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 observe the changes of serum C-terminal peptide of type Ⅰ collagen (CTX-1) and N-terminal lengthening peptide of type Ⅰ collagen (P1NP) in adult patients with skeletal fluorosis in the tea-drinking-borne endemic fluorosis area in Qinghai Province, and to find sensitive indicators for diagnosis of skeletal fluorosis.Methods:From April to August 2019, a case-control study was carried out in tea-drinking-borne endemic fluorosis area in Zhiduo County, Yushu Tibetan Autonomous Prefecture, and Gangcha County, Haibei Tibetan Autonomous Prefecture of Qinghai Province. According to the Diagnostic Standard for Endemic Skeletal Fluorosis (WS/T 192-2008), the clinical diagnosis and X-ray examination of skeletal fluorosis were carried out for permanent residents ≥25 years old and living for more than 10 years in the area, combined with face-to-face inquiry and investigation of past disease history, lifestyle and clinical manifestations. The patients with skeletal fluorosis and healthy people were selected as skeletal fluorosis group and control group, respectively. Randomized urine samples and fasting venous blood from the two groups were collected. The content of fluoride in urine was determined by ion selective electrode method, and the contents of CTX-1 and P1NP in serum were determined by enzyme-linked immunosorbent assay (ELISA).Results:A total of 127 people in the disease area were investigated, including 63 cases in skeletal fluorosis group and 64 cases in control group. There was no statistically significant difference in age and sex ratio between the two groups ( t = 0.42, χ 2 = 0.07, P > 0.05). The X-ray examination results showed that the patients with skeletal fluorosis were mainly mild, accounting for 71.43% (45/63); X-ray changes were mainly ossification of interosseous membrane and tendon. The urinary fluoride in control group and skeletal fluorosis group was 1.62 (1.12, 1.95) and 3.22 (2.38, 4.89) mg/L, respectively, with statistically significant difference between the two groups ( Z = 7.07, P < 0.001). The difference of serum CTX-1 and P1NP contents between the two groups was statistically significant ( Z = 2.00, 4.89, P < 0.05). Conclusions:The levels of serum CTX-1 and P1NP in patients with skeletal fluorosis are higher than those in healthy people. Serum CTX-1 and P1NP may be used as sensitive indicators for diagnosis of skeletal fluorosis.

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 investigate the contents of soil metal elements in the plague high incidence area and resting area in the plague natural foci of Qingnan region in Qinghai Province, and to compare and analyze the differences of the contents of soil metal elements between the two areas.Methods:A total of 69 soil samples were collected from 11 sites in the plague high incidence area (Yushu Prefecture) and resting area (Guoluo Prefecture) in Qingnan region, including 39 samples from high incidence area and 30 samples from resting area. The contents of 12 soil metal elements, such as iron (Fe), magnesium (Mg), calcium (Ca), barium (Ba), cobalt (Co), copper (Cu), manganese (Mn), lead (Pb), rubidium (Rb), titanium (Ti), vanadium (V) and zinc (Zn), were measured by X-ray fluorescence spectrometry and SPSS 20.0 software was used for Spearman correlation and other statistical analysis.Results:The contents of Fe and Ca in the soil of the plague natural foci of Qingnan region were relatively high. The contents of 12 soil metal elements in the high incidence area were significantly higher than those in the resting area ( P < 0.01 or < 0.05). There were statistical significant differences in the contents of Mg, Ca, Ba, Mn, Pb and Zn in the soil among the sample plots of the plague high incidence area ( P < 0.01 or < 0.05). There were statistical significant differences in the contents of Fe, Mg, Ca, Rb and Ti in the soil among the sample plots of the plague resting area ( P < 0.05 or < 0.01). Except for Mg and Ca, Fe was positively correlated with other metal elements in the high incidence area and resting area ( P < 0.01 or < 0.05), and Fe was strongly positively correlated with Rb, Ti and V ( r = 0.780 - 0.838). Mg was only positively correlated with Ca in the high incidence area and resting area ( P < 0.01). Ca was negatively correlated with Mn, Pb, Rb, Ti, V and Zn in the high incidence area, and with Rb and Zn in the resting area ( P < 0.01 or < 0.05). The rest of the metal elements were mostly positively correlated in the high incidence area and resting area. Conclusions:The contents of Fe and Ca are rich in the plague natural foci of Qingnan region in Qinghai Province. There are correlations among most soil metal elements in the high incidence area and resting area. The correlation between the contents of soil metal elements in the plague natural foci and the epidemic of plague is worth further exploring.

Objective:To detect serum Col2-3/4 C-terminal cleavage product of type Ⅱ collagen (C2C) and pyridinoline (PYD) among brucellosis patients at early period, and to provide a better understanding of the changes of bone and joint collagen metabolism in the early stage of brucellosis.Methods:From 2013 to 2016, 61 cases of brucellosis patients at early period (within 6 months) from brucellosisout patient of Qinghai Institute for Endemic Disease Prevention and Control were selected as case group, and 67 cases of healthy volunteers were selected as control group. Serum C2C and PYD levels in all samples were measured simultaneously with enzyme linked immunosorbent assay (ELISA).Results:The median serum C2C of patients with early brucellosis was 83.45 ng/ml and that of the control group was 73.35 ng/ml. There was significant difference in serum C2C between the case group and the control group ( Z = 5.027, P < 0.05). The median serum PYD of patients with early brucellosis was 278.45 nmol/L and that of the control group was 212.75 nmol/L. There was significant difference in serum PYD between the case group and the control group ( Z = 6.967, P < 0.05). Conclusion:Serum C2C and PYD levels of brucellosis patients at early period are increased.

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.