Associations of 10 trace element levels in the whole blood with risk of three types of obesity in the elderly.

BACKGROUND: Currently, over 2 billion people worldwide suffer from obesity, which poses a serious health risk. More and more attention is being given to the effects of trace elements on obesity in recent years. Synergistic or antagonistic interactions among these elements can adversely or positively impact human health. However, epidemiological evidence on the relationship between trace element exposure levels and obesity has been inconclusive. METHODS: Baseline data of 994 participants from the Cohort of Elderly Health and Environment Controllable Factors were used in the present study. ICP-MS was used to measure the concentrations of 10 trace elements in the whole blood of the older population. Binary logistic regression, restricted cubic splines (RCS) models, and Bayesian kernel machine regression (BKMR) models were employed to assess single, nonlinear, and mixed relationships between 10 trace element levels and three types of obesity based on body mass index (BMI), waist circumference (WC), and body fat percentage (BFP) in the elderly. RESULTS: Based on BMI, WC and BFP, 51.8% of the included old population were defined as general overweight/obesity, 67.1% as abdominal obesity, and 36.2% as having slightly high/high BFP. After multivariable adjustment, compared with the lowest tertile, the highest tertile of blood selenium (Se) concentration was associated with an increased risk of all three types of obesity. Additionally, compared with the lowest tertile, higher tertiles of strontium (Sr) concentrations were associated with a lower risk of general overweight/obesity and having slightly high/high BFP, and the highest tertile of barium (Ba) was associated with a lower risk of having slightly high BFP, while higher tertiles of arsenic (As) concentrations were associated with an increased risk of having slightly high/high BFP, and the highest tertile of manganese (Mn) was associated with a higher risk of abdominal obesity. BKMR analyses showed a strong linear positive association between Se and three types of obesity. Higher blood levels of trace element mixture were associated with increased obesity risks in a dose-response pattern, with Se having the highest value of the posterior inclusion probability (PIP) within the mixture. CONCLUSIONS: In this study, we found higher Se levels were associated with an elevated risk of obesity and high levels of Ba, Pb and Cr were associated with a decreased risk of obesity. Studies with larger samples are needed to confirm these findings.

The association between the essential metal mixture and fasting plasma glucose in Chinese community-dwelling elderly people.

BACKGROUND: Epidemiological studies about the effect of essential metal mixture on fasting plasma glucose (FPG) levels among elderly people are sparse. The object of this study was to examine the associations of single essential metals and essential metal mixture with FPG levels in Chinese community-dwelling elderly people. METHODS: The study recruited 2348 community-dwelling elderly people in total. Inductively coupled plasma-mass spectrometry was adopted to detect the levels of vanadium (V), selenium (Se), magnesium (Mg), cobalt (Co), calcium (Ca), and molybdenum (Mo) in urine. The relationships between single essential metals and essential metal mixture and FPG levels were evaluated by linear regression and Bayesian kernel machine regression (BKMR) models, respectively. RESULTS: In multiple-metal linear regression models, urine V and Mg were negatively related to the FPG levels (ß = - 0.016, 95 % CI: - 0.030 to - 0.003 for V; ß = - 0.021, 95 % CI: - 0.033 to - 0.009 for Mg), and urine Se was positively related to the FPG levels (ß = 0.024, 95 % CI: 0.014-0.034). In BKMR model, the significant relationships of Se and Mg with the FPG levels were also found. The essential metal mixture was negatively associated with FPG levels in a dose-response pattern, and Mg had the maximum posterior inclusion probability (PIP) value (PIP = 1.0000), followed by Se (PIP = 0.9968). Besides, Co showed a significant association with decreased FPG levels in older adults without hyperlipemia and in women. CONCLUSIONS: Both Mg and Se were associated with FPG levels, individually and as a mixture. The essential metal mixture displayed a linear dose-response relationship with reduced FPG levels, with Mg having the largest contribution to FPG levels, followed by Se. Further prospective investigations are necessary to validate these exploratory findings.

Selenium and Zinc Intakes of Staple Grains and Their Correlation with Urine Selenium and Zinc in the Tibetan Rural Residents along the Yarlung Zangbo River.

Grains account for a large proportion of the diet of rural residents in Tibet. The lack of selenium (Se) and zinc (Zn) threatens the population's nutrition and health. However, the intakes of selenium and zinc in grains remains unclear. To clarify the nutritional status of selenium and zinc consumed from staple grains of residents along the Yarlung Zangbo River in Tibet, 341 grain samples and 242 urine samples were collected, and 244 food frequency questionnaires were completed along the Yarlung Zangbo River in 2020-2021. The results showed that the selenium concentrations of 88.5% of self-produced tsampa and 80.8% of self-produced flour were lower than the grain selenium threshold (<25 µg·kg-1). The intake of selenium and zinc from staple grains (tsampa, flour, and rice) contributed 15.0% and 43.5% to the recommended nutrient intake (RNI) on average, respectively. A geographical detector model analyzed factors affecting urinary selenium and zinc levels. Selenium and zinc intakes in rice and flour, and dietary diversity score (DDS) were the main factors affecting urinary selenium and zinc (p < 0.01). Their interaction effects on urinary selenium and zinc were greater than those of a single factor. The staple grains of rural residents along the Yarlung Zangbo River were in a state of selenium deficiency. The zinc content of the staple grain purchased was lower than that of the main grain produced by rural residents. Changing the grain consumption pattern and adjusting the proportion of exogenous grains can improve selenium and zinc nutrition in residents.

Selenium attenuates the association of co-exposure to arsenic, cadmium, and lead with cognitive function among Chinese community-dwelling older adults.

The effects of interactions between the toxic and essential metal mixtures on cognitive function are poorly understood. This study aims to identify the joint association of arsenic (As), cadmium (Cd), and lead (Pb) with cognitive function in older adults and the moderating role of selenium (Se), zinc (Zn), and copper (Cu) in this association. This study included 1000 community-dwelling older adults. Cognitive function was assessed by the Mini-Mental State Examination (MMSE). Blood concentrations of As, Cd, Pb, Se, Zn, and Cu were measured using inductively coupled plasma mass spectrometry. Linear regression and Bayesian kernel machine regression (BKMR) models were applied to assess the individual and joint associations of As, Cd, and Pb with cognitive function and to examine whether Se, Zn, and Cu (individually and as a mixture) modified these associations. In the adjusted single-metal models, both Cd (ß = - 0.37, 95% CI: - 0.73 to - 0.01) and Pb (ß = - 0.44, 95% CI: - 0.86 to - 0.02) were associated with MMSE scores, while Se (ß = 0.71, 95% CI: 0.30 to 1.13) exhibited a positive relationship with MMSE scores. Univariate exposure-response functions from BKMR models showed similar results. Moreover, the toxic metal mixture (As, Cd, and Pb) exhibited a significant negative association with MMSE scores in a dose-response pattern, with Pb being the greatest contributor within the mixture. The negative association of Pb alone or the toxic metal mixture with MMSE scores became weaker at higher concentrations of Se within its normal range, especially when Se levels were greater than the median (89.18 µg/L). Our findings support that Se can attenuate the negative associations of exposure to single Pb or the As, Cd, and Pb mixtures with cognitive function. Future prospective studies are needed to replicate our findings.

The association between essential trace element mixture and cognitive function in Chinese community-dwelling older adults.

BACKGROUND: The evidence about the effect of essential trace element (ETE) mixture on cognitive function amongst older adults is limited. This study aims to evaluate the associations of single ETEs and ETE mixture with cognitive function using a representative sample of community-dwelling older adults in China. METHODS: A total of 3814 older adults were included in the study. Urinary concentrations of selenium (Se), vanadium (V), cobalt (Co), strontium (Sr), and molybdenum (Mo) were detected by inductively coupled plasma mass spectrometry. Cognitive function in older adults was assessed using the Chinese version of the Mini-Mental State Examination (MMSE). Linear regression and Bayesian kernel machine regression (BKMR) were performed to explore the associations of single ETEs and ETE mixture with cognitive function, respectively. RESULTS: Linear regression showed that urinary levels of Se and V were positively associated with MMSE scores in the adjusted single-element models. BKMR also showed marginally positive associations of Se and V with MMSE scores. Moreover, higher urinary levels of ETE mixture were significantly associated with increased MMSE scores in a dose-response pattern, and Se was the most important contributor within the mixture. Both Se and V demonstrated positive additive effects on the associations of other ETEs with MMSE scores, whereas Co had a negative additive effect. CONCLUSIONS: V and Se are positively associated with cognitive function, individually and as a mixture. ETE mixture exhibits a linear dose-response association with improved cognitive function, with Se being the most important component within the mixture. Mixture analyses rather than single ETE analyses may provide a real-world perspective on the relationship between ETE mixture and cognitive function. Further cohort studies are needed to clarify the association of multiple ETEs with cognitive function.

Association of selenium, arsenic, and other trace elements in drinking water and urine in residents of the plateau region in China.

Drinking water is considered to be an important exposure pathway for humans to ingest trace elements; human urine samples are widely accepted as biometric substrates that can reflect human exposure to trace elements. The current study aimed at investigating the concentrations of trace elements including selenium (Se), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in drinking water and human urine in plateau region of China, determining the association among trace elements in drinking water and urine, and analyzing their associations with age and gender. The results showed that the majority of trace element concentrations were in the range of the World Health Organization (WHO 2011) guideline values, in both urine samples of male and female, and the median values were descending in the order: Zn > Cu > As > Se > Cr > Ni > Mn > Pb > Cd > Co. Selenium contributed to the excretion of As, Cr, Cu, Cd, and Zn in human body, group of 31-40 years appeared to present the greatest excretion ability in most of the trace elements. Weak positive correlations were observed between age and Mn in female urine samples, and negative correlations were observed between age and Se, As, Co, and Cu in male urine samples and between age and Co in female urine samples, respectively. Significant positive correlation was observed in As between drinking water and the whole human urine. In the same family, female seemed to show higher proportions of urinary As levels than male. This study will provide elementary information regarding trace element levels in drinking water and human urine in residents in plateau region of China and is helpful to provide reference for dietary nutrient trace element intake and effective control for local resident.

[Evaluation of dietary diversity of rural residents in Arun Banner, a typical area of low selenium belt in China].

OBJECTIVE: To understand the dietary diversity and food sources of different groups in Arun Banner. Comparing and analyzing the changes of dietary diversity of local residents in different periods. METHODS: In October 2019, according to the differences of Kashin-Beck disease conditions and land use patterns of Arun Banner, Hulun Buir, 78 rural residents were randomly selected from four villages to investigate the frequency of daily food consumption by using self-made food frequency questionnaire. Dietary diversity score(DDS) was used to evaluate the dietary diversity of different populations. RESULTS: The average DDS of the investigated residents was 9. 76±2. 32. DDS of the residents of Minzu and Tieshan villages(10. 14±2. 66) in the West was higher than that of Longtoushan and Hongqi villages(9. 42±1. 95) in the East. However, the difference was not statistically significant(Z=-1. 875, P& gt; 0. 05). DDS in males(10. 37±2. 47) was significantly higher than that in females(9. 36±2. 14)(P& lt; 0. 05). There was no significant difference in DDS(9. 52±2. 29) between Kashin-Beck disease affected patients and healthy residents(9. 85±2. 34)(Z=-0. 601, P& gt; 0. 05). There was no significant difference in DDS among different age groups. The average of DDS was higher in those younger than 60 years old(9. 90±2. 35). Residents mainly eat rice and flour, and the proportion of purchasing food from other places reaches 96% and 95%, respectively. CONCLUSION: The staple food in Arun Banner was mainly rice and flour purchased from other places. The dietary structure of residents tends to be diversified. Residents reduced dependence on low selenium natural environment is an important factor for local selenium-susceptible endemic diseases to be stable and gradually controlled.

Spatial distribution and determinants of health loss from Kashin-Beck disease in Bin County, Shaanxi Province, China.

BACKGROUND: Kashin-Beck disease (KBD) is one of the major endemic diseases in China, which severely impacts the physical health and life quality of people. A better understanding of the spatial distribution of the health loss from KBD and its influencing factors will help to identify areas and populations at high risk so as to plan for targeted interventions. METHODS: The data of patients with KBD at village-level were collected to estimate and analyze the spatial pattern of health loss from KBD in Bin County, Shaanxi Province. The years lived with disability (YLDs) index was applied as a measure of health loss from KBD. Spatial autocorrelation methodologies, including Global Moran's I and Local Moran's I, were used to describe and map spatial clusters of the health loss. In addition, basic individual information and environmental samples were collected to explore natural and social determinants of the health loss from KBD. RESULTS: The estimation of YLDs showed that patients with KBD of grade II and patients over 50 years old contributed most to the health loss of KBD in Bin County. No significant difference was observed between two genders. The spatial patterns of YLDs and YLD rate of KBD were clustered significantly at both global and local scales. Villages in the southwestern and eastern regions revealed higher health loss, while those in the northern regions exhibited lower health loss. This clustering was found to be significantly related to organically bound Se in soil and poverty rate of KBD patients. CONCLUSIONS: Our results suggest that future treatment and prevention of KBD should focus on endemic areas with high organically bound Se in soil and poor economic conditions. The findings can also provide important information for further exploration of the etiology of KBD.

Assessing the Health Loss from Kashin-Beck Disease and Its Relationship with Environmental Selenium in Qamdo District of Tibet, China.

Kashin-Beck Disease (KBD) is one of major endemic diseases in China. In this study, we estimated the health loss from KBD in Qamdo district of Tibet using the years lived with disability (YLD) metric and investigated the influence of environmental selenium (Se) on it by multiple regression model. The results showed that YLD rates produced a different ranking of health loss of KBD from that produced by prevalence rates between Basu and Luolong County, with higher health loss from KBD (43.61 YLD/1000) but lower prevalence (17.86%) in Basu County. YLD rates in two counites were both highest for the 45-64 years age group. Compared with the prevalence rate, the YLD rate had a closer relation to environmental Se and was significantly negatively correlated with Se in both soil and highland barley. The multiple linear regression further revealed that Se contents in cultivated soil and highland barley were main influencing factors for the health loss of KBD, which could explain 90.5% of the variation in YLD rates. The information obtained highlights the significance of the YLD metric in exploring the environmental etiology of KBD and provides important information on which to base decisions on future prevention and control of endemic diseases.

Selenium Nutritional Status of Rural Residents and Its Correlation with Dietary Intake Patterns in a Typical Low-Selenium Area in China.

China is recognized as a selenium-deficient country, and nutritional selenium intake has always been a concern. To clarify the current inhabitants' selenium nutrition status and the characteristics of dietary consumption in low-selenium areas, samples of human hair and grains were collected, and food frequency questionnaires were administered in Binxian County, Shaanxi Province, a typical low-selenium area in the Loess Plateau. The subject number of the study is 85, and the age range is from 11 to 81 years, with an average of 60. The results showed that the average hair selenium content of the residents was 231.7 µg/kg, and 62.4% of the participants had levels higher than the selenium deficiency threshold (200 µg/kg). There was a significant positive correlation between the hair selenium content and the food consumption score after adjusting for rice outsourcing. Three different dietary patterns were noted according to hierarchical cluster analysis. This study provides a tool for assessing the selenium nutrition of inhabitants in low-selenium areas and has considerable significance for improving the dietary pattern of residents.

Dietary selenium intake based on the Chinese Food Pagoda: the influence of dietary patterns on selenium intake.

BACKGROUND: Selenium (Se) is essential for humans, with many critical roles in physiological and pathophysiological processes. Fish, eggs and meats are usually the rich food sources of Se. To improve the nutritional status of population, a new version of balanced dietary pattern in the form of the Chinese Food Pagoda (2016) was proclaimed. This study aimed to evaluate the contribution of this balanced dietary pattern to daily Se intake, and to assess Se intake status of Chinese residents under this Food Pagoda scenario. METHODS: Based on the food consumption recommended in the Food Pagoda, this study collected the data of Se contents in various food composites and estimated dietary Se intakes (EITDS) in 12 provinces from the 4th China Total Diet Study. The estimated Se intakes based on the Chinese Food Pagoda (EICHFP) in 12 provinces were calculated. EITDS and EICHFP in various food groups among different regions were compared. RESULTS: The average EICHFP in all regions, within the range of 66.23-145.20 µg/day, was greater than the China recommended nutrient intake (RNI) (60 µg/day). None of the highest EICHFP went beyond the tolerable upper intake level of Se (400 µg/day). Animal source foods should be the primary source of daily Se intake according to the EICHFP. The average EITDS in China (88 µg/day) was in line with its range of EICHFP (81.01-124.25 µg/day), but that in half of the regions failed to achieve their lowest EICHFP. Significant differences between EITDS and EICHFP were observed in cereal food, aquatic and dairy products (P < 0.05), among which Se intake from aquatic and dairy products presented seriously insufficient in almost all regions. CONCLUSIONS: The ideal dietary pattern recommended in the Food Pagoda can meet the daily requirements of Chinese population for Se intake to maintain optimal health. From the perspective of the balanced diet and Se-rich sources, the consumption of aquatic products should be increased appropriately to improve the general Se intake level of Chinese population.

Trace Element Levels in Scalp Hair of School Children in Shigatse, Tibet, an Endemic Area for Kaschin-Beck Disease (KBD).

Kaschin-Beck disease (KBD) is an endemic osteoarthritis, and the etiology is closely related with levels of trace elements in the human body. Currently, it is clear that the selenium (Se) status of children in KBD areas is lower than that in non-KBD areas in the Tibetan Plateau, whereas role of other elements are yet unknown. This study aimed to assess some essential trace elements (Se, Mo, Mn, Zn, Fe, Cu, Co, and Sr) in children using scalp hair as a biomarker, and 157 samples from school children aged 8-14 years old were collected from both KBD and non-KBD areas in Shigatse, Tibet. Se and Mo were measured by inductive coupled plasma mass spectrometry, and the other elements were determined by inductive coupled plasma optical emission spectrometry. Compared with the non-KBD areas, Se, Mo, Mn, Fe, Zn, Co, and Sr levels of children in KBD areas were found to be significantly different (P < 0.05); while in linear discriminant analysis, only Se and Zn were found to contribute to the KBD prevalence in the study area. The hair Se level of children in KBD areas ranged from 0.115 to 0.299 mg/kg, while in non-KBD areas it ranged from 0.135 to 0.519 mg/kg. The Zn content of children's hair was between 83 and 207 mg/kg in KBD areas, while it was 37 and 219 mg/kg in non-KBD areas. Lower Se and higher Zn levels in children in KBD areas was found when compared with non-KBD groups. In addition, Mo levels were found to be different between KBD areas and non-KBD areas on the opposite side of the Yarlung Zangbo River, but no close relationship was shown because there was no difference compared with the non-KBD area on the same side of the river. Our observations suggest that Se deficiency is still an important factor for the occurrence and prevalence of KBD, while the relationship between Zn and KBD needs to be further explored in the Tibetan Plateau.

Distribution and translocation of selenium from soil to highland barley in the Tibetan Plateau Kashin-Beck disease area.

Kashin-Beck disease (KBD), which is still active and severe in the Tibetan Plateau, is considered to be a kind of selenium (Se)-deficient disease. Highland barley as the most popular staple food in the Tibetan Plateau is one of the dominant Se sources for local people. To improve Se levels in crops in the Tibetan Plateau KBD area, the distribution and translocation of Se from soil to highland barley in both non-KBD and KBD endemic areas were investigated. The results showed that Se levels in highland barley were too low to meet the minimum requirements of human for daily intake of Se. The total Se concentrations of highland barley fractions in KBD areas were lower than that in non-KBD areas (grain P = 0.238; straw P = 0.087; root P = 0.008). However, no significant difference was observed in corresponding cultivated soil Se between the two areas (P = 0.993). The calculation of Se transfer factors indicated that the restricting step for Se translocation was from soil to root. Water-soluble, exchangeable and fulvic acid-bound Se fractions in the soil are key species dominating in this transfer process, according to their significant correlations with root Se. Se transfer from soil to root significantly increases as the pH value of soil increases (P = 0.007), and soil organic matter content decreases (P = 0.019). The information obtained may have considerable significance for proposing effective agricultural measures to increase grain Se in KBD endemic areas.

[Exposure levels of lead, selenium, arsenic and mercury in brick-teas from main producing areas in China].

OBJECTIVE: To study the levels of Pb, Se, As and Hg in brick-teas from main producing areas in China and evaluate the safety. METHODS: A total of 31 samples of brick tea from seven provinces where minority nationalities were accustomed to drinking a large quantity of brick tea were collected, Pb concentrations were determined by inductively coupled plasma-mass spectrometry, and concentrations of As, Se, Hg were detected by hydride generation atomic fluorescence spectrometry. The data were analyzed by SPSS 22. 0 software. RESULTS: The average lead levels in brick tea was 6. 232 mg/kg, which exceeded the limit standard of GB 2762-2012. There was a great difference of Pbconcentrations among the various kinds of brick tea producing in different provinces, and the lower Pb concentrations detected in Tuo tea and Puerh tea producing in Yunnan Province, was 1. 337 mg/kg, and the highest determined in Kang brick producing in Sichuan Province, was 9. 998 mg/kg. In addition, the concentrations of As and Hg were all below the limit standard of NY 659-2003. For people accustomed to drinking brick tea for a long term, the average intake amounts of Pb, As, Hg through brick tea contributed 13. 63%, 1. 71% and 0. 29% to dietary Pb, As, Hg of the provisional tolerable weekly intake( PTWI) recommended by Joint FAO/WHO Expert Committee of Food Additives( JECFA) which was in safe range. Otherwise, the daily selenium intake through brick tea was 0. 188 µg, which contributed 0. 38% to the selenium recommended nutrient intake( RNI) by Chinese Nutrition Society. CONCLUSION: Excessive levels of lead in the brick tea is prominent. As, Hg and Se in brick tea are in low exposure level.

Hair Selenium Levels of School Children in Kashin-Beck Disease Endemic Areas in Tibet, China.

Previous studies have shown that the selenium (Se) deficiency is an important factor for the etiology of Kashin-Beck disease (KBD). Although KBD is presently controlled in most regions of China, it is still active in the Tibetan Plateau. The present study aimed to assess the nutritional status of selenium in school children by using the Se level in hair as a biomarker in KBD endemic areas of Lhasa in Tibet, China. Hair samples of 155 school children aged 6-15 years were collected in both KBD areas and non-KBD areas of Lhasa in 2013. The Se level in the hair samples was determined by inductive coupled plasma mass spectrometry (ICP-MS). The average concentration of Se in children's hair was 0.232 µg/g in KBD areas of Lhasa, which was significantly higher than the data reported decades ago. A significant difference in hair Se was observed between the boys (0.255 µg/g) and the girls (0.222 µg/g) in the studied KBD areas (P < 0.01, Mann-Whitney U test), but hair Se did not vary by age or region. School children in KBD endemic areas in Lhasa likely have improved Se status as a result of high Se content staple food substitution with the enforcement of Free Education Policy and Nutrition Improvement Plan in Tibet. Nevertheless, there were still 20.3 % of students with low Se status (hair Se <0.20 µg/g), which showed that Se status of school children was also partly affected by low Se environment in KBD endemic areas of Lhasa.

Speciation, distribution, and bioavailability of soil selenium in the Tibetan Plateau Kashin-beck disease area-a case study in Songpan County, Sichuan Province, China.

To clarify the relationship between the soil selenium distribution and its bioavailability with the distribution of Kashin-Beck disease (KBD) endemic areas on the eastern edge of the Tibetan Plateau, samples of natural soil (0-20 cm), cultivated topsoil, and main crops of the region (highland barley) were collected at different altitudes according to topographical and geomorphological features in both KBD and non-KBD areas of Songpan County. These samples were used for determination and analysis of total selenium content in soil and highland barley and available selenium that can be absorbed and utilized by plants. The results showed that the average total selenium content of natural and cultivated topsoil in KBD areas was lower than that in non-KBD areas (natural soil, P = 0.061; cultivated soil, P = 0.002), which is in agreement with the geographical distributions of selenium in other KBD-affected areas. However, the total soil selenium content exhibits certain micro-spatial distribution features, namely, the total selenium content in some endemic areas was significantly higher than that of non-KBD areas. This result was contrary to the general distribution that total selenium content in a KBD-affected area is lower than that in a non-KBD area. We further studied the extraction rate and content of soil selenium in six different fractions. The results indicated that the content and extraction rate of available selenium in KBD-affected areas were significantly lower than those in non-KBD areas. There is a distinct positive correlation between plant-available selenium and highland barley selenium (r = 0.875, P = 0.001) and a distinct negative correlation with altitude (r = -0.801, P = 0.010). Therefore, in KBD endemic areas, the selenium content in crops decreases as the available selenium content in soil decreases and is closely related to the geographical environment features (such as altitude and precipitation). These results suggest that the soil available selenium and ecological features are important factors that restrict the dietary selenium flux for residents in KBD endemic areas of the Tibetan Plateau, providing a theoretical and experimental basis for implementing agricultural measures to regulate the ecological cycle of the selenium flux in the KBD endemic area.

Levels of Cd, Pb, As, Hg, and Se in hair of residents living in villages around Fenghuang polymetallic mine, southwestern China.

Heavy metal levels in hair of residents living in villages around Fenghuang mine were investigated. Samples belonging to mine areas showed the highest values, with mean concentrations (mg kg(-1)) of 0.17 for Cd, 8.67 for Pb, 0.11 for As, 2.19 for Hg, and 0.64 for Se. Significant correlations (p < 0.01) were found between Cd-Pb, Cd-As, Pb-As, and Se-Hg. There is no significant difference in any of the elements among age groups. However, significant differences in Cd and Pb levels were found between genders. Results revealed that children and females were more susceptible to Cd and Pb exposure.

Environmental selenium in the Kaschin-Beck disease area, Tibetan Plateau, China.

Now, there is a decreasing trend for the prevalence rate of Kaschin-Beck disease (KBD) in most parts of China, but the disease is still active and severe in the Tibetan Plateau for some reason. To further explore the role of selenium in the occurrence of KBD, We collected samples including drinking water, cultivated topsoil, Highland Barley grains, and tsamba in Rangtang County and Aba County, Sichuan Province and determined concentrations of selenium by Hydride Generation Atomic Fluorescence Spectrometry. Levels of selenium in the environment were analyzed in detail. Selenium in the soil-plant-food system and their relationship with prevalence rate of KBD were also discussed. The results indicate: (a) the levels of environmental selenium are very low and the study area belongs to a selenium-deficient ecological landscape; (b) the KBD becomes much more severe with decreasing environmental selenium under the selenium-deficient condition. Namely, the lower the environmental selenium is, the more severe the disease is; (c) soil selenium deficiency plays a critical role for the prevalence of local KBD, and more factors inducing selenium deficiency should be more concerned in the future.

Quantification and comparison of soil elements in the Tibetan Plateau Kaschin-Beck disease area : a case study in Zamtang County, Sichuan Province, China.

The prevalence rate of Kaschin-Beck disease (KBD) in most parts of China is currently decreasing, but the disease is still active and severe on the Tibetan Plateau. Soil samples including the surface layer (0-20 cm) and the subsurface layer (20-40 cm) in the cultivated and natural soil profiles were collected, and the mechanical composite and total concentration of arsenic, cobalt, copper, iron, mercury, manganese, molybdenum, selenium, and zinc were determined. Concentrations of arsenic, iron, manganese, copper, and selenium in the surface soil were lower than those in the subsurface soil. The same was true of physical clay in the soil profiles. However, there were no significant differences between the different soil layers. The concentrations of selenium, molybdenum, and mercury were somewhat lower compared with the average concentrations of soils in China. Deficiencies of molybdenum and selenium both play a critical role in occurrence of KBD, but whether or not soil mercury at a low level contributes to KBD is still unclear. A correlation analysis of soil elements showed that there is a positive correlation between iron, cobalt, and manganese due to their similar chemical characteristics. Selenium concentrations in soil as well as the physical clay and iron descend with the deterioration of KBD, but mercury concentrations in soil ascend with the aggravation of the disease. The results show that selenium deficiencies greatly influence the disease, and a deficiency of molybdenum is likely another important factor in inducing KBD. Moreover, determining whether low levels of soil mercury contribute to KBD should be investigated in the future.

Fluoride in drinking water, brick tea infusion and human urine in two counties in Inner Mongolia, China.

The objective of this study was to detect the fluoride level in the drinking water and the urine of habitants aged 16-55 years living in Inner Mongolia China. Furthermore, fluoride concentration of the brick tea infusion samples which were drunk by Mongolia herdsmen in everyday life living in SumuErga village of Ejin Horo Banner, Inner Mongolia China was also determined. A total of 117 participants (61 female and 56 male) were recruited from two counties for a cross-sectional study on health effects of chronic fluoride exposure from drinking water and drinking brick tea infusion. The fluoride concentration in drinking water, urine and brick tea infusion samples were determined using fluoride ion selective electrode method obtained from the Ministry of Health of the People's Republic of China. The average fluoride concentration in drinking water samples was 0.32+/-0.01 mg/L at AretengXire town of Ejin Horo Banner, 0.70+/-0.19 mg/L at SumuErga village of Ejin Horo Banner, and 2.68+/-1.15 mg/L at ZhalaiNuoer district of Manzhouli city. The average fluoride concentration in brick tea infusion samples which collected from Mongolia herdsmen at SumuErga village of Ejin Horo Banner was 1.81+/-1.09 mg/L. The average urinary fluoride concentration at AretengXire town of Ejin Horo Banner was 0.59+/-0.48 mg/L, at SumuErga village of Ejin Horo Banner was 1.45+/-0.93 mg/L and at ZhalaiNuoer district of Manzhouli city was 3.06+/-1.53 mg/L. The higher fluoride levels in the urine of participants may be associated to higher fluoride in drinking water at ZhalaiNuoer of Manzhouli city. However, drinking brick tea infusions with higher fluoride may be the cause of the higher fluoride contents in the Mongolia herdsmen's urine.