Objective To understand the pathway of iodine intaking among Tibetan, and provide basic data for prevention and control of iodine deficiency disorders (IDD). Methods Through the method of random sampling, the boarding and day student aged 8 - 10 and women of childbearing age were conducted dietary survey to understand the condition of food intaking via the 24 h review method in 2015. Samples of urine, drinking water, dried beef, milk, Qula and fried noodles were collected and tested iodine level. Results Due to taking iodized salt three times a day with meals, the median of urinary iodine among 492 investigated boarding students was 179.2 μg/L;differently, the median of urinary iodine among 298 day students in this investigation was 79.6 μg/L who taking iodized salt only at lunch at school;and in the study, the median of urinary iodine among 158 women of childbearing age who took iodine-free salt daily was 33.7 μg/L. The iodine contents in 51 drinking water samples, 66 dried beef samples, 48 milk samples, 20 Qula samples and 37 fried noodle samples were quantified respectively, and the average iodine contents of each food were 0.8 μg/L in drinking water, 59.1 μg/kg in dried beef, 61.5 μg/kg in milk, 226.4 μg/kg in Qula and 17.0 μg/kg in fried noodles. The acceptable daily intake (ADI) of iodine of the boarding and day students aged from 8 to 10 and women of child bearing age were 234.0, 126.4 and 76.7 μg/d, respectively, among which the ADI of iodine with iodized salt were 208.0, 78.0 and 0.0 μg/d. Conclusion Consuming iodized salt is a main method to get iodine among Tibetans in Nangqian County, so that it is significant to carried out this measure for a long time for free to let them have iodized salt every day instead of iodine-free one.

Objective To analyze the radiographic characteristics of right hand X-ray film of adult patients with Kaschin-Beck disease (KBD) in Qinghai Province, to understand the most affected locations in adult KBD. Methods According to the criteria of KBD diagnose (WS/T 207-2010), 111 cases of patients were taken X-ray films of right hands. Joint space narrow, joint deformity, subchondral sclerosis, osteophyte, coarse and irregularity of joint, marginal retraction sign and capsule changes were chosen as the descriptive indexes, and these indexes were analyzed with SPSS 17.0. Results A total of 111 cases adult patients with KBD were examined right hand by X-ray, abnormality on X-ray film were 103 cases, the abnormal rate was 92.79%. The most affected fingers were Ⅱ- Ⅳphalanx bones, Ⅱphalanx bones accounted for about 92.23% (95/103), Ⅲ phalanx bones accounted for about 99.03% (102/103), and Ⅳ phalanx bones accounted for about 99.03% (102/103). There was significant difference of the abnormality between th e proximal phalanx and the middle phalanx among the Ⅱ - Ⅳ phalanx bones(χ2=79.33, P<0.05). Abnormal numbers of joint deformity, marginal retraction sign, coarse and irregularity of joint, osteophyte, capsule changes and joint space narrow in the proximal phalanx were 212, 7, 134, 47, 15 and 115 in Ⅱ - Ⅳ proximal phalanx, respectively; while the abnormal numbers of joint deformity, marginal retraction sign, coarse and irregularity of joint, osteophyte, capsule changes and joint space narrow in the middle phalanx were 77, 37, 137, 26, 19 and 126 in Ⅱ - Ⅳmiddle phalanx, respectively. Conclusion The Ⅱ - Ⅳ phalanx bones of right hand are the most affected locations in adult KBD.

Objective To observe the illness change trend of drinking water type endemic arsenic poisoning in Qinghai Province, comprehensively evaluate the effect of prevention and control measures, in order to provide a scientific basis for timely adjustment of the prevention and control measures. Methods From 2010 to 2013, according to the Drinking Water Type Endemic Arsenic Poisoning Monitoring Programs, 3 villages in 2 counties within Qinghai Province were randomly selected as monitoring sites. The arsenic content in drinking water of residents was measured, water improvement projects in all monitoring villages were investigated; at the same time an investigation of arsenic disease in resident population was conducted, and urinary arsenic content was monitored. Arsenic in drinking water and urine was determined by hydride generation atomic fluorescence spectrometry, and arsenic poisoning was diagnosed using Endemic Arsenic Poisoning Diagnostic Criteria (WS/T 211-2001). Results Of the three water improvement projects, two were water arsenic exceeded the standard, and one was intermittently operated. From 2010 to 2013, the arsenic poisoning detec tion rate in Baoning Village was 27.30% (193/707), 31.90%(245/768), 29.35%(221/753) and 28.22%(219/776); in Kecai Village was 32.62%(107/328), 34.83%(124/356), 31.26%(131/419) and 29.35%(118/402);and in Manimotai Village was 56.58%(43/76), 52.81%(47/89), 45.10%(46/102) and 34.69% (34/98), there was no significant difference statistically of the arsenic poisoning detection rates in the three monitored villages in the 4 years (χ2 =3.09, 0.04, 0.92, all P>0.05). From 2010 to 2013, women arsenic poisoning detection rate was 36.45%(203/557), 40.59%(246/606), 36.12%(225/623) and 34.77%(218/627), respectively;men was 25.27%(140/554), 28.01%(170/607), 26.57%(173/651) and 23.57%(153/649), respectively;women arsenic poisoning detection rates were higher than those of men (χ2 = 16.25, 21.32, 13.49, 19.38, all P < 0.05). Arsenic poisoning detection rate of people younger than 60 years old had a tendency to increase with age. In 2012 and 2013, 105 and 93 urine samples were tested, respectively; urinary arsenic geometric mean was 0.113 and 0.149 mg/L. Conclusions Water improvement projects and water quality are not optimistic, and prevalence of arsenic poisoning is still at a higher level. A sound long-term monitoring program should be established as soon as possible, the management and maintenance of water improvement projects should be strengthened, and the monitoring and prevention work should not be neglected.

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 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.

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 investigate the relationship between thyroid volume and multiple body indexes such as urinary iodine level,height,and weight,respectively,in order to provide a theoretical basis for evaluation of goiter disease in the future. Methods The height and weight were measured, and urine samples were collected from children aged 8 to 10 years old from 10 township schools of Nangqian County in Qinghai Province in 2014 and urinary iodine was tested via the As (Ⅲ)-Ce4+catalytic spectrophotometry method. Meanwhile, the thyroid volume was immediately measured via the B-ultrasound method. Statistical analyses were employed finally to assess the difference and correlation between thyroid volume and multiple physiological indexes including urinary iodine level, height, weight, gender and age. Results The thyroid volume of 773 children aged 8 to 10 years old showed skewed distribution (W = 0.088, P < 0.05), with median of 3.53 ml and quartile of 3.05, 4.15 ml. The thyroid volume was not significantly different between different urinary iodine levels (H = 1.644, P > 0.05). There were significant differences of the thyroid volume among different height groups, weight groups and age groups (H=59.845,64.888,28.590,P<0.05),and the thyroid volume was positively correlated with height weight and age,respectively(r = 0.389, 0.359, 0.155, P < 0.05). Conclusions The thyroid volume is related to the level of children's physiological parameters, such as age, height, weight. Therefore, the diagnosis of thyroid volume via the B-ultrasound method for a individual child should not only take age,but also height and weight into account, to reduce the diagnostic error of goiter disease.

Objective To explore the prevalence state of drinking brick-tea type fluorosis in children in Guoluo Prefecture,Qinghai Province.Methods According to the historical prevalence of drinking tea-type fluorosis in Guoluo Prefecture,in 2017,in 5 counties of Guoluo Prefecture,according to the pastoral area,agricultural area,semi-agricultural and semi-pastoral areas,each township (town) was selected,in each township (town) drawed a natural village in a ward as a survey point.At each survey site,drinking water samples of local residents were collected,and 10 households were selected,tea samples were collected,and dental fluorosis was investigated for children aged 8-12 years old.The mean of fluoride was determined by fluoride ion selective electrode method (GB/T 5750.5-2006,GB 19965-2005),and the dental fluorosis was diagnosed based on "Diagnosis of Dental Fluorosis" (WS/T 208-2011).Results The mean of fluoride in 85 water samples was 0.34 mg/L (0.20-0.77 mg/L),the mean of fluoride in 161 brick-tea samples was 579 mg/kg (110-1 278 mg/kg).The mean of daily fluoride intake of each person was 6.78 mg,among them,73.29％ (118/161) drank brick-tea,the detection rate of dental fluorosis of 2 083 children was 22.85％ (476/2 083),and the index of dental fluorosis was 0.42,the prevalence was weak.Conclusion The prevalence of drinking brick-tea type fluorosis of children in Guoluo Prefecture is less serious.

Objective To understand the current environmental selenium and T-2 toxin levels in the critically ill areas of Kaschin-Beck disease in Qinghai Province.Methods In three historical villages with serious diseases of Kaschin-Beck disease,Xia,Xiemalang and Yaoshidao were selected;at the same time,three villages from non-diseased areas were selected as control villages including Damitan,Gongba and Deang in 2018.Six villages were used as survey sites.Collected hair samples of children aged 6-12 years old,to measure the hair selenium content in Xinghai and Guide survey sites [children's selenium content reference value was (0.60 ± 0.03)mg/kg].Ten samples of self-produced grain were collected from each survey site,selenium content [wheat selenium content reference value was (0.053 ± 0.007) mg/kg] and T-2 toxin content in grain was detected in the six survey sites.Ten soil samples were collected from each survey sites.Soil selenium content was detected in the six survey sites [soil selenium content reference value was (0.24 ± 0.03) mg/kg].Results The selenium contents of children's hair in the diseased and non-diseased areas of Xinghai County,Guide County were (0.252 ± 0.071),(0.296 ± 0.087);(0.225 ± 0.032),(0.238 ± 0.040) mg/kg,respectively.The selenium contents of wheat in the diseased and nondiseased areas of the three counties were 0.000 19,0.003 66;0.000 15,0.004 16;0.016 78,0.016 94 mg/kg.The soil selenium contents in the diseased and non-diseased areas of the three counties were (0.095 ± 0.015),(0.114 ± 0.014);(0.082 ± 0.013),(0.083 ± 0.018);(0.080 ± 0.005),(0.060 ± 0.013) mg/kg.The T-2 toxin contents of wheat in the diseased and non-diseased areas of the three counties were (3.173 ± 0.762),(3.100 ± 0.473);(2.506 ± 0.430),(3.186 ± 0.451);(2.416 ± 0.619),(2.879 ± 0.456) μg/kg.Conclusions The content of hair selenium of children is close to the normal reference value in the area of Kaschin-Beck disease in Qinghai Province.The contents of soil selenium and the main grain selenium of the residents are low in the diseased village.A certain amount of T-2 toxin is detected in the main grain of residential households.

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.