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 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 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 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 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 investigate the epidemic situation of coal-burning-fluorosis,and to explore key areas for implementing prevention and control measures in Guizhou Province.Methods Survey data of dental fluorosis of children aged 8-10,anti-fluoride knowledge and health-related behaviors of target students and their families before implementing the comprehensive disease control measures in 2010,were analyzed and evaluated using the method of factor analysis in 23 diseased districts.Results ①The three main factors (F) related to the endemic of coal-burning-fluorosis were economic factor (F 1),knowledge factor (F2) and behavior factor (F3):F1 included the detection rate of 8 to 12 years old children's dental fluorosis,iron stove ownership,corn correct drying rate and chili correct drying rate; F2 included stove correct utilization rate,students awareness and head of the household awareness; F3 included corn food washing rate before cooking and chili food washing rate.②In the economic factor score arrangement,the first three were Zunyi,Xiuwen and Qingzhen.In the F2 score arrangement,the first three were Zunyi,Xishui and Xixiu.In the F3 score arrangement,the first three was Liuzhi,Bijie and Xixiu.③After comprehensive score,Zunyi,Qingzhen,Xishui,Xixiu,Puding and Liuzhi Counties were found to be relatively stronger in control of the epidemic of coal-burning-fluorosis; Xiuwen,Renhuai,Guanling and so on 13 counties were found to be relatively moderate,and Tongzi,Hezhang,Shuicheng and Nayong Counties were found to be relatively weak.Conclusions ①The endemic of coal-burning-fluorosis is related with many factors,and the indexes we selected in this study have a strong correlation and sensitivity,which may be used in evaluating the prevention effect of control measures to coal-buming-fluorosis.②The endemic of coal-burning-fluorosis in Guizhou Province is quite different,and key prevention and control measures can be applied according to a comprehensive factor analysis.

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.