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.

Objective To evaluate the urinary fluorine detection quality of endemic fluorosis monitoring network laboratories in Guizhou Province and promote the improvement of quality control.Methods From 2010 to 2012,according to the method for determination of fluoride in urine by ion selective electrode,in 11 endemic fluorosis monitoring network laboratories in Guizhou,an quality control assessment was done.In the internal quality control assessment,standard substance detection inspection was used for personnel parallel samples and equipment comparison,t test was used to compare the inter-group differences.In the external quality control inspection,blind urine fluorine sample was tested,and a Z score value evaluation method was used to compare the relative error of the test results.Results In the assessment of internal quality control,the parallel comparison test results of sample,personnel and instrument showed that the differences were not statistically significant (t =-1.81-1.80,P ＞ 0.05).In 2010,in the external quality control inspection,there was 1 laboratory |Z|≥3,and 2 test results |Z| ＞2;in 2011,there was 4 test results |Z| ＞ 2;in 2012,there was 5 test results |Z| ＞ 2;in 2010,there was one laboratory in a blind test,relative error of the results ＞ 20％;in 2011 and 2012,there was a laboratory in a blind test,relative error of the results ＞ 10％.Conclusion The endemic fluorosis monitoring network laboratory testing ability in Guizhou is relatively good,but there is an obvious individual laboratory system error.

Objective To evaluate the effectiveness of comprehensive prevention and control measures on coal-burning-borne endemic tluorosis in Xishui,on residents healthy behavior and situation of the disease.Methods In 2013,five towns were selected according to their location of east,south,west,north and centre.Three villages and one elementary school in each town were chosen,and 20 families' related behavior and fluorine prevention knowledge questionnaire in each village were surveyed.All the students from one class aged 8-12 of grade 3-6 in each school were selected,according to the Diagnosis of Dental Fluorosis,dental fluorosis was examined and fluorine knowledge questionnaire was surveyed.At the same time,the detection rate of dental fluorosis of children aged 8-12,information of the knowledge about prevention and cure of fluorosis and related behavior of target groups in 2007,and the urinary fluoride contents of children aged 8-12 in 2000 were collected.Analysis and comparison of the data in 2000,2007 and 2013 were done.Results After the intervention,the witting rates of students and family householders 90.95％ (11 773/12 945),84.27％ (3 792/4 500),were significantly higher than those of before the intervention [19.29％ (1 039/5 385),26.27％ (394/1 500),x2 =9 279.14,1 794.22,all P ＜ 0.01].Proper utilization rate of cooking stove was 100.00％ (37/37),iron stove utilization rate was 99.64％ (279/280),dry chili correct rate was 100.00％ (299/299) and before the intervention,these values were 3.20％ (43/1 345),90.28％ (1 207/1 337)and 62.14％ (855/1 376),respectively,and the differences were statistically significant (x2 =601.12,27.28,27.28,all P ＜ 0.01).Children's dental fluorosis detection rate was 24.21％ (206/851),compared with that of before the intervention,61.62％ (2 150/3 489),the difference was statistically significant (x2 =385.93,P ＜ 0.01).Children's urine fluoride was (0.51 ± 0.29) mg/L,and before the intervention [(1.55± 1.59) mg/L],the difference was statistically significant (t'=10.25,P ＜ 0.01).Conclusions The effect of comprehensive prevention and control measures against coal-burning-borne endemic fluorosis in Xishui are remarkable.The residents health related behavior has been formed and the condition is reduced markedly.

Objective To explore the changes of children's dental fluorosis before and after implementation of comprehensive prevention and control intervention in coal-burning-borne endemic fluorosis areas of Guizhou Province,and to provide a scientific basis for making corresponding prevention and control measures.Methods In 2010,according to a simple random cluster sampling method,1/5 of the villages out of 1/5 of the towns of Zunyi,Kaiyang and Longli Counties,were selected as investigation sites for inspection of dental fluorosis in 8-12 years old children and a longitudinal comparison was done with historical related dental fluorosis (year 1986 and 2000).Dental fluorosis of children was diagnosed by Dean method.Results In Zunyi,Kaiyang and Longli Counties,the detection rates of 8-12 years old children's dental fluorosis were 23.76％(202/850),15.77％ (79/501) and 11.17％(42/376),respectively.The detection rates of dental fluorosis in the 8,9,10,11 and 12 years old age group of children were 11.52％(19/165),17.19％(44/256),20.20％ (81/401),18.61％ (75/403) and 20.72％ (104/502),respectively,and there was no significant difference between groups (x2 =2.90,P ＞ 0.05).The survey results of this investigation in the three counties in 2000 were 34.20％(7 805/22 821),39.77％(1 782/ 4 481),60.88％(2 806/4 609),and the differences were statistically significant between the results of 2010 and 2000(x2 =37.81,110.91,350.76,all P ＜ 0.01).And compared with the results of 1986[34.29％ (9 463/27 596),36.30％ (2 708/7 460),35.72％ (1 896/5 308)],the difference of Zunyi County was not statistically significant (x2 =0.045,P ＞ 0.05),but for Kaiyang and Longli the differences were statistically significant(x2 =14.35,626.39,all P ＜ 0.01).Conclusions The effect of comprehensive prevention and control intervention is very obvious.In the 3 counties,the incidence rates of 8-12 years old children's dental fluorosis are already dropped to below 30％ of the control standard.Subsequent management should be carried out and the state of disease should be evaluated for organization-assessment acceptance in accordance with relevant hygiene standards in a planned way.

Objective To analyze the quality control measures on urinary fluoride testing in the implementation,and to provide experience in quality control for testing activities.Method According to the Determination of Fluoride in Urine-Ion Selective Electrode Method (WS/T 89-1996),focusing on ways to complete testing all the samples in a short time,implementing internal quality control measures in the testing before,during and after the implementation by different ways as blank experiment,standard substance detection,personnel parallel experiment,paralleled detection,instrument comparison and sample test repeat,were carried out.Results The test results of blank experiment were lower than the lowest detection limit;the test results of standard material were within the scope of the standard reference,there was no significant difference between the mean value and the reference value (t =0.01,0.00,0.02,all P ＞ 0.05),|Z| values were all less than 1;the results of personnel parallel experiment,paralleled detection,instrument comparison test results and sample test repeat were not significantly different statistically (all P ＞ 0.05);the results of instrument comparison and sample test repeat were not significantly different statistically (t =0.129,0.034,all P ＞ 0.05).A total of 9 123 urine samples were tested,the geometric mean of urinery fluoride was 0.58 mg/L.Conclusion Different quality control measures should be implemented through all the testing,control personnel errors,instruments,and reagents,etc,to ensure the quality of the entire test results.

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 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 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.