Objective:This paper analyzed the operation of network laboratory and external quality control assessment of endemic arsenic disease laboratories at all levels in Guizhou Province, to provide reliable experimental quality assurance for evaluating the prevention and treatment effect and taking targeted intervention measure of endemic arsenic poisoning.Methods:The results of network operation and external quality control (arsenic in water, arsenic in urine) were statistically analyzed from 2008 to 2017. The assessment scope included the arsenic detection laboratory of provincial (1), municipal (1) and county level (2) which undertook endemic arsenic poisoning monitoring tasks.Results:From 2008 to 2017, 1 provincial laboratory for the determination of arsenic in water and urine was qualified. From 2011 to 2017, 1 municipal laboratory for the determination of arsenic in water and urine was qualified. From 2014 to 2017, 2 county level laboratories for the determination of arsenic in water and urine were qualified. From 2014 to 2017, the water and urinary arsenic in provincial, municipal and county laboratories had been continuously assessed as all qualified. The │Z│ values of water arsenic in provincial laboratories from 2008 to 2017 and urine arsenic from 2009 to 2017 were ≤2, and the results were satisfactory. The │Z│ values of arsenic in water after 2010 and in urine after 2011 in municipal and one county level laboratories were ≤2, which were all qualified and the results were satisfactory.Conclusions:The network laboratory of endemic arsenic disease in Guizhou Province operates well. The quality control of the laboratory and the results of external quality control of arsenic samples meet the quality requirements of the national laboratory, which can provide accurate and reliable test data guarantee for the continuous elimination of endemic arsenic disease.

Objective: To explore the application of new pretreatment technology of automatic electrothermal digestion instrument in the detection of arsenic in urine samples, in order to achieve rapid, convenient and accurate detection results. Methods: Using wet digestion, an advanced sample preparation and digestion method (referred to as new pretreatment technology) was established by hydride generation-atomic fluorescence spectrometry (HG-AFS). Wet digestion: took 1.0 ml urine samples and put them into 10.0 ml corked scale digestive tubes, and added 0.20 ml sulfuric acid, 0.30 ml nitric acid and 0.50 ml hydrogen peroxide into the tubes successively. Shook solution and put them at AED-IV automatic electrothermal digestion instrument with 160 ℃ for half an hour, then heated up to 200 ℃ for 1 hour. It needed to be continually heated up to 260 ℃ and dissolved the solution until colorless transparent or light yellow. When the liquid level calm, and uniform reflux appeared, which meant the digestion finished, and then measured by atomic fluorescence photometer. At the same time, the new pretreatment technology was compared with the current standard (WS/T 474-2015) method, and the standard curve and linear range were calculated, as well as the detection line, precision and accuracy of the sample measurement. Results: The new pretreatment technology could digest 60 samples per sample, which was superior to the current standard methods (20 samples) and reduced the amount of reagent used. There was no statistically significant difference between the two methods (P > 0.05). In the linear range of 0-100 μg/L, the correlation coefficient (r) > 0.999 3, the detection limit of the method was 0.066 μg/L, and the relative standard deviation (RSD) < 5%. Conclusions The new pretreatment technology is fast, efficient, environmentally friendly, economical, highly automated. The experimental result error is in a controllable range. It can be used for digestion of arsenic content in urine of different concentrations and has high applicability.

Objective To understand the status of total fluoride intake for persons over 16 years old after implementation of comprehensive prevention and control measures in historical severe diseased areas of coal-burning-borne endemic fluorosis in Guizhou Province.Methods In 2017,a total of 3 villages were selected as survey sites in Hehua,Jifeng and Jiping villages,which were heavier and did not meet the standards for elimination of the disease areas.Dental fluorosis of all children aged 8-12 were examined in these three villages.In each village,10 households were selected and average daily intake of staple foods,vegetables and drinking water per person over 16 years of age were surveyed.Samples of corn,rice,dried pepper,drinking water,and indoor air were collected and the content of fluoride was measured,and total fluoride intakes for adults were calculated.The survey results were compared with the survey data of 2006.Results The detection rates of dental fluorosis of children aged 8-12 in Hehua,Jifeng and Jiping were 16.86％ (29/172),17.90％ (29/162),7.94％ (10/126),respectively,and the differences were statistically significant compared to those of 2006 [94.32％ (216/229),100.00％ (72/72)、99.63％ (267/268),x2 =247.97,136.95,345.13,P ＜ 0.01].The fluorosis indices were 0.36,0.40,and 0.12,respectively.In the three villages,the medians of fluoride in drinking water were 0.040,0.029 and 0.033 mg/L.The staple food was rice,and their medians fluorine content were 0.019,0.016,and 0.015 mg/kg,respectively,which decreased 99.89％,99.96％,99.95％,compared with those of 2006 (the staple food was corn,with medians of 17.520,36.620 and 27.770 mg/kg).The medians of fluorine in dried pepper were 2.09,1.97 and 0.35 mg/kg,respectively,which decreased 99.59％,99.81％,99.96％,respectively,compared with those of 2006 (514.21,1 035.29,947.78 mg/kg),the differences were statistically significant (Z =2.079,2.542,2.449,P ＜ 0.01).No fluoride was detected in indoor air samples 24 hours a day.The average daily intake of fluorine per person over 16 years in the three villages were 0.304,0.279,0.273 mg,which decreased 98.45％,99.18％ and 99.00％,respectively compared to those of 2006 (19.564,33.837,27.224 mg).Conclusion Total fluoride levels are significantly lower in people over 16 years of age in the historical severe disease areas of coal-burning-borne endemic fluorosis in Guizhou Province.

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.

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 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 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 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 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 observe the effects of comprehensive prevention and control measures through the trend change analysis of the prevalence of dental fluorosis of children and urinary fluoride in Guizhou.Methods Three villages were selected in each county from Qianxi,Pu'an and Renhuai,in 2009,2011 and 2013.Dental fluorosis of all children aged 8-12 were examined using the reference Diagnosis of Dental Fluorosis (WS/T 208-2011);50 children were selected randomly from each village to detect urinary fluoride content according to the reference Determination of Fluoride in Urine-ion Selective Electrode Method (WS/T 89-1996).Results The detectable rates of dental fluorosis of children aged 8-12 from Qianxi,Pu'an and Renhuai were 53.20％ (490/921),89.97％ (547/608) and 51.73％ (629/1 216),respectively,in 2009,46.68％ (281/602),63.60％ (332/522) and 43.84％ (530/1 209),respectively,in 2011 and 34.04％ (256/752),14.29％ (80/560) and 26.97％ (243/901),respectively,in 2013,and the detection rate in each county was reduced year by year (x2 =60.46,674.96,125.95,all P ＜ 0.01).In 2009,3 counties' urinary fluoride levels of children aged 8-12 were (1.21 ± 1.29),(0.89 ± 0.80) and (1.00 ± 0.59) mg/L,respectively,which were significantly higher than those of 2013 [(0.94 ± 0.52),(0.68 ± 0.26) and (0.87 ± 0.33) mg/L,t =3.743,4.778,3.743,all P ＜ 0.01].Conclusions The dental fluorosis prevalence and urinary fluorine content of children aged 8-12 are falling obviously through comprehensive prevention and control measures.The target to control and eliminating the disease of endemic fluorosis is not reached.It should be continue to strengthen management after comprehensive prevention and control measures.