Reference values of trace elements in blood and/or plasma in adults living in Belgium.

OBJECTIVES: Trace elements (TEs) from natural and anthropogenic sources are ubiquitous. Essential or not, their relevance for human health and disease is constantly expanding. Biological monitoring is a widely integrated tool in risk assessment both in occupational and environmental settings. However, the determination of appropriate and accurate reference values in the (specific) population is a prerequisite for a correct interpretation of biomonitoring data. This study aimed at determining the reference distribution for TEs (Al, As, Sb, Be, Bi, Cd, Co, Cu, Mn, Hg, Mo, Ni, Pb, Se, Tl, Sn, V, Zn) in the blood and/or plasma of the adult population in Belgium. METHODS: Blood and plasma samples were analyzed for 178 males and 202 females, recruited according to an a priori selection procedure, by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: Reference values were established with high confidence for AsT, Cd, Cu, HgT, Mn, Mo, Pb, Sn, Se, Tl and Zn. Compared to previously published data in the Belgian population, a decreasing time trend is observed for Zn, Cd and Pb. Globally, the results also indicate that the current exposure levels to TEs in the Belgian population are similar to those from other recent national surveys. CONCLUSIONS: These reference values and limits obtained through validated analytical and statistical methods will be useful for future occupational and/or environmental surveys. They will contribute to decision-making concerning both public health policies but also exposure assessments on an individual scale.

Calibration strategies for elemental analysis of biological samples by LA-ICP-MS and LIBS - A review.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS) are widely accepted techniques for direct sampling of biological materials for elemental analysis, with increasing applications being reported over the recent years. This review is focused on the calibration materials used to quantify trace elements in different biological samples such as soft tissues (for instance brain, liver, hair) and hard tissues (bones and teeth). The design of a correct calibration strategy relies on the choice of an adapted reference material that can be commercially available or prepared in-house, which will be reviewed here. A large variety of methods has been approached and considered promising over the years, and the development of matrix-matched reference biological materials seems now closer than ever and gives hope to even better quantitation using LIBS and LA-ICP-MS.

Development and characterization of reference materials for trace element analysis of keratinized matrices.

Biomonitoring for human exposure to lead, arsenic, mercury, and other toxic metal(loid)s often relies on analyzing traditional biospecimens such as blood and urine. While biomonitoring based on blood and urine is well-established, non-traditional biospecimens such as hair and nails can offer the potential to explore past exposures as well as the advantages of non-invasive collection and ease of storage. The present study describes the production of four reference materials (NYS RMs 18-01 through 18-04) based on caprine horn, a keratinized tissue similar to human hair and nails, intended to serve as a resource for calibration, quality control, and method validation purposes. The elemental content and homogeneity of these candidate reference materials were characterized for 17 elements using inductively coupled plasma mass spectrometry (ICP-MS). Commutability between two or more of the NYS caprine horn RMs and human nails was established for 8 elements (Ba, Ca, Cr, Cu, Mn, Pb, Sr, and Zn) based on analysis by ICP-MS/MS and ICP-optical emission spectrometry. The development and optimization of an ICP-MS/MS instrumental method for the determination of 17 elements in keratinized tissues is described. The method was validated against three certified reference materials based on human hair showing good accuracy and method repeatability better than 25% for all analytes. This study also describes sample preparation issues and addresses common challenges including surface contamination, microwave digestion, matrix effects, and spectral interferences in inorganic mass spectrometry. New York State Department of Health Keratin Matrix Reference Materials. Graphical abstract.

Assessment of water quality and trace metal contaminations in Mondolkiri province in the Northeastern part of Cambodia.

The aim of the present study is to investigate water quality and potential trace metal contaminations in the Northeastern part of Cambodia. Tube well (n = 35), hand-dug well (n = 18), channel (n = 10) and lake/pond (n = 8) water samples were randomly collected from Mondolkiri province which is located in the Northeastern highland of Cambodia. A water sample was collected in two different bottles. One was filled in 30-mL polyethylene bottle after which was acidified to pH < 2 with concentrated HNO3. Another was filled in 250-mL polyethylene bottle. The collected water sampled was stored in a cooler during fieldwork and transferred to a fridge where they are stored at 4 °C for analysis. The measurement of pH, ORP, dissolved oxygen (DO), turbidity, conductivity, total dissolved solids (TDS) and salinity was taken at laboratory following standard procedures. All chemical measurement of trace metals were taken by inductively coupled plasma mass spectrometry (ICP-MS). Analytical results reveal that tube well (47.1%), hand-dug well (77.8%) and channel water (20%) have pH < 6.5. Turbidity of tube well (32.4%), hand-dug well (5.6%), lake water (12.5%) and all channel water samples are exceeded Cambodia regulation of 5 NTU. Mean As, Cd, Cr, Cu, Ni, Pb and Zn concentrations in Mondolkiri's water sources are below Cambodian drinking water quality standard and WHO's drinking water quality guideline. However, the upper range of Pb in tube well and channel water and Zn in tube well are exceeding Cambodia regulation. Concurrently, the mean concentrations of Fe and Mn in tube well and channel water are exceeded Cambodian aesthetic guideline of 300 µg L-1 and 100 µg L-1, respectively. This study suggests that appropriate treatment technologies are necessary for residents in the Mondolkiri province to access to clean water and minimize their potential health risks.

High Precision Zinc Stable Isotope Measurement of Certified Biological Reference Materials Using the Double Spike Technique and Multiple Collector-ICP-MS.

Biological reference materials with well-characterised stable isotope compositions are lacking in the field of 'isotope biochemistry', which seeks to understand bodily processes that rely on essential metals by determining metal stable isotope ratios. Here, we present Zn stable isotope data for six biological reference materials with certified trace metal concentrations: fish muscle, bovine muscle, pig kidney, human hair, human blood serum and human urine. Replicate analyses of multiple aliquots of each material achieved reproducibilities (2sd) of 0.04-0.13‰ for δ66/64Zn (which denotes the deviation of the 66Zn/64Zn ratio of a sample from a pure Zn reference material in parts per 1000). This implies only very minor isotopic heterogeneities within the samples, rendering them suitable as quality control materials for Zn isotope analyses. This endorsement is reinforced by (i) the close agreement of our Zn isotope data for two of the samples (bovine muscle and human blood serum) to previously published results for different batches of the same material and (ii) the similarity of the isotopic data for the samples (δ66/64Zn ≈ -0.8 to 0.0‰) to previously published Zn isotope results for similar biological materials. Further tests revealed that the applied Zn separation procedure is sufficiently effective to enable accurate data acquisition even at low mass resolving power (M/ΔM ≈ 400), as measurements and analyses conducted at much higher mass resolution (M/ΔM ≈ 8500) delivered essentially identical results.

Background concentrations and reference values for heavy metals in soils of Cuba.

The potential threat of heavy metals to human health has led to many studies on permissible levels of these elements in soils. The objective of this study was to establish quality reference values (QRVs) for Cd, Pb, Zn, Cu, Ni, Cr, Fe, Mn, As, Hg, V, Ba, Sb, Ag, Co, and Mo in soils of Cuba. Geochemical associations between trace elements and Fe were also studied, aiming to provide an index for establishing background concentrations of metals in soils. Surface samples of 33 soil profiles from areas of native forest or minimal anthropic influence were collected. Samples were digested (USEPA method 3051A), and the metals were determined by ICP-OES. The natural concentrations of metals in soils of Cuba followed the order Fe > Mn > Ni > Cr > Ba > V > Zn > Cu > Pb > Co > As > Sb > Ag > Cd > Mo > Hg. The QRVs found for Cuban soils were as follows (mg kg(-1)): Ag (1), Ba (111), Cd (0.6), Co (25), Cr (153), Cu (83), Fe (54,055), Mn (1947), Ni (170), Pb (50), Sb (6), V (137), Zn (86), Mo (0.1), As (19), and Hg (0.1). The average natural levels of heavy metals are above the global average, especially for Ni and Cr. The chemical fractionation of soil samples presenting anomalous concentrations of metals showed that Cu, Ni, Cr, Sb, and As have low bioavailability. This suggests that the risk of contamination of agricultural products via plant uptake is low. However, the final decision on the establishment of soil QRVs in Cuba depends on political, economic, and social issues and in-depth risk analyses considering all routes of exposure to these elements.

Multivitamins/multiminerals in Switzerland: not as good as it seems.

BACKGROUND: Multivitamin/multimineral (MVM) supplements are commonly consumed by the general population, but little is known regarding their composition and compliance with local regulations. We assessed the composition and compliance with regulations [no indication in the label of vitamin/minerals amounting <15% of the acceptable daily intake (ADI)] of MVM available in Switzerland. METHODS: The composition of vitamin/minerals supplements was obtained from the Swiss drug compendium, the Internet, pharmacies, parapharmacies and supermarkets. MVM was defined as the presence of at least 5 vitamins and/or minerals. RESULTS: Of the 254 vitamin/mineral supplements collected, 95 (37%) were considered as MVM. The most frequent vitamins were B6 (73.7%), C (71.6%), B2 (69.5%) and B1 (67.4%); the least frequent were K (17.9%), biotin (51.6%), pantothene (55.8%) and E (56.8%). Approximately half of MVMs provided >150% of the ADI for vitamins. The most frequent minerals were zinc (66.3%), calcium (55.8%), magnesium (54.7%) and copper (48.4%), and the least frequent were fluoride (3.2%), phosphorous (17.9%), chrome (22.1%) and iodine (25%). More than two thirds of MVMs provided between 50 and 150% of the ADI for minerals, and few MVMs provided >150% of the ADI. While few MVMs provided <15% of the ADI for vitamins, a considerable fraction did so for minerals (32.7% for magnesium, 26.1% for copper and 22.6% for calcium). CONCLUSION: There is a great variability regarding the composition of MVMs available in Switzerland. Several MVM do not comply with Swiss regulations, which calls for monitoring and corrective measures.

Reference values and upper reference limits for 26 trace elements in the urine of adults living in Belgium.

BACKGROUND: Trace elements (TEs) are ubiquitous and their potential interest for human health has been constantly expanding. Biological monitoring is generally considered to be a useful tool to assess human exposure to chemical agents in risk assessment both at occupational and environmental levels. However, the knowledge of accurate reference values, which may vary across countries or regions, is a prerequisite for correct interpretation of biomonitoring data. This study aimed at determining the reference distribution and the upper reference limit for 26 TEs (Al, As, Sb, Ba, Be, Bi, Cd, Cr, Co, Cu, In, Li, Mn, Hg, Mo, Ni, Pd, Pt, Pb, Se, Te, Tl, Sn, U, V, Zn) in the urine of the general adult population residing in Belgium. METHODS: In total, 1022 adults not occupationally or extra-occupationally (mainly via hobbies, drugs) exposed to these TEs were recruited by occupational physicians and toxicologists according to an a priori selection procedure. Non-fasting spot urine samples were analyzed for 460 males and 541 females by inductively coupled plasma mass spectrometry (ICP-MS). Careful control was applied during collection, handling and analyses of the samples to avoid any contamination. RESULTS: Globally, the results indicate that the exposure levels of the Belgian population to these TEs are low and grossly similar to those recently published by other national surveys. CONCLUSIONS: These new reference values and upper reference limits will be useful for future occupational and/or environmental surveys.

Defining reference values of trace elements in the tear film: diagnostic methods and possible applications.

The study has been performed on tears of apparently healthy subjects who live and work in urban and rural areas, respectively. After the collection the following elements were investigated: chromium (Cr); arsenic (As); copper (Cu); zinc (Zn); selenium (Se); rubidium (Rb); barium (Ba); lead (Pb) and cobalt (Co). Significantly higher values of As were found in subjects living and working in rural areas as compared to those found in urban area residents (0.290 vs. 0.025; p<0.001). Conversely, Ba and Pb were significantly lower in rural area residents (1.10 vs. 2.50, p=0.027 and 1.70 vs. 1.10, p=0.057, respectively). Our data show that trace elements analysis in tears is possible; further studies could define if it could be a reliable biomarker in persons exposed to high concentration of trace elements due to working or environmental reasons.

Baseline element composition of foliose and fruticose lichens along the steep climatic gradient of SW Patagonia (Aisén Region, Chile).

Samples of foliose (Nephroma antarcticum) and fruticose (Usnea sp.) lichens were collected across a steep climatic and vegetation gradient in a remote, almost pristine region of SW Chilean Patagonia. Concentrations of major and trace elements in lichens from the rainforest were among the lowest ever reported worldwide for foliose and fruticose lichens and can be considered background levels for the region. The two lichen growth forms showed different elemental compositions mainly due to the greater capacity of foliose thalli to intercept elements from windborne and canopy-leached particles. The patterns of spatial variation in the chemical composition of lichens were effectively explained by statistical methods and reflected the different availability of wet and dry deposition along the steep climatic gradient. Baseline values established for N. antarcticum samples growing in temperate Nothofagus forests were therefore distinct from those of samples growing in more open, drier habitats. The fruticose Usnea sp. showed a higher affinity for atmophile Hg, low concentrations of lithophilic elements, and the same baseline composition whether from temperate forests or from dry, barren environments. The provided background and baseline values against which variations can be measured will be useful in the early detection of local or regional climatic and environmental change, especially in view of the planned construction of hydropower dams under the recently approved HidroAysén Project.

Assessment of sampling and analytical uncertainty of trace element contents in arable field soils.

Assessment of trace element contents in soils is required in Germany (and other countries) before sewage sludge application on arable soils. The reliability of measured element contents is affected by measurement uncertainty, which consists of components due to (1) sampling, (2) laboratory repeatability (intra-lab) and (3) reproducibility (between-lab). A complete characterization of average trace element contents in field soils should encompass the uncertainty of all these components. The objectives of this study were to elucidate the magnitude and relative proportions of uncertainty components for the metals As, B, Cd, Co, Cr, Mo, Ni, Pb, Tl and Zn in three arable fields of different field-scale heterogeneity, based on a collaborative trial (CT) (standardized procedure) and two sampling proficiency tests (PT) (individual sampling procedure). To obtain reference values and estimates of field-scale heterogeneity, a detailed reference sampling was conducted. Components of uncertainty (sampling person, sampling repetition, laboratory) were estimated by variance component analysis, whereas reproducibility uncertainty was estimated using results from numerous laboratory proficiency tests. Sampling uncertainty in general increased with field-scale heterogeneity; however, total uncertainty was mostly dominated by (total) laboratory uncertainty. Reproducibility analytical uncertainty was on average by a factor of about 3 higher than repeatability uncertainty. Therefore, analysis within one single laboratory and, for heterogeneous fields, a reduction of sampling uncertainty (for instance by larger numbers of sample increments and/or a denser coverage of the field area) would be most effective to reduce total uncertainty. On the other hand, when only intra-laboratory analytical uncertainty was considered, total sampling uncertainty on average prevailed over analytical uncertainty by a factor of 2. Both sampling and laboratory repeatability uncertainty were highly variable depending not only on the analyte but also on the field and the sampling trial. Comparison of PT with CT sampling suggests that standardization of sampling protocols reduces sampling uncertainty, especially for fields of low heterogeneity.

Review: Bioavailability of trace elements in farm animals: definition and practical considerations for improved assessment of efficacy and safety.

Currently, the authorisation procedure of trace elements as feed additives in the European Union according to Regulation (EC) No. 1831/2003 does not consider the bioavailability of trace element sources. This manuscript provides framework conditions for in vivo experiments that aim to estimate differences in the relative bioavailability between supplements of essential trace elements. Framework conditions encompass necessary technical information on the test substance, the experimental design and diet composition as well as the suitability of status parameters that allow for relative comparisons of regression variables. This manuscript evolves recommendations for researchers to conduct solid and reliable experiments on the matter as well as decision makers to interpret the value of studies submitted with authorisation applications regarding a certain trace element supplement.

Homogeneity and stability studies during the preparation of a laboratory reference material of soy leaves for the determination of metals.

The homogeneity and stability of metals were tested in a candidate laboratory reference material of soy leaves. Inductively coupled plasma-optical emission spectrometry was used to quantify calcium, magnesium, manganese, iron, zinc, copper, and vanadium. A 6 kg amount of the material, which was dried, ground, and classified as mesh 60, was distributed among 100 bottles. The between-bottle homogeneity test was established by analyzing two subsamples from nine bottles. For the within-bottle test, five determinations of each element of a single bottle were performed. The stability test was performed at temperatures of -10, +27, and +40 degrees C, and after storage times of 4, 12, 24, and 52 weeks. The obtained results indicated that the material was homogeneous and stable under the conditions studied.

Characterization of NIES CRM No. 23 Tea Leaves II for the determination of multielements.

A candidate environmental certified reference material (CRM) for the determination of multielements in tea leaves and materials of similar matrix, NIES CRM No. 23 Tea Leaves II, has been developed and characterized by the National Institute for Environmental Studies (NIES), Japan. The origin of the material was tea leaves, which were ground, sieved through a 106-microm mesh, homogenized, and then subdivided into amber glass bottles. The results of homogeneity and stability tests indicated that the material was sufficiently homogeneous and stable for use as a reference material. The property values of the material were statistically determined based on chemical analyses by a network of laboratories using a wide range of methods. Sixteen laboratories participated in the characterization, and nine certified values and five reference values were obtained. These property values of the candidate CRM, which are expressed as mass fractions, were close to the median and/or mean values of the mass fractions of elements in various tea products. The candidate CRM is appropriate for use in analytical quality control and in the evaluation of methods used in the analysis of tea and materials of similar matrix.

The Reference Values of Hair Content of Trace Elements in Dairy Cows of Holstein Breed.

The objective of this study was to assess trace element content in hair of Holstein dairy cows bred in the Leningrad Region of Russia and to calculate the site-specific reference intervals. Hair content of arsenic, boron, cadmium, cobalt, chromium, copper, iron, mercury, iodine, lithium, manganese, lead, selenium, silicon, tin, strontium, vanadium, and zinc in 148 cows during first (n = 50), second (n = 48), and third (n = 50) lactation periods of life was determined using inductively coupled plasma mass spectrometry. Dietary intake of trace elements corresponded to the adequate values according to national and international recommendations. Comparative analysis did not reveal any significant differences in hair content of main essential elements on the animals depending on the number of lactation. At the same time, the first-lactation cows had significantly (P < 0.05) lower concentration of lead in hair as compared to the third-lactation cows and a higher level of mercury as compared to the second-lactation cows. The reference intervals and 90% confidence intervals for the lower and upper limits were calculated in agreement with the American Society for Veterinary Clinical Pathology Quality Assurance and Laboratory Standard Guidelines.

Establishing baseline trace metals in marine bivalves in China and worldwide: Meta-analysis and modeling approach.

Bivalves are extensively employed as biomonitors of coastal pollution, but the comparability among different species and geographic environments needs to be further scrutinized. The present study conducted a meta-analysis of trace metals (Ag, Cd, Cr, Cu, Ni, Pb, Ti, and Zn) in the soft tissues of three groups of marine bivalves (oysters, mussels, and clams) collected from China and worldwide. By conducting cumulative frequency distribution analysis of metal distribution, we modeled the 5% cumulative values as the bio-baseline metal concentrations in these bivalves. We further modeled their potential baseline concentrations using a well-developed biokinetic model. The baseline concentrations of Cd, Cu, and Zn in the tissue-specific Environmental Quality Standards (EQSs) for China were 0.99, 34.5, and 340 µg/g dw in oysters, 0.38, 4.32, and 49.6 µg/g dw in mussels, and 0.35, 3.02, 51.4 µg/g dw in clams, respectively. Of the 8 metals examined in this study, the calculated baseline concentrations of Ag, Cr, Cd, Cu and Zn in the oysters were 3.7-48, 2.7-3.6, 2.6-2.8, 8.0-11.4, 6.6-6.8 times higher than those in the mussels and clams, and only Ti showed comparable baseline concentrations among the three bivalves (8.43-9.67 µg/g dw). These data strongly suggested the inter-group as well as inter-metal difference in the baseline metal concentrations in marine bivalves. Further, the potential baseline concentrations of Cd and Cu predicted by the biokinetic model were comparable to those modeled by the probability frequency distribution. Combined statistical frequency analysis and biokinetic modeling therefore provided an innovative method to establish the baseline metal concentrations in bivalves and the tissue-specific EQSs, which are now urgently needed for coastal management, biomonitoring, and geochemical records in the world.

Extractability of trace elements in precipitated calcium carbonate (PCC) waste from an integrated pulp and paper mill complex.

From the utilization point of view, it is notable that the total element concentrations in the precipitated calcium carbonate (PCC) waste were significantly lower than the maximal allowable heavy metal concentrations for fertilizers used in agriculture and in forestry, set on the basis of the EU and Finnish legislation. The easily soluble Ca concentration of 168.5g kg(-1) (d.w.) in PCC waste was 105 times higher than the typical value of 1.6g kg(-1) (d.w.) in the coarse mineral soil in Finland indicates that the PCC waste is a potential agent for soil remediation and for improving soil fertility if it is used as fertilizer. According to a five-stage sequential extraction procedure, the highest concentrations of most of the elements occurred either in HF+HNO3+HCl or H2O2+CH3COONH4 fraction. This means that the major part of the elements retained in the PCC waste are not easy to extract (leach) under conditions normally found in nature. This is beneficial since, if inorganic materials and by-products are utilized in earth construction, the content of harmful compounds must be low and the harmful components must be tightly bound to the matrix.

Nutritionally recommended food for semi- to strict vegetarian diets based on large-scale nutrient composition data.

Diet design for vegetarian health is challenging due to the limited food repertoire of vegetarians. This challenge can be partially overcome by quantitative, data-driven approaches that utilise massive nutritional information collected for many different foods. Based on large-scale data of foods' nutrient compositions, the recent concept of nutritional fitness helps quantify a nutrient balance within each food with regard to satisfying daily nutritional requirements. Nutritional fitness offers prioritisation of recommended foods using the foods' occurrence in nutritionally adequate food combinations. Here, we systematically identify nutritionally recommendable foods for semi- to strict vegetarian diets through the computation of nutritional fitness. Along with commonly recommendable foods across different diets, our analysis reveals favourable foods specific to each diet, such as immature lima beans for a vegan diet as an amino acid and choline source, and mushrooms for ovo-lacto vegetarian and vegan diets as a vitamin D source. Furthermore, we find that selenium and other essential micronutrients can be subject to deficiency in plant-based diets, and suggest nutritionally-desirable dietary patterns. We extend our analysis to two hypothetical scenarios of highly personalised, plant-based methionine-restricted diets. Our nutrient-profiling approach may provide a useful guide for designing different types of personalised vegetarian diets.

[Determination of trace impurities in high purity titanium dioxide by high resolution inductively coupled plasma mass spectrometry].

An analytical method using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for the rapid simultaneous determination of twenty six elements (Be, Na, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Mo, Cd, Sn, Sb, Ba, Ce, Nd, Sm, Pt, Pb and Bi) in high purity titanium dioxide was described. Samples were decomposed by (NH4)2SO4 and H2SO4. Most of the spectral interferences could be avoided by measuring in the high-resolution mode. The matrix effects due to the presence of excess sulfuric acid and Ti were evaluated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits are 0.004-0.63 microg x g(-1), the recovery ratio is 87.6%-106.4%, and the RSD is less than 3.5%. The method is accurate, quick and convenient. It has been applied to the determination of trace impurities in high purity titanium dioxide with satisfactory results.