Objective:To analyze the epidemiological characteristics, spatial clustering, and correlation between dental fluorosis detection rates and meteorological factors in children aged 8 - 12 years old in 37 counties (cities, districts, hereinafter referred to as counties) affected by coal-burning-borne endemic fluorosis in Guizhou Province, and to provide a scientific basis for prevention and control of the disease.Methods:Monitoring data on dental fluorosis in children aged 8 - 12 years old from 2019 to 2022 were collected from the National Health Security Information System for Endemic Diseases. Meteorological data, including annual average temperature, annual average precipitation, annual sunshine hours, and annual average relative humidity, were obtained from the Guizhou Provincial Bureau of Statistics. Descriptive epidemiology, analytical epidemiology, and spatial correlation analysis methods were used to analyze the data. Visual maps were created based on the clustering levels of annual dental fluorosis detection rates (high-high, low-low, high-low, low-high). Spatial autocorrelation and meteorological factors were used to analyze the epidemiological characteristics, spatial clustering, and the impact of meteorological factors on dental fluorosis.Results:From 2019 to 2022, a total of 3 649 161 children aged 8 - 12 in the counties affected by coal-burning-borne endemic fluorosis were monitored, and 115 793 children were diagnosed with dental fluorosis, with a detection rate of 3.17%. The detection rates were 4.73% (45 093/954 338) in 2019, 3.35% (31 424/938 445) in 2020, 2.86% (21 727/760 195) in 2021, and 1.76% (17 549/996 183) in 2022, respectively. The dental fluorosis indices were 0.09, 0.07, 0.06, and 0.03, respectively. The number of counties with detection rates > 6% was 7, 5, 5, and 0 in 2019 - 2022, respectively. Dafang County consistently had the highest detection rates, with rates of 10.06% (6 783/67 408), 10.07% (1 955/19 421), 13.54% (4 017/29 667), and 4.83% (3 284/76 206) in 2019 - 2022, respectively. The Moran's I indices for dental fluorosis detection rates were 0.45, 0.53, 0.53, and 0.53 in 2019 - 2022, with Z = 4.29, 5.07, 5.31, and 5.10, respectively ( P < 0.05), indicating global spatial autocorrelation (positive) and spatial clustering of dental fluorosis detection rates. The number of counties with "high-high" clustering of detection rates was 7, 7, 6, and 7 in 2019 - 2022, mainly concentrated in the northwestern region, including Qixingguan District, Nayong County, Dafang County, Zhijin County, and Jinsha County of Bijie City. "Low-high" clustering areas were distributed in Zhongshan District of Liupanshui City in 2019, 2020, and 2022. The detection rate of dental fluorosis was associated with local annual average temperature (°C) and annual precipitation (mm) ( r = - 0.393, - 0.337, P = 0.016, 0.041). Conclusions:From 2019 to 2022, the detection rate of dental fluorosis in children aged 8 - 12 in coal-burning-borne endemic fluorosis areas in Guizhou Province has been decreasing year by year, and it shows spatial clustering. The high clustering area is in the northwest of Guizhou Province, which should be regarded as a key prevention and control area for coal-burning-borne fluorosis in the future. At the same time, areas with lower temperatures and precipitation should also strengthen prevention and control efforts.

Objective:To analyze the epidemiological characteristics, spatial clustering, and correlation between dental fluorosis detection rates and meteorological factors in children aged 8 - 12 years old in 37 counties (cities, districts, hereinafter referred to as counties) affected by coal-burning-borne endemic fluorosis in Guizhou Province, and to provide a scientific basis for prevention and control of the disease.Methods:Monitoring data on dental fluorosis in children aged 8 - 12 years old from 2019 to 2022 were collected from the National Health Security Information System for Endemic Diseases. Meteorological data, including annual average temperature, annual average precipitation, annual sunshine hours, and annual average relative humidity, were obtained from the Guizhou Provincial Bureau of Statistics. Descriptive epidemiology, analytical epidemiology, and spatial correlation analysis methods were used to analyze the data. Visual maps were created based on the clustering levels of annual dental fluorosis detection rates (high-high, low-low, high-low, low-high). Spatial autocorrelation and meteorological factors were used to analyze the epidemiological characteristics, spatial clustering, and the impact of meteorological factors on dental fluorosis.Results:From 2019 to 2022, a total of 3 649 161 children aged 8 - 12 in the counties affected by coal-burning-borne endemic fluorosis were monitored, and 115 793 children were diagnosed with dental fluorosis, with a detection rate of 3.17%. The detection rates were 4.73% (45 093/954 338) in 2019, 3.35% (31 424/938 445) in 2020, 2.86% (21 727/760 195) in 2021, and 1.76% (17 549/996 183) in 2022, respectively. The dental fluorosis indices were 0.09, 0.07, 0.06, and 0.03, respectively. The number of counties with detection rates > 6% was 7, 5, 5, and 0 in 2019 - 2022, respectively. Dafang County consistently had the highest detection rates, with rates of 10.06% (6 783/67 408), 10.07% (1 955/19 421), 13.54% (4 017/29 667), and 4.83% (3 284/76 206) in 2019 - 2022, respectively. The Moran's I indices for dental fluorosis detection rates were 0.45, 0.53, 0.53, and 0.53 in 2019 - 2022, with Z = 4.29, 5.07, 5.31, and 5.10, respectively ( P < 0.05), indicating global spatial autocorrelation (positive) and spatial clustering of dental fluorosis detection rates. The number of counties with "high-high" clustering of detection rates was 7, 7, 6, and 7 in 2019 - 2022, mainly concentrated in the northwestern region, including Qixingguan District, Nayong County, Dafang County, Zhijin County, and Jinsha County of Bijie City. "Low-high" clustering areas were distributed in Zhongshan District of Liupanshui City in 2019, 2020, and 2022. The detection rate of dental fluorosis was associated with local annual average temperature (°C) and annual precipitation (mm) ( r = - 0.393, - 0.337, P = 0.016, 0.041). Conclusions:From 2019 to 2022, the detection rate of dental fluorosis in children aged 8 - 12 in coal-burning-borne endemic fluorosis areas in Guizhou Province has been decreasing year by year, and it shows spatial clustering. The high clustering area is in the northwest of Guizhou Province, which should be regarded as a key prevention and control area for coal-burning-borne fluorosis in the future. At the same time, areas with lower temperatures and precipitation should also strengthen prevention and control efforts.

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.

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 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 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 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 evaluate the effects of health education and improved stoves on control of coalburning-borne endemic fluorosis in Guizhou Province.Methods In 2014,according to the detectable rate of dental fluorosis of children aged 8-12 before implementing control measures,11 counties were divided into three layers:low detection rate (detection rate was less than 60％),medium detection rate (detection rate from 60％ to 90％) and high detection rate (detection rate was greater than 90％).One county was selected from each layer and two towns were selected in each county.According to the Diagnosis of Dental Fluorosis (WS/T 208-2011),dental fluorosis of all children aged 8-12 was examined in all towns;At the same time,in the 2 villages in each town,20households and students of one class in grade 4 to 6 were selected to survey knowledge about prevention and control of coal-burning-borne endemic fluorosis;and to survey the situation of improved stoves,drying and elutriation of corn and chillies,and related life behavior.Results The detectable rate of dental fluorosis of children aged 8-12was 5.49％ (198/3 607),8.33％ (72/864),12.46％ (179/1 437),and it was significantly lower than before implementing control measures [41.88％ (931/2 223),61.91％ (4 863/7 855),91.25％(2 439/2 673),x2 =1 166.43,909.56,2 508.96,all P ＜ 0.01].Correct answer rates of students about knowledge on endemic fluorosis were 78.03％ (792/1 015),84.93％ (1 465/1 725) and 80.18％ (910/1 135),the correct answer rates of knowledge were significantly higher than those before implementing control measures [23.19％ (640/2 760),47.41％ (2 368/4 995) and 40.25％ (3 405/8 460),x2 =947.96,736.61,644.69,all P ＜ 0.01].Correct answer rates of family householders about knowledge on endemic fluorosis were 86.75％ 047/400),95.25％ (381/400) and 86.25％ (345/400),the correct answer rates of knowledge were higher than those before implementing control measures [17.78％ (80/450),37.20％ (279/750) and 25.27％ (139/550);x2 =402.97,359.49,344.55,all P ＜ 0.01].The percentages of households whose stoves were qualified and can be used correctly to the total households were 96.25％ (77/80),96.25％ (77/80) and 93.75％ (75/80),and before implementing control measures [4.92％ (348/7 078),21.51％ (7 461/34 693) and 6.73％ (475/7 062)],and the differences were statistically significant (x2 =1 181.55,262.63,842.82,all P ＜ 0.01).The percentages of households using clean energy in heating season to the total households increased from 0 (0/7 078),0 (0/34 693),0(0/7 062) to 98.75％ (79/80),98.75％ (79/80),96.25％ (77/80).The rates of the three counties whose inhabitants could bake the chillies correctly were 96.25％ (77/80),95.00％ (76/80) and 97.50％ (78/80),which were significantly higher than before implementing control measures [5.55％(5/90),26.00％ (39/150),52.73％ (58/110),x2=139.52,99.36,45.64,all P ＜ 0.01].Who cooked chillies after washing were 93.75％ (75/80),95.00％ (76/80),93.75％ (75/80),which were significantly higher than before implementing control measures [74.44％ (67/90),87.33％ (131/150),34.55％ (38/110),x2 =11.47,3.91,67.36,all P ＜ 0.05].Conclusion The effects of health education and improving stoves on coal-burning-borne endemic fluorosis in the three counties of Guizhou Province are remarkable.

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 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.