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 iodine nutrition status of children aged 8 - 10 and pregnant women in Xining City, Qinghai Province.Methods:From 2019 to 2021, a stratified cluster sampling method was used to divide 7 counties (districts) under the jurisdiction of Xining City, Qinghai Province into 5 sampling areas according to east, west, south, north, and center each year. One township (town, street) was selected from each area. Forty non boarding students aged 8 to 10 from each primary school (half male and half female, age balanced) and 20 pregnant women from each township (town, street) location were selected to collect edible salt samples at home and a random urine sample to measure salt iodine and urinary iodine level. B-ultrasound was used to measure thyroid volume in children and the goiter rate was calculated.Results:A total of 6 534 samples of household edible salt were collected from children and pregnant women, with an average salt iodine concentration of 25.58 mg/kg. The coverage rate of iodized salt was 97.50% (6 371/6 534), and the qualified iodized salt consumption rate was 89.46% (5 845/6 534). A total of 4 362 urine samples were collected from children, with a median urinary iodine level of 183.10 μg/L. The difference between different years was statistically significant ( H = 20.27, P < 0.001). A total of 2 169 urine samples were collected from pregnant women, with a median urinary iodine level of 168.90 μg/L. The difference between different years was statistically significant ( H = 107.09, P < 0.001). A total of 3 336 cases of thyroid gland examination were conducted in children, including 33 cases of thyroid enlargement, with a goiter rate of 0.99%. There was a statistically significant difference between different years (χ 2 = 15.00, P < 0.001). Conclusion:From 2019 to 2021, children aged 8 to 10 and pregnant women in Xining City are at an appropriate level of iodine, and the achievements in prevention and treatment of iodine deficiency disorders still need to be continuously consolidated.

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 iodine nutrition status of children aged 8 - 10 and pregnant women in Xining City, Qinghai Province.Methods:From 2019 to 2021, a stratified cluster sampling method was used to divide 7 counties (districts) under the jurisdiction of Xining City, Qinghai Province into 5 sampling areas according to east, west, south, north, and center each year. One township (town, street) was selected from each area. Forty non boarding students aged 8 to 10 from each primary school (half male and half female, age balanced) and 20 pregnant women from each township (town, street) location were selected to collect edible salt samples at home and a random urine sample to measure salt iodine and urinary iodine level. B-ultrasound was used to measure thyroid volume in children and the goiter rate was calculated.Results:A total of 6 534 samples of household edible salt were collected from children and pregnant women, with an average salt iodine concentration of 25.58 mg/kg. The coverage rate of iodized salt was 97.50% (6 371/6 534), and the qualified iodized salt consumption rate was 89.46% (5 845/6 534). A total of 4 362 urine samples were collected from children, with a median urinary iodine level of 183.10 μg/L. The difference between different years was statistically significant ( H = 20.27, P < 0.001). A total of 2 169 urine samples were collected from pregnant women, with a median urinary iodine level of 168.90 μg/L. The difference between different years was statistically significant ( H = 107.09, P < 0.001). A total of 3 336 cases of thyroid gland examination were conducted in children, including 33 cases of thyroid enlargement, with a goiter rate of 0.99%. There was a statistically significant difference between different years (χ 2 = 15.00, P < 0.001). Conclusion:From 2019 to 2021, children aged 8 to 10 and pregnant women in Xining City are at an appropriate level of iodine, and the achievements in prevention and treatment of iodine deficiency disorders still need to be continuously consolidated.

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 analyze the external quality control assessment results of urinary iodine, salt iodine and water iodine in iodine deficiency disorders laboratories in Qinghai Province, to evaluate the testing capacity of provincial, municipal and county-level laboratories and the operation of external quality control network, so as to provide quality assurance for consolidating and eliminating iodine deficiency disorders.Methods:In 2021, 1 provincial, 8 municipal, and 43 county-level laboratories in Qinghai Province had participated in the assessment of urinary iodine and salt iodine, while 1 provincial and 8 municipal-level laboratories had participated in the assessment of water iodine. The assessment results were evaluated using the method of reference value ± uncertainty of external quality control samples.Results:All laboratories that participated in the assessment had provided feedback. One provincial-level laboratory passed the assessment of urinary iodine, salt iodine, and water iodine. Among 8 municipal-level laboratories, 2 laboratories failed the urinary iodine assessment, with a pass rate of 6/8; the assessment of salt iodine and water iodine in 8 laboratories were all qualified. Among 43 county-level laboratories, 7 laboratories failed the urinary iodine assessment, with a pass rate of 83.7% (36/43); the assessment of salt iodine in 43 laboratories were all qualified.Conclusions:The external quality control network of iodine deficiency disorders laboratories in Qinghai Province has fully covered all municipal and county-level laboratories. The testing capability of provincial-level laboratory is stable and maintains a high level; the testing quality of some municipal and county-level laboratories is still unstable and needs to be further strengthened.

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 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 water iodine content in Qinghai Province and draw a distribution map of water iodine, so as to provide a basis for scientific supplementation of iodine and continuous elimination of iodine deficiency hazards.Methods:In 2017, in all counties (cities, districts) in Qinghai Province, with townships (towns, streets, referred to as townships) as the unit, the residents' drinking water samples were collected, water iodine content was tested, the median water iodine was calculated, and the water iodine distribution map of Qinghai Province was drew.Results:Totally 1 836 drinking water samples were collected in 392 townships, the median water iodine was 1.7 μg/L. Townships that had the median water iodine < 5 μg/L, in the range of 5 to 10 μg/L and > 10 μg/L accounted for 80.6% (316/392), 17.1% (67/392) and 2.3% (9/392), respectively. Among all townships, the highest of the median water iodine was 24.8 μg/L. Based on the results, water iodine distribution map of Qinghai Province, water iodine distribution map of Xining City and water iodine distribution map of Haidong City were compiled.Conclusions:Iodine deficiency is widespread throughout natural environment in Qinghai Province. Hence, salt iodization measures to prevent iodine deficiency disorders should be implemented continuously. According to the water iodine distribution map, the people should be guided to supplement iodine scientifically.

Objective:To investigate the dietary iodine intake of people in different areas of Qinghai Province, and to provide the basis for scientific iodine supplementation and continuous elimination of iodine deficiency hazards.Methods:From 2018 to 2019, according to administrative division, natural geographical regions, population distribution and economic development level of Qinghai Province, a total of 14 survey sites were selected. One village was selected from each survey site, and 20 households were selected from each village, the salt samples and 24 h urine samples of all family members were collected to detect salt iodine and urinary iodine. One drinking water sample was collected at the five directions of east, west, south, north and middle of each village to detect water iodine. Salt iodine was detected by direct titration, urinary iodine and water iodine were detected by arsenic-cerium catalytic spectrophotometry. At the same time, the 3-day weighing method was used to investigate the diet, the daily dietary iodine intake per capita (the result was expressed as average) and the proportion of dietary iodine in urinary iodine were calculated, the daily dietary iodine intake per capita of different production modes (agricultural region and pastoral region), different geographical environment (Hehuang Valley, Qaidam Basin, Qilian Mountain and Qingnan Plateau), different nationalities (Han, Tibetan, Hui, Mongolian, Tu, Salar) and different economic levels (< 8 000, 8 000 -, 10 000 -, ≥12 000 Yuan) were compared.Results:A total of 999 people from 280 families were surveyed, including 511 males and 488 females. The median water iodine of each survey site was less than 10 μg/L, all of which were environmentally iodine-deficient areas. A total of 280 salt samples were collected, the median salt iodine was 26.0 mg/kg, and the consumption rate of qualified iodized salt was 100% (280/280). A total of 999 urine samples were tested, and the median urinary iodine of people was 192.5 μg/L, which was at an appropriate level of iodine. There was no statistically significant difference ( t =-1.599, P > 0.05) in the daily dietary iodine intake per capita (28.53, 33.44 μg) of people in agricultural region ( n = 643) and pastoral region ( n = 356). The daily dietary iodine intake per capita (25.38, 33.30, 32.98, 34.79 μg) of people in Hehuang Valley ( n = 448), Qaidam Basin ( n = 125), Qilian Mountain ( n = 157), and Qingnan Plateau ( n = 269) were compared, the difference was statistically significant ( F = 2.883, P < 0.05); among them, the daily dietary iodine intake per capita in Hehuang Valley was lower than that in Qingnan Plateau ( P < 0.05). The daily dietary iodine intake per capita of different nationalities were compared, the difference was statistically significant ( F = 3.647, P < 0.05), Salar ( n = 68) and Tibetan ( n = 239) were higher (37.21 and 32.21 μg). The daily dietary iodine intake per capita (38.97, 17.01, 30.86, 33.14 μg) of annual per capita disposable income < 8 000 ( n = 194), 8 000-( n = 221), 10 000-( n = 302), ≥12 000 Yuan ( n = 282) were compared, the difference was statistically significant ( F = 9.407, P < 0.05). The proportions of dietary iodine in urinary iodine of various population ranged from 5.35% to 15.54%. Conclusions:The iodine nutrition of people in Qinghai Province is suitable, the dietary iodine intake of people is closely related to geographical environment, nationality and economic level. But the proportion of dietary iodine in urinary iodine is relatively low, the consumption of iodized salt is still the main way for people to intake iodine, and it is also the main measure to continuously eliminate the harm of iodine deficiency in Qinghai Province.