normal reference value of the kit is ≤9 mU/L.And urinary iodine of 150 children aged 8-10 and 150 pregnant women was determined.Results A total of 5 400 edible salt samples were tested,the median of salt iodine was 27.9 mg/kg,and the consumption rate of qualified iodized salt was 94.89％ (5 124/5 400);5 400 neonatal heel blood samples were collected,the median of TSH was 2.62 mU/L,TSH P97 was 6.91 mU/L,and samples proportion with TSH ＞ 5 mU/L was 10.67％ (576/5 400),and ＞ 9 mU/L (the cut-off value of kit) was 1.00％ (54/5 400).Among 3 588 cases of children aged 8 to 10 years,the median of urinary iodine was 212.3 μg/L,those with urinary iodine ＜ 50 μg/L was 2.81％ (101/3 588),and ＜ 100 μg/L was 12.76％ (458/3 588).Among the 2 695 pregnant women,the median of urinary iodine was 163.1 μg/L,and 44.04％ (1 187/2 695) were ＜ 150 μg/L.Conclusions The quality of iodized salt is stable in Guizhou,the iodine nutrition status of children and pregnant women are good.The neonatal TSH and nutritional status of pregnant women should be monitored in the future.

Objective:To analyze the monitoring results of skeletal fluorosis in coal-burning type endemic fluorosis areas in Guizhou Province, and evaluate the effectiveness of comprehensive treatment of coal-burning type endemic fluorosis in the affected areas.Methods:In 2009, 2014, and 2019, monitoring of skeletal fluorosis was carried out in six counties (cities, districts) of Renhuai City, Qixingguan District, Dafang County, Qianxi City, Puding County, and Pu'an County in Guizhou Province. Age stratification was conducted in each county (city, district) for permanent residents aged 25 and above, and survey subjects were selected for X-ray examination of skeletal fluorosis.Results:The detection rates of skeletal fluorosis in 2009, 2014, and 2019 were 51.48% (798/1 550), 34.88% (308/883), and 6.51% (60/922), respectively, showing a decreasing trend year by year (χ 2trend = 505.83, P < 0.001), decreased by 44.97 percentage points from 2009 to 2019. The age distribution of patients with skeletal fluorosis was mainly in the age group of 55 years and older, with annual proportions of 53.88% (430/798), 56.49% (174/308), and 78.33% (47/60), all higher than 50%. In 2009, 2014, and 2019, 483, 222 and 21 cases of mild skeletal fluorosis were detected, and 315, 86, and 39 cases of moderate to severe skeletal fluorosis were detected. There was a statistically significant difference in disease grading among different years(χ 2 = 32.63, P < 0.001). Among them, there were statistically significant differences in the grading of skeletal fluorosis in Qixingguan District, Qianxi City, Puding County, and Pu'an County(χ 2 = 14.56, 12.24, 35.01, 23.35, P < 0.05). Conclusions:The detection rate of skeletal fluorosis in Guizhou Province decreases year by year, and the prevention and control effect is significant. Patients with skeletal fluorosis are mainly in the age group of 55 years and older, and the proportion of patients with moderate to severe skeletal fluorosis is increasing. We should continue to monitor and manage the treatment of current patients with skeletal fluorosis.