Selenium In Environment Research Articles

A Comparative Study on Soil-Crop Selenium Characteristics in High-Incidence Areas of Keshan Disease in Chinese Loess and Black Soil

With the gradual emphasis on health by people, the research on the pathogenesis of endemic diseases has become increasingly in-depth. Through analyzing the environmental selenium characteristics and conducting a comparative study in typical areas of Chinese loess and black soil in this paper, it is concluded that the environmental selenium in the two regions has different characteristics. The soil in the loess area has the characteristics of high alkalinity, low selenium, and relatively high selenium availability, and the crops are selenium-deficient, while the soil in the black soil area has the characteristics of high organic matter, low selenium availability, and relatively high selenium in crops. The research concluded that the environmental occurrence mechanism of Keshan disease in the loess area and the black soil area is different. Keshan disease can be induced in both low-selenium and sufficient-selenium environments, and environmental selenium should be one of the inducing factors of Keshan disease. This research provides a reference for predicting the areas where Keshan disease occurs and for disease prevention, and it can also serve in the prevention and control of endemic diseases.

Guidance on assessing the potential impacts of selenium in freshwater ecosystems.

Despite decades of fate and effects studies, environmental selenium (Se) contamination and management remain an issue for many freshwater systems in North America. Several regulatory bodies have promulgated updated targets or management levels for Se; however, additional guidance on best practices for monitoring Se to protect freshwater aquatic life is warranted. In this article, we describe current approaches to assessing the ecological risks of Se in impaired freshwater systems and outline recommended methods for collecting and analyzing biological and abiotic samples and interpreting data. Because reproductive impairment of fish populations is most commonly used to determine the potential impacts of Se, several biological factors that could affect Se toxicity are explored, including diet, trophic positions, reproductive biology, body size and maturity, migratory movements, and use of seasonal habitats. Measuring Se concentrations in mature eggs is the most reliable metric for estimating potential reproductive impairment in fish populations because the range of toxicity thresholds is relatively narrow for all but a few tolerant fish species. In situations where collecting mature eggs is not feasible, we review the use of alternative fish tissue for estimating potential effects. Factors affecting Se uptake from freshwater are also considered with guidance on collecting abiotic (e.g., water and sediment) and biotic components of aquatic food webs (e.g., macroinvertebrates, biofilm). Integr Environ Assess Manag 2024;00:1-16. © 2024 SETAC.

Recent Advances on Selenium Nutrition and Keshan Disease.

Keshan disease (KD) is a type of endemic cardiomyopathy with an unknown cause. It is primarily found in areas in China with low selenium levels, from northeast to southwest. The nutritional biogeochemical etiology hypothesis suggests that selenium deficiency is a major factor in KD development. Selenium is important in removing free radicals and protecting cells and tissues from peroxide-induced damage. Thus, low environmental selenium may affect the selenium level within the human body, and selenium level differences are commonly observed between healthy people in KD and nonKD areas. From the 1970s to the 1990s, China successfully reduced KD incidence in endemic KD areas through a selenium supplementation program. After years of implementing prevention and control measures, the selenium level of the population in the KD areas has gradually increased, and the prevalence of KD in China has remained low and stable in recent years. Currently, the pathogenesis of KD remains vague, and the effect of selenium supplementation on the prognosis of KD still needs further study. This paper comprehensively reviews selenium deficiency and its connection to KD. Thus, this study aims to offer novel ideas and directions to effectively prevent and treat KD in light of the current situation.

Environmental selenium volatilization is possibly conferred by promiscuous reactions of the sulfur metabolism

Selenium deficiency affects many million people worldwide and volatilization of biogenically methylated selenium species to the atmosphere may limit Se entering the food chain. However, there is very little systematic data on volatilization at nanomolar concentrations prevalent in pristine natural environments. Pseudomonas tolaasii cultures efficiently methylated Se at these concentrations. Nearly perfect linear correlations between the spiked Se concentrations and Dimethylselenide, Dimethyldiselenide, Dimethylselenylsulfide and 2-hydroxy-3-(methylselanyl)propanoic acid were observed up to 80 nM. The efficiency of methylation increased linearly with increasing initial Se concentration, arguing that the enzymes involved are not constitutive, but methylation proceeds promiscuously via pathways of S methylation. From the ratio of all methylated Se and S species, one can conclude that between 0.30% and 3.48% of atoms were Se promiscuously methylated at such low concentrations. At concentrations higher than 640 nM (∼50 μg/L) a steep increase in methylation and volatilization was observed, which suggested the induction of specific enzymes. Promiscuous methylation at low environmental concentrations calls into question that view that methylated Se in the atmosphere is a result of a purposeful Se metabolism serving detoxification. Rather, the concentrations of methylated Se in the atmosphere may be “coincidental” i.e., determined by the activity of S cycling microorganisms. Further, a steep increase in methylation efficiency when surpassing a certain threshold concentration (here ∼50 μg/L) calls into question that natural methylation can be estimated from high Se spikes in laboratory systems, yet highlights the possibility of using bacterial methylation as an effective remediation strategy for media higher concentrated in Se.

Isolation and identification of green alga Chlorella vulgaris HNUFU001 for environmental selenium enrichment in heterotrophic growth regime

Microalgae, particularly Chlorella, have promising selenium (Se) enrichment capacity and great potential in wastewater treatment and the development of nutraceuticals. To acquire Chlorella strains with strong heterotrophic propensity and robust Se tolerance, this research utilized a heterotrophic isolation strategy along with a high Se concentration medium as selection factors. The combined sequence of the ribosomal small subunit (SSU) and internal transcribed spacer (ITS) was utilized for phylogenetic analysis, and comparative analysis of ITS secondary structures was also integrated to identify the desired strain. A novel subtropical microalgal strain, Chlorella vulgaris HNUFU001 with high Se tolerance, was isolated from water samples in a lake at Hainan University, China. Gaussian process regression was utilized to assess the strain's growth under varying Se concentrations. The intracellular accumulation and extracellular removal of Se were measured using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), respectively. The maximum intracellular organic Se (92 % of total Se) was observed as 108.835 μg/g dry weight (DW) for 1 mg/L Se treatment. The highest Se removal rate was 40 %. The high Se tolerance and enrichment traits enable Chlorella vulgaris HNUFU001 to be a promising candidate for the heterotrophic production of organic Se-related nutraceuticals.

Selenium Concentration Levels in Two Polluted Lagoons, Eastern Red Sea Coastal Waters

The importance of selenium in the marine environment is highlighted by its bilateral behavior as a nutrient and toxic element. The cathodic stripping voltammetry validated method was used to determine the selenium concentration. The concentration of total dissolved selenium (TDSe) in Al-Arbaeen and Sharm Obhur lagoons along the eastern Red Sea coastal waters was determined. The total selenium concentration in seven fish species’ muscles was determined. TDSe in the surface water of Al-Arbaeen and Sharm Obhur lagoons showed a maximum concentration of 18.56 and 8.38 nM, respectively. TDSe in the surface water of Al-Arbaeen revealed high concentrations near the wastewater discharging pipes in the lagoon. The linear regression between the TDSe and salinity reflected that the discharged water is the source of selenium with a significant negative correlation of (R2 = 0.80, p < 0.05). In contrast, TDSe in the surface water of Sharm Obhur showed a significant positive correlation (R2 = 0.78, p < 0.05). In the lagoon head, hypoxic and anoxic conditions were dominant. This condition reflected the low TDSe concentration and may affect the selenium chemical forms’ abundance in the lagoon. Two fish species Herklotsichthys punctatus and Herklotsichthys revealed high concentrations of 3.99 and 2.40 µg/g, respectively, which exceeded the permissible levels of the WHO, FAO, and ASTDR.

Topographic constraints on the distribution of selenium in the supergene environment: A case study at Yutangba, China

The local topography and leaching conditions significantly affect the spatial distribution of selenium (Se) in the local environment. However, the driving factors controlling Se distribution have not been well addressed. In this paper, taking Yutangba, a village known for human selenosis in China, as an example, we demonstrate how topographic factors influence the spatial distribution of Se in soils and plants. In the scenarios of slope ≤25°, the correlations among slope and soil/extractable/plant Se are significantly negative (P < 0.05), whereas they become weak or unclear when the slope is > 25°, suggesting that 25° of slope is a critical transition boundary. Similar observations were further verified by the soil erosion modulus (SEM) and the surface runoff intensity index (SRI), indicating that Se transport via soil erosion is limited and accounts for 11.2–17% of the soil Se, while surface runoff plays a dominant role in the Se distribution, accounting for 83–88.1%. Soil extractable Se is negatively correlated with SRI (Pearson r = −0.87 at slope < 25°), showing that the migration capacity of Se is higher at steep terrain and controlled by topography through soil erosion and surface runoff. The positive relationship between plant Se and soil/extractable Se demonstrates that topography indirectly influences plant Se through soil Se bioavailability. Abnormally local Se enrichment observed at the elevated steep hillside (>25°) in northwestern Yutangba primarily was resulted from the weathering of Se-rich rocks. These observations confirm that the topographic slope gradient influences the transport and spatial distribution of soil Se, implying that topography should be considered when studying the spatial distribution of soil Se at a regional scale, especially for the Se-poor belt in China.

Monoclonal antibody based immunoassay: An alternative way for aquatic environmental selenium detection

Environmental concerns about human health encouraged increasing methodological interest in selenium (Se), which is an essential non-metal trace element and varies within a narrow concentration range between essential and toxic. In this study, two types of long-armed Se haptens (Se-hapten-lc-NHS) were synthesized for the first time using active ester formalization. In producing monoclonal antibodies (mAbs), the derivatization of haptenized Se at para- (meta-) and ortho-sites showed different properties. Finally, a mAb derived from hybridoma 5A52 was confirmed to be capable of establishing an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). There was a successful quantitative determination of Se4+ with a detection range of 17 to 207 pmol mL−1 and a limit of detection of approximately 3.9 pmol mL−1. The mAb was found to be remarkably sensitive and specific, with no evidence of cross-reactivity with other ions. The assay was validated for four kinds of Se forms in water samples and showed satisfactory recoveries between 80 % and 108 %, with coefficients of variation of 2.1 %–11 %. The method proposed in our study offers a useful protocol for the rapid screening of Se and provides an alternative solution for the analysis of Se in aquatic environments.

Uptake, distribution, and elimination of selenite in earthworm Eisenia fetida at sublethal concentrations based on toxicokinetic model

Natural and anthropogenic causes have promoted the rapid increase in environmental selenium (Se) levels, and the complex Se metabolism and dynamic in organisms make it challenging to evaluate the toxicity and ecological risks. In this study, the kinetics of selenite in earthworm Eisenia fetida were investigated based on toxicokinetic (TK) model (uptake-elimination phases: 14–14 days). The results showed the highest sub-tissue Se concentrations in pre-clitellum (PC), post-clitellum (PoC) parts, and total earthworms were 95.71, 70.40, and 79.94 mg/kg, respectively, which indicates the distinctive Se uptake capacities of E. fetida. Se kinetic rates in PCs were faster than that of the total E. fetida for both uptake (Kus = 0.30–0.80 mg/kg/day) and elimination phases (Kee = 0.024–0.056 mg/kg/day). Longer half-life times (LT1/2) were observed in the total earthworms (17.85–47.15 d) than PCs (12.28–29.22 d), while non-significant difference was found for the kinetic Se bioaccumulation factor (BAFk) in PC and total earthworms (12–19), which demonstrates that Se can be efficiently bioaccumulated and eliminated in earthworm PC part. Besides, the significant increase Se concentration in PoC with rapid elimination in PC also illustrates that earthworms can alleviate the Se stress by the transformation strategy of Se from the head to tail tissues. In conclusion, the investigation of Se kinetic accumulation and elimination characteristics in this study is helpful for understanding the metabolism and detoxification processes of Se in earthworms, and also providing a theoretical basis for further Se risk assessment using TK model.

Investigation Into Environmental Selenium and Arsenic Levels and Arseniasis Prevalence in an Arsenic-Affected Coal-Burning Area.

This study aims to explore whether selenium (Se) concentration correlates with arseniasis in a high-arsenic coal area in the southern Shaanxi Province, China. Herein, an epidemiological investigation was conducted among 100 arsenic (As)-poisoned patients in Ziyang County, an area with high soil As and Se levels. Fifty healthy subjects were selected from areas without endemic As poisoning. The subjects in the high-As coal area were diagnosed with either normal, suspicious, mild, moderate, or severe As poisoning. Local coal, water, soil, corn, and pepper samples, as well as hair, blood, and urine samples of subjects and patients were collected and analyzed for their As and Se contents. The contents of As and Se in coal, soil, corn, pepper, and hair samples from Ziyang County were significantly higher than those in the control area. The As content of hair in Ziyang County positively correlated with As poisoning, whereas the Se content of hair and urine negatively correlated with As poisoning. The Se content in the body was negatively correlated with the degree of As poisoning, indicating that Se may accelerate the metabolism and decumulation of As and antagonize As toxicity.

Does atmospheric dimethyldiselenide play a role in reducing COVID-19 mortality?

Environmental selenium (Se) distribution in the US is uneven, yet US residents appear to have a relatively narrow range of serum Se concentrations, according to the NHANES III survey data; this is probably due to the modern food-distribution system. In the US, Se concentration in alfalfa leaves has been used as a proxy for regional Se exposure (low, medium or high, corresponding to ≤ 0.05, 0.06–0.10 and ≥ 0.11 ppm respectively). Se in plants, soil, water, and bacteria can be transformed into volatile dimethyldiselenide, which can be inhaled and excreted via the lung. Hence, pulmonary Se exposure may be different in states with different atmospheric Se levels. We found a significantly higher death rate from COVID-19 in low-Se states than in medium-Se or high-Se states, though the case densities of these states were not significantly different. Because inhaled dimethyldiselenide is a potent inducer of nuclear-factor erythroid 2 p45-related factor 2 (Nrf2), exposure to higher atmospheric dimethyldiselenide may increase Nrf2-dependent antioxidant defences, reducing the activation of NFκB by SARS-CoV-2 in the lung, thereby decreasing cytokine activation and COVID-19 severity. Atmospheric dimethyldiselenide may thereby play a role in COVID-19 mortality, although the extent of its involvement is unclear.

Interactive effects of freshwater acidification and selenium pollution on biochemical changes and neurotoxicity in Oreochromis mossambicus

Effect of selenium and acidification in freshwater environment was assessed solitary but no reports are available on the impacts of both factors act together. In the present study, effects of combined simultaneous exposure to selenium (Se) and low pH were assessed in Mozambique tilapia, Oreochromis mossambicus. Responses were measured based on antioxidant defenses (enzymatic SOD, CAT, GPx and non-enzymatic GSH), biotransformation enzyme (GST), metallothionein levels (MT), oxidative damage (LPO, CP), Na+/K+-ATPase (NKA) activity in gills and liver tissues and neurotoxicity (acetylcholinesterase, AChE) response in brain tissue. Fish were exposed to combined treatment at different pH levels (7.5, control (optimum pH for tilapia growth); 5.5, low pH) and Se concentrations (0, 10, and 100 μg L−1). Toxicity levels of Se were not significantly different under control and low pH indicating that pH did not affect Se toxicity. Levels of GSH and MT were enhanced in Se-exposed fish at both pH. Combined effects of high Se concentration and low pH decreased SOD and CAT activities and increased those of GPx and GST. However, organisms were not able to prevent cellular damage (LPO and CP), indicating a condition of oxidative stress. Furthermore, inhibition of Na+/K+-ATPase activity was showed. Additionally, neurotoxicity effect was observed by inhibition of cholinesterase activity in organisms exposed to Se at both pH conditions. As a result, the combined stress of selenium and freshwater acidification has a slight impact on antioxidant defense mechanisms while significantly inhibiting cholinesterase and Na+/K + -ATPase activity in fish. The mechanisms of freshwater acidification mediating the toxic effects of trace non-metal element on freshwater fish need to investigate further.

Application of Supramolecular Nano-Material Adsorbent in the Treatment of Heavy Metal Pollution in Acid Selenium-Rich Soils in South China

In China, soil heavy metal pollution is becoming more and more serious, and supramolecular nanomaterial adsorbents are very effective in the treatment of heavy metal pollution in acid selenium-rich soil environments. Pollution control related research is essential. The purpose of this article is to solve the problem of pollution control of heavy metals in the acid selenium-rich soil environment in southern China. By understanding the existing methods of pollution control of heavy metals in the soil environment, especially the use of supramolecular nanomaterial adsorbents to control the pollution of heavy metals in the soil Methods and related principles, and then conducted a detailed investigation and research on the application of existing supramolecular nanomaterial adsorbents in the treatment of heavy metal pollution in acid selenium-rich soil environment. The research results show that the use of supramolecular nanomaterial adsorbents to treat heavy metal pollution in acid selenium-rich soil environment is very effective. The acid selenium-rich soil treated with supramolecular nanomaterial adsorbents not only reduces the exogenous selenium fertilizer The amount of application, but also reduces the food selenium caused by the application of exogenous selenium fertilizer, safety risks and environmental selenium poisoning caused by improper application of selenium fertilizer, verified by experiments, the quality of contaminated soil treated by supramolecular nanomaterial adsorbent The index increased by 15% and the crop harvest rate increased by 20%.

A systematic review and dose-response meta-analysis of exposure to environmental selenium and the risk of type 2 diabetes in nonexperimental studies

Accumulating evidence from both experimental and nonexperimental human studies in the last 15 years indicates that exposure to high levels of the trace element selenium increases the risk of type 2 diabetes. However, the relation of dose to effect is not well understood because randomized controlled trials used only one dose (200 μg/day) of selenium supplementation. While no new trial on this topic has been published since 2018, several nonexperimental studies have appeared. We therefore updated a previous meta-analysis to include recently published observational studies, and incorporated the recently developed one-stage random-effects model to display the dose-response relation between selenium and type 2 diabetes. We retrieved 34 potentially eligible nonexperimental studies on selenium and diabetes risk up to April 15, 2021. The bulk of the evidence indicates a direct relation between blood, dietary and urinary levels of selenium and risk of diabetes, but not with nail selenium, which may be considered a less reliable biomarker. The association was nonlinear, with risk increasing above 80 μg/day of dietary selenium. Whole blood/plasma/serum selenium concentrations of 160 μg/L corresponded to a risk ratio of 1.96 (95% CI 1.27–3.03) compared with a concentration of 90 μg/L (approximately 60 μg of daily selenium intake). The cohort studies, which are less susceptible to reverse causation bias, indicated increased risk for both blood and urine selenium levels and dietary selenium intake, whereas no such pattern emerged from studies relying on nail selenium content. Overall, the nonexperimental studies agree with findings from randomized controlled trials, indicating that moderate to high levels of selenium exposure are associated with increased risk for type 2 diabetes.

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

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

Selenium in natural environment and food chains. A Review

The analytical review attempts to summarize the results of numerous scientific research conducted by scientists around the world on selenium scattering and accumulation in natural environment, with considerable attention paid to the concentration of this trace element in soils, natural waters and plants. It is shown that selenium content in agricultural products is caused by the processes of physico-chemical and biogenic migration of this element in the biogeochemical food chain. According to the modern classification of trace elements, which is based on their biological significance for living organisms, selenium belongs to the vital group or biogenic elements. As a biotic element, it has unique physicochemical and biochemical properties and with adequately absorbed into the human body has a positive effect on a number of physiological processes. Various research shows that the majority of the world population (except in some regions) today consumes less selenium with the food than necessary and its consumption decreases every year. Insufficient selenium intake in the human body (less than 15–30 μg/day) leads to the development one of the hypomicroelementosis – hyposelenosis. Selenium deficiency is considered as a possible etiological factor in some cardiovascular, cancer, osteoarticular and neurodegenerative diseases that threaten to human life. Providing the human body with selenium in optimal amounts is one of the important conditions of nutrition. A number of countries have developed recommended selenium intake standards for the adults, which range from 55 to 120 μg/day. We can calculate the physiological need for selenium in children and adolescents by extrapolation. The most safe and effective way to maintain the necessary level of selenium for the human body can be achieved only through the poultry and livestock products by mandatory introduction of premixes containing highly effective biologically available selenium forms into animal feed. This will ensure a relatively high level of trace element in meat, eggs, and milk and would eliminate the cases of toxicosis in human population due to buffer effect of animal tissues.

Risk Assessment of Selenium and Boron Pollutants in Environment

According to the literature, there are increasingly more scientific data regarding the environmental pollution of selenium(Se) and the boron(B). The purpose of this review is to give an overview of environmental pollutants for Se andB and the use of plants to alleviate worldwide problems associated with Se and B toxicity. Selenium is an essential element for many species, plant, as well as humans, but it is toxic at higher levels. Boron is relatively soluble in water and commonly causes environmental problems, especially for surface waters where most of the discarded B will end up. Using phytoremediation plants can address this problem. To prevent Se and B toxicity due to excess environmental Se or B, plants may be used to phytoremediate to take up Se and B from soil or water. Research in the past decades had provided a riches ofknowledge regarding the mechanisms by which plants uptake, metabolize, and accumulate Se or B. Moreover, environment studies have revealed the important effects for plantsuptake of Se or B and interactions with herbivores, pollinators, neighbouring vegetation.

Selenite-induced Expression of a Caenorhabditis elegans Pro-aging Factor and Ortholog of Human Selenium-binding Protein 1

Background: The essential trace element and micronutrient selenium exerts most of its biological actions through incorporation into selenoproteins as selenocysteine. Two further types of Se-containing proteins exist, including those that have selenomethionine incorporated instead of methionine, and the group of selenium-binding proteins. We previously described an ortholog of selenium-binding protein 1 (SELENBP1) in the nematode Caenorhabditis elegans, Y37A1B.5, and demonstrated that it confers resistance to toxic selenite concentrations while impairing general stress resistance and life expectancy of C. elegans. Objective: We tested for the effect of selenite on Y37A1B.5 expression, and we analyzed whether Y37A1B.5 also shows a lifespan-modulating effect when the nematodes are deficient in the selenoenzyme thioredoxin reductase-1 (TRXR-1). Methods: C. elegans expressing a translational reporter construct encoding GFP-tagged Y37A1B.5 under the control of the Y37A1B.5 promoter were exposed to selenite, followed by fluorescence microscopic analysis of GFP levels. Lifespan analyses and RNA interference experiments were performed in trxr-1-deficient worms. Results: We here demonstrate that selenite at toxic concentrations stimulates the expression of the translational Y37A1B.5 reporter. The lifespan-extending effect of Y37A1B.5 deficiency was preserved upon the deletion of the only selenoprotein in C. elegans, TRXR-1. Conclusion: These data suggest that (1) Y37A1B.5 may serve as a selenite-responsive buffer against high environmental selenium concentrations and that (2) lifespan extension elicited by Y37A1B.5 knockdown does not require functional TRXR-1.

Chemical composition, energy and biological value of broiler chicken meat caused by various doses of selenium

From the standpoint of modern ideas, the normal functioning of the poultry body and full implementation her of the genetic potential is impossible without the presence of selenium in the diet. The biochemical diversity of selenium puts it in a number of priority trace elements. Scientists who were studying the effects of selenium on poultry body and paid relatively little attention to the quality of the meat. In scientific experiment are studied the effect of additives different doses of selenium in compound feed on the chemical composition, energy and biological value of meat of the cross chickens-broilers COBB 500. Introduction of selenium into the feed for broiler chickens in the doses which are studied (0.3 mg/kg, 0.4 and 0.5 mg/kg) did not significantly affect to the quality of their muscle tissue although it positively affected on some indicators that characterizing its chemical composition, nutritional and biological value. Among the experimental groups, the best meat quality indicators were in the second group of chickens for which was introduced into the feed selenium from the calculation of 0.3 mg/kg. When feeding mixed feeds with selenium additives to broiler chickens it was found that it is likely to increase the concentration of this trace element in muscle tissue by 60.6-100% (P?0.001), which does not exceed the maximum permissible level (MPL). Consumption of selenium-enriched meat of broiler chickens within the limits of the physiological norms recommended in Ukraine will ensure the daily requirement of an adult in this trace element by 23.6-29.4%. This meat product can be especially useful for people who live in regions with low levels of selenium in the natural environment.

Exposure to a high selenium environment in Punjab, India: Effects on blood chemistry.

Many studies have shown that overexposure to environmental selenium may exert a wide pattern of adverse effects on human health, but much uncertainty still surrounds some of them as well as the exact amounts of exposure involved. In particular, very few studies have addressed the possible changes in blood chemistry following high selenium exposure. In a Northeastern part of Punjab, India, very high soil selenium content has been documented, with a value exceeding 2mg/kg (up to 5) as compared with the <0.5mg/kg selenium content characterizing the surrounding referent areas. In seven villages located in that seleniferous areas, we carried out a survey by recruiting volunteers and sampling blood, hair and nail specimens. We administered a questionnaire to the participants and analyzed the specimens for the selenium, along with a series of biochemical and haematological parameters in blood. We included 680 adult volunteers (267 men and 413 women), who showed median selenium levels of 171.30µg/L in serum, 1.25µg/g in hair, and 5.7µg/g in nails. Overall, increasing selenium exposure tended to correlate with higher levels of total cholesterol, albumin, free triiodothyronine, deionidase activity, and with red cell and platelet counts. After stratifying the subjects according to category of selenium exposure, we observed a dose-response relation between serum selenium and risk of high total cholesterol, and between hair selenium and risk of high total and low-density lipoprotein cholesterol, high pancreatic lipase, altered thyroid-stimulating hormone and free triiodothyronine levels. Nail selenium exposure category positively correlated with risk of high alanine-aminotransferase, altered albumin levels, high pancreatic lipase and low levels of thyroid-stimulating hormone. Chronic selenium overexposure appears to adversely affect lipid profiles and pancreatic, liver, and thyroid function, with selenium biomarkers having different abilities to predict such effects.