Serum selenium levels in healthy slovak children and adolescents

Blood serum selenium levels were measured in 891 healthy children and adolescents (aged 11–18 yr, 450 girls and 441 boys) residing in both rural and urban areas from eight regions of Slovakia. Subjects were divided into four age groups (11–12 y, 13–14 y, 15–16 y, and 17–18 y). Serum selenium concentration was determined by the electrothermal atomic absorption spectrometric method. The mean (±SD) serum selenium concentrations were 0.750 ±0.255 μmol/L in girls and 0.773 ±0.235 μmol/L in boys. A large proportion of the individuals (25.7% in girls, 18.1% in boys) exhibited serum selenium levels under 0.57 μmol/L (45 μg/L). An increasing trend of the serum selenium values with age has been observed in both boys (p < 0.01) and girls (p < 0.05). Boys had higher serum selenium levels in the all age groups but the differences were not statistically significant.     

Blood chromium determination in assessing reference values in an unexposed mediterranean population

Plasma chromium levels were determined in 243 healthy subjects. The study group consisted of 134 men and 109 women, ages 19–71 yr, all residing in Barcelona in northeastern Spain. The study was designed to assess the reference levels for plasma chromium and to investigate its relationships to age and sex. The assays were performed by means of a graphite-furnace atomic absorption spectrometer. The mean plasma chromium concentration was 3.01 ±1.45 nmol/L, ranging from 0.6 to 6 nmol/L. The upper reference values in the 0.95 percentile for this population was 5 nmol/L. No significant differences were observed with respect to the subjects’ sex.     

A contribution to the world selenium map

Atomic absorption spectrophotometric method was used to determine the serum selenium levels of 86 healthy individuals. Variations in age, sex, and geographically different urban regions of Yugoslavia were investigated. A group of 63 healthy children, ages 8–15 yr, were examined. Mean±standard deviation of the serum selenium concentration was 57±9 μg/L; age and geographic area had no effect on the Se status of children, but the difference between boys and girls was significant (P<0.05). A group of 23 men from Zagreb, ages 22–37 yr, were examined. The group was divided into three age subgroups and no difference was found among these groups. The mean Se concentration was 69±18 μg/L, and a statistically significant difference was found only between the group of adults and the group of children (P<0.05).     

Serum levels of selenium, manganese, copper, and iron in colorectal cancer patients

This article describes a study in which four trace elements (Se, Mn, Cu, and Fe) were analyzed in the blood serum of the patients with colorectal cancer from the Moravian region of the Czech Republic. Atomic absorption spectrometry with graphite furnace atomization was used for analysis of selenium and manganese and with flame atomization for analysis of copper and iron. The observed serum concentrations in adenocarcinoma colorectal patients of selenium were significantly lower (41.8 ± 11.6 μg/L) and those of manganese (16.3 ± 4.5 μg/L) and iron (2.89 ± 1.23 mg/L) were significantly higher as compared to the age-matched control group. Copper serum content (0.95 ± 0.28 mg/L) did not significantly differ as compared to healthy population.     

Serum selenium levels in diabetic children

The effect of increased selenium uptake on serum selenium in diabetic children was investigated during the first 9 yr of the Finnish nationwide selenium fertilization program, which started in 1984. Serum selenium concentrations were followed in 237 diabetic children (mean age 8.1 yr) and 214 controls from 1984 to 1992. The control group consisted of 107 siblings of the diabetics and of 107 other healthy children of corresponding age groups. Selenium was determined by direct electrothermal atomic absorption spectrophotometry. The effect of the increased uptake was seen in both diabetic and in control persons. Before the autumn of 1985, diabetic patients had significantly higher serum selenium levels than their siblings or the other healthy controls. Toward the end of year 1987, this difference had disappeared. After that, serum selenium levels continued to increase until the year 1990. In 1990 the mean selenium serum level of diabetic patients was 1.36 μmol/L and that of controls 1.33 μmol/L. The duration of diabetes did not have any effect on selenium serum levels. Slightly higher serum selenium in new diabetic patients before the start of therapy was explained by the dehydration state. The patients who were younger than 3 yr had slightly lower selenium serum levels when compared with older age groups. This difference was observed, however, only during the first 3 yr of the study. After that, when the selenium intake increased in general, no age-dependent differences were found anymore. There were no significant differences in serum selenium levels between males and females in either diabetic patients or in controls.     

Serum selenium and selenoprotein P status in adult Danes – 8-year followup

Selenium is an essential micronutrient important to human health. The main objective of this study is to describe serum selenium and selenoprotein P status in two samples of the Danish population. In addition, the influence of various factors potentially associated with selenium status was investigated.Blood samples from a total of 817 randomly selected subjects from two cities in Denmark were analyzed. Half of the samples were collected in 1997–1998 and the other half in 2004–2005. Samples from women aged 18–22, 40–45 and 60–65 years, and men aged 60–65 years were selected for this study. All subjects had filled in a food frequency questionnaire (FFQ) and a questionnaire with information about smoking habits, alcohol consumption and exercise habits.Mean serum selenium level was 98.7±19.8 μg/L and median selenoprotein P level was 2.72 (2.18–3.49) mg/L. Serum selenium and selenoprotein P increased with age, and selenoprotein P was higher in men than in women. Serum selenium levels decreased by 5% on average from 1997–98 to 2004–05 (P<0.001), whereas selenoprotein P level increased (P<0.001). The intake of fish correlated weakly with serum selenium level (r=0.14, P<0.001) but not with selenoprotein P level. Smoking status, alcohol intake, exercise habits, BMI and medicine use did not influence selenium status.It is concluded that selenium status in this Danish population is at an acceptable level. No major groups with regard to age, sex or lifestyle factors could be identified as being in risk for selenium deficiency.     

Serum selenium levels in the US population: Third National Health and Nutrition Examination Survey, 1988-1994

The published literature on serum selenium levels in the US population describes studies on small samples that may not be representative of the US population. This analysis provides the first nationally representative serum selenium levels in the US population by age group, sex, race-ethnicity, poverty income ratio (PIR), geographic region, and urban status. The Third National Health and Nutrition Examination Survey (NHANES III) is a national population-based cross-sectional survey with an in-person interview and serum selenium measurements. For the 18,597 persons for whom serum selenium values were available in NHANES III, the mean concentration was 1.58 μmol/L and the median concentration was 1.56 μmol/L. Mean serum selenium levels differed by age group, sex, race-ethnicity, PIR, and geographic region. The US population has slight differences in serum selenium levels by demographic factors.     

Serum zinc levels in healthy subjects from southeastern Spain

The serum zinc (Zn) concentrations of 80 healthy subjects (48 male, 32 female) from southeastern Spain were determined by atomic absorption spectrometry. The samples were digested by heating in a 4:1 mixture of nitric and perchloric acids. The concentration of Zn was determined against a Contox Trace Metal Serum Control Panel A standard reference. Zn concentrations in the standard were found to be 2.332 ±0.489 mg/L, with a mean recovery of 102.7%. In the serum samples, the relative standard deviation was <6% for the range of concentrations determined: 0.420-1.540 mg/L for women (mean value 0.947 ±0.265 mg/L) and 0.490-1.480 mg/L for men (mean value 0.951 ±0.243 mg/L). In healthy subjects, no statistically significant differences were observed in the Zn levels with respect to their sex (p > 0.05) or the location where they lived (mountainous vs coastal zones). It is concluded that the dietary Zn intake and Zn status for healthy adults in this region of Spain are within normal values.     

The effect of nationwide selenium enrichment of fertilizers on selenium status of healthy finnish medical students living in south western Finland

In Finland commercial fertilizers have been enriched with sodium selenate since July 1, 1984 in order to compensate for the poor selenium content of the soil. Fertilizers that are used for the production of hay and fodder were supplemented with 6 mg/kg of selenium, whereas fertilizers used for the production of cereals were supplemented with a higher dose, 16 mg/kg fertilizer. The effects of selenium fertilization were first seen in dairy products in June 1985, and from the beginning of August 1985, the effect was evident also in wheat flour, beef, and bovine liver. In this study the selenium status of 108 healthy young adults has been systematically documented since November 1985, at which time the mean selenium serum level (S-Se) was 1.05 umol/L. A steady increase was observed until November 1989, when the maximum level, with a mean of S-Se 1.6 umol/L was reached. After that, a slight decrease has occurred. The mean serum selenium level in autumn 1991 in a new group of 35 students was 1.58 umol/L. This decrease can be explained by the high amount of imported cereals in 1988 and 1989, which was reflected also in the serum selenium levels. The glutathione peroxidase activity in erythrocytes in 1989–1990 was at the same level as in 1985 and 1986.     

Selenium status of healthy immigrant parisian preschool children

Plasma selenium (Se) concentration and erythrocyte glutathione peroxidase activity (GPx) were assessed in a population of healthy preschool children two to five years old, residing in the city of Paris. In the 118 subjects, mean (±SD) plasma Se concentration was 62.10 ±13.96 μg/L, and mean GPx activity was 23.58±8.52 U/g Hb. Mean plasma Se of male children was significantly (p=0.001) higher (12%) than levels of girls. Plasma selenium levels were not correlated with erythrocyte GPx activity. Children from Mediterranean origin had a slightly lower erythrocyte GPx activity (p<0.05) than children from other regions. Mean plasma Se concentration of this group corresponded to the lower limit of intervals, which characterizes geographical regions of intermediate selenium concentrations.     

Generational differences in selenium status of women

In this cross-sectional study of three generations of women, daughters (19–26 yr), mothers (40–58 yr) and maternal grandmothers (67–84 yr) from the same 10 families in central Ohio were studied to determine the effect of life-cycle differences, including estrogen status, on selenium status. Plasma and red blood cell (RBC) selenium and glutathione peroxidase (GPx) activities were determined and typical dietary selenium intakes were calculated from food-frequency questionnaires. Selenium status was lowest in the oldest generation. Plasma selenium of daughters and grandmothers were significantly lower than those of mothers, and plasma GPx and RBC selenium of grandmothers were also lower than those of the mothers. A positive correlation (r=0.42, p<0.04) was found between plasma estrogen and plasma selenium concentrations. Selenium intakes of all groups were adequate and no differences in selenium intakes were found among groups. The results of this study indicate that selenium status fluctuates during the female life cycle and is related to estrogen status.     

Evaluation of methods for total selenium determination in yeast

The selenium determination in biological materials by the classical fluorometric method (FM) is time-consuming and also hazardous, as it requires the destruction of the organic matrix samples with hot HNO₃/HClO₄ mixtures prior to analysis. Accordingly, commercial analytical laboratories are increasingly using faster instrumental methods; for sample digestion, avoid using HClO₄. Because of these procedural changes, the results obtained by commercial laboratories may be unreliable, especially for samples containing Se in organic forms. One such “difficult” substrate is Se yeast, which contains most of its Se as selenomethionine. To establish which methods for Se analysis and sample digestion are applicable, samples of Se yeast and of selenomethionine standards were sent to laboratories employing either flame atomic absorption spectrometry (FAAS), inductively coupled plasma-mass spectrometry (ICP-MS), or hydride generation atomic absorption spectrometry (HGAAS). The result were compared with those obtained by FM and non-destructive instrumental neutron activation analysis (INAA). ICP-MS, after microwave digestion of sample with HNO₃/H₂O₂, produced results within 5% of the expected values, as did those obtained by FM and INAA. With FAAS, acceptable results were obtained after digestion with HNO₃/HCl. With HGAAS, sample digestion with HNO₃/H₂O₂ produced values that were systematically elevated by about 10% and exhibited standard deviations of ≥10%. Thus, current methods of sample digestion are applicable for Se yeast analysis by ICP-MS and FAAS, but not by HGAAS.     

Dietary selenium intake of chinese adult women in the 1990s

To assess the levels of daily dietary intake of selenium (Se) among the general Chinese population, a series of field surveys were conducted in the 1990s. Samples of 24-h duplicates of foods were collected from 500 participants (300 in 6 cites and 200 from 4 villages). Se levels were determined by microwave digestion followed by inductively coupled plasma-mass spectrometry (ICP-MS), and the measurements were compared with FCT (Food Composition Tables)-based estimates. The average daily intake of Se was 69.2 μg/d (79.9 and 53.1 μg/d in urban and rural areas, respectively) by instrumental determination and 35.1 μg/d (36.7 and 32.7 μg/d) by FCT-based estimation. As the distribution of Se should be uneven within China, the FCT-based estimation is of a limited value and the ICP-MS determination of Se is more accurate and reliable when evaluating the nutritional status of local people. Taking ICP-MS-based values, Se intakes were lower in rural areas than in urban areas, and the intakes of about half of the people in rural areas were less than the Recommended Daily Allowance (RDA) in China of 50 μg/d. The low intake might be resulted from difference in the types of food consumed. Thus, the dietary intake of Se basically meets the recommended RDA in most of urban areas, but insufficiency may be still a nutritional and public health problem in some rural areas.     

Trace element status (Se, Cu, Zn) in healthy portuguese subjects of Lisbon population

Serum levels of selenium, copper, and zinc were systematically determined in healthy subjects of the Lisbon population. The sample consisted of 183 blood donors of both genders who were divided into two age groups: 20–44 and 45–70 yr of age; relationships with gender, age, the lipid profile, and tobacco consumption were investigated. In the female group, the intake of oral contraceptives and pregnancy were considered for the youngest women, and hormonal replacement therapy (HRT) was taken into account for the oldest ones. Serum concentrations of these elements were in the same range as those found for populations of other European countries. Differences between genders were observed for the three elements studied, with serum selenium and zinc concentrations higher in men and copper levels higher in women. Age-dependent differences were found for selenium: The oldest subjects (regardless gender) presented the highest concentrations of selenium in serum as further demonstrated by the positive correlation with age. In both pregnant and contraceptive-using women, copper was greatly increased, confirming the influence of estrogen status and/or oral contraceptive intake on increased serum copper levels. However, in postmenopausal women, HRT did not significantly affect serum copper levels. Selenium, copper, and zinc status were not different between normolipidemic and hyperlipidemic subjects for the same gender and age range, but selenium levels tended to increase with hyperlipidemia when considering the whole group of subjects. With respect to the lifestyle, higher serum zinc levels were found in tobacco-consuming men. Albumin serum levels were similar for all considered subgroups, except for the pregnant women, for whom a decrease in this parameter was observed. The present study allowed one to obtain reference values for this healthy group of population, which will serve for a comparative study with groups having pathological conditions, such as cardiovascular disease.     

Changes of serum selenium in pregnant women with gestational diabetes mellitus

Gestational diabetes is one of the most common diseases in pregnancy. In the present work, the possible relationship between serum selenium concentration and gestational diabetes was investigated. Blood samples of 234 pregnant women were collected, including 98 subjects with impaired glucose tolerance (IGT), 46 subjects with gestational diabetes mellitus (GDM), and 90 normal pregnant women (NPW). An additional 17 samples of normal women of fertile age (NW) were collected for comparison. The hydride generation atomic fluorescence spectrometry was used for selenium determination. The mean serum selenium levels obtained for each group were 0.0741±0.0167 mg/L for NPW, 0.0631±0.0132 mg/L for IGT, 0.0635±0.0120 mg/L for GDM, and 0.108±0.0170 mg/L for NW. Serum selenium levels were significantly lower in pregnant woman with IGT (p<0.001) and GDM (p<0.001) than in NPW. Furthermore, an inverse correlation between the serum selenium concentration and the gestational period was also observed. Selenium supplementation during gestation for pregnant women, especially with IGT and GDM, should be considered.     

Determination of cadmium and lead levels in human blood of a general Czech population by GFAAS

The development of a method for the direct determination of cadmium (Cd) and lead (Pb) in blood samples by GFAAS, is described. Samples were properly diluted by a matrix modifier to enable measuring both analytes in one solution. For the determination of Cd, a matrix-matched, and for the determination of Pb, an aqueous calibration was used. The precision, accuracy, and detection limits of this method are presented. A method is applied to the investigation of Cd and Pb levels in a general Czech population, selected according to the WHO-MONICA project criteria. To avoid possible contaminations, samples were treated in a clean room class 100.     

Effects of excess selenomethionine on selenium status indicators in pregnant long-tailed macaques (Macaca fascicularis)

Forty pregnant long-tailed macaques were treated daily for 30 d with 0, 25, 150 or 300 μg selenium as L-selenomethionine/kg body weight. Erythrocyte and plasma selenium and glutathione peroxidase specific activities, hair and fecal selenium, and urinary selenium excretion were increased by and were linearly related to L-selenomethionine dose. Hair selenium was most sensitive to L-selenomethionine dose, with an 84-fold increase in the 300 μg selenium/(kg-d) group relative to controls (r=0.917). Daily urinary selenium excretion (80-fold,r=0.958), plasma selenium (22-fold,r=0.885), erythrocyte selenium (24-fold,r=0.920), and fecal selenium (18-fold,r=0.911) also responded strongly to L-selenomethionine. Erythrocyte and plasma glutathione peroxidase specific activities increased 154% and 69% over controls, respectively. Toxicity was associated with erythrocyte selenium >2.3 μg/mL, plasma selenium >2.8 μg/mL, and hair selenium >27 μg/g. Plasma, erythrocyte, and hair selenium concentrations may be useful for monitoring and preventing the toxicity of L-selenomethionine administered to humans in cancer chemoprevention trials.     

On reconstructing the (once) living population from osteological age data

It is shown how the sex and age distribution of the (once) living population can be calculated from estimated mortalities. Fertility calculations and estimations of the number of children per woman are provided as well. The method is applied to two materials from the Middle Ages: Westerhus and Helgeandsholmen.     

Determination of urinary arsenic, mercury, and selenium in steel production workers

The fumes and dust of trace elements and their compounds are very toxic and have been related to an increase in the incidence of diseases. Occupational exposure to toxic metals and metalloids can be determined by means of workplace air measurements and biological monitoring. The aim of our investigation was to determine the concentrations of As, Hg, and Se in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. The method was employed for the quantitative determination of arsenic, mercury, and selenium in urine samples from steel production and quality control workers and healthy unexposed controls. After pretreatment with acids, the samples were digested by means of a microwave oven. Arsenic was determined by hydride atomic absorption spectrometry and mercury was determined by cold vapor atomic absorption spectrometry, whereas selenium was determined by a graphite furnace atomic absorption spectrometry. The results indicate those urinary arsenic, mercury, and selenium levels of the exposed workers are significantly higher than those of the controls. The possibility that these elements are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.     

Determination of urinary beryllium,arsenic, and selenium in steel production workers

Some of the most pernicious dangers of pollution arise from the presence of traces of toxic elements in the environment. In this work, we report on the determination of beryllium, arsenic, and selenium in the urine of steel production and steel quality control (QC) workers, in comparison to healthy control subjects. The urine samples were digested by a microwave system. Graphite furnace and hydride atomic absorption was used for the quantitative measurements of Be and As and Se, respectively. A quality control method for these procedures was established with concurrent analysis of Standard Trace Metals 7879 Level II and NIST SRM 2670 (Toxic Elements in Freeze Dried Urine). The results show that the urinary levels of these elements in steel production (As, 38.1±28.7 μg/L; Be, 1.58±0.46 μg/L, and Se, 69.2±28.8μg/L) and in quality control workers (As, 23.9±18.1 μg/L; Be, 1.58±0.46 μg/L, and Se, 54.8±25.1 μg/L) are significantly higher than in the controls (As, 10.3±8.7 μg/L; Be, 0.83±0.46 μg/L; and Se, 32.3±13.5 μg/L). The possible connection of these elements with the etiology of disease and the possible role of selenium as a protective agent against the oncogenic and teratogenic action of other substances is discussed. We suggest the need for improvement of environmental conditions in the workplace through better ventilation and industrial hygiene practices.