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.

Assessing gestational exposure to trace elements in an area of unconventional oil and gas activity: comparison with reference populations and evaluation of variability.

BACKGROUND: Located in Northeastern British Columbia, the Montney formation is an important area of unconventional oil and gas exploitation, which can release contaminants like trace elements. Gestational exposure to these contaminants may lead to deleterious developmental effects. OBJECTIVES: Our study aimed to (1) assess gestational exposure to trace elements in women living in this region through repeated urinary measurements; (2) compare urinary concentrations to those from North American reference populations; (3) compare urinary concentrations between Indigenous and non-Indigenous participants; and (4) evaluate inter- and intra-individual variability in urinary levels. METHODS: Eighty-five pregnant women participating in the Exposures in the Peace River Valley (EXPERIVA) study provided daily spot urine samples over 7 consecutive days. Samples were analyzed for 20 trace elements using inductively-coupled mass spectrometry (ICP-MS). Descriptive statistics were calculated, and inter- and intra-individual variability in urinary levels was evaluated through intraclass correlation coefficient (ICC) calculation for each trace element. RESULTS: When compared with those from North American reference populations, median urinary levels were higher in our population for barium (~2 times), cobalt (~3 times) and strontium (~2 times). The 95th percentile of reference populations was exceeded at least 1 time by a substantial percentage of participants during the sampling week for barium (58%), cobalt (73%), copper (29%), manganese (28%), selenium (38%), strontium (60%) and vanadium (100%). We observed higher urinary manganese concentrations in self-identified Indigenous participants (median: 0.19 µg/g creatinine) compared to non-Indigenous participants (median: 0.15 µg/g of creatinine). ICCs varied from 0.288 to 0.722, indicating poor to moderate reliability depending on the trace element. SIGNIFICANCE: Our results suggest that pregnant women living in this region may be more exposed to certain trace elements (barium, cobalt, copper, manganese, selenium, strontium, and vanadium), and that one urine spot sample could be insufficient to adequately characterize participants' exposure to certain trace elements. IMPACT STATEMENT: Unconventional oil and gas (UOG) is an important industry in the Peace River Valley region (Northeastern British Columbia, Canada). Information on the impacts of this industry is limited, but recent literature emphasizes the risk of environmental contamination. The results presented in this paper highlight that pregnant women living near UOG wells in Northeastern British Columbia may be more exposed to some trace elements known to be related to this industry compared to reference populations. Furthermore, our results based on repeated urinary measurements show that one urine sample may be insufficient to adequately reflect long-term exposure to certain trace elements.

Variability and Seasonal Change of Urinary Selenium, Molybdenum, and Iodine Excretion in Healthy Young Japanese Adults.

Selenium (Se), molybdenum (Mo), and iodine (I) are essential trace elements or nutrients and their adequate intake is essential for human health. These elements in foods are easily absorbed from the digestive tract and excreted predominantly into the urine, and their nutritional status is reflected in urinary excretion; however, information on the variability of urinary excretion is limited. To characterize the urinary Se, Mo, and I concentrations and their intra- and inter-individual coefficients of variation (CV), correlation, and seasonal change, spot urine samples were collected from 24 healthy university students, 10 males and 14 females, with the mean age of 20.6 years, for 10 consecutive days in each of the four seasons according to a defined schedule of an interval of 3 months throughout 1 year. The median Se, Mo, and I concentrations for all urine samples (n = 947) were 52.8, 127.0, and 223 µg/L, respectively. The Se and Mo intakes were highest in summer and lowest in spring, while the I intake was highest in autumn and lowest in summer. In all three elements, the intra-individual CVs were smaller than their inter-individual CVs. The log-transformed intra- and inter-individual CVs were 10.5 and 14.7% for Se, 12.3 and 15.1% for Mo, and 15.5 and 18.1% for I. There was no gender difference in Se and I concentrations, while Mo and Mo/Cr values in males were higher than those in females. Our results suggest adequate nutritional status of Se, Mo, and I with a relatively smaller variability of dietary intake except for I in this population.

Trimethylselenonium ion determination in human urine by high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry optimization of the hydride generation step.

This work describes the intricacies of the determination of the trimethylselenonium ion (TMSe) in human urine via high-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). By definition, this technique requires that the separated TMSe can be online converted into a volatile compound. Literature data for the determination of TMSe via the hydride generation technique are contradictory; i.e., some authors claim that direct formation of volatile compounds is possible under reduction with NaBH4, whereas others reported that a digestion step is mandatory prior to conversion. We studied and optimized the conditions for online conversion by varying the mobile phase composition (pyridine, phosphate, and acetate), testing different reaction coils, and optimizing the hydride generation conditions, although technically no hydride (H2Se) is formed but a dimethylselenide (DMSe). The optimized conditions were used for the analysis of 64 urine samples of 16 (unexposed) volunteers and the determination of low amounts of TMSe (LOD = 0.2 ng mL-1). Total (specific gravity-corrected) selenium concentrations in the urine samples ranged from 7.9 ± 0.7 to 29.7 ± 5.0 ng mL-1 for individual volunteers. Four volunteers were characterized as TMSe producers (hINMT genotype GA) and 12 were non-producers (hINMT genotype GG). Urine of TMSe producers contained 2.5 ± 1.7 ng mL-1 of TMSe, compared to 0.2 ± 0.2 ng mL-1 for non-producers.

The impact of essential and toxic elements on cardiometabolic risk factors in adults and older people.

BACKGROUND AND AIM: Evidence suggests an association between essential and toxic elements and the worsening of cardiometabolic risk factors. This study aimed to investigate the concentrations of zinc, copper, selenium, arsenic, cadmium, and mercury and their relationship with cardiometabolic risk factors in adults and older people. METHODS: This cross-sectional study was carried out with 112 adults with a mean age of 59 (sd 14) years old and a BMI of 29.30 (sd 5.11) Kg/m2. The subject's weight and height were measured for body mass index (BMI) calculation, classified according to the cut-off points recommended by the World Health Organization (WHO). We evaluated sociodemographic, clinical, lifestyle, waist circumference - WC, visceral adiposity index - VAI, glycemic lipid profile, blood pressure, and high-sensitive C-reactive protein (hs-CRP). Cardiovascular risk was defined by The Global Risk Score (GRS) score. Plasma zinc, selenium, copper levels, urinary arsenic, cadmium, and mercury levels were measured using the inductively coupled plasma mass spectrometry technique (ICP-MS). RESULTS: There was a negative association between urinary arsenic and VAI (ß - 0.03, p < 0.01), triglycerides (ß - 1.10, p < 0.01), and VLDL cholesterol (ß - 0.14, p = 0.02). Plasma copper and copper/zinc ratio were positively associated with fasting glucose and hs-CRP (ß 0.38, p < 0.01; ß 36.02, p = 0.01, ß 0.004, p < 0.01, ß 0.68, p < 0.001, respectively). Urinary arsenic (ß - 0.14, p = 0.04) and cadmium (ß - 36.42, p = 0.04) were negatively associated with systolic blood pressure. Also, urinary cadmium was negatively associated with diastolic blood pressure (ß - 21.55, p = 0.03), and urinary mercury showed an opposite behavior (ß 1.45, p = 0.03). CONCLUSION: Essential and toxic elements in urine and plasma could be potential biomarkers for cardiovascular risk factors. A healthy lifestyle should be adopted; in addition, government policies should be developed to guarantee sustainable production and a safe environment.

Impact of modernization on urinary concentrations of arsenic, cadmium, lead, and selenium in rural residents of Northern Laos.

OBJECTIVES: The impacts of modernization on toxic heavy metal exposure and essential trace element intake in indigenous populations of subsistence societies are unknown. We assessed urinary trace element concentrations in rural residents of Northern Laos and examined associations with levels of modernization. METHODS: A cross-sectional study was conducted comprising 380 residents of three villages in Northern Laos with different levels of modernization. We surveyed general characteristics and measured the weight and height of 341 participants. Arsenic, cadmium, lead, and selenium concentrations were measured in spot urine samples by inductively coupled plasma mass spectrometry. We examined associations between urinary trace element concentrations and variables related to modernization (village, roofing material, possessions index [total number of possessions], and body mass index [BMI]) using multilevel analyses with household as a random effect, after adjusting for sex, age, and smoking status. RESULTS: Urinary concentrations of arsenic and cadmium were high, while those of lead and selenium were low in comparison to previous reports of populations in non-contaminated regions or without excess/deficiency. We observed associations between urinary trace element concentrations and village-level modernization: lead and selenium concentrations were higher in more modernized villages and cadmium concentration was highest in the least modernized village. Urinary arsenic concentration was not predicted by the modernization level of a village, although we observed significant differences among villages. In addition, urinary selenium concentration was higher in participants inhabiting more modernized houses. CONCLUSION: Modernization of villages may impact toxic heavy metal exposure and selenium intake in rural residents of Northern Laos.

Alcohol Consumption Moderated the Association Between Levels of High Blood Lead or Total Urinary Arsenic and Bone Loss.

Metal exposure and lifestyle are important risk factors for osteoporosis. Our study aimed to investigate the association between red blood cell lead and cadmium, total urinary arsenic, and plasma selenium levels and bone mineral density (BMD). In addition, we explored whether alcohol and coffee consumption modified the association between BMD and metals and metalloids. In total, 437 participants who underwent adult or senile physical examinations were recruited. Bone loss was defined as a calcaneus BMD T-score of <-1. Blood cadmium and lead and plasma selenium levels were measured using inductively coupled plasma mass spectrometry. Levels of urinary arsenic species were determined using high-performance liquid chromatography-hydride generator-atomic absorption spectrometry. The total urinary arsenic level was defined as the sum of the levels of urinary arsenic species. The BMD T-scores decreased significantly with increasing blood lead levels. The BMD T-scores also showed a downward trend with increasing total urinary arsenic levels. The odds ratio (OR) and 95% confidence interval (CI) for bone loss in patients with blood lead levels >57.58 versus 35.74 µg/dL were 1.98 and 1.17-3.34. In addition, the greater the lead or arsenic exposure and alcohol intake was the higher the OR for bone loss with multivariate ORs of 2.57 (95% CI 1.45-4.56) and 2.96 (95% CI 1.67-5.22), respectively. To the best of our knowledge, this study is the first to demonstrate that high total urinary arsenic or blood lead levels and frequent or occasional alcohol consumption had a significant multiplicative interaction for increasing the OR for bone loss.

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries.

BACKGROUND: Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam). METHODS: This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index. RESULTS: The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 µg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them. CONCLUSIONS: Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Selenium status and oxidative stress in obese: Influence of adiposity.

BACKGROUND: Selenium deficiency appears to limit antioxidant defense in obese individuals. This study evaluated the association between adiposity indices, selenium status, and oxidative stress in obese women. METHODS: This was a cross-sectional study involving 139 women who were divided into the following two groups: the case group (obese women, n = 63) and the control group (normal-weight women, n = 76). Plasma, erythrocyte, and urinary selenium levels were determined using inductively coupled plasma optical emission spectrometry. Body weight, height, waist circumference, hip circumference and neck circumference were measured. Body mass index, waist/height ratio, conicity index, body fat index, body adiposity index, body circularity index, and visceral adiposity index were calculated. Plasma levels of thiobarbituric acid reactive substances were determined. The erythrocyte glutathione peroxidase activity was determined using an automatic biochemical analyzer and Ransel kit. RESULTS: Obese women had selenium deficiency characterized by reduction in plasma and erythrocyte concentrations (P < .001). The urinary selenium excretion was higher in the case group compared to the control group (P < .001). Adiposity indices values and plasma concentrations of thiobarbituric acid reactive substances were significantly elevated in obese women (P < .001). There was a significant association between adiposity indices and selenium status (P < .001), and between erythrocyte selenium and erythrocyte glutathione peroxidase activity (P < .001). CONCLUSION: Obese women evaluated in the study have reduced plasma and erythrocyte concentrations of selenium and an increased urinary excretion of selenium. The correlation analysis reveals an association between intra-abdominal fat accumulation and selenium metabolism and oxidative stress.

Prenatal metal mixtures and child blood pressure in the Rhea mother-child cohort in Greece.

BACKGROUND: Child blood pressure (BP) is predictive of future cardiovascular risk. Prenatal exposure to metals has been associated with higher BP in childhood, but most studies have evaluated elements individually and measured BP at a single time point. We investigated impacts of prenatal metal mixture exposures on longitudinal changes in BP during childhood and elevated BP at 11 years of age. METHODS: The current study included 176 mother-child pairs from the Rhea Study in Heraklion, Greece and focused on eight elements (antimony, arsenic, cadmium, cobalt, lead, magnesium, molybdenum, selenium) measured in maternal urine samples collected during pregnancy (median gestational age at collection: 12 weeks). BP was measured at approximately 4, 6, and 11 years of age. Covariate-adjusted Bayesian Varying Coefficient Kernel Machine Regression and Bayesian Kernel Machine Regression (BKMR) were used to evaluate metal mixture impacts on baseline and longitudinal changes in BP (from ages 4 to 11) and the development of elevated BP at age 11, respectively. BKMR results were compared using static versus percentile-based cutoffs to define elevated BP. RESULTS: Molybdenum and lead were the mixture components most consistently associated with BP. J-shaped relationships were observed between molybdenum and both systolic and diastolic BP at age 4. Similar associations were identified for both molybdenum and lead in relation to elevated BP at age 11. For molybdenum concentrations above the inflection points (~ 40-80 µg/L), positive associations with BP at age 4 were stronger at high levels of lead. Lead was positively associated with BP measures at age 4, but only at high levels of molybdenum. Potential interactions between molybdenum and lead were also identified for BP at age 11, but were sensitive to the cutoffs used to define elevated BP. CONCLUSIONS: Prenatal exposure to high levels of molybdenum and lead, particularly in combination, may contribute to higher BP at age 4. These early effects appear to persist throughout childhood, contributing to elevated BP in adolescence. Future studies are needed to identify the major sources of molybdenum and lead in this population.

Selenium dietary intake, urinary excretion, and toxicity symptoms among children from a coal mining area in Brazil.

Selenium (Se) is necessary for several physiological functions in the human body; however, high concentrations of this element in coal mining areas raise the possibility of Se-related health risks. Children are much more vulnerable and at risk to environmental hazards than adults. The largest coal mining area of Brazil is located in the city of Candiota, where previous studies point to significant urinary Se concentrations among children. Food intake is the main Se source. The study aimed to evaluate dietary Se intake, as well as urinary Se excretion and classic symptoms of Se intoxication among children from Candiota and a control city in the same region. A cross-sectional study was carried out, with participation from 242 children between 6 and 12 years old in two cities in Rio Grande do Sul state, Brazil. Socioeconomic variables, dietary intake, and Se toxicity symptoms were evaluated through a structured questionnaire, and urinary Se levels were measured. Children from both cities had normal levels of Se intake and urinary excretion; however, children from Candiota had significantly higher levels of Se in both parameters in relation to the control city, especially for Se urinary excretion. There was low prevalence of Se toxicity symptoms. We conclude that coal mining activities may increase Se intake in children and consequently its urinary excretion.

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries

BACKGROUND@#Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam).@*METHODS@#This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index.@*RESULTS@#The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 μg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them.@*CONCLUSIONS@#Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Influence of a high-temperature programme on serum, urinary and sweat levels of selenium and zinc.

INTRODUCTION: The effect of hyperthermia on the antioxidant system in the human organism is well known. AIM: The objective of this study was to observe the effects of heat on the concentration of Se and Zn, elements related to antioxidant systems. METHODS: Twenty-nine subjects voluntarily participated in this study. They were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). All of them underwent two incremental tests until exhaustion in normothermia (22 °C, 20-40%RH) and hyperthermia (42 °C, 20-40%RH). EG experienced nine sessions of repeated heat exposure at high temperatures (100 °C, 20%RH) for three weeks (HEHT). After the intervention, the initial measurements were repeated. Urine and blood samples were collected before and after each test. Additionally, sweat samples were collected after tests in hyperthermia. RESULTS: There were no significant changes in serum. An increase in the elimination of Zn and Se in EG was observed in urine after HEHT (p < .05). The elimination of Zn by sweating decreased after HEHT in EG (p < .05). CONCLUSIONS: Exposure to heat at high temperatures increases the urinary excretion of Se and Zn.

Chirality-Driven Transportation and Oxidation Prevention by Chiral Selenium Nanoparticles.

The chirality of nanoparticles directly influences their transport and biological effects under physiological conditions, but the details of this phenomenon have rarely been explored. Herein, chiral GSH-anchored selenium nanoparticles (G@SeNPs) are fabricated to investigate the effect of their chirality on their transport and antioxidant activity. G@SeNPs modified with different enantiomers show opposite handedness with a tunable circular dichroism signal. Noninvasive positron emission tomography imaging clearly reveals that 64 Cu-labeled l-G@SeNPs experience distinctly different transport among the major organs from that of their d-and dl-counterparts, demonstrating that the chirality of the G@SeNPs influences the biodistribution and kinetics. Taking advantage of the strong homologous cell adhesion and uptake, l-G@SeNPs have been shown here to effectively prevent oxidation damage caused by palmitic acid in insulinoma cells.

Acute human toxicity and mortality after selenium ingestion: A review.

BACKGROUND: Although selenium is an essential element for humans, acute toxicity has been reported after high oral exposure. METHODS: The published literature on the acute toxicity of oral selenium was gathered and reviewed. RESULTS: Reported symptoms and signs include abdominal symptoms, such as vomiting, diarrhea, pain, and nausea, as well as garlic-like odor on the breath. In cases of severe toxicity, cardiac and pulmonary symptoms may develop and ultimately lead to mortality. Mortality has been described after the ingestion of gun bluing solutions, which often contain selenous acid among other potentially toxic substances. Mortality has also been reported after the ingestion of other forms of selenium. Ingested doses associated with mortality are in the range of 1-100 mg Se/kg body weight. Blood levels associated with mortality are above 300 µg Se/L (normal level: 100 µg/L), whereas urinary levels associated with the same endpoint are above170 µg Se/L (normal level: 20-90 µg/L). CONCLUSION: The acute toxicity associated with oral selenium ingestion and the blood and urinary levels of selenium in different cases of poisonings were reviewed. Mortality is a risk of acute selenium poisoning. Concentrations of selenium in blood and urine samples in non-fatal cases are close to those observed in fatal cases.

Evaluation of urinary selenium as a biomarker of human occupational exposure to elemental and inorganic selenium.

PURPOSE: Selenium (Se) is an essential trace element, which however, exhibits a narrow safe range of intake. Selenium also occurs at several workplaces, which results in an inhalative selenium exposure of the employees. Thus, an efficient exposure assessment strategy is demanded. The most established parameter, selenium in plasma, mostly consists of protein-bound selenium. This study aimed to investigate urinary total selenium (Se-U) as an additional biomarker of recent human occupational exposure to elemental and inorganic selenium. METHODS: Pre- and post-shift urine samples from employees with exposure to selenium-containing dust were analyzed to total selenium and compared with Se levels in urine samples from controls without occupational exposure to selenium as well as correlated with the recent ambient Se exposure by personal air monitoring. RESULTS: Se-U in post-shift samples was considerably increased compared to the levels in pre-shift samples as well as to the controls. However, Se-U in pre-shift urine was elevated compared to the Se-U in controls too. Se-U in post-shift urine and even better the shift increment in Se-U correlated with the air exposure of the present shift. A rough estimation by Se-U shift increment and external exposure accounted for an inhalative resorption rate of about 1%. CONCLUSION: Our data indicate that Se-U can display the exposure. Pre-shift Se-U levels may be based on previous exposure and indicate a slow urinary elimination kinetics. The results hint for a rather low resorption rate of selenium and inorganic selenium compounds via the lung.

Serum, erythrocyte and urinary concentrations of iron, copper, selenium and zinc do not change during an incremental test to exhaustion in either normothermic or hyperthermic conditions.

AIM: The aim of this study was to evaluate the effect of the performance of an incremental exercise test until exhaustion in normothermic and hyperthermic conditions on serum, erythrocyte and urine concentrations of Iron (Fe), Copper (Cu), Selenium (Se) and Zinc (Zn). METHODS: Nineteen adult males (age: 22.58 ±â€¯1.06 years) performed two maximum incremental exercise tests on a cycloergometer in normothermia (22 ±â€¯2 °C) and hyperthermia (42±2 °C) separated by 48 h. Urine, serum and erythrocyte samples were collected before and after each test. RESULTS: Serum Se (p < 0.01) and Cu (p < 0.05) levels were altered after each test, but the significance disappeared with the correction for haematocrit. The rest of the values did not undergo alterations in either condition. CONCLUSIONS: It seems that a higher stimulus is necessary to obtain changes in these minerals. The study reveals the need to correct serum concentrations concerning possible changes in these volumes after an acute effort.

Global survey of urinary selenium in children: A systematic review.

BACKGROUND: Selenium (Se) is an essential element in the human body that plays an important role in numerous fundamental physiological functions. However, the distribution of Se in the environment varies widely resulting in this element being available in a large concentration range in the ecosystem, and thus, in the human body. Urinary Se is a biomarker considered to be involved in adaptive mechanisms that help prevent health problems. OBJECTIVES: The purpose of the present study was to conduct a systematic review to identify studies reporting the status of urinary Se in healthy children and create a global map. METHODS: A literature search was conducted using MEDLINE (United States National Library of Medicine), Web of Science, Toxicology Bibliographic Information (TOXLINE), Latin-American and Caribbean Literature on Health Sciences (LILACS), and the grey literature. This study was registered in PROSPERO (international prospective register of systematic reviews) and was conducted in accordance with the PRISMA guidelines. RESULTS: We identified 322 relevant articles, out of which 15 were included in this systematic review. The study identified a total of 4038 healthy children worldwide with urinary Se concentrations from 7.7 to 145.0 µg/L. CONCLUSION: This is a pioneering study that provides evidence for the presence of Se in the urine of healthy children; we have shown that the available data is restricted to a small number of individuals and specific groups. Furthermore, there is a lack of information on urinary Se, especially in Latin America, Africa, and Asia.

Estimation of daily selenium intake by 3- to 5-year-old Japanese children based on selenium excretion in 24-h urine samples.

To evaluate the daily Se intake of 3- to 5-year-old Japanese children, we used seventy-two urine samples collected from fifty-three children (twenty-seven male and twenty-six female) from two cities in Miyagi prefecture, Japan. For measuring low Se concentrations with high precision, accuracy and rapidity in the 24-h urine samples, we developed an instrumental neutron activation analysis (INAA) method, that is without any chemical separation, using the short-lived 77mSe (t1/2 = 17·4 s) nuclide. The estimated Se intake of the fifty-three children was 51·5 (sd 30·2) µg/d (geometric mean: 42·7 µg/d). Ten subjects (three male and seven female), successfully provided 24-h urine samples over two or three consecutive days; their Se intake was 37·4 (sd 5·9) µg/d. Based on the logarithmically transformed data of these ten subjects, the ratio of intra-/inter-individual variances of usual Se intake was 16·7 (28·0/1·7) and geometric mean was 27·7 µg/d. The 5th to 95th percentile of usual Se intake of these ten subjects was 17·5 to 40·4 µg/d, which ranged between the recommended dietary allowance and tolerable upper intake level of Se by the Dietary Reference Intakes for Japanese (2015).

Reproducibility of essential elements chromium, manganese, iron, zinc and selenium in spot samples, first-morning voids and 24-h collections from healthy adult men.

Evaluation of Cr, Mn, Fe, Zn and Se in humans is challenged by the potentially high within-individual variability of these elements in biological specimens, which are poorly characterised. This study aimed to evaluate their within-day, between-day and between-month variability in spot samples, first-morning voids and 24-h collections. A total of 529 spot urine samples (including eighty-eight first-morning voids and 24-h collections) were collected from eleven Chinese adult men on days 0, 1, 2, 3, 4, 30, 60 and 90 and analysed for these five elements using inductively coupled plasma-MS. Intraclass correlation coefficients (ICC) were utilised to characterise the reproducibility, and their sensitivity and specificity were analysed to assess how well a single measurement classified individuals' 3-month average exposures. Serial measurements of Zn in spot samples exhibited fair to good reproducibility (creatinine-adjusted ICC = 0·47) over five consecutive days, which became poor when the samples were gathered months apart (creatinine-adjusted ICC = 0·33). The reproducibility of Cr, Mn, Fe and Se in spot samples was poor over periods ranging from days to months (creatinine-adjusted ICC = 0·01-0·12). Two spot samples were sufficient for classifying 60 % of the men who truly had the highest (top 33 %) 3-month average Zn concentrations; for Cr, Mn, Fe and Se, however, at least three specimens were required to achieve similar sensitivities. In conclusion, urinary Cr, Mn, Fe, Zn and Se concentrations showed a strong within-individual variability, and a single measurement is not enough to efficiently characterise individuals' long-term exposures.