Whole blood selenium content in healthy adults in the Czech Republic

Emerging evidence on selenoneine and its public health relevance in coastal populations: a review and case study of dietary Se among Inuit populations in the Canadian Arctic

Selenium is an essential mineral yet both deficiency and excess are associated with adverse health effects. Dietary intake of Se in humans varies greatly between populations due to food availability, dietary preferences, and local geological and ecosystem processes impacting Se accumulation into agricultural products and animal populations. We argue there is a need to evaluate and reconsider the relevance of public health recommendations on Se given recent evidence, including the metabolic pathways and health implications of Se. This argument is particularly pertinent for Inuit populations in Northern Canada, who often exceed dietary tolerable upper intake levels and exhibit very high whole blood Se concentrations due to their dependence on local country foods high in the newly discovered Se compound, selenoneine. Since selenoneine appears to have lower toxicity compared to other Se species and does not contribute to the circulating pools of Se for selenoprotein synthesis, we argue that total dietary Se or total Se in plasma or whole blood are poor indicators of Se adequacy for human health in these populations. Overall, this review provides an overview of the current evidence of Se speciation, deficiency, adequacy, and excess and implications for human health and dietary recommendations, with particular reference to Inuit populations in the Canadian Arctic and other coastal populations consuming marine foods.

The Associations of Selenoprotein Genetic Variants with the Risks of Colorectal Adenoma and Colorectal Cancer: Case–Control Studies in Irish and Czech Populations

Background: Selenium manifests its biological effects through its incorporation into selenoproteins, which play several roles in countering oxidative and inflammatory responses implicated in colorectal carcinogenesis. Selenoprotein genetic variants may contribute to colorectal cancer (CRC) development, as we previously observed for SNP variants in a large European prospective study and a Czech case–control cohort. Methods: We tested if significantly associated selenoprotein gene SNPs from these studies were also associated with CRC risk in case–control studies from Ireland (colorectal neoplasia, i.e., cancer and adenoma cases: 450, controls: 461) and the Czech Republic (CRC cases: 718, controls: 646). Genotyping of 23 SNPs (20 in the Irish and 13 in the Czechs) was performed by competitive specific allele-specific PCR (KASPar). Multivariable adjusted logistic regression was used to assess the associations with CRC development. Results: We found significant associations with an increased CRC risk for rs5859 (SELENOF) and rs2972994 (SELENOP) in the Irish cohort but only with rs4802034 (SELENOV) in the Czechs. Significant associations were observed for rs5859 (SELENOF), rs4659382 (SELENON), rs2972994 (SELENOP), rs34713741 (SELENOS), and the related Se metabolism gene variant rs2275129 (SEPHS1) with advanced colorectal neoplasia development. However, none of these findings retained significance after multiple testing corrections. Conclusions: Several SNPs previously associated with CRC risk were also associated with CRC or colorectal neoplasia development in either the Irish or Czech cohorts. Selenoprotein gene variation may modify CRC risk across diverse European populations, although the specific variants may differ.

Blood lead in children and associations with trace elements and sociodemographic factors

BACKGROUND

No safe blood lead concentration in children has been identified. Lead can affect nearly every system in the body and is especially harmful to the developing central nervous system of children. The aim of this study is to analyze blood lead in a population of children and its association with sociodemographic variables, biochemical parameters, copper, iron, selenium and zinc.

METHODS

We recruited 155 children (86 boys and 69 girls) with a mean age of 7.3 (SD:4.1). Blood lead and serum selenium concentrations were measured by electrothermal atomic absorption spectrometry. Serum copper and zinc concentrations were measured by flame atomic absorption spectrometry. Serum iron levels were determined by colorimetric assay. A risk exposure questionnaire for lead was administered to the participants.

RESULTS

The median blood lead level was 1.1 (IQR 0.7-1.6) μg/dL. Regarding risk exposure factors, the youngest children (<2 years) who played outdoors presented a median blood lead concentration of 1.1 μg/dL IQR: 0.48-1.48, compared to the median of 0.3 μg/dL IQR:0.2-0.48 in the children who stated they played at home (p = 0.024). Significant differences were also found when taking into account those parents who smoked (median 1.3 IQR 0.8-1.9 μg/dL vs 0.9 IQR 0.5-1.4 μg/dL of non-smokers, p = 0.002). Children who drank tap water had higher blood lead levels (median 1.2 IQR 0.7-1.6 μg/dL) than those who drank bottled water (median 0.7 IQR 0.2-1.3 μg/dL p = 0.014). In addition, children whose mothers had not finished school had higher blood lead levels (median 1.7 IQR 1.2-2.3 μg/dL) than those whose mothers had finished school (median 1.2 IQR 0.7-1.7 μg/dL) and those whose mothers had gone to university (median 0.9 IQR 0.5-1.4 μg/dL) p = 0.034. In the multivariate lineal regression analysis we continue to observe the association between mother's higher level of education and lower blood levels (p = 0.04) and the interaction between age and outdoor play (p = 0.0145).

CONCLUSIONS

In spite of the decline in blood lead concentrations, associated risk factors continue to exist in vulnerable populations such as children.

Prenatal selenium status, neonatal cerebellum measures and child neurodevelopment at the age of 18 months

OBJECTIVES

The aim of this study was to evaluate the association of maternal blood selenium (Se) levels and cord blood Se levels with neonatal cerebellum measures and child neurodevelopment at the age of 18 months. Moreover, to investigate whether the neonatal cerebellum measures could be used as a potential biomarker for selenium homeostasis during pregnancy.

STUDY GROUP AND METHODS

The study population consisted of 205 mother-child pairs from Croatian Mother and Child Cohort. Maternal blood and cord blood were obtained at delivery and selenium level was analyzed by Inductively Coupled Plasma Mass Spectrometry. Cranial ultrasonography examination was performed on 49 newborns - cerebellum length and width have been measured. Neurodevelopmental assessment of cognitive, language and motor skills were conducted on 154 children, using The Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III), at the age of 18 months.

RESULTS

The mean levels of selenium in maternal blood and cord blood were 92.6 ng/g and 97.0 ng/g, respectively. Maternal blood selenium levels were moderately and negatively correlated (r = -0.372; p = 0.008) with cerebellum length, while cord blood selenium levels were positively correlated with cerebellum width (r = 0.613; p = 0.007) among female children group. Maternal blood selenium levels were weakly and positively correlated (r = 0.176; p = 0.029) with child's cognitive abilities.

CONCLUSION

To the best of our knowledge, our study is the first one investigating the association between neonatal brain measures and selenium levels in mother-child pairs. Our results indicate that prenatal selenium intake correlated with cerebellum length and width measured by cranial ultrasonography. Hence, cerebellum may be used as a potential biomarker and a target "organ" for early detection of possible adverse effects of prenatal status to various micronutrients.

Selenium status in lactating mothers-infants and its potential protective role against the neurotoxicity of methylmercury, lead, manganese, and DDT

A total of 206 lactating mothers and their infants (3-12 months) were included in this study to evaluate postnatal exposure to neurotoxic pollutants such as methylmercury (MeHg), lead (Pb), manganese (Mn), dichlorodiphenyltrichloroethane (DDT) and its metabolites [dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE)] and their association with delayed neurological development and to explore the protective role of selenium (Se) against chemical neurotoxicity. Neurodevelopmental performance was evaluated using Denver Developmental Screening Test II and Parents' Evaluation of Developmental Status (PEDS). Multivariate log-binomial regression modeling was applied for both single and multiple exposures to chemicals using a principal component analysis that generated six principal components. Both mothers and their infants had been exposed to metals and DDT metabolites, with some exceeding the accepted permissible limits. The geometric means of MeHg, Pb, Mn, DDD, DDE and DDT levels in breast milk were 1.333, 45.327, 15.576, 0.069, 0.542 and 1.08 μg/l, respectively. A single-exposure model identified a high risk of reduced PEDS performance significantly associated with DDD in breast milk [relative risk (RR) = 1.484; 95% confidence interval (95%CI) = 1.091-2.019] and marginally significantly associated with Pb in the mothers' blood (RR = 2.164; 95%CI = 0.87-5.382). We did not find a protective role of Se in neurodevelopment due to its high levels in the mothers. Models of multi-chemical exposure indicated that Mn in blood and breast milk, Se in blood and Pb in the mothers' urine were marginally significantly associated with a high risk of reduced PEDS performance (RR = 0.424; 95%CI = 0.176-1.022). The use of multi-chemical exposure approach in early life risk assessments is important because it indicates real-world exposure. Our results were not conclusive because the sample size was small, so future studies examining the implications to health of the impact of prenatal/postnatal exposure to a mixture of chemicals in the Saudi population are merited.

Determinants of selenoneine concentration in red blood cells of Inuit from Nunavik (Northern Québec, Canada)

Selenium (Se) is a trace mineral essential to human health, and is especially abundant in marine foods consumed by Inuit populations in Nunavik (northern Quebec, Canada), leading to exceptionally high whole blood Se levels. While most epidemiological studies to date examine plasma or whole blood Se, little is known about the health implications of specific Se biomarkers (e.g. selenoproteins and small Se compounds). Selenoneine, a novel Se compound, is found in high concentrations in marine foods (and particularly beluga mattaaq) and the red blood cells (RBCs) of populations that consume them. We report here RBC selenoneine concentrations in a population of Inuit adults (n = 885) who participated in the Qanuippitaa? 2004 survey. Simple associations between RBC selenoneine and other Se and mercury (Hg) biomarkers were assessed using Spearman correlations and linear regressions. Wilcoxon ranksum tests were used to examine differences in biomarkers and characteristics between tertiles of RBC selenoneine concentration. A multiple linear regression analysis was used to determine factors (sociodemographic, lifestyle, and dietary) associated with RBC selenoneine concentrations. Selenoneine comprised a large proportion of whole blood Se and RBC Se in this population. Age and sex-adjusted geometric mean RBC selenoneine concentration was 118 μg/L (range: 1-3226 μg/L) and was much higher (p = 0.001) among women (150.3 μg/L) than men (87.6 μg/L) across all regions of Nunavik after controlling for age, region, and diet. RBC selenoneine was highly correlated with RBC Se (r_s = 0.96, p < 0.001) and whole blood Se (r_s = 0.89, p < 0.001), but only weakly correlated with plasma Se (r_s = 0.13, p < 0.001). Overall, increasing age (standardized β = 0.24), higher body-mass index (BMI; β = 0.08), female sex (β = 0.10), living in a Hudson Strait community (compared to Hudson Bay and Ungava Bay; β = 0.38), and consuming beluga mattaaq (g/day; β = 0.19) were positively associated with RBC selenoneine. Meanwhile, consumption of market meats (g/day; β = -0.07) was negatively associated with RBC selenoneine. RBC selenoneine is an important biomarker of Se dietary intake from local marine foods in Inuit populations. Further studies are needed to examine the health effects of selenoneine intake and the underlying mechanisms for sex differences among Inuit populations.

Associations and interactions between variants in selenoprotein genes, selenoprotein levels and the development of abdominal aortic aneurysm, peripheral arterial disease, and heart failure

Background

Little is known on the role of selenoprotein genes in cardiovascular disease. This study examines the associations of the SEPP1, SELENOS, TXNRD1, TXNRD2, GPX4, and SOD2 polymorphisms and selenoprotein P (SeP) and thioredoxin concentrations with the development of abdominal aortic aneurysm (AAA) and aortoiliac occlusive disease (AOID), as well as their influence on cardiac phenotype.

Methods

564 patients with AAA, 400 patients with AIOD, and 543 controls were enrolled and characterized for coronary artery disease, myocardial infarction, and systolic heart failure (HF) occurrence. In AAA, the coexistence of peripheral arterial disease (PAD) was examined. Genotypes were determined using TaqMan-based assays. Selenoprotein concentration was assessed using the ELISA method.

Results

The SELENOS rs34713741T, SEPP1 rs3877899A, and GPX4 rs713041T alleles were related to a 30–60% increase in the AIOD/PAD risk in the recessive or dominant model (all associations at P < .05). The SEPP1 rs3877899A allele was a protective factor for the development of AAA without concomitant PAD (OR = 0.68 for the dominant model, P = .014), but not AAA with concomitant PAD. The cumulative two-locus effects of selenoprotein genes on the AAA/AIOD risk were observed, including the multiplicative interaction between the SELENOS rs34713741T and GPX4 rs713041T alleles (both in the recessive model) affecting the AIOD risk (OR = 5.27, P = .001) and its clinical phenotype. Coexistence of HF in aortic diseases was related to both the SEPP1 rs7579A allele (OR = 1.83 for carriers, P = .013) and increased SeP concentrations; SeP level ≥8.5 mg/mL caused a 3.5-fold increase in the risk of HF. In AAA, SeP levels were correlated with BMI (r = -0.575, P < .0001).

Conclusions

Our results provide evidence that selenoprotein polymorphisms constitute a risk factor for HF and peripheral atherosclerosis, but prevent the development of AAA. Excessive weight might result in reduced antioxidant reserve efficiency in AAA. Validation studies are required to establish whether SeP concentration may be a marker for HF.

Relationship between serum selenium, sociodemographic variables, other trace elements and lipid profile in an adult Spanish population

INTRODUCTION

Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain.

MATERIALS AND METHODS

We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry.

RESULTS

The mean of serum selenium was 79.5μg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (β=0.223; CI 95%: 0.101-0.345), p<0.001; widowhood (β=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (β=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (β=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (β=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5μg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium <79.5μg/L.

CONCLUSIONS

Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows.

Plasma levels of selenium-containing proteins in Inuit adults from Nunavik

Selenium (Se) is highly abundant in marine foods traditionally consumed by Inuit of Nunavik (Northern Quebec, Canada) and accordingly, their Se intake is among the highest in the world. However, little is known regarding the biological implications of this high Se status in this Arctic indigenous population. We used a method combining affinity chromatography and inductively coupled plasma-mass spectrometry with quantification by post-column isotope dilution to determine total Se levels and concentrations of Se-containing proteins in archived plasma samples of Inuit adults who participated to the 2004 Nunavik Inuit Health Survey (N = 852). Amounts of mercury (Hg) associated with Se-containing proteins were also quantified. Results show that glutathione peroxidase 3 (GPx3), selenoprotein P (SelP) and selenoalbumin (SeAlb) represented respectively 25%, 52% and 23% of total plasma Se concentrations. In addition, small amounts of Hg co-eluted with each Se-containing protein and up to 50% of plasma Hg was associated to SelP. Total plasma Se concentrations (median = 139 μg L− 1; interquartile range (IQR) = 22.7 μg L− 1) were markedly lower and less variable than whole blood Se concentration (median = 261 μg L− 1, IQR = 166 μg L− 1). A non linear relation was observed between whole blood Se and plasma Se levels, with plasma Se concentrations leveling off at approximately 200 μg L− 1, whereas 16% and 3% of individuals exhibited whole blood concentrations higher than 500 μg L− 1 and 1000 μg L− 1, respectively. In contrast, a linear relationship was previously reported in communities consuming Brazil nuts which are rich Se, mainly present as selenomethionine. This suggests that a different selenocompound, possibly selenoneine, is present in the Arctic marine food chain and accumulates in the blood cellular fraction of Inuit.

The role of selenium in human conception and pregnancy

Selenium (Se) is a trace element essential for the appropriate course of vital processes in the human body. It is also a constituent of the active center of glutathione peroxidase that protects cellular membranes against the adverse effects of H2O2 lipid peroxides. Epidemiological surveys have demonstrated that selenium deficiency in the body may contribute to an increased risk for certain neoplasmic diseases (including colonic carcinoma, gastric carcinoma, pulmonary carcinoma and prostate carcinoma), as well as diseases of the cardiovascular, osseous and nervous systems. Apart from its cancer prevention and antioxidative activities, selenium protects the body against detrimental effects of heavy metals and determines the proper functioning of the immunological system. Furthermore, selenium plays a significant role in the undisturbed functioning of the reproductive system. Many studies have addressed correlations between its intake and fertility as well as disorders of procreation processes. Selenium deficiencies may lead to gestational complications, miscarriages and the damaging of the nervous and immune systems of the fetus. A low concentration of selenium in blood serum in the early stage of pregnancy has been proved to be a predictor of low birth weight of a newborn. A deficiency of this element may also cause infertility in men by causing a deterioration in the quality of semen and in sperm motility. For this reason, supplementation in the case of selenium deficiencies in the procreation period of both women and men is of utmost significance.

Hair selenium levels in hepatic steatosis patients

The purpose of this study was to assess hair selenium levels of liver patients suffering from hepatic simple steatosis and non-alcoholic steatohepatitis (NASH) in central areas of China. Selenium was measured by an atomic absorption spectrophotometer equipped with the hydride generation system. The levels of selenium in healthy individuals ranged between 0.3 and 0.9 μg/g, and mean hair selenium levels in the male population and female population were 0.59 ± 0.18 and 0.57 ± 0.15 μg/g, respectively. These concentrations did not vary significantly (P > 0.05) in relation to the gender. One hundred-eighteen individuals of both sexes aged between 15 and 60 years with hepatic simple steatosis and NASH were selected for this study. The mean and standard deviation of hair selenium concentrations observed in male and female patients with hepatic simple steatosis were 0.54 ± 0.16 and 0.50 ± 0.15 μg/g, respectively, while the mean and standard deviation of hair selenium concentrations observed in male and female patients with NASH were 0.40 ± 0.14 and 0.41 ± 0.12 μg/g. Analysis of t test showed a significant difference between NASH (P < 0.001) patients in hair selenium concentrations when compared with controls.

Mercury, arsenic and selenium exposure levels in relation to fish consumption in the Mediterranean area

In order to assess mercury (Hg), selenium (Se) and arsenic (As) exposure in the Mediterranean area, total mercury (THg), monomethylmercury (MeHg), Se and As levels were measured in umbilical cord blood and breast milk from Italian (n=900), Slovenian (n=584), Croatian (n=234) and Greek (n=484) women. THg, MeHg, As, and Se levels were also determined in blood samples of the same mothers from Italy and Croatia. In addition, THg and MeHg were determined in the same women's hair from all the countries involved in this study and As and Se levels were determined in the mother's urine samples from Italy, Croatia and Greece. Besides recording the consumption of other food items, the frequencies of fish consumption were assessed by detailed food frequency questionnaires, since fish represents an important source of Hg, Se and As in humans. The highest levels of THg and As were found in cord blood (Med((THg))=5.8 ng/g; Med((As))=3.3 ng/g) and breast milk (Med((THg))=0.6 ng/g; Med((As))=0.8 ng/g) from Greek women, while the highest Se levels were found in cord blood (Med=113 ng/g) from Italy. Significant linear correlations were found between Hg, Se and As in blood, cord blood and breast milk. In addition, significant relations were found between the frequencies of total fish consumption and biomarkers of As, MeHg and Se exposure, with the strongest Spearman rank coefficients between frequencies of total fish consumption and THg levels in cord blood (r(s)=0.442, p<0.001) or THg levels in hair (r(s)=0.421, p<0.001), and between frequencies of total fish consumption and As levels in cord blood (r(s)=0.350, p<0.001). The differences in Hg and As exposure between countries were probably due to different amounts of fish consumption and the consumption of different species of fish of different origin, while the highest Se levels in women from Italy were probably the consequence of the more frequent consumption of different non specific food items. Moreover, fish consumption, the possible common source of As, Hg and Se intake, could explain the correlations between the elements determined in cord blood, mother's blood or breast milk.

Trace elements in the blood of institutionalized elderly in the Czech Republic

Whole blood selenium, copper, zinc and manganese concentrations of 197 institutionalized senior citizens (46 males, 151 females) aged 61-100 years (mean age 83.6 years) were determined using atomic absorption spectrometry and inductively coupled plasma mass spectrometry from two localities in the Czech Republic (Prague and Teplice) from 2009 through 2011. Geometric means (GM) of whole blood selenium (B-Se), copper (B-Cu), zinc (B-Zn) and manganese (B-Mn) levels were 74.0 μg/l, 941.0 μg/l, 5898.0 μg/l and 10.9 μg/l, respectively. Gender-related differences were found with significantly higher B-Cu levels in women and significantly higher B-Zn levels in men. The percentage of seniors with B-Se levels lower than 56 μg/l (which is equivalent to the critical value of 45 μg/l of Se in serum (S-Se)) was 8.6%. A negative correlation between age and B-Se levels was found. B-Zn positively correlated with serum albumin and prealbumin whereas a negative correlation between age and B-Zn was observed. Seniors with diabetes mellitus and atherosclerosis had higher B-Cu and B-Mn levels, respectively, than those without these diagnoses. The elderly from Prague had significantly higher B-Mn concentrations than those from Teplice. We found no evidence of serious essential elements deficiencies or excesses in the seniors who participated in this study.

Influence of serum selenium concentrations on hypertension: the Lipid Analytic Cologne cross-sectional study

AIMS

Selenium is an antioxidant micronutrient with potential associations with hypertension. Few studies have investigated the association of serum selenium concentrations with blood pressure and hypertension in countries with low dietary selenium intake such as Germany, with inconsistent findings.

METHODS

We undertook a cross-sectional analysis of participants in the Lipid Analytic Cologne (LIANCO) cohort. To reduce potential confounding, we restricted the analysis to 792 participants who were never smokers, who did not use antihypertensive medications, and who did not have diabetes or known atherosclerotic disease. Hypertension was defined as blood pressure at least 140 and/or at least 90  mmHg. About half of the cohort was diagnosed as hypertensive. Selenium was measured by inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS).

RESULTS

Mean ± standard deviation (SD) serum selenium concentration was 68  ±  32 μg/l. The multivariable adjusted differences (95% confidence intervals) in blood pressure levels comparing the highest (>91.9 μg/l) to the lowest (≤ 42.8 μg/l) quartile of serum selenium were 5.2 (1.4 to 8.9), 2.8 (0.7 to 4.8), and 2.4 (-0.4 to 5.2) mmHg for systolic, diastolic, and pulse pressure, respectively (P for trend for all <0.003). The corresponding multivariable adjusted odds ratio for the presence of hypertension was 1.52 (0.98 to 2.36; P trend = 0.004).

CONCLUSIONS

The data suggest that even in a population with very low serum selenium concentrations higher serum selenium concentrations are associated with higher blood pressure levels and a higher prevalence of hypertension. These findings call for careful evaluation of the effects of selenium on blood pressure endpoints in randomized clinical trials.

Blood selenium concentration in a selected population of children inhabiting industrial regions in Upper Silesia (Poland)

PURPOSE

Present study aimed at determining blood selenium concentration (Se-B) in a selected population of children inhabiting industrial regions.

METHODS

The studies were conducted on a group of 267 children inhabiting industrial regions in Upper Silesia (Poland). Determination of Se-B was performed using hydride generation atomic absorption technique.

RESULTS

In the studied group of children mean Se-B amounted to 76.75±12.52μg/L. Only in 38.20% of studied children the estimated Se-B could be regarded as an optimal. Children with underweight (BMI<15th centile) manifested a significantly lower Se-B than children with BMI within the normal range (BMI 15-85th centile). In the entire study group of children a significant positive linear correlation was disclosed between BMI and Se-B (r=0.16, p<0.05). Regression analysis demonstrated that in the studied subgroup of children (with normal height, body mass and BMI) a higher BMI represented an independent factor of Se-B increase and a more pronounced age an independent factor of Se-B decrease. Moreover, maternal education represented an independent factor of Se-B increase in the studied group of children (with normal height, body mass and BMI).

CONCLUSIONS

Se-B in the studied group children from industrial area in Upper Silesia corresponded with the lower range of blood selenium concentrations noted in recent years in other populations. A negative relationship was documented between age and Se-B and a positive relationship between BMI of a child and maternal education on one hand and Se-B of a child on the other.

Daily intake of selenium and concentrations in blood of residents of Riyadh City, Saudi Arabia

Concentrations of selenium (Se) in food from local markets of Riyadh, Kingdom of Saudi Arabia (KSA) were measured and daily intake calculated based on information from a questionnaire of foods eaten by healthy Saudis. The daily intake of Se was then compared to concentrations of Se in blood serum. Primary sources of Se in the diet of Saudis were as follows: meat and meat products (31%), egg (20.4%), cereals and cereal products (16%), legumes (8.7%), fruits (6.8%), milk and dairy products (2.0%), beverages (2%), sweets (1.8%), pickles (0.2%), and oil (0.02%). Daily intake of Se, estimated to be 93 μg Se/person/day, was slightly greater than that calculated from the Food and Agriculture Organization (FAO) food balance sheet for KSA, which was approximately 90 μg Se/person/day. The daily intake of Se by Saudis in Riyadh was greater than that of Australians or Dutch but less that of Canadians and Americans. There was a statistically significant correlation (R = +0.38, P < 0.05) between daily intake of Se and concentrations of Se in blood serum of Saudis in Riyadh. The mean concentration of Se in serum was 1.0 × 10(2) ± 30.5 μg Se/l. Taken together, the results suggest that the average Se intake and Se serum concentrations are within the known limits and recommendations, making it unlikely that Saudis are on average at risk of deficiency or toxicity.

Whole blood selenium levels in healthy adults from the west of Algeria

The purpose of this study was to assess whole blood selenium levels of 300 healthy adults living in four selected areas of the west of Algeria. Selenium was measured using differential pulse cathodic stripping voltammetry with a detection limit of 29.20 μg/L. The mean of whole blood selenium concentrations was 85.65 ± 21.60 μg/L ranging between 30.90 and 144.04 μg/L. This concentration did not vary significantly (P > 0.05) in relation to the gender of the subject, with concentrations of 87.75 ± 21.30 μg/L in men and 83.95 ± 21.60 μg/L in women group. Individuals older than 60 years had a whole blood selenium concentration significantly lower than the rest of the population. However, the measured selenium concentrations in the residential areas were not statistically different (P > 0.05). A total of 32 (10.70%) individuals exhibited whole blood selenium level below 60 μg/L. These results are similar to those of some European countries but are much lower than data observed in USA or seleniferous regions.

Human biomonitoring in the Czech Republic: an overview

In the Czech Republic, the Human Biomonitoring Project (CZ-HBM) was launched in 1994 as an integral part of the nationwide Environmental Health Monitoring System (EHMS). Until now, the HBM covers two time periods: the first covered 1994-2003 and the second, 2005-2009. Altogether three population groups were included in the HBM: adults (blood donors aged 18-58 years), children aged 8-10 years, and breastfeeding primiparas. Sampling is organized on a yearly basis. Altogether three groups of biomarkers were analyzed: (a) selected heavy metals (Pb, Cd, Hg) and essential elements (Cu, Se, Zn) in blood and urine of adults and children, (b) indicator PCBs, DDT, DDE, HCB and HCHs in human milk and blood serum of adults and (c) cytogenetic changes in peripheral lymphocytes in blood of adults and children. This paper is focused on the general design of the CZ-HBM, the trends over time, and reference values. A significant downward time trend was observed for the blood lead levels in adults and children. Increased urinary cadmium levels were observed in Czech children compared to German children. The blood and urinary mercury levels were higher in women than in men. The levels of indicator PCB congeners in the Czech human milk samples were still higher than in most other European countries, because of existing hot spots. The levels of organochlorine pesticides showed a substantial continuous downward trend.

Selenium in food and the human body: a review

Selenium levels in soil generally reflect its presence in food and the Se levels in human populations. Se food content is influenced by geographical location, seasonal changes, protein content and food processing. Periodic monitoring of Se levels in soil and food is necessary. Diet is the major Se source and approximately 80% of dietary Se is absorbed depending on the type of food consumed. Se bioavailability varies according to the Se source and nutritional status of the subject, being significantly higher for organic forms of Se. Se supplements can be beneficial for subjects living in regions with very low environmental levels of Se. Several strategies have been followed: (1) employment of Se-enriched fertilizers; (2) supplementation of farm animals with Se; (3) consumption of multimicronutrient supplements with Se. Nevertheless, detailed investigations of possible interactions between Se supplements and other food components and their influence on Se bioavailability are needed. Suppliers also need to provide more information on the specific type of Se used in supplements. In addition, research is lacking on the mechanisms through which Se is involved in hepatocyte damage during hepatopathies. Although Se potential as an antioxidant for the prevention of cardiovascular diseases (CVD) is promising, additional long-term intervention trials are necessary. As a result, indiscriminate Se supplements cannot be reliably recommended for the prevention of CVD in human beings. Some interesting findings reported an association of Se intake with a reduced prevalence and risk for prostate and colon cancer. However, random trials for other cancer types are inconclusive. As a final conclusion, the general population should be warned against the employment of Se supplements for prevention of hepatopathies, cardiovascular or cancer diseases, because benefits of Se supplementation are still uncertain, and their indiscriminate use could generate an increased risk of Se toxicity.

Determination of mercury and methylmercury in hair of the Czech children's population

The developed method for mercury speciation analysis has been validated and used for the biomonitoring study of mercury species in human hair. Statistical evaluation proved the reliability of simplified determination of inorganic mercury (difference between total mercury and methylmercury). The results of the validation showed that the method is very well suitable for the determination of both species of mercury in hair for biomonitoring purposes. Non-exposed schoolchildren from three areas in the western and central part of the Czech Republic were chosen as the target group. Tenth of a microgram per gram of the total mercury were generally found in the analyzed hair; values higher than 1 microg g(-1) were detected only exceptionally. Comparable results were obtained for two western areas and differed significantly from those for the third area located in the central part of the Czech Republic. In the areas examined, the mean methylmercury contents amounted to 23-46% of the total mercury in the hair. The results confirm an assumption that exposure to mercury does not pose a significant risk to the population in the Czech Republic.

The influence of copper, selenium and zinc on the response to the Montenegro skin test in subjects vaccinated against American cutaneous leishmaniasis

We evaluated the relationship between the trace elements copper, zinc and selenium and the response to the Montenegro skin test (MST) in 172 volunteers vaccinated against American cutaneous leishmaniasis. The MST diameter was categorized as negative and in quartiles of positive response, constituting five groups. Trace element serum levels were analyzed by coupled plasma atomic emission spectrometry and hydride generation atomic absorption spectrometry, with study subjects classified into two groups depending on low or high levels of trace elements observed. MST-positive subjects had an MST diameter (mean+/-SD) of 10.35+/-4.64mm, with copper, selenium and zinc serum levels of 1433.7+/-665.7microg/l, 88.6+/-39microg/l and 999.2+/-366microg/l, respectively. The MST diameter was significantly different in the selenium groups only. The selenium levels also differed with the quartiles of the MST diameters of individuals testing positive (P<0.05). Our findings suggest that trace elements, particularly selenium, should be measured in future vaccine trials so that vaccine immunogenicity and response can be assessed and compared between different studies.

Metabolism of low-dose inorganic arsenic in a central European population: influence of sex and genetic polymorphisms

BACKGROUND

There is a wide variation in susceptibility to health effects of arsenic, which, in part, may be due to differences in arsenic metabolism. Arsenic is metabolized by reduction and methylation reactions, catalyzed by reductases and methyltransferases.

OBJECTIVES

Our goal in this study was to elucidate the influence of various demographic and genetic factors on the metabolism of arsenic.

METHODS

We studied 415 individuals from Hungary, Romania, and Slovakia by measuring arsenic metabolites in urine using liquid chromatography with hydride generation and inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS). We performed genotyping of arsenic (+III) methyltransferase (AS3MT), glutathione S-transferase omega 1 (GSTO1), and methylene-tetrahydrofolate reductase (MTHFR).

RESULTS

The results show that the M287T (T-->C) polymorphism in the AS3MT gene, the A222V (C-->T) polymorphism in the MTHFR gene, body mass index, and sex are major factors that influence arsenic metabolism in this population, with a median of 8.0 microg/L arsenic in urine. Females < 60 years of age had, in general, higher methylation efficiency than males, indicating an influence of sex steroids. That might also explain the observed better methylation in overweight or obese women, compared with normal weight men. The influence of the M287T (T-->C) polymorphism in the AS3MT gene on the methylation capacity was much more pronounced in men than in women.

CONCLUSIONS

The factors investigated explained almost 20% of the variation seen in the metabolism of arsenic among men and only around 4% of the variation among women. The rest of the variation is probably explained by other methyltransferases backing up the methylation of arsenic.

Human biomonitoring system in the Czech Republic

The human biomonitoring (HBM) is an integral part of Environmental Health Monitoring System in the Czech Republic since 1994. Selected biomarkers of the internal dose (heavy metals, PCBs) and cytogenetic analysis of peripheral lymphocytes as a biomarker of the exposure/effect to/of environmental genotoxic factors are systematically followed up in the blood and urine of adults (blood donors), in children aged 8 to 10 years, and in the breast milk of nursing mothers. Selected outputs documented the declining trend of blood lead levels, with the recent reference value of 80 mg/l for men, and the rising trend of blood selenium levels in adults, but not in children. PCBs and chlorinated pesticides in human milk show a long-term downward trend, but still higher than in neighbouring countries. The frequency of aberrant cells revealed a downward trend, but the increase obtained in the last monitored period needs to be explained. Further HBM activities are required to demonstrate the corresponding trends and to reduce human exposure and health risks.

Plasma selenium levels in healthy blood bank donors in the central-eastern part of Belgium

Graphite furnace atomic absorption spectrometry, with Zeeman background correction and after improved matrix modification, was used to measure the plasma selenium content of healthy blood bank donors in the central part of Belgium. The mean plasma selenium concentration of 80 men and 80 women was 79.7+/-4.4ng/mL with a range of 55.0-117.4ng/mL. There was no gender difference observed. Plasma selenium level was significantly highest for the adult group, aged 45-64 years, compared to the others, except the young adults (18-24 years). The mean plasma selenium concentration measured corresponded well with literature data for Belgium. The obtained values were found to be in the medium range, compared with recent literature values for the European countries.