Objective:To investigate the prevalence of adult skeletal fluorosis caused by drinking tea-type endemic fluorosis in Yushu Tibetan Autonomous Prefecture (hereinafter referred to as Yushu Prefecture), Qinghai Province, and provide scientific basis for prevention and control of the disease.Methods:In August 2021, one village was selected as a survey site in six counties (cities) in Yushu Prefecture, including Nangqian, Chindu, Yushu, Zadoi, Qumarlêb, and Zhiduo. Drinking water samples and 10 brick tea samples were collected from each village to determine the fluoride content in water and brick tea; at least 100 permanent residents aged ≥ 25, who had a habit of drinking brick tea and had lived in the local area for more than 5 years, were selected for X-ray imaging to examine the prevalence of adult skeletal fluorosis.Results:A total of 75 samples of residential drinking water were collected, with a fluoride content of (0.21 ± 0.05) mg/L, ranging from 0.11 to 0.34 mg/L; 60 samples of brick tea, with a fluoride content of (626.70 ± 157.27) mg/kg, ranging from 324.00 to 2 102.00 mg/kg. A total of 1 136 adults were examined, and 318 cases of skeletal fluorosis were diagnosed, with a detection rate of 27.99%. Among them, the detection rates of mild, moderate, and severe skeletal fluorosis were 20.95% (238/1 136), 6.07% (69/1 136), and 0.97% (11/1 136), respectively, with mild symptoms being the main. The detection rates of skeletal fluorosis in males and females were 29.09% (121/416) and 27.36% (197/720), respectively, with no statistically significant difference between the gender (χ 2 = 0.39, P = 0.533). Comparison of the skeletal fluorosis in different gender, the differences were statistically significant (χ 2 = 22.31, P < 0.001). The detection rates of skeletal fluorosis in the age groups of 25 - 35, 36 - 45, 46 - 55, 56 - 65, 66 - 75, and ≥76 years old were 6.86% (7/102), 22.37% (51/228), 24.02% (92/383), 37.44% (73/195), 43.48% (70/161), and 37.31% (25/67), respectively. The differences between the groups were statistically significant (χ 2 = 59.84, P < 0.001). Moreover, there was a statistically significant difference in the composition of skeletal fluorosis among different age groups ( H = 37.66, P < 0.001). The Spearman correlation analysis results showed that the severity of adult skeletal fluorosis was positively correlated with age ( r = 0.34, P < 0.001). Conclusions:There is a certain degree of prevalence of adult skeletal fluorosis in Yushu Prefecture. And as age increases, the condition of skeletal fluorosis becomes more severe.

Objective:To learn about the detection quality and external quality control assessment of fluoride and arsenic in laboratories at all levels in Qinghai Province.Methods:The Z-score method was used to analyze and evaluate the evaluation results of 1 provincial, 8 municipal and 43 county level laboratories of disease prevention and control institutions participating in the external quality control assessment of water fluoride and brick tea fluoride in Qinghai Province in 2021, as well as 1 provincial, 1 municipal and 2 county level laboratories of disease prevention and control institutions participating in the external quality control assessment of water arsenic and urine arsenic. The feedback rate and qualification rate of external quality control of each assessment laboratory were calculated.Results:In 2021, the feedback rate of external quality control of water fluoride, brick tea fluoride, water arsenic and urine arsenic in provincial and municipal level laboratories of Qinghai Province were 100.00%; except that the qualified rate of water fluoride was 7/9, the qualified rate of external quality control of other projects was 100.00%. The feedback rate of external quality control of water fluoride, brick tea fluoride, water arsenic and urine arsenic in county level laboratories was 100.00%; except that the qualified rate of water fluoride was 86.05% (37/43), the qualified rate of external quality control of other projects was 100.00%. In the specific assessment results of the laboratory, the assessment results of water fluoride sample FS20210101 from 1 provincial, 1 municipal and 2 county level laboratories, and FS20210102 from 1 county level laboratory were suspicious; the assessment results of water fluoride sample FS20210101 from 3 county level laboratories were not satisfactory; the assessment results of fluoride and arsenic sample in other laboratories were satisfactory.Conclusions:The qualified rate of external quality control of fluoride and arsenic in laboratories at all levels in Qinghai Province is relatively high, but some county level laboratories are still dissatisfied with the assessment results of water fluoride. Therefore, it is necessary to strengthen the detection level of water fluoride in laboratories.

Objective:To follow up the iodine nutrition and intellectual development of school children aged 8-10 years old in Nangqian County of Qinghai Province after 9 years of the implementation of iodine deficiency disorders intervention measures with iodine supplement as the main measure.Methods:In order to improve the iodine nutritional status of the population in Nangqian County, free iodized salt distribution, health education and other intervention measures for iodine deficiency disorders were implemented for 9 consecutive years since 2013. In May 2012 (before iodine supplementation) and September 2021 (after iodine supplementation), the same 5 townships (towns) were selected, and children aged 8-10 years old (half male and half female, age balanced) born locally in the central primary school of each township (town) were selected as the survey subjects. Household edible salt samples and random urine samples were collected for salt iodine and urinary iodine detection; the second revised version of the Chinese Combined Raven's Test (rural version) was used to assess the intelligence quotient (IQ) of children. The Flynn effect (FE) gain was used to adjust IQ, the corrected IQ = (IQ starting point value - current year's IQ value) - FE gain (calculated by 0.74/year). The differences of salt iodine and urinary iodine related indexes, IQ value and corrected IQ were compared before and after iodine supplementation.Results:After iodine supplementation, the coverage rate of iodized salt reached 100.00% (300/300), and the consumption rate of qualified iodized salt reached95.00% (285/300), the median urinary iodine increased to 157.20 μg/L, and all indexes met the elimination standard of iodine deficiency disorders. The IQ value of children aged 8-10 years old after iodine supplementation was 99.00 ± 14.90, significantly higher than that before iodine supplementation (82.00 ± 13.20, F = 156.82, P < 0.001). The FE gain in 9 years was 6.66, and the actual IQ gain of children aged 8-10 years old after iodine supplementation was 10.34. There were statistically significant differences in IQ value before and after iodine supplementation in male and female children ( F = 78.84, 78.88, P < 0.001). After iodine supplementation, there was a statistically significant difference in IQ value between children in the 8-year-old group and the 10-year-old group ( P = 0.010). There were statistically significant differences in IQ value before and after iodine supplementation in 8, 9 and 10 years old groups ( F = 55.23, 65.79, 36.85, P < 0.001). Conclusion:Intervention measures for iodine deficiency disorders, mainly iodine supplement, can significantly improve the iodine nutrition status of children aged 8-10 years old, and significantly promote the intellectual development of children.

Objective:To evaluate the water fluoride detection ability of county (city, district) level (referred to as the county-level) laboratories in Qinghai Province.Methods:During the "13th Five-Year Plan" period (2016 - 2020), 4, 4, 4, 43, 43 county-level laboratories in Qinghai Province were organized to participate in the national water fluoride external quality control assessment, and the assessment results were evaluated by Z-ratio scoring method.Results:The response rate of county-level laboratories was 86.05% (37/43) in 2019, and 100.00% in other years. The qualified rate of county-level laboratories was 100.00% from 2016 to 2018; in 2019 and 2020, the assessment was fully covered, and the qualified rate was 81.40% (35/43) and 95.35% (41/43), respectively. Compared with 2019, the response rate and qualified rate in 2020 increased significantly, and the differences were statistically significant (χ 2 = 6.450, 4.074, P < 0.05). In the past 5 years, two assessment samples│Z│ < 1 in each laboratory were the most common, but with two assessment samples 2≤│Z│ < 3 in some qualified laboratories. Conclusion:The consistency of water fluoride determination in Qinghai Province is not very ideal, and the detection ability of county-level laboratories still needs to be strengthened.

Objective:To understand the detection quality and external quality control assessment of fluorine and arsenic laboratories at all levels in Qinghai Province.Methods:Z-ratio scoring method was used to analyze and evaluate the results of provincial, municipal and county-level laboratories participating in the national fluorine and arsenic external quality control assessment from 2014 to 2020 in Qinghai Province, │Z│≤ 2 was qualified, 2 <│Z│ < 3 was basically qualified and│Z│≥ 3 was unqualified. At the same time, the feedback rate and pass rate of the participating laboratories were calculated.Results:From 2014 to 2020, the external quality control assessment results of water arsenic, urinary arsenic and brick tea fluorine in Qinghai Provincial laboratory were all qualified; except for the external quality control assessment of water fluorine in 2018 that was basically qualified, the results of other years were all qualified. Municipal and county-level laboratories did not give feedback the external quality control assessment results of water arsenic and urinary arsenic in 2017, and the feedback rate and pass rate in other years were 100.0%; except for the external quality control feedback rate and pass rate of water fluorine and brick tea fluorine in 2014 that were all 100.0%, there were laboratories that did not give feedback or failed the assessment in other years.Conclusion:The testing ability of provincial laboratory in Qinghai Province meets the standard, and the testing ability of municipal and county-level laboratories still need to be improved continuously.

Objective:To analyze the results of serum erythropoietin (EPO) in adults patients with Kaschin-Beck disease (KBD) in Qinghai Province.Methods:According to the "Diagnosis of Kaschin-Beck Disease" (WS/T 207-2010), by using clinical examination and X-ray, adults over 20 years old in KBD areas of Xinghai County and Guide County, Hainan Tibetan Autonomous Prefecture, Qinghai Province, were divided into KBD case group ( n = 109) and internal control group ( n = 95) in July 2019. At the same time, healthy people were selected as external control group ( n = 90) in Xunhua County. Then 2 ml fasting cubital venous blood was collected from the target population to separate serum. The serum EPO level was determined by enzyme-linked immunosorbent assay (ELISA). Results:There was no significant difference in age and sex ratio among the 3 groups ( F = 0.73, P = 0.484; χ 2 = 1.03, P = 0.611). There was significant difference in serum EPO levels among the 3 groups [KBD case, internal and external control groups: (30.74 ± 26.23), (19.73 ± 11.53) and (10.83 ± 4.48) U/L, F = 26.51, P < 0.001]. Multiple comparisons showed that there were statistically significant differences in serum EPO levels between KBD case group and the internal and external control groups ( P < 0.05), but there was no significant difference between the internal and external control groups ( P > 0.05). Conclusions:The serum EPO level in adult KBD patients in Qinghai Province is increased significantly.

Objective:To analyze the external quality control assessment results of fluoride in brick tea in the provincial, city (prefecture) and county (city, district)-level endemic fluorosis laboratories in Qinghai Province, and to evaluate the testing capabilities of laboratories at all levels.Methods:The Z-score method was used to analyze and evaluate the results of provincial, city (prefecture) and county (city, district)-level laboratories that participated in the external quality control assessment of fluoride in brick tea in Qinghai Province from 2014 to 2020, and│Z│≤2 was qualified; 2 <│Z│ < 3 was basic qualified; │Z│≥3 was unqualified.Results:From the feedback, the feedback rate of external quality control of fluoride in brick tea in provincial and city (prefecture)-level laboratories in Qinghai Province from 2014 to 2020 was 100.00%; the feedback rate of county (city, district)-level laboratories from 2014 to 2018 was 100.00%, and there were no feedback units in 2019 and 2020. From the assessment of qualification, the qualification rate of provincial, city (prefecture)-level laboratories was 100.00% in all other years except one unit failed in 2017; the qualification rate of county (city, district)-level laboratories was 100.00% in 2014, 2015, 2016 and 2019, and there were 6 unqualified units in other years.Conclusions:From 2014 to 2020, some endemic fluorosis laboratories in Qinghai Province still fail to pass the external quality control assessment of fluoride in brick tea. In the future, it will be the focus of work to strengthen personnel training and improve the detection ability.

Objective:To understand the situation of drinking water-borne endemic fluorosis (short for drinking water fluorosis) in Huangzhong, Ping'an and Ledu districts of Qinghai Province and operation status of water improvement projects, and to evaluate the effect of control measures.Methods:In historical drinking water fluorosis villages of Huangzhong, Ping'an and Ledu districts of Qinghai Province in 2018, the status of water improvement, the operation of water improvement projects and the content of water fluoride were investigated; the dental fluorosis of 8-12 years old children in all investigated villages was checked; 3 villages from 3 districts were selected, X-ray examination for skeletal fluorosis and urinary fluoride detection of adults over 25 years old of age were performed.Results:Eight-two historical drinking water fluorosis villages in 3 districts were investigated and all the villages had water improvement projects, in addition, the water improvement projects were operating normally, and the water fluoride content ranged from 0.10 to 0.37 mg/L, which were in line with the drinking water fluoride content standard (< 1.2 mg/L). Totally 2 503 children aged 8-12 years old were examined, the detection rate of dental fluorosis was 6.03% (151/2 503), the index of dental fluorosis was 0.13, the epidemic intensity was negative; the detection rates of dental fluorosis in 3 districts were 6.24% (129/2 068), 4.05% (7/173), 5.73% (15/262), respectively, reaching the control standard (< 30%), and the detection rate of dental fluorosis in 81 villages was less than 30%; 198 adults over 25 years old were examined, the detection rate of skeletal fluorosis was 5.05% (10/198), the geometric mean of urinary fluoride was 0.81 mg/L, and skeletal fluorosis cases were mainly in the age group over 40 years old, all of them were mild cases.Conclusions:The fluoride content in drinking water and the detection rate of children's dental fluorosis are all up to the control standard, and the condition of skeletal fluorosis is significantly reduced after the implementation of water improvement measures in Huangzhong, Ping'an and Ledu districts. It can be seen that the prevention and control of drinking water fluorosis in Huangzhong, Ping'an and Ledu districts have achieved good results, but later management and condition monitoring of water improvement projects should be strengthened to prevent the disease from rebounding.

Objective:To verify the revised method of cerium sulfate catalytic spectrophotometry for iodide index of "Standard Examination Methods for Drinking Water-Nonmetal Parameters" (GB/T 5750.5-2006).Methods:From July to September 2019, the Laboratory of Department for Endemic Disease Prevention and Control of Qinghai Institute for Disease Prevention and Control verified the revised method (determination of iodide in drinking water by cerium sulfate catalytic spectrophotometry) of cerium sulfate catalytic spectrophotometry (hereinafter referred to as original method) in "Standard Examination Methods for Drinking Water-Nonmetal Parameters" (GB/T 5750.5-2006). The revised method was verified according to the requirements of "Standard Examination Methods for Drinking Water-Water Analysis Quality Control" (GB/T 5750.3-2006), including standard curve, detection limit, precision, accuracy and actual sample determination.Results:The linear range of the revised method was 0 - 20.0 μg/L, the correlation coefficient was - 0.999 4 - 0.999 8, and the detection limit was 0.231 μg/L. The relative standard deviation ( RSD) of low, medium and high iodine water samples of 6 times detection ranged from 1.4% to 9.6%, and the recoveries of low and medium water samples ranged from 89.0% to 108.0%. The detection results of national first-class reference materials for iodine composition analysis in water were within the range of standard value ± uncertainty. There was no significant difference in the test of results of 12 tap water samples between the revised method and the original standard method ( t = - 0.075, P > 0.05). Conclusion:The revised method has a good linear relationship of standard curve, high precision and accuracy, and good reproducibility, is simple and easy to operate, and is suitable for promotion and application.

Objective:To study the epidemic status of drinking tea type endemic fluorosis in Qinghai Province.Methods:In 2019, in counties (cities, districts, referred to as counties) that had the habit of drinking brick tea in 8 cities (prefectures) of Qinghai Province, epidemiological investigation of drinking tea type endemic fluorosis was carried out in villages. Ten households were randomly selected from each village, to investigate the demographic data of each household and the drinking situation of brick tea, residents' drinking water and brick tea samples were collected to determine the fluorine content, and calculate the daily per capita tea fluorine intake. At the same time, skeletal fluorosis was examined in all adults over 25 years old, and dental fluorosis was examined in all children aged 8 to 12 years old in survey sites. The content of fluorine in tea and water was detected by ion selective electrode method; the diagnosis of skeletal fluorosis was based on "Diagnostic Criteria for Endemic Skeletal Fluorosis" (WS 192-2008), the diagnosis of dental fluorosis was based on "Diagnosis of Dental Fluorosis" (WS/T 208-2011).Results:The mean (range) of fluorine of the 3 602 water samples was 0.31 (0.20 - 1.00) mg/L. The geometric mean (range) of fluorine of the 31 067 brick tea samples was 646 (40 - 2 295) mg/kg, the fluorine content of the brick tea ≤300 mg/kg accounted for 7.80% (2 422/31 067) of the total samples. The proportion of drinking Fu brick-tea was 89.97% (27 952/31 067); and the daily per capita tea fluorine intake was 1.93 mg, the daily per capita tea fluorine intake in Guoluo, Yushu and Hainan prefectures were higher than the health standard (3.50 mg). The detection rate of skeletal fluorosis in adults was 0.16% (2 357/1 484 907), Yushu Prefecture was the highest [29.23% (592/2 025)], followed by Guoluo Prefecture, which was 8.21% (771/9 393). The detection rate of dental fluorosis in children was 4.79% (8 076/168 623), Yushu Prefecture was the highest [32.61% (1 562/4 790)].Conclusion:Drinking tea type endemic fluorosis is prevalent in Qinghai Province, with obvious regional characteristics, covering a large population. The disease is relatively popular in Yushu Prefecture and Guoluo Prefecture.