Higher Se Levels Research Articles

Satisfaction with health and oneself and the Unplugged program among Slovak Schoolchildren

Abstract Background The investigation of protective factors and intervention effects on health are important issues of prospective studies. The aims of this study were to explore the changes in schoolchildren’s satisfaction with their health and themselves (SH) following their participation in the Unplugged program (PU). Methods This study was carried out as a cluster randomized controlled trial (1195 participating schoolchildren, Mean age=11.52; 47.4% boys) with data collection conducted immediately before PU implementationT1, immediately after the implementationT2 then 3 monthsT3, 12 monthsT4, and 18 months after the implementationT5. The schools were randomly assigned to either an experimental (EG, n = 540) or control group (CG, n = 655). EG was exposed to PU consisting of 12 lessons (http://www.eudap.net/). The effect of participating in PU, gender, and self-efficacy (SET1) were explored in relation to changes in SH in both EG and CG. GLM Repeated Measures were used for the data analyses. Results There was a significant main effect of time on SH, F(4, 1096)=6.685, p < 0.001. The contrast analysis revealed that SH was significantly lower at every follow-up when compared to SH at T1. There was a significant interaction effect SHxSE, F(4, 1096)=2.868, p < 0.05. The contrast analysis revealed that SH was significantly lower at T2 than at T1 among the schoolchildren with a lower level of SE. Finally, the SHxSExPU interaction was significant F(4, 1096)=2.779, p < 0.05 and the contrast analysis revealed that SH was significantly higher at T5 than at T1 among those participants of PU with a higher level of SE. Conclusions The findings generally suggest that while there was a decrease of SH among schoolchildren between T1 and T5 a long-term effectT5 of PU was found among the program participants with higher levels of SE who were able to maintain higher level of SH. Key messages Schoolchildren’s satisfaction with their health and themselves was found to generally decrease in time during the 22 months when Unplugged was implemented and evaluated. A long-term effect of Unplugged was detected among program participants with higher levels of self-efficacy who were able to maintain higher level of satisfaction with their health and themselves.

Epidemiological study of kidney health in an area with high levels of soil cadmium and selenium: Does selenium protect against cadmium-induced kidney injury?

Chronic exposure to cadmium (Cd) can cause renal dysfunction. Studies of animals, cell cultures, and plants have found that selenium (Se) can effectively alleviate the hazard generated by Cd, but there has been little study of this in general human populations. This study recruited 313 subjects from China's Hubei Province, including 160 living in areas with high soil Cd and Se (exposure group) and 153 living in clean areas (control group). The levels of the following were detected: Cd and Se in blood (B-Cd and B-Se), urine (U-Cd and U-Se), and hair (H-Cd and H-Se); N-acetyl-β-D-glucosaminidase (U-NAG), β2-microglobulin (U-β2-MG), and albumin (U-ALB) in urine; and malondialdehyde (S-MDA), superoxide dismutase (S-SOD), and glutathione peroxidase (S-GSH-Px) in serum. In addition, the interactions between Cd and Se were assessed. The median levels of B-Cd, B-Se, U-Cd, U-Se, H-Cd, H-Se, S-MDA, and S-GSH-Px of exposure group (2.60 ng/mL, 238.90 ng/mL, 3.13 μg/g Cr, 45.43 μg/g Cr, 0.06 μg/g, 0.70 μg/g, 5.22 nmol/mL, and 308.89 U, respectively) were significantly higher than of controls (0.95 ng/mL, 130.50 ng/mL, 1.08 μg/g Cr, 30.51 μg/g Cr, 0.04 μg/g, 0.49 μg/g, 4.71 nmol/mL, and 267.54 U, respectively), but there were no significant differences in U-NAG, U-β2-MG, U-ALB, or S-SOD between the two groups. U-NAG levels were significantly negatively associated with the interaction between Cd and Se (B: −0.511, 95% CI: −0.886, −0.136). Additionally, changes in the direction of the estimated regression coefficient in the low and high H-Se groups were observed for U-Cd and S-MDA (from 0.018 to −0.090), U-Cd and S-GSH-Px (from −0.039 to 0.101). This study found that populations living in areas with high levels of soil Cd and Se did not show greater Cd-induced renal tubular and glomerular injuries than the control population, which could attribute to the protective effects of Se. The protective effects may be related to the peculiar function of Se that Se can combine with free Cd to activate the antioxidant enzyme system.

Selenium decreases methylmercury and increases nutritional elements in rice growing in mercury-contaminated farmland

Methylmercury (MeHg) in rice grains grown in Hg-contaminated areas has raised environmental health concerns. Pot experiments found that selenium (Se) could reduce MeHg levels in rice grains. However, relatively high levels of Se (up to 6 mg/kg) were applied in these pot experiments, which may have adverse effects on the soil ecology due to the toxicity of Se. The aims of this work were thus to study 1) the effect of low levels of Se on the accumulation and distribution of Hg, especially MeHg, in rice plants grown in a real Hg-contaminated paddy field and 2) the effect of Se treatment on Se and other nutritional elements (e.g., Cu, Fe, Zn) in grains. A field study amended with different levels of Se was carried out in Hg-contaminated paddy soil in Qingzhen, Guizhou, China. The levels of MeHg and total Hg were studied using cold vapor atomic fluorescence spectrometry (CVAFS) and inductively coupled plasma mass spectrometry (ICP-MS). The distribution and relative quantification of elements in grains were examined by synchrotron radiation X-ray fluorescence analysis (SR-XRF). This field study showed that low levels of Se (0.5 μg/mL, corresponding to 0.15 mg Se/kg soils) could significantly reduce total Hg and MeHg in rice tissues. Se treatment also reduced Hg distribution in the embryo and endosperm and increased the levels of Fe, Cu, Zn and Se in grains and especially embryos. This field study implied that treatment with an appropriate level of Se is an effective approach to not only decrease the level of MeHg but to also increase the levels of nutritional elements such as Fe, Cu, Zn and Se in rice grains, which could bring beneficial effects for rice-dependent residents living in Hg-contaminated areas.

Dynamics of Selenium uptake, speciation, and antioxidant response in rice at different panicle initiation stages

Selenium (Se) is an essential element in animals and humans, and its deficiency may cause conditions such as cardiac disease. The production of Se-enriched rice is one of the most important ways to supply Se in the human body, and thus, understanding of the mechanisms of Se-enriched rice is of great significance. A pot experiment was conducted to study the effects of Se addition on the growth, antioxidation, Se uptake and distribution, and Se speciation in three different stages of panicle initiation stage (i.e., pistil and stamen formation stage, pollen mother cell formation stage, pollen mother cell meiosis stage) and the maturity stage. The results showed that soil Se application significantly increased Se uptake in rice. Low rates of Se (<5 mg kg-1) application enhanced the plant growth and rice yield. Se speciation assays showed that SeCys and SeMet were the two main forms found in rice, of which SeMet accounted for 65.5%-100% in the ears and leaves, while SeCys accounted for 61.4%-75.6% in brown rice. SeMet was also the main Se-species found in different subcellular parts at the panicle initiation stage. However, inorganic Se was present in brown rice, mainly as Se(VI), when the soil Se addition exceeded 5 mg kg-1. Lower rates of Se (<5 mg kg-1) promoted the antioxidant capacity, while high levels of Se (≥5 mg kg-1) reduced the antioxidant capacity of rice. The results indicate that Se effects are dose dependent, and the suitable amount of soil Se application for Se-enriched rice production would be <5 mg kg-1.

The role of the freshwater oligochaete Limnodrilus hoffmeisteri in the distribution of Se in a water/sediment microcosm

Selenite(IV) and selenate(VI) are the major species of Se in the seleniferous aquatic ecosystem. The redistribution of Se in the water/sediment microcosm by bioturbation remains largely unknown. In this study, the redistribution of Se in the water/sediment microcosm by the benthic oligochaete Limnodrilus hoffmeisteri was assessed. The worms were exposed to 2–40 μg/g dry weight of Se(IV) or Se(VI) in the sediment (diet) for 2 months. The changes in the Se levels in different compartments of the microcosm (sediment, overlying water, and worms) were quantified after 2 weeks and 2 months. The subcellular distribution of Se in the worms were also evaluated. Finally, the volatilization of Se from the two Se sources was estimated. The results showed that Se concentration in the overlying water and Se bioaccumulation in the worms were increased with Se levels in the sediments. Approximately 1.6–9.8% of Se was volatilized in the absence of the worms and was intensified in the presence of the worms (2.1–25.7%). The subcellular distribution witnessed high levels of Se in the cell debris (>60%). Se(IV) and Se(VI) differ in their bioaccumulation, redistribution and the effects on the growth of the worms. Our results suggest that the bioturbation by benthos play an essential role in the redistribution of Se in the water/sediment microcosm.

Association between selenium, cadmium, and arsenic levels and genetic polymorphisms in DNA repair genes (XRCC5, XRCC6) in gastric cancerous and non-cancerous tissue

Gastric cancer is one of the most prevalent cancers in northern Iran. The DNA repair genes X-ray repair cross-complementing (XRCC) group 5, XRCC6, which are important members of non-homologous end-joining repair system, play an important role in repairing the DNA double-strand breaks. Chronic exposure to heavy metals has long been recognized as being capable of augmenting gastric cancer incidence among exposed human populations. Since trace elements could directly or indirectly damage DNA, and polymorphism in DNA DSBs-repair genes can alter the capacity of system repair, we assumed that XRCC5 VNTR and XRCC6-61C >G polymorphism also impress the DSBs-repair system ability and contribute to gastric cancer. Therefore, the objective of this research was to evaluate the tissue accumulation of Selenium (Se), Cadmium (Cd) and Arsenic (As), and XRCC5 VNTR, XRCC6-61C >G polymorphisms in cancerous and non-cancerous tissues in Golestan province. The study population included 46 gastric cancer patients and 43 cancer-free controls. Two polymorphisms of XRCC5, XRCC6 were genotyped using polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Further employed was atomic absorption spectroscopy so as to determine the levels of Se, Cd and As. Finally, the data were analyzed by SPSS (version 16) statistical software. The Se level was significantly higher in tumors as compared to non-tumor tissues, but there was no significant correlation between As and Cd in cancerous and noncancerous tissues. Allele frequencies of the selected genes were not statistically different between groups regarding XRCC6 (-61C>G). XRCC5 0R/0R, 0R/1R, 1R/1R, and 0R/2R genotypes were more common in cancerous group. High levels of Se in cancerous tissues vs. non-cancerous tissues may be one of the carcinogenic factors; in Golestan province, unlike other regions of Iran and the world, the level of Se is high, hence the higher risks of gastric cancer.

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 (rs = 0.96, p < 0.001) and whole blood Se (rs = 0.89, p < 0.001), but only weakly correlated with plasma Se (rs = 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.

Consumption of Brazil nuts with high selenium levels increased inflammation biomarkers in obese women: A randomized controlled trial.

Increased inflammatory response is an important factor in the pathophysiology of obesity. The mineral selenium (Se), of which one of the main food sources is the Brazil nut, has important antioxidant and anti-inflammatory functions through the action of selenoproteins. Thus, the evaluation of the influence of this micronutrient in this context is of great relevance. The aim of this study was to evaluate the effects of Brazil nut intake with high Se concentrations on inflammatory biomarkers and its relation to Se status in obese women. A randomized controlled clinical trial was carried out with 55 women recruited at Clinical Hospital in São Paulo, Brazil. Patients were randomly assigned to either the Brazil nut group (BN) or the control group (CO) and followed up for 2 mo. The BN group consumed 1 unit/d of Brazil nuts (∼ 1261 μg/Se); the CO group did not receive any intervention. At baseline and after 2 mo, analysis of biochemical parameters related to Se status, oxidative stress, and inflammatory biomarkers were performed. At baseline, both groups did not present Se deficiency. In the BN group, a significant increase (P < 0.05) in all Se biomarkers and in gene expression of several proinflammatory parameters (interleukin-6, tumor necrosis factor-α, and Toll-like receptors 2 and 4) were observed after the intervention period. No changes were observed for the CO group. Although there were no changes in plasma inflammatory biomarkers levels, a significant increase in gene expression may be an indication of a proinflammatory stimulus in obesity, induced by the consumption of Brazil nuts with high Se levels.

Determination of Metal Hazard in the Processed E-Waste Types, Floor Dust and Pulverized Epoxy Powder Generated at an E-Waste Handling Site in India

At the e-waste handling site, the obsolete electronic items are dismantled and it releases dust laden with fine metallic fragments, called as floor dust. Further, the broken cables are denuded from its plastic insulation and shredded to fine grained pulverized epoxy powder. These two-processed e-wastes appear to contain metal residues. Hence, the aim is to examine the metal composition and identify the hazard, if any. Pulverized epoxy powder measured high values of Cd (7.43±0.48 μg/g), Pb (338.85±0.13 μg/g), Ni (534.62±53.68 μg/g), Li (30.12±0.02 μg/g), K (508109.90±31605.89 μg/g), Ca (817395.40±2.52 μg/g) and Na (3528.00±539.07 μg/g) while floor dust had high levels of Cr (39.61±5.78 μg/g), Cu (4778.14±861.91 μg/g), Zn (4172.88±821.75 μg/g), Fe (11164.90±1111.61 μg/g) and Se (1613.00±259.04 μg/g) with significant differences (p&lt;0.05). The worn out electronic oddments attributes to high levels of metals. Principal component analysis could extract two components accounting for 78% variance in total. Although the values are less in comparison with the statutory limits, the processed e-wastes still pose a risk of metal toxicity due to their high volume. The composition of metals in the processed e-wastes presents us a new challenge to handle them.

Association between selected essential trace element concentrations in umbilical cord and risk for cleft lip with or without cleft palate: A case-control study

A deficiency or excess of zinc (Zn), selenium (Se), cobalt (Co), molybdenum (Mo), or manganese (Mn) may interfere with fetal organogenesis. However, the impact of these essential trace elements on the occurrence of cleft lip with or without cleft palate (CL ± P) remains to be elucidated. We aimed to investigate the associations between the amounts of Zn, Se, Co, Mo, and Mn in umbilical cord tissue and risk for CL ± P. This case-control study included 200 controls without congenital malformations and 88 CL ± P cases. Zn, Se, Co, Mo, and Mn concentrations in the umbilical cord were determined using inductively coupled plasma mass spectrometry. Information was collected on demographics, lifestyle behaviors, and dietary intake. The median concentrations of Zn in cases of CL ± P and cleft lip with cleft palate (CLP), of Se in cases of CL ± P and cleft lip only (CLO), and of Co in cases of CLO were lower than in the controls. In utero exposure to higher levels of Zn was associated with reduced risk for CL ± P (OR = 0.44, 95% CI, 0.20–0.93) and for CLP (OR = 0.35, 95% CI, 0.14–0.86), and a higher level of Se was associated with reduced risk for CL ± P and CLO, with ORs of 0.47 (95% CI, 0.23–0.95) and 0.22 (95% CI, 0.08–0.67), respectively. By contrast, higher levels of Mo in the umbilical cord were associated with 2.52-fold (95% CI, 1.23–5.20) and 2.59-fold (95% CI, 1.12–5.95) higher risk for CL ± P and CLP, respectively. No association was found between Co or Mn and risk for CL ± P. In conclusion, in utero exposure to higher levels of Zn and Se was associated with reduced risk for CL ± P, but higher levels of Mo were associated with increased risk for CL ± P.

Association between Serum Selenium Level and the Presence of Diabetes Mellitus: A Meta-Analysis of Observational Studies.

BackgroundEpidemiological studies have suggested an association between selenium (Se) and diabetes mellitus (DM). However, different studies have reported conflicting results. Therefore, we performed a comprehensive meta-analysis to clarify the impact of Se on DM.MethodsWe searched the PubMed database for studies on the association between Se and DM from inception to June 2018.ResultsTwenty articles evaluating 47,930 participants were included in the analysis. The meta-analysis found that high levels of Se were significantly associated with the presence of DM (pooled odds ratios [ORs], 1.88; 95% confidence interval [CI], 1.44 to 2.45). However, significant heterogeneity was found (I2=82%). Subgroup analyses were performed based on the Se measurement methods used in each study. A significant association was found between high Se levels and the presence of DM in the studies that used blood (OR, 2.17; 95% CI, 1.60 to 2.93; I2=77%), diet (OR, 1.61; 95% CI, 1.10 to 2.36; I2=0%), and urine (OR, 1.49; 95% CI, 1.02 to 2.17; I2=0%) as samples to estimate Se levels, but not in studies on nails (OR, 1.24; 95% CI, 0.52 to 2.98; I2=91%). Because of significant heterogeneity in the studies with blood, we conducted a sensitivity analysis and tested the publication bias. The results were consistent after adjustment based on the sensitivity analysis as well as the trim and fill analysis for publication bias.ConclusionThis meta-analysis demonstrates that high levels of Se are associated with the presence of DM. Further prospective and randomized controlled trials are warranted to elucidate the link better.

Effect of selenium yeast supplementation on growth performance, feed utilization, lipid profile, liver and intestine histological changes, and economic benefit in meagre, Argyrosomus regius, fingerlings

This study was conducted to determine the effects of selenium (Se)-yeast supplementation on the growth, survival, nutrient utilization, plasma lipid profile, economic benefit, and histological alterations of liver and intestine of meagre, Argyrosomus regius, fingerlings (3.20 ± 0.17 g). Four treatments (three replicates each in 100 × 40 × 30 cm aquaria) included a control group (not supplemented with Se) and three groups fed Se-supplemented diets at doses of 1, 2 and 3 mg Se-yeast kg−1 diet for nine weeks. The final estimated Se concentrations were 0.77, 1.51, 2.97 and 3.98 mg Se kg−1 diet. The results indicated that there is a significant polynomial 2nd order regression improvement in growth performance with a strong correlation coefficient with increasing dietary Se concentrations. The estimated curves beak of WG and SGR values ranged between 4.15 and 3.62 mg Se kg−1, respectively. The survival (%), feed intake, feed and nutrient utilization and whole-body protein content increased significantly with the highest two Se doses (2.97 and 3.98 mg Se kg−1 diet). There was a significant increase in muscle Se accumulation with dietary Se supplementation in a linear dose-dependent manner. The total lipids, cholesterol and low-density lipoprotein cholesterol decreased significantly with increasing dietary Se levels. Moreover, the liver histological investigation showed an improvement in liver histostructure and the absence of pathological signs at high Se levels. Intestinal sections revealed an increase in the area of absorption in the Se-yeast-supplemented groups. The economic evaluation of feed cost kg−1 gain and kg−1protein production decreased with increasing Se-yeast supplementation levels, reaching a 41.63 and 39.57% cost reduction, respectively, with a 3 mg Se-yeast supplementation kg−1 diet. Dietary Se at a dose of 3.98 mg Se kg−1 diet (3 mg Se-yeast) is recommended to improve growth performance, feed utilization, liver and kidney histology, and the economic benefit of meagre juveniles. Additionally, the estimated Se requirement of meagre is around 4 mg kg−1 diet according to the polynomial 2nd order regression.

Metal/metalloid levels in urine and seminal plasma in relation to computer-aided sperm analysis motion parameters

BackgroundExposure to high levels of metals/metalloids may impair semen quality. Computer-aided sperm analysis (CASA) can be used for kinematic analysis of spermatozoa, which provides additional insights into sperm motion characteristics. ObjectiveTo explore the associations of urinary and seminal plasma metal/metalloid concentrations with CASA motion parameters and assess the degree of correspondence between the two sample types. MethodsEighteen metals/metalloids in seminal plasma and repeated urine samples were determined among 746 men recruited from a reproductive center. We assessed their associations with 6 CASA motion parameters [i.e., straight-line velocity (VSL), curvilinear velocity (VCL), average path velocity (VAP), linearity (LIN), straightness (STR) and amplitude head displacement (ALH)] using multivariable linear regression models. ResultsWe found significantly inverse dose-dependent relationships between seminal plasma arsenic (As) and VSL, VCL and VAP, between seminal plasma selenium (Se) and VSL and VAP, between seminal plasma zinc (Zn) and STR and LIN, and between seminal plasma manganese (Mn) and LIN in single-metal models [all false discovery rate (FDR) adjusted P for trend < 0.05]. These dose-response relationships remained statistically significant based on multiple-metal models and restricted cubic spline functions. Metal/metalloid concentrations in urine poorly predicted the same-day seminal plasma concentrations [coefficient of determination (R2) < 0.15]. We didn't find any significant associations between urinary metal/metalloid concentrations and the CASA motion parameters. ConclusionExposure to high levels of As, Se, Mn and Zn may impair sperm motion capacity. Concentrations of metals/metalloids in spot urine samples cannot accurately predict same-day seminal plasma exposure levels.

Assessment of Heavy Metals Contamination in Drinking Water of Garmian Region, Iraq

Drinking water of safe quality is a critical issue for human survival and health. Water pollution by heavy metals is very crucial because of their toxicity. This study assesses potential of heavy metals pollution in drinking water in Garmian Region, East Iraq. Water samples were investigated for 23 heavy metals and 6 chemical contaminants collected from 16 locations. The analysis was performed by using coupled plasma optical emission spectroscopy (ICPOES, Spectro Arcos). High levels of Al, Se, Sr, and Fe have been detected at certain locations in study area. Statistical analysis techniques of the correlation matrix (CM), and cluster hierarchical analysis (CA) were conducted. The heavy metals pollution index (HPI), heavy metals evaluation index (HEI), and contamination Index (Cd) were used applied. These indices linked with the statistical analysis to interpret relationships among the tested parameters in water samples and to investigate the pollution sources over the study region. Even with the significant correlations between the HPI, Cd, and HEI, they showed dissimilar impact of examined heavy metals on the water quality. The most reliable pollution evaluation index of HEI for drinking water showed that 44% of the water samples is critically polluted. Sources of the contamination are most likely coming from natural geological sources. Anthropogenic impact was only noticed at several sites in the study area.

Selenium and drinking water quality indicators in Mongolia.

Mongolia is characterized by restricted sources of drinking water and intensive water pollution due to high rates of urbanization, mining industry development, enormous amount of livestock, and ever-growing attempts in domestic production of cereals and vegetables. Among others, Se is the least studied element in Mongolian water resources. Based on fluorimetric method of analysis, the first results on Se levels in drinking water of five aimags, Ulaanbaatar, and Erdenet were obtained. Uneven distribution of Se in Mongolia was manifested, the highest Se concentrations being typical for the southern resources (up to 18,600μg/L) and the lowest, for the Northern ones (up to 0.022μg/L). ICP-MS data of Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Hg, I, K, Li, Mg, Mn, Na, Ni, P, Pb, Si, Sn, Sr, V, and Zn contents indicate poly-microelementosis existence in the South of Mongolia (Dorno-Gobi aimag) where ground water is characterized by elevated levels of As and extremely high levels of Se, Li, Na, F, Cl, B, and nitrates ions, exceeding maximum permissible levels by 1.86; 4.3; 3.1; 3.1; 2.7; 3.4; and 1.8 times respectively. Toxic concentrations of Se in groundwater of Dorno-Gobi aimag contradict with the published low human serum Se and low content of the element in horseflesh that suggests the possible effect of the above pollutants on Se bioavailability. Revealed phenomenon and mosaic distribution of heavy metals in areas with high and low Se content in water resources indicate the need of direct search for Se and other pollutant transfer in food chain in various ecological loading conditions, creation of a map of Se distribution in water resources of other Mongolian regions, and large-scale evaluation of the human poly-elemental status.

Effect of Selenium and Vitamin E Supplementation on Lactate, Cortisol, and Malondialdehyde in Horses Undergoing Moderate Exercise in a Polluted Environment

The objective was to evaluate the supplementation effect of selenium (Se) and DL-tocopherol (E) on blood lactate (LAC), cortisol (COR), and malondialdehyde (MDA), in horses moderately exercised in a polluted environment. Police horses of Mexico City were arranged in a balanced factorial trial (2 × 2) with repeated measures. Low (L) and high (H) levels of Se and E supplementation were evaluated (LSe, 0.1; HSe, 0.3 mg Se/kg dry matter; LE, 1.6; HE, 2.0 IU vitamin E/kg body weight). Experimental groups were LSeLE, LSeHE, HSeLE, and HSeHE. The study that lasted 77 days was distributed as follows: adaptation (28 days), exercise (28 days, three consecutive days of moderate exercise were alternated with four days of inactivity), rest (7 days), and recovery without supplementation for readjustment to police handling (14 days). Once a week (11 week), blood samples for LAC, COR, MDA, blood selenium (B-Se), and α-tocopherol (TOC) quantifications were taken. Data were analyzed with a model for fixed (Se, E, day, and their interactions) and random (the horse nested within the treatment) effects. The relationships between Mexico City's criteria air pollutants (CAPs) concentrations and blood analytes were analyzed by multiple sequential regression analysis. Concentrations of all blood analytes were affected (P < .05) by day while Se affected (P < .05) COR, B-Se, and TOC. No analyte was affected by E (P > .05). Relationships were observed between LAC, COR, MDA, CAP, and day (P < .05). It is concluded that supplementation with high selenium levels could benefit horses exercising in polluted environments. Further research on chemical forms and feeding doses of both Se and E is needed.

Association between prenatal nickel exposure and preterm low birth weight: possible effect of selenium.

There is a proposed link between prenatal nickel (Ni) exposure and preterm low birth weight (PLBW); however, this association remains unclear. Selenium (Se) may modify this relationship by protecting against Ni toxicity. Concentrations of Ni and Se were measured in urine samples collected from 408 pregnant women (102 PLBW cases and 306 matched controls) in China. Conditional logistic regression was utilized to explore the association between Ni levels and PLBW, as well as the effect modification by Se on this association. A significant association was observed between higher maternal urinary Ni levels and risk of PLBW [adjusted odds ratio (OR) = 2.80 (95% confidence interval (CI): 1.44, 5.44) for the highest tertile], and this association was more apparent among female infants than that among male infants. Further analyses showed that mothers with high urinary Ni and low urinary Se levels had a significantly increased risk for PLBW [adjusted OR = 2.87 (95% CI: 1.09, 7.56)] compared with the mothers with low urinary Ni and high urinary Se levels. Our study indicates that prenatal exposure to Ni was a risk factor for PLBW. Se might provide protection against the toxicity of Ni.

Removal of selenium containing algae by the bivalve Sinanodonta woodiana and the potential risk to human health

Selenium (Se) is an essential micronutrient for animals and humans with a relatively narrow margin between nutritional essentiality and potential toxicity. Even though our previous studies have demonstrated algae could efficiently remove Se, mainly through volatilization, concern is raised about eco-risks posed by the remaining Se in algae. Here, Sinanodonta woodiana was investigated as a biofilter for the removal of Se-containing Chlorella vulgaris and for its potential risk to human health. Our results suggest filtration rates of S. woodiana were independent of Se levels in algal biomass, with a removal efficiency of between 60 and 78%. However, Se concentrations accumulated in mussels were significantly correlated with algal-borne Se levels, with a dietary assimilation efficiency ranging from 12% to 46%. Thus, a pilot biofiltration system was set up to assess uptake and depuration processes. The system was found to efficiently remove Se laden algae through the uptake by mussels, while 21% of Se in mussels could be depurated in 6 days. Among tissues, gills accumulated the highest Se concentration after assimilating algal-borne Se but shed Se compounds in the fastest pace during depuration. Health risks posed by consumption of mussels exposed to different sources of Se were further assessed. S. woodiana accumulated the highest Se concentration after exposure to waterborne SeMet, followed by dietary Se, selenite and control. The relatively higher Se levels were found in gills for all the treatments. After boiling, the most common method of cooking mussels, the greatest reduction in Se concentration occurred in mantle for the control and dietary Se groups and in muscle for the SeMet and selenite treatments. Therefore, within the safe limits, Se-containing mussels can be consumed as a dietary supplement. Overall, our research suggests incorporation of mussels into an algal treatment system can improve Se removal efficiency and also provide financial incentives for practitioners.

Comparative orchestrating response of four oilseed rape (Brassica napus) cultivars against the selenium stress as revealed by physio-chemical, ultrastructural and molecular profiling

Selenium (Se) is an essential micro-element for human and animals. In higher plants, Se essentiality or phyto-toxicity is less explored. Therefore, we aimed to examine the effects of Se (0, 25, 50, and 100 µM) as sodium selenite on the physio-chemical, cell ultra-structural and genomic alterations in hydroponically grown seedlings of four cultivars of B. napus (cvs. Zheda 619, Zheda 622, ZS 758, and ZY 50). Results showed that excessive (100 µM) Se (IV) exhibited significant reduction in plant growth parameters, declined pigment contents, lower water-soluble protein levels, and overproduction of H2O2 and MDA contents. A significant increase in antioxidant enzyme activities and transcript levels of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR), except catalase (CAT) were noticed in the leaves and roots. Non-enzymatic antioxidants including glutathione (GSH) and oxidized glutathione (GSSG), except GSSG in roots were enhanced under higher Se (IV) levels. Transmission electron microscopy analysis revealed the ultrastructural damages in leaf mesophyll and root tip cells induced by excessive Se (IV). Less-significant phytotoxic effects were observed in above-mentioned parameters at 50 µM Se (IV). Overall, Se (IV) supplementation at 25 µM displayed marginal beneficial effect by enhancing plant growth, pigment contents, protein levels and restrict H2O2 and MDA overproduction. A marginal increase/decrease in ROS-detoxifying enzymes (except CAT activity) and elevated GSH and GSSG levels were noticed. The accumulation of Se (IV) was much higher in roots as compared to leaves. This accumulation was maximum in Zheda 622 and minimum in ZS 758, followed by Zheda 619 and ZY 50. Overall findings showed that Zheda 622 was the most sensitive and ZS 758 as most tolerant to Se (IV) phyto-toxicity. In addition, Se (IV) was found beneficial until 25 µM Se (IV) but phytotoxic at higher Se levels especially at 100 µM Se (IV).

Geochemistry and environmental impact of neutral drainage from an uraniferous coal waste heap

Mining in the former Novátor coal and uranium mine ceased in 1957 and a part of the wastes underwent spontaneous ignition in 1959–1970. Since the 1970s, the waste heap has been exposed to continuous weathering. The objective of this study was to assess to what extent the burnt and unburnt parts of the heap contribute to contamination of the local drainage system over a period lasting >40 years after the end of the mining. Analyses of water collected by lysimeters located on the slope of the heap have shown that the burnt part of the pile is still a source of aqueous sulfate and volatile elements (F, Se, and Pb) that have accumulated in this part of the heap during the self-ignition processes. The unburned part of the heap is mainly the source of aqueous carbonate, Mo, and U. The pH values of water flowing through the heap are in the narrow interval of 6.9–8.6. Rare layers of unburnt coal-bearing sediments rich in sulfides, where the pH values are between 2.9 and 3.7 are rather exceptional. These layers are the main source of Zn, Cu, and Co as a result of weathering of pyrite, chalcopyrite and sphalerite. The chemical composition of water draining from the heap ranges between the values determined in both its burnt and unburnt parts. The water collected at the foot of the heap in periods of low drainage contains high levels of aqueous sulfate (up to 400 mg/L), carbonate (up to 208 mg/L), U (up to 585 μg/L), Se (up to 50 μg/L), and Mo (up to 28 μg/L). On the other hand, the concentrations of these elements are lower in periods of high drainage. The pH values in the water drainage are in the near-neutral range, and uranium is mostly present as U(VI) with dominant phosphate and carbonate complexes in the order UO2(HPO4)22− > UO2(CO3)22− > UO2(CO3)34− > UO2CO30. The concentrations of sulfate and trace elements rapidly decrease with increasing distance from the heap as a result of dilution due to influx of water from uncontaminated streams. Stream sediments sampled in the marshy area at the foot of the heap contain high U contents (up to 460 mg/kg), and other elements (Cu, Pb, Zn, Cd, and Se) due to their sorption on Fe- and Mn-hydroxides, organic matter, and co-precipitation with carbonate or sulfate. Similarly, the amount of uranium and other trace elements in sediments decreases with the distance from the heap because of the influx of clastic material from uncontaminated streams. Consequently, potentially harmful elements in water and sediments represent environmental risks only in the close vicinity of the heap.