Objective:To investigation the situation of water improvement projects in villages affected by drinking water-type endemic fluorosis in Qinghai Province and the prevalence of dental fluorosis among children, in order to provide a basis for consolidating the achievements in prevention and control of drinking water-type endemic fluorosis and adjusting prevention and control measures.Methods:The monitoring data on drinking water-type endemic fluorosis were collected from the disease prevention and control centers in various counties of Qinghai Province from 2021 to 2023, the situation of water improvement projects, the fluorine content of domestic drinking water and the prevalence of dental fluorosis in children aged 8 to 12 years old were retrospectively analyzed.Results:From 2021 to 2023, the numbers of villages affected by drinking water-type endemic fluorosis in Qinghai Province were 338, 335, and 328, respectively. The numbers of water improvement projects were 125, 127 and 124, respectively. The normal operation rates were 100%, 100% and 99.19% (123/124), respectively. The qualified rates of water fluoride level were 100%, 99.21% (126/127) and 99.19% (123/124), respectively. The detection rates of dental fluorosis among children aged 8 to 12 were 4.34% (515/11 877), 5.70% (646/11 331) and 4.48% (490/10 943), respectively. There was a statistically significant difference in the detection rate of dental fluorosis among children in different years (χ 2 = 22.79, P < 0.001). Conclusions:The overall operation status of water improvement project in villages affected by drinking water-type endemic fluorosis in Qinghai Province is generally good, but there has been some relaxation in management and maintenance in the later stage, and there is a phenomenon of project intermittency. The detection rate of dental fluorosis among children aged 8 to 12 remains low, and endemic fluorosis caused by drinking water is under continuous control.

Objective:To analyze the differences in determination of fluoride level in drinking water by ion-selective electrode method and high-throughput rapid determination method.Methods:The precision test was carried out by using the two methods to measure two kinds of fluoride standard substances, water samples of external quality control assessment from 2021 to 2023 (two kinds each year) and the fluoride level in three drinking water samples (for 5 times/each sample). Accuracy testing was conducted by measuring the external quality control assessment water samples and the spiked recovery rates drinking water, and water samples were grouped (water fluoride ≤1.00, > 1.00 mg/L) and analyzed according to the "Hygienic Standards for Drinking Water" (GB 5749-85). SPSS 23.0 software was used for statistical analysis of the measurement results.Results:(1) The correlation coefficients ( r) of the working curves of the two methods were both > 0.990, meeting the quality control requirements. (2) In the precision test, when comparing the results of the two methods for detecting two kinds of fluoride standard substances, there was no statistically significant difference ( F = 0.36, 0.15, P = 0.564, 0.707), and the coefficients of variation ( CV) were all < 5%. The CV of the detection results of the external quality control assessment water samples and drinking water samples were < 5%. (3) In the accuracy test, when the fluoride concentration in water was ≤1.00 mg/L, there was no statistically significant difference in the spiked recovery rates between the two methods ( F = 0.49, P = 0.504). When the fluoride concentration in water was > 1.00 mg/L, there was a statistically significant difference in the spiked recovery rates between the two methods ( F = 24.75, P = 0.003). Conclusions:The ion-selective electrode method has the advantages of wide detection range and wide adaptability, while the high-throughput rapid determination method has high accuracy. Testing personnel can weigh and choose the appropriate determination method based on the actual laboratory conditions and sample concentration range.

Objective:To investigation the situation of water improvement projects in villages affected by drinking water-type endemic fluorosis in Qinghai Province and the prevalence of dental fluorosis among children, in order to provide a basis for consolidating the achievements in prevention and control of drinking water-type endemic fluorosis and adjusting prevention and control measures.Methods:The monitoring data on drinking water-type endemic fluorosis were collected from the disease prevention and control centers in various counties of Qinghai Province from 2021 to 2023, the situation of water improvement projects, the fluorine content of domestic drinking water and the prevalence of dental fluorosis in children aged 8 to 12 years old were retrospectively analyzed.Results:From 2021 to 2023, the numbers of villages affected by drinking water-type endemic fluorosis in Qinghai Province were 338, 335, and 328, respectively. The numbers of water improvement projects were 125, 127 and 124, respectively. The normal operation rates were 100%, 100% and 99.19% (123/124), respectively. The qualified rates of water fluoride level were 100%, 99.21% (126/127) and 99.19% (123/124), respectively. The detection rates of dental fluorosis among children aged 8 to 12 were 4.34% (515/11 877), 5.70% (646/11 331) and 4.48% (490/10 943), respectively. There was a statistically significant difference in the detection rate of dental fluorosis among children in different years (χ 2 = 22.79, P < 0.001). Conclusions:The overall operation status of water improvement project in villages affected by drinking water-type endemic fluorosis in Qinghai Province is generally good, but there has been some relaxation in management and maintenance in the later stage, and there is a phenomenon of project intermittency. The detection rate of dental fluorosis among children aged 8 to 12 remains low, and endemic fluorosis caused by drinking water is under continuous control.

Objective:To analyze the differences in determination of fluoride level in drinking water by ion-selective electrode method and high-throughput rapid determination method.Methods:The precision test was carried out by using the two methods to measure two kinds of fluoride standard substances, water samples of external quality control assessment from 2021 to 2023 (two kinds each year) and the fluoride level in three drinking water samples (for 5 times/each sample). Accuracy testing was conducted by measuring the external quality control assessment water samples and the spiked recovery rates drinking water, and water samples were grouped (water fluoride ≤1.00, > 1.00 mg/L) and analyzed according to the "Hygienic Standards for Drinking Water" (GB 5749-85). SPSS 23.0 software was used for statistical analysis of the measurement results.Results:(1) The correlation coefficients ( r) of the working curves of the two methods were both > 0.990, meeting the quality control requirements. (2) In the precision test, when comparing the results of the two methods for detecting two kinds of fluoride standard substances, there was no statistically significant difference ( F = 0.36, 0.15, P = 0.564, 0.707), and the coefficients of variation ( CV) were all < 5%. The CV of the detection results of the external quality control assessment water samples and drinking water samples were < 5%. (3) In the accuracy test, when the fluoride concentration in water was ≤1.00 mg/L, there was no statistically significant difference in the spiked recovery rates between the two methods ( F = 0.49, P = 0.504). When the fluoride concentration in water was > 1.00 mg/L, there was a statistically significant difference in the spiked recovery rates between the two methods ( F = 24.75, P = 0.003). Conclusions:The ion-selective electrode method has the advantages of wide detection range and wide adaptability, while the high-throughput rapid determination method has high accuracy. Testing personnel can weigh and choose the appropriate determination method based on the actual laboratory conditions and sample concentration range.

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 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 find out the variety, producing area, fluorine content of brick tea in Qinghai Province, and the drinking situation of brick tea among people, so as to provide basis for preventing and curing endemic fluorosis of drinking tea type.Methods:From April to November 2019, according to historical data, in 3 066 administrative villages in 39 counties (cities, districts, hereinafter referred to as counties) in Qinghai Province that had the habit of drinking brick tea, 10 families were randomly selected from each village to investigate the demographic data of each family and the drinking situation of brick tea, to collect brick tea samples to determine the fluorine content, and to calculate the daily average brick tea fluorine intake of the population > 16 years old.Results:A total of 31 067 brick tea samples were collected. The main brick tea consumed by the residents in the whole province was Fu brick tea, accounting for 89.97% (27 952/31 067), followed by Kang brick tea [5.12% (1 592/31 067)], Green brick tea [2.29% (710/31 067)], Black brick tea [1.85% (574/31 067)], and golden tip, mosaic, black wool and other brick tea [0.77% (239/31 067)]. There were 523 brands of brick tea in circulation in the province, among which there were 410 brands produced in Hunan Province, 26 brands in Sichuan Province, 11 brands in Hubei Province, and 76 brands in Henan Province and other provinces. The average content of fluorine in brick tea was 646.1 mg/kg, which ranged from 40.0 to 2 295.0 mg/kg. Brick tea with fluorine content ≤300 mg/kg accounted for 7.80% (2 422/31 067) of all samples. The annual average consumption of brick tea by population > 16 years old was 1.09 (0.35 - 7.40) kg, and the daily average brick tea fluorine intake was 1.93 (0.39 - 18.64) mg. There were 15 counties and 486 administrative villages in which the daily average brick tea fluorine intake exceeded the national standard (3.5 mg).Conclusion:The main brick tea in circulation in Qinghai Province is Fu brick tea, which has high fluorine content and is harmful to people, and prevention and control measures should be taken as soon as possible.

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.