Pregnancy exposome and child psychomotor development in three European birth cohorts

Characterization of the exposome, the totality of all environmental factors that one is exposed to from conception onwards, has been recommended to better evaluate the role of environmental influences on developmental programming and life-course vulnerability to major chronic diseases. In the framework of the Health and Environment-wide Associations based on Large population Surveys (HEALS) project we considered the pregnancy exposome exploiting two databases (PHIME and REPRO_PL) that include birth cohorts from three EU countries (Croatia, Slovenia and Poland). The databases contained information on several chemical exposures, socio-demographic, lifestyle and health related factors from conception to child birth, and neuropsychological scores assessed by the Bayley Scales of Infant and Toddler Development in the first two years of life. Our main goal was to assess consistency of environmental influences on neurodevelopment, if any, across European countries differing for geographical, socio-demographic characteristics and levels of chemical exposures to metals such as lead (Pb), mercury (Hg), cadmium (Cd) and trace elements, including micronutrients such as zinc (Zn) and selenium (Se). To this aim, we first selected variables common to the different databases, then applied univariate and multivariate regression analyses to identify factors linked to neurodevelopment, and finally performed meta-analysis to detect potential heterogeneity among cohorts and pooled estimates. Significant differences in exposure levels among the three sub-cohorts were observed as for Hg and Se; exposure levels under study were relatively low and within the range described in existing EU biomonitoring studies. The univariate analyses did not show any common pattern of association as only in the Polish cohort chemical exposure had an impact on neuropsychological outcome. In the meta-analysis, some consistent trends were evident, relative to the adverse influence of Pb on children's language and cognition and the positive influence of Se on language abilities. The effects of the neurotoxic metal Hg positively influenced the motor scores in the Polish cohorts, while it decreased the motor scores in the Slovenia and Croatian sub-cohorts. The only socio-demographic factor consistently associated to the outcome among cohorts was child's sex, with females performing better than males on cognitive and language scores. These findings point to the need of harmonizing existing cohorts or creating prospective study designs that facilitate comparisons in the exposome over time, places and kind of environmental exposures.

Socio-demographic and lifestyle determinants of the micronutrients status during pregnancy

Key messages

In the case of a high proportion of the women the intake of majority of the analyzed micronutrients was below recommendations for the pregnancy period. More effort should be taken to educational programs and interventions that focus on healthy diet recommendations during pregnancy.

Setting up a collaborative European human biological monitoring study on occupational exposure to hexavalent chromium

The EU human biomonitoring initiative, HBM4EU, aims to co-ordinate and advance human biomonitoring (HBM) across Europe. Within its remit, the project is gathering new, policy relevant, EU-wide data on occupational exposure to relevant priority chemicals and developing new approaches for occupational biomonitoring. In this manuscript, the hexavalent chromium [Cr(VI)] study design is presented as the first example of this HBM4EU approach. This study involves eight European countries and plans to recruit 400 workers performing Cr(VI) surface treatment e.g. electroplating or stainless steel welding activities. The aim is to collect new data on current occupational exposure to Cr(VI) in Europe and to test new methods for Cr biomonitoring, specifically the analysis of Cr(VI) in exhaled breath condensate (EBC) and Cr in red blood cells (RBC) in addition to traditional urinary total Cr analyses. Furthermore, exposure data will be complemented with early biological effects data, including genetic and epigenetic effects. Personal air samples and wipe samples are collected in parallel to help informing the biomonitoring results. We present standard operational procedures (SOPs) to support the harmonized methodologies for the collection of occupational hygiene and HBM samples in different countries.

A urinary metabolomics study of a Polish subpopulation environmentally exposed to arsenic

BACKGROUND

Almost every organ in the human body can be affected by arsenic (As) exposure associated with various industrial processes, as well as with contaminated food, drinking water and polluted air. Much is known about high exposure to inorganic As but there is little data on the metabolic changes connected to a low exposure e.g. in people living in smelter areas.

OBJECTIVES

The objectives of the study were: (1) characterise urinary concentration of total arsenic (AsT) in Polish inhabitants of the vicinity of a copper smelter area, (2) speciation analysis of various forms of arsenic in girls (GL), boys (BL), women (WL) and men (ML) with a slightly elevated AsT concentration and age/sex matched groups with a substantially higher AsT concentration, (GH, BH, WH and MH - respectively), (3) comparison of metabolomics profiles of urine between the age/sex matched people with low and high AsT concentrations.

METHODS

Urine samples were analysed for total arsenic and its chemical forms (As^III; As^V, methylarsonic acid, dimethylarsinic acid, arsenobetaine) using HPLC-ICP-MS. Untargeted metabolomics analysis of the urine samples was performed using UPLC system connected to Q-TOF-MS equipped with an electrospray source. The XCMS Online program was applied for feature detection, retention time correction, alignment, statistics, annotation and identification. Potentially identified compounds were fragmented and resulting spectra were compared to the spectra in the Human Metabolome Database.

RESULTS

Urine concentration of AsT was, as follows: GL 16.40 ± 0.83; GH 115.23 ± 50.52; BL 16.48 ± 0.83; BH 95.00 ± 50.03; WL 16.93 ± 1.21; WH 170.13 ± 96.47; ML 16.91 ± 1.20; MH 151.71 ± 84.31 μg/l and percentage of arsenobetaine in AsT was, as follows: GL 65.5 ± 13.8%, GH 87.2 ± 4.7%, BL 59.8 ± 12.5%, BH 90.5 ± 2.4%, WL 50.8 ± 14.1%, WH 90.4 ± 3.5%, ML 53.3 ± 10.0%, MH 74.6 ± 20.2%. In the people with low and high AsT concentrations there were significant differences in the intensity of signal (is.) from numerous compounds being metabolites of neurotransmitters, nicotine and hormones transformation (serotonin in the girls and women; catecholamines in the girls, boys and women; mineralocorticoids and glucocorticoids in the boys, androgens in the women and men and nicotine in the boys, women and men). These changes might have been associated with higher is. from metabolites of leucine, tryptophan, purine degradation (in the GH, WH), urea cycle (in the WH and MH), glycolysis (in the WH) and with lower is. from metabolites of tricarboxylic acid cycle (in the BH) in comparison with low AsT matched groups. In the MH vs. ML higher is. from metabolite of lipid peroxidation (4-hydroxy-2-nonenal) was observed. Additionally, the presence of significant differences was reported in is. from food components metabolites, which might have modulated the negative effects of As (vitamin C in the girls, boys and men, vitamin B₆ in the girls, boys and women as well as phenolic compounds in the boys and girls). We hypothesize that the observed higher is. from metabolites of sulphate (in MH) and glucoronate degradation (in BH, WH and MH) than in the matched low AsT groups may be related to the impaired glucuronidation and sulfonation and higher is. from catecholamines, nicotine and hormones.

CONCLUSION

Our results indicated that even a low exposure to As is associated with metabolic changes and that urine metabolomics studies could be a good tool to reflect their wide spectrum connected to specific environmental exposure to As, e.g. in smelter areas.

Environmental mercury exposure and selenium-associated biomarkers of antioxidant status at molecular and biochemical level. A short-term intervention study

Mercury (Hg) is a potent toxicant. In the field of public health a chronic-low-level environmental Hg exposure resulting from fish consumption in general population is still being discussed. The objective of the study was to assess the influence of real Hg exposure on biomarkers of selenium (Se) status and selected biomarkers of pro-oxidant/anti-oxidant effects in healthy men (n = 67) who participated in the short-term intervention study consisting in daily fish consumption for two weeks. The analysis included Se level, Se-associated antioxidants at molecular (profile of 7 genes encoding selected proteins related to antioxidant defense) and biochemical levels (Se-dependent glutathione peroxidases activities and plasma selenoprotein P concentration). A pro-oxidant/anti-oxidant balance was explored using a biomarker of plasma lipid peroxidation and total antioxidant activity. The study revealed significant correlations (p < 0.05) between the biomarkers of exposure to Hg, Se level and Se-dependent antioxidants. Even though the risk of adverse effects of Hg for volunteers was substantially low, biomarkers of Hg altered levels of circulation selenoproteins and their genes expression. Changes in genes expression during study differed between the main enzymes involved in two systems: downregulation of thioredoxin reductase1 and upregulation of glutathione peroxidases. Hg exposure caused imbalance between the biomarkers of pro-oxidant/anti-oxidant effects.

Revision of reciprocal action of mercury and selenium

Diverse forms of mercury (Hg) have various effects on animals and humans because of a variety of routes of administration. Inorganic mercury (iHg) binds to thiol groups of proteins and enzymes in one's body or is methylated by microorganisms. Organic form of Hg, contrary to the iHg, is more stable but may be demethylated to Hg²⁺ in the tissue of intestinal flora. Selenium (Se) also occurs in a variety of chemical forms in one's body but both of these elements behave very differently from one another. Mercury binding to selenide or Se-containing ligands is a primary molecular mechanism that reduces toxicity of Hg. Complexes formed in such a way are irreversible, and thus, biologically inactive. Se deficiency in a human body may impair normal synthesis of selenoproteins and its expression because expression of mRNA may be potentially regulated by the Se status. This paper provides a comprehensive review concerning Hg-Se reciprocal action as a potential mechanism of protective action of Se against Hg toxicity as well as a potential detoxification mechanism. Although interactions between Hg-Se have been presented in numerous studies concerning animals and humans, we have focused mainly on animal models so as to understand molecular mechanisms responsible for antagonism better. The review also investigates what conclusions have been drawn by researchers with respect to the chemical species of Se and Hg (and their relationship) in biological systems as well as genetic variations and expression and/or activity of selenoproteins related to the thioredoxin (thioredoxin Trx/TrxR) system and glutathione metabolism. Int J Occup Med Environ Health 2018;31(5):575-592.

Biomarkers of selenium status and antioxidant effect in workers occupationally exposed to mercury

The present observation based research was designed to evaluate the influence of occupational human exposure to metallic mercury (Hg°) vapor on the biomarkers of selenium status involved in the antioxidant defense system. For this purpose we determined Hg and selenium (Se) concentrations in body fluids, the markers of antioxidant effect measured as an activity of Se-dependent enzymes (red blood cell and plasma glutathione peroxidase: GPx1-RBC and GPx3-P), concentration of selenoprotein P in the plasma (SeP-P) and total antioxidant activity in the plasma (TAA-P) in 131 male workers from a chloralkali plant exposed to Hg° and 67 non-exposed males (control group). The mRNA expression levels of glutathione peroxidases (GPX1, GPX3), selenoprotein P (SEPP1), thioredoxin reductase 1 (TRXR1), thioredoxin 1 (TRX1), peroxiredoxins (PRDX1, PRDX2) were also examined in the leukocytes of peripheral blood. Hg concentration in the blood (Hg-B) and urine (Hg-U) samples was determined using the thermal decomposition amalgamation/atomic absorption spectrometry (TDA-AAS) method and Se concentrations in plasma (Se-P) and urine (Se-U) using the inductively coupled plasma mass spectrometry (ICP-MS) method. Activities of GPx1-RBC, GPx3-P and TAA-P were determined using the kinetic and spectrophotometric method, respectively. Gene expression analysis was performed using the quantitative Real-Time PCR. The results showed significant higher Hg levels among the Hg°-exposed workers in comparison to control group (12-times higher median for Hg-B and almost 74-times higher median for Hg-U concentration in chloralkali workers). Se-P was also significantly higher (Me (median): 82.85 μg/L (IQR (interquartile range) 72.03-90.28 μg/L) for chloralkali workers vs. Me: 72.74 μg/L (IQR 66.25-80.14 μg/L) for control group; p = 0.0001) but interestingly correlated inversely with Hg-U in chloralkali workers suggesting depletion of the Se protection among the workers with the highest Hg-U concentration. The mRNA level for GPX1, PRXD1 were markedly but significantly higher in the workers compared to the control group. Moreover, concentrations of Hg-B and Hg-U among the workers were significantly positively correlated with the levels of selenoprotein P at both the mRNA and selenoprotein levels. In the multivariate model, after adjusting to cofounders (dental amalgam fillings, age, BMI, job seniority time, smoking), we confirmed that Hg-U concentration was inversely correlated with genes expression of TRXR1. This is the first comprehensive assessment of the impact of occupational exposure of workers to Hg° at both the mRNA and selenoprotein levels, with investigation of fish intake obtained by means of a questionnaire. These findings suggest that exposure to Hg° alters gene expression of the antioxidant enzymes and the level of Se-containing selenoproteins.

Effect of Arsenic Exposure on NRF2-KEAP1 Pathway and Epigenetic Modification

Arsenic (As) is a known toxic element and carcinogen. Transcription factor nuclear factor-erythroid 2-related factor 2 (NRF2) controls cellular adaptation to oxidants and electrophiles by inducing antioxidant genes in response to redox stress. To explore associations between As level and NRF2-regulated cytoprotective genes expression, an observational study was conducted in a population of 61 occupationally exposed men with median (Me) age 50 years (interquartile range (IQR) 42-54) and in a control group of 52 men aged 40 (IQR 31-51.5) without occupational exposure. NRF2, KEAP1, GSTP1, HMOX1, NQO1, PRDX1, and TXNRD1 transcript levels were determined by means of quantitative real-time PCR along with the gene expression, methylation of NRF2 and KEAP1, as well as global DNA methylation were assessed. The median urine As tot. level in the exposed and control group was found to be 21.8 μg/g creat. (IQR 15.5-39.8 μg/g creat.) and 3.8 μg/g creat. (IQR 2.5-9.3) (p < 0.001). Global DNA methylation was significantly higher in occupationally exposed workers than in controls (Me 14.1 (IQR 9.5-18.1) vs Me 8.5 (IQR 5.9-12.6) p < 0.0001). NRF2 mRNA level was positively correlated with expression of all investigated NRF2-target genes in both groups (0.37 > R < 0.76, all p values < 0.0001). The multivariate linear regression adjusting for global methylation showed that As(III) level was significantly associated with expression of TXNRD1, GSTP1, HMOX1, and PRDX1. The results of this study indicate that arsenic occupational exposure is positively associated with global DNA methylation. The findings provide evidence for rather inactivation of NRF2-KEAP1 pathway in response to chronic arsenic exposure.

Micronutrients during pregnancy and child psychomotor development: Opposite effects of Zinc and Selenium

Studies on the impact of micronutrient levels during different pregnancy periods on child psychomotor functions are limited. The aim of this study was to evaluate the association between maternal plasma concentrations of selected micronutrients, such as: copper (Cu), zinc (Zn), selenium (Se), and child neuropsychological development. The study population consisted of 539 mother-child pairs from Polish Mother and Child Cohort (REPRO_PL). The micronutrient levels were measured in each trimester of pregnancy, at delivery and in the cord blood. Psychomotor development was assessed in children at the age of 1 and 2 years using the Bayley Scales of Infant and Toddler Development. The mean plasma Zn, Cu and Se concentrations in the 1st trimester of pregnancy were 0.91±0.27mg/l, 1.98±0.57mg/l and 48.35±10.54μg/l, respectively. There were no statistically significant associations between Cu levels and any of the analyzed domains of child development. A positive association was observed between Se level in the 1st trimester of pregnancy and child language and motor skills (β=0.18, p=0.03 and β=0.25, p=0.005, respectively) at one year of age. Motor score among one-year-old children decreased along with increasing Zn levels in the 1st trimester of pregnancy and in the cord blood (β=-12.07, p=0.003 and β=-6.51, p=0.03, respectively). A similar pattern was observed for the association between Zn level in the 1st trimester of pregnancy and language abilities at one year of age (β=-7.37, p=0.05). Prenatal Zn and Se status was associated with lower and higher child psychomotor abilities, respectively, within the first year of life. Further epidemiological and preclinical studies are necessary to confirm the associations between micronutrient levels and child development as well as to elucidate the underlying mechanisms of their effects.

Assessment of Mercury Intake from Fish Meals Based on Intervention Research in the Polish Subpopulation

The paper's objective was to estimate weekly Hg intake from fish meals based on intervention research. Total Hg (THg) concentrations in blood and hair samples collected from men (n = 67) from an intervention study as well as muscular tissues of fresh and after heat-treating fish were determined using the thermal decomposition amalgamation atomic absorption spectrometry method (TDA-AAS) using direct mercury analyzer (DMA-80). The mean of the estimated weekly intake (EWI) was estimated at 0.62 μg/kg bw/week in the range 0.36-0.96 μg/kg body weight (bw) /week through the consumption of 4 edible marine fish species every day (for 10 days) by the participants from the intervention research in Lodz, Poland. The Hg intake in the volunteers in our intervention study accounted for 38.6% of the provisional tolerable weekly intake (PTWI) (1.6 μg/kg bw, weekly) value. The average Hg concentration in the analyzed fish ranged from 0.018 ± 0.006 mg/kg wet weight (Gadus chalcogrammus) to 0.105 ± 0.015 mg/kg wet weight (Macruronus magellanicus). The results for the average consumers were within PTWI of methylmercury (MeHg). Moreover, the average concentration of Hg in the selected fish after heat treatment did not exceed the maximum permitted concentrations for MeHg (MPCs = 0.5 mg/kg wet weight) in food set by the European Commission Regulation (EC/1881/2006). Hence, the risk of adverse effects of MeHg for the participants is substantially low.

Urinary cadmium levels in active and retired coal miners

A meta-analysis, based upon 24 publications, showed a significantly elevated risk for urinary bladder cancer amongst miners. In European underground hard coal mining areas, an increased risk for urinary bladder cancer development was noted among hard coal miners, in particular in three investigations in the greater Dortmund area. However, the cause remains unclear. As cadmium (Cd), which was reported to be a bladder carcinogen in humans and is a constituent of coal, the aim of this study was to determine urinary Cd levels in active and retired hard coal miners and assess whether hard coal miners demonstrated elevated metal levels. In total, 103 retired and 25 active hard coal miners as well as 18 controls without any history of hard coal mining were investigated for urinary Cd levels. Urinary Cd concentrations, in addition to other elements, were analyzed in spot urines by ICP-MS-based multi-element analysis in a Department for Forensic and Clinical Toxicology. Limit of detection (LOD) for Cd was 0.5 μg/L. Reference value for occupationally non-exposed working age population was 0.8 μg/L. In total, 49% of all underground coal miners were exposed to coal dust, 12% to grinded rock, and 39% to both. Urinary Cd levels in retired as well as active coal miners and controls were clearly below the Biological Exposure Index. Urinary Cd concentration is a suitable biomarker to evaluate the metallic load of the body, as the half-life is > than 10 years. The detected urinary Cd levels in retired and active coal miners indicated underground hard coal miners were not apparently exposed to Cd to a occupationally-relevant concentration.

Relationship between arsenic and selenium in workers occupationally exposed to inorganic arsenic

The interaction between arsenic (As) and selenium (Se) has been one of the most extensively studied. The antagonism between As and Se suggests that low Se status plays an important role in aggravating arsenic toxicity in diseases development. The objective of this study was to assess the Se contents in biological samples of inorganic As exposed workers (n=61) and in non-exposed subjects (n=52). Median (Me) total arsenic concentration in urine of exposed workers was 21.83μg/g creat. (interquartile range (IQR) 15.49-39.77) and was significantly higher than in the control group - (Me 3.75μg/g creat. (IQR 2.52-9.26), p<0.0001). The median serum Se concentrations in the study group and the control were: 54.20μg/l (IQR 44.2-73.10μg/l) and 55.45μg/l (IQR 38.5-69.60μg/l) respectively and did not differ significantly between the groups. In the exposed group we observed significantly higher urine concentrations of selenosugar 1 (SeSug 1) and selenosugar 3 (SeSug3) than in the control group Me: 1.68μg/g creat. (IQR 1.25-2.97 vs Me: 1.07μg/g creat. (IQR 0.86-1.29μg/g), p<0.0001 for SeSug1; Me: 0.45μg/g creat. (IQR 0.26-0.69) vs Me: 0.28μg/g creat. (IQR 0.17-0.45μg/g), p=0.0021). In the multivariate model, after adjusting to cofounders (age, BMI, job seniority time, consumption of fish and seafood and smoking habits) the high rate of arsenic urine wash out (measured as a sum of iAs+MMA+DMA) was significantly associated with the high total selenium urine excretion (B=0.14 (95%CI (confidence interval) 0.05-0.23)). Combination of both arsenic and selenium status to assess the risk of arsenic-induced diseases requires more studies with regard to both the analysis of speciation, genetics and the influence of factors such as nutritional status.

A study on the in vitro percutaneous absorption of silver nanoparticles in combination with aluminum chloride, methyl paraben or di-n-butyl phthalate

Some reports indicate that the silver released from dermally applied products containing silver nanoparticles (AgNP) (e.g. wound dressings or cosmetics) can penetrate the skin, particularly if damaged. AgNP were also shown to have cytotoxic and genotoxic activity. In the present study percutaneous absorption of AgNP of two different nominal sizes (Ag15nm or Ag45nm by STEM) and surface modification, i.e. citrate or PEG stabilized nanoparticles, in combination with cosmetic ingredients, i.e. aluminum chloride (AlCl₃), methyl paraben (MPB), or di-n-butyl phthalate (DBPH) was assessed using in vitro model based on dermatomed pig skin. The inductively coupled plasma mass spectrometry (ICP-MS) measurements after 24h in receptor fluid indicated low, but detectable silver absorption and no statistically significant differences in the penetration between the 4 types of AgNP studied at 47, 470 or 750μg/ml. Similarly, no significant differences were observed for silver penetration when the AgNP were used in combinations with AlCl₃ (500μM), MPB (1250μM) or DBPH (35μM). The measured highest amount of Ag that penetrated was 0.45ng/cm² (0.365-0.974ng/cm²) for PEG stabilized Ag15nm+MPB.

Fish consumption patterns and hair mercury levels in children and their mothers in 17 EU countries

The toxicity of methylmercury (MeHg) in humans is well established and the main source of exposure is via the consumption of large marine fish and mammals. Of particular concern are the potential neurodevelopmental effects of early life exposure to low-levels of MeHg. Therefore, it is important that pregnant women, children and women of childbearing age are, as far as possible, protected from MeHg exposure. Within the European project DEMOCOPHES, we have analyzed mercury (Hg) in hair in 1799 mother-child pairs from 17 European countries using a strictly harmonized protocol for mercury analysis. Parallel, harmonized questionnaires on dietary habits provided information on consumption patterns of fish and marine products. After hierarchical cluster analysis of consumption habits of the mother-child pairs, the DEMOCOPHES cohort can be classified into two branches of approximately similar size: one with high fish consumption (H) and another with low consumption (L). All countries have representatives in both branches, but Belgium, Denmark, Spain, Portugal and Sweden have twice as many or more mother-child pairs in H than in L. For Switzerland, Czech Republic, Hungary, Poland, Romania, Slovenia and Slovakia the situation is the opposite, with more representatives in L than H. There is a strong correlation (r=0.72) in hair mercury concentration between the mother and child in the same family, which indicates that they have a similar exposure situation. The clustering of mother-child pairs on basis of their fish consumption revealed some interesting patterns. One is that for the same sea fish consumption, other food items of marine origin, like seafood products or shellfish, contribute significantly to the mercury levels in hair. We conclude that additional studies are needed to assess and quantify exposure to mercury from seafood products, in particular. The cluster analysis also showed that 95% of mothers who consume once per week fish only, and no other marine products, have mercury levels 0.55 μg/g. Thus, the 95th percentile of the distribution in this group is only around half the US-EPA recommended threshold of 1 μg/g mercury in hair. Consumption of freshwater fish played a minor role in contributing to mercury exposure in the studied cohort. The DEMOCOPHES data shows that there are significant differences in MeHg exposure across the EU and that exposure is highly correlated with consumption of fish and marine products. Fish and marine products are key components of a healthy human diet and are important both traditionally and culturally in many parts of Europe. Therefore, the communication of the potential risks of mercury exposure needs to be carefully balanced to take into account traditional and cultural values as well as the potential health benefits from fish consumption. European harmonized human biomonitoring programs provide an additional dimension to national HMB programs and can assist national authorities to tailor mitigation and adaptation strategies (dietary advice, risk communication, etc.) to their country's specific requirements.

Gender differences in cadmium and cotinine levels in prepubertal children

Susceptibility to environmental stressors has been described for fetal and early childhood development. However, the possible susceptibility of the prepubertal period, characterized by the orchestration of the organism towards sexual maturation and adulthood has been poorly investigated and exposure data are scarce. In the current study levels of cadmium (Cd), cotinine and creatinine in urine were analyzed in a subsample 216 children from 12 European countries within the DEMOCOPHES project. The children were divided into six age-sex groups: boys (6-8 years, 9-10 years and 11 years old), and girls (6-7 years, 8-9 years, 10-11 years). The number of subjects per group was between 23 and 53. The cut off values were set at 0.1 µg/L for Cd, and 0.8 µg/L for cotinine defined according to the highest limit of quantification. The levels of Cd and cotinine were adjusted for creatinine level. In the total subsample group, the median level of Cd was 0.180 µg/L (range 0.10-0.69 µg/L), and for cotinine the median wet weight value was 1.50 µg/L (range 0.80-39.91 µg/L). There was no significant difference in creatinine and cotinine levels between genders and age groups. There was a significant correlation between levels of cadmium and creatinine in all children of both genders. This shows that even at such low levels the possible effect of cadmium on kidney function was present and measurable. An increase in Cd levels was evident with age. Cadmium levels were significantly different between 6-7 year old girls, 11 year old boys and 10-11 year old girls. As there was a balanced distribution in the number of subjects from countries included in the study, bias due to data clustering was not probable. The impact of low Cd levels on kidney function and gender differences in Cd levels needs further investigation.

Mercury analysis in hair: Comparability and quality assessment within the transnational COPHES/DEMOCOPHES project

Human biomonitoring (HBM) is an effective tool for assessing actual exposure to chemicals that takes into account all routes of intake. Although hair analysis is considered to be an optimal biomarker for assessing mercury exposure, the lack of harmonization as regards sampling and analytical procedures has often limited the comparison of data at national and international level. The European-funded projects COPHES and DEMOCOPHES developed and tested a harmonized European approach to Human Biomonitoring in response to the European Environment and Health Action Plan. Herein we describe the quality assurance program (QAP) for assessing mercury levels in hair samples from more than 1800 mother-child pairs recruited in 17 European countries. To ensure the comparability of the results, standard operating procedures (SOPs) for sampling and for mercury analysis were drafted and distributed to participating laboratories. Training sessions were organized for field workers and four external quality-assessment exercises (ICI/EQUAS), followed by the corresponding web conferences, were organized between March 2011 and February 2012. ICI/EQUAS used native hair samples at two mercury concentration ranges (0.20-0.71 and 0.80-1.63) per exercise. The results revealed relative standard deviations of 7.87-13.55% and 4.04-11.31% for the low and high mercury concentration ranges, respectively. A total of 16 out of 18 participating laboratories the QAP requirements and were allowed to analyze samples from the DEMOCOPHES pilot study. Web conferences after each ICI/EQUAS revealed this to be a new and effective tool for improving analytical performance and increasing capacity building. The procedure developed and tested in COPHES/DEMOCOPHES would be optimal for application on a global scale as regards implementation of the Minamata Convention on Mercury.

Association between plasma selenium level and NRF2 target genes expression in humans

Animal studies in rodent and in vitro studies indicate compensatory role of nuclear factor (erythroid-derived 2)-like (Nrf2) and Nrf2-regulated antioxidant and phase II biotransformation enzymes for the dietary selenium (Se) deficiency or for the loss of selenoproteins. To explore associations between plasma Se level and NRF2-regulated cytoprotective genes expression, an observational study was conducted in a population of 96 healthy non-smoking men living in Central Poland aged 18-83 years with relatively low plasma Se level. NRF2, KEAP2, CAT, EPHX1, GCLC, GCLM, GPX2, GSR, GSTA1, GSTM1, GSTP1, GSTT1, HMOX1, NQO1, PRDX1, SOD1, SOD2, TXNRD1 transcript levels in peripheral blood leukocytes and polymorphism of NRF2-617C/A (rs6721961) in blood genomic DNA were determined by means of quantitative real-time PCR. Mean plasma Se level was found to be 51.10±15.25μg/L (range 23.86-96.18μg/L). NRF2 mRNA level was positively correlated with expression of investigated NRF2-target genes. The multivariate linear regression adjusting for selenium status showed that plasma Se level was significantly inversely associated only with expression of GSTP1 (β-coef.=-0.270, p=0.009), PRDXR1 (β-coef.=-0.245, p=0.017) and SOD2 with an inverse trend toward significance (β-coef.=-0.186, p=0.074), but without an effect of NRF2 gene variants. NRF2 expression was inversely associated with age (r=-0.23, p=0.03) and body mass index (r=-0.29, p<0.001). The findings may suggest a possible link between plasma Se level and cytoprotective response at gene level in humans.

Biological monitoring and the influence of genetic polymorphism of As3MT and GSTs on distribution of urinary arsenic species in occupational exposure workers

Purpose

To examine the differences in urinary arsenic metabolism patterns in men affected by occupational exposure, we performed a study on 149 participants—workers of a copper mill and 52 healthy controls without occupational exposure. To elucidate the role of genetic factors in arsenic (As) metabolism, we studied the associations of six polymorphisms: As3MT Met287Thr (T>C) in exon 9; As3MT A>G in 5′UTR; As3MT C>G in intron 6; As3MT T>G in intron 1; GSTP1 Ile105Val and GSTO2 T>C.

Methods

Air samples were collected using individual samplers during work shift. Urine samples were analyzed for total arsenic and arsenic chemical forms (As^III; As^V, MMA, DMA, AsB) using HPLC–ICP-MS. A specific polymerase chain reaction was done for the amplification of exons and flanking regions of As3MT and GSTs.

Results

The geometric mean arsenic concentrations in the air were 27.6 ± 4.9 µg/m³. A significant correlation (p < 0.05) was observed between arsenic in air and sum of iAs +MMA and iAs. As3MT (rs3740400) GG homozygotes showed significantly (p < 0.05) higher %iAs (21.8 ± 2.0) in urine than GC+CC heterozygotes (16.0 ± 2.1). A strong association between the gene variants and As species in urine was observed for GSTO2 (rs156697) polymorphism.

Conclusions

The findings of the study point out that the concentration of iAs or the sum of iAs + MMA in urine can be a reliable biological indicator of occupational exposure to arsenic. This study demonstrates that As3MT and/or GSTs genotype may influence As metabolism. Nevertheless, further studies investigating genetic polymorphism in occupational conditions are required.

Useful and Fast Method for Blood Lead and Cadmium Determination Using ICP-MS and GF-AAS; Validation Parameters

BACKGROUND

In case of clinical analysis, especially in blood lead (Pb-B) and cadmium (Cd-B) determination, the accuracy and precision of the method are crucial. The objective of this article is to present a simple and useful method for Pb-B and Cd-B determination using ICP-MS (inductively coupled plasma-mass spectrometry) as well as GF-AAS (graphite furnace-atomic absorption spectrometry).

METHODS

The principle of the method is based on the deproteinization of blood samples by addition of 5% nitric acid that eliminates the presence of the protein in the samples, thereby excluding the influence of the organic matrix on the result determinations. A comparison of the two techniques ICP-MS and GF-AAS was established for Pb and Cd determinations in the same 40 blood samples collected from lead workers.

RESULTS

The results showed that validation parameters for ICP-MS and GF-AAS were similar, however better for ICP-MS for Pb-B determinations. The detection limit (3×SD) for Pb-B determinations for ICP-MS and GF-AAS was, respectively, 0.16 and 1.0 μg/l, and for Cd-B it was, respectively, 0.08 and 0.02 μg/l. Correlation coefficients (rs) for comparable Pb-B and Cd-B determinations, using these two techniques, showed very good statistically significant correlations and were r = 0.9988, P < 0.0001 for Pb-B and r = 0.9949, P < 0.0001 for Cd-B.

CONCLUSIONS

The obtained results indicate that the method of deproteinization of blood samples is still the best way to eliminate spectral interferences and influence of the organic matter. The elaborated method is especially dedicated to clinical laboratories and determined low concentrations of lead and cadmium in biological samples.

Health effects and arsenic species in urine of copper smelter workers

The aim of this study was to compare indices of exposure in workers employed at different work posts in a copper smelter plant using neurophysiological tests and to evaluate the relationship between urinary arsenic species with the aid of sensitive respiratory and renal biomarkers. We have attempted to elucidate the impact of different arsenic speciation forms on the observed health effects. We focused on the workers (n = 45) exposed to atmospheres containing specific diverse mixtures of metals (such as those occurring in Departments of Furnaces, Lead and Electrolysis) compared to controls (n = 16). Subjective symptoms from the central (CNS) and the peripheral (PNS) nervous system were recorded and visual evoked potential (VEP), electroneurography (ENeG) and electroencephalography (EEG) curves were analysed. Levels of airborne lead (PbA), zinc (ZnA) and copper (CuA) and Pb levels in blood (PbB) and the relationships between airborne As concentrations (AsA) and the urinary levels of the inorganic (iAs); As(+3), As(+5) and the organic; methylarsonate (MMA(V)), dimethylarsinate (DMA(V)) and arsenobetaine (AsB) arsenic species were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Effects of exposure were expressed in terms of biomarker levels: Clara cell protein (CC16) in serum as early pulmonary biomarker and β2-microglobulin (β2M) in urine and serum, retinol binding protein (RBP) as renal markers, measured by sensitive latex-immunoassay (LIA). Abnormal results of neurophysiological tests, VEP, EEG and ENeG showed dominant subclinical effects in CNS and PNS of workers from Departments of Lead and Furnace. In group of smelters from Departments of Furnace exposed to arsenic above current TLV, excreted arsenic species As(+3) and As(+5) seemed to reduce the level of Clara cell protein (CC16), thereby reducing anti-inflammatory potential of the lungs and increasing the levels of renal biomarker (β2M) and copper in urine (CuU). The study confirmed deleterious arsenic effects to the kidney by increased levels of low-molecular weight protein in urine and the extent of the renal copper accumulation/excretion. The results of our work also support the usefulness of application of the sensitive neurophysiologic tests, such as VEP, EEG and ENeG, for the detection of early subclinical effects of the exposure of the nervous system in copper smelters.