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Sökning: WFRF:(Vahter Marie)

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1.
  • Ahmed, Sultan, et al. (författare)
  • Arsenic-Associated Oxidative stress, Inflammation, and Immune Disruption in Human Placenta and Cord Blood
  • 2011
  • Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 119:2, s. 258-264
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Arsenic (As) exposure during pregnancy induces oxidative stress and increases the risk of fetal loss and low birth weight. OBJECTIVES: This study aimed to elucidate the effects of As exposure on immune markers in the placenta and cord blood, and the involvement of oxidative stress. METHODS: Pregnant women were enrolled around gestational week (GW) 8 in our longitudinal, population-based, mother-child cohort in Matlab, an area in rural Bangladesh with large variations in As concentrations in well water. Women (n=130) delivering at local clinics were included in the present study. We collected maternal urine twice during pregnancy (GW8 and 30) for measurements of As, and placenta and cord blood at delivery for assessment of immune and inflammatory markers. Placental markers were measured by immunohistochemistry and cord blood cytokines by multiplex cytokine assay. RESULTS: In multivariable adjusted models, maternal urinary As (U-As) exposure both at GW8 and 30 was significantly positively associated with placental markers of 8-oxoguanine (8-oxoG) and IL-1β, U-As at GW8 with TNF- α and IFN-γ, U-As at GW30 with leptin , and U-As at GW8 was inversely associated with CD3-T cells in the placenta. Cord blood cytokines (IL-1β, IL-8, IFN-γ, TNF-α) showed a U-shaped association with U-As at GW30. Placental 8-oxoG was significantly positively associated with placental pro-inflammatory cytokines. Multivariable adjusted analyses suggested that enhanced placental cytokine expression (TNF-α and IFN-γ) was primarily influenced by oxidative stress, while leptin expression appeared to be mostly mediated by As, and IL-1β appeared to be influenced by both oxidative stress and As. CONCLUSION: As exposure during pregnancy appeared to enhance placental inflammatory responses (in part by increasing oxidative stress), reduce placental T cells, and alter cord blood cytokines. These findings suggest that effects of As on immune function may contribute to impaired fetal and infant health.
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2.
  • Ahmed, Sultan, et al. (författare)
  • Arsenic Exposure Affects Plasma Insulin-Like Growth Factor 1 (IGF-1) in Children in Rural Bangladesh
  • 2013
  • Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:11, s. e81530-
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Exposure to inorganic arsenic (As) through drinking water during pregnancy is associated with lower birth size and child growth. The aim of the study was to assess the effects of As exposure on child growth parameters to evaluate causal associations. Methodology/Findings: Children born in a longitudinal mother-child cohort in rural Bangladesh were studied at 4.5 years (n=640) as well as at birth (n=134). Exposure to arsenic was assessed by concurrent and prenatal (maternal) urinary concentrations of arsenic metabolites (U-As). Associations with plasma concentrations of insulin-like growth factor 1 (IGF-1), calcium (Ca), vitamin D (Vit-D), bone-specific alkaline phosphatase (B-ALP), intact parathyroid hormone (iPTH), and phosphate (PO4) were evaluated by linear regression analysis, adjusted for socioeconomic factor, parity and child sex. Child U-As (per 10 mu g/L) was significantly inversely associated with concurrent plasma IGF-1 (beta=-0.27; 95% confidence interval: -0.50, -0.0042) at 4.5 years. The effect was more obvious in girls (beta=-0.29; -0.59, 0.021) than in boys, and particularly in girls with adequate height (beta=-0.491; -0.97, -0.02) or weight (beta=-0.47; 0.97, 0.01). Maternal U-As was inversely associated with child IGF-1 at birth (r=-0.254, P=0.003), but not at 4.5 years. There was a tendency of positive association between U-As and plasma PO4 in stunted boys (beta=0.27; 0.089, 0.46). When stratified by % monomethylarsonic acid (MMA, arsenic metabolite) (median split at 9.7%), a much stronger inverse association between U-As and IGF-1 in the girls (beta=-0.41; -0.77, -0.03) was obtained above the median split. Conclusion: The results suggest that As-related growth impairment in children is mediated, at least partly, through suppressed IGF-1 levels.
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3.
  • Akhtar, Evana, et al. (författare)
  • A longitudinal study of rural Bangladeshi children with long-term arsenic and cadmium exposures and biomarkers of cardiometabolic diseases
  • 2021
  • Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 271
  • Tidskriftsartikel (refereegranskat)abstract
    • There is growing interest in understanding the contribution of environmental toxicant exposure in early life to development of cardiometabolic diseases (CMD) in adulthood. We aimed to assess associations of early life exposure to arsenic and cadmium with biomarkers of CMD in children in rural Bangladesh. From a longitudinal mother-child cohort in Matlab, Bangladesh, we followed up 540 pairs. Exposure to arsenic (U–As) and cadmium (U–Cd) was assessed by concentrations in urine from mothers at gestational week 8 (GW8) and children at ages 4.5 and 9 years. Blood pressure and anthropometric indices were measured at 4.5 and 9 years. Metabolic markers (lipids, glucose, hemoglobin A1c, adipokines, estimated glomerular filtration rate (eGFR) were determined in plasma/blood of 9 years old children. In linear regression models, adjusted for child sex, age, height-for-age z score (HAZ), BMI-for-age z score (BAZ), socioeconomic status (SES) and maternal education, each doubling of maternal and early childhood U–Cd was associated with 0.73 and 0.82 mmHg increase in systolic blood pressure (SBP) respectively. Both early and concurrent childhood U–Cd was associated with diastolic (D)BP (β = 0.80 at 4.5 years; β = 0.75 at 9 years). Each doubling of U–Cd at 9 years was associated with decrements of 4.98 mg/dL of total cholesterol (TC), 1.75 mg/dL high-density lipoprotein (HDL), 3.85 mg/dL low-density lipoprotein (LDL), 0.43 mg/dL glucose and 4.29 units eGFR. Each doubling of maternal U–Cd was associated with a decrement of 1.23 mg/dL HDL. Both maternal and childhood U–As were associated with decrement in TC and HDL. Multiple comparisons were checked with family-wise error rate Bonferroni-type-approach. The negative associations of arsenic and cadmium with biomarkers of CMD in preadolescent children indicated influence of both metal(loid)s on fat and carbohydrate metabolism, while cadmium additionally influenced kidney function and BP. Thus, fewer outcomes were associated with U–As compared to U–Cd at preadolescence.
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4.
  • Ali, Imran, et al. (författare)
  • Associations between cadmium exposure and circulating levels of sex hormones in postmenopausal women.
  • 2014
  • Ingår i: Environmental Research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 134, s. 265-269
  • Tidskriftsartikel (refereegranskat)abstract
    • Recent epidemiological as well as in vivo and in vitro studies collectively suggest that the metalloestrogen cadmium (Cd) could be a potential risk factor for hormone-related cancers in particularly breast cancer. Assessment of the association between Cd exposure and levels of endogenous sex hormones is of pivotal importance, as increased levels of such have been associated with a higher risk of breast cancer in postmenopausal women. The present study investigated the perceived relationship (multivariable-adjusted linear regression analyses) between Cd exposure [blood Cd (B-Cd) and urinary Cd (U-Cd)], and serum levels of androstenedione, testosterone, estradiol, and sex-hormone binding globulin (SHBG), in 438 postmenopausal Swedish women without hormone replacement therapy (HRT). A significant positive association between B-Cd (median 3.4nmol/L) and serum testosterone levels, as well as a significant inverse association between B-Cd and serum estradiol levels and with the estradiol/testosterone ratio were encountered. However, U-Cd (median 0.69nmol/mmol creatinine) was inversely associated with serum estradiol levels only. Our data may suggest that Cd interferes with the levels of testosterone and estradiol in postmenopausal women, which might have implications for breast cancer risk.
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5.
  • Ameer, Shegufta, et al. (författare)
  • Exposure to Inorganic Arsenic Is Associated with Increased Mitochondrial DNA Copy Number and Longer Telomere Length in Peripheral Blood
  • 2016
  • Ingår i: Frontiers in Cell and Developmental Biology. - : Frontiers Media SA. - 2296-634X. ; 4
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Exposure to inorganic arsenic (iAs) through drinking water causes cancer. Alterations in mitochondrial DNA copy number (mtDNAcn) and telomere length in blood have been associated with cancer risk. We elucidated if arsenic exposure alters mtDNAcn and telomere length in individuals with different arsenic metabolizing capacity.METHODS: We studied two groups in the Salta province, Argentina, one in the Puna area of the Andes (N = 264, 89% females) and one in Chaco (N = 169, 75% females). We assessed arsenic exposure as the sum of arsenic metabolites [iAs, methylarsonic acid (MMA), dimethylarsinic acid (DMA)] in urine (U-As) using high-performance liquid chromatography coupled with hydride generation and inductively coupled plasma mass spectrometry. Efficiency of arsenic metabolism was expressed as percentage of urinary metabolites. MtDNAcn and telomere length were determined in blood by real-time PCR.RESULTS: Median U-As was 196 (5-95 percentile: 21-537) μg/L in Andes and 80 (5-95 percentile: 15-1637) μg/L in Chaco. The latter study group had less-efficient metabolism, with higher %iAs and %MMA in urine compared with the Andean group. U-As was significantly associated with increased mtDNAcn (log2 transformed to improve linearity) in Chaco (β = 0.027 per 100 μg/L, p = 0.0085; adjusted for age and sex), but not in Andes (β = 0.025, p = 0.24). U-As was also associated with longer telomere length in Chaco (β = 0.016, p = 0.0066) and Andes (β = 0.0075, p = 0.029). In both populations, individuals with above median %iAs showed significantly higher mtDNAcn and telomere length compared with individuals with below median %iAs.CONCLUSIONS: Arsenic was associated with increased mtDNAcn and telomere length, particularly in individuals with less-efficient arsenic metabolism, a group who may have increased risk for arsenic-related cancer.
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6.
  • Ameer, Syeda Shegufta, et al. (författare)
  • Arsenic exposure from drinking water is associated with decreased gene expression and increased DNA methylation in peripheral blood
  • 2017
  • Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 321, s. 57-66
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Exposure to inorganic arsenic increases the risk of cancer and non-malignant diseases. Inefficient arsenic metabolism is a marker for susceptibility to arsenic toxicity. Arsenic may alter gene expression, possibly by altering DNA methylation. Objectives To elucidate the associations between arsenic exposure, gene expression, and DNA methylation in peripheral blood, and the modifying effects of arsenic metabolism. Methods The study participants, women from the Andes, Argentina, were exposed to arsenic via drinking water. Arsenic exposure was assessed as the sum of arsenic metabolites in urine (U-As), using high performance liquid-chromatography hydride-generation inductively-coupled-plasma-mass-spectrometry, and arsenic metabolism efficiency was assessed by the urinary fractions (%) of the individual metabolites. Genome-wide gene expression (N = 80 women) and DNA methylation (N = 93; 80 overlapping with gene expression) in peripheral blood were measured using Illumina DirectHyb HumanHT-12 v4.0 and Infinium Human-Methylation 450K BeadChip, respectively. Results U-As concentrations, ranging 10–1251 μg/L, was associated with decreased gene expression: 64% of the top 1000 differentially expressed genes were down-regulated with increasing U-As. U-As was also associated with hypermethylation: 87% of the top 1000 CpGs were hypermethylated with increasing U-As. The expression of six genes and six individual CpG sites were significantly associated with increased U-As concentration. Pathway analyses revealed enrichment of genes related to cell death and cancer. The pathways differed somewhat depending on arsenic metabolism efficiency. We found no overlap between arsenic-related gene expression and DNA methylation for individual genes. Conclusions Increased arsenic exposure was associated with lower gene expression and hypermethylation in peripheral blood, but with no evident overlap.
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  • Amzal, Billy, et al. (författare)
  • Population Toxicokinetic Modeling of Cadmium for Health Risk Assessment
  • 2009
  • Ingår i: Journal of Environmental Health Perspectives. - : US DEPT HEALTH HUMAN SCIENCES PUBLIC HEALTH SCIENCE. - 0091-6765 .- 1552-9924. ; 117:8, s. 1293-1301
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Cadmium is a widespread environmental pollutant that has been shown to exert toxic effects on kidney and bones in humans after long-term exposure. Urinary cadmium concentration is considered a good biomarker of accumulated cadmium in kidney, and diet is the main source of cadmium among nonsmokers. OBJECTIVE: Modeling the link between urinary cadmium and dietary cadmium intake is a key step in the risk assessment of long-term cadmium exposure. There is, however, little knowledge on how this link may vary, especially for susceptible population strata. METHODS: We used a large population-based study (the Swedish Mammography Cohort), with repeated dietary intake data covering a period of 20 years, to compare estimated dietary cadmium intake with urinary cadmium concentrations on an individual basis. A modified version of the Nordberg-Kjellstrom model and a one-compartment model were evaluated in terms of their predictions of urinary cadmium. We integrated the models and quantified the between-person variability of cadmium half-life in the population. Finally, sensitivity analyses and Monte Carlo simulations were performed to illustrate how the latter model could serve as a robust tool supporting the risk assessment of cadmium in humans. RESULTS: The one-compartment population model appeared to be an adequate modeling option to link cadmium intake to urinary cadmium and to describe the population variability. We estimated the cadmium half-life to be about 11.6 years, with about 25% population variability. CONCLUSIONS: Population toxicokinetic models can be robust and useful tools for risk assessment of chemicals, because they allow quantification and integration of population variability in toxicokinetics.
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9.
  • Arsenic Research and Global Sustainability: Proceedings of the Sixth International Congress on Arsenic in the Environment (As2016), June 19-23, 2016, Stockholm, Sweden
  • 2016
  • Proceedings (redaktörskap) (refereegranskat)abstract
    • The Congress "Arsenic in the Environment" offers an international, multi- and interdisciplinary discussion platform for research and innovation aimed towards a holistic solution to the problem posed by the environmental toxin arsenic, with considerable societal impact. The congress has focused on cutting edge and breakthrough research in physical, chemical, toxicological, medical, agricultural and other specific issues on arsenic across a broader environmental realm. The Congress "Arsenic in the Environment" was first organized in Mexico City (As2006) followed by As2008 in Valencia, Spain, As2010 in Tainan, Taiwan, As2012 in Cairns, Australia and As2014 in Buenos Aires, Argentina. The 6th International Congress As2016 was held June 19-23, 2016 in Stockholm, Sweden and was entitled Arsenic Research and Global Sustainability.
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10.
  • Ask, Karolin, et al. (författare)
  • Kvicksilverexponering hos kvinnor med högt fiskintag
  • 2002
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Den övergripande målsättningen med den hälsorelaterade miljöövervakningen (HÄMI) är att följa exponering för miljöföroreningar över tid, speciellt hos känsliga och riskutsatta grupper, och att så långt som möjligt identifiera de huvudsakliga exponeringskällorna för att möjliggöra en effektiv exponeringsreduktion. Det specifika syftet med föreliggande projekt var att belägga exponeringsnivåer för kvicksilver, framförallt metylk vicksilver (MeHg), hos kvinnor i barnafödande ålder med hög fiskkonsumtion. De utgör en potentiell riskgrupp i den allmänna befolkningen eftersom fostret är speciellt känsligt för MeHg. Kvicksilverhalter i blod och hår utvärderas i relation till fiskintag (sort och mängd). Tidigare undersökningar inom den hälsorelaterade miljöövervakningen har påvisat stor variation i exponeringen för MeHg även bland kvinnor med måttlig fiskkonsumtion. Genom denna studie och upprepade undersökningar kan eventuella förändringar i exponering över tid detekteras. Resultaten från studien jämförs med resultat från tidigare projekt inom HÄMI och andra svenska studier. På lång sikt är förhoppningen att exponeringen sjunker till en nivå som medför att kostrekommendationerna för fiskintag kan tas bort. Detta är i linje med det nationella miljömålet ”giftfri miljö” som regering och riksdag beslutat om. Föreliggande undersökning har utförts i samarbete mellan Institutet för Miljömedicin (IMM), Karolinska Institutet och Livsmedelsverket på uppdrag av Naturvårdsverket.
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15.
  • Barman, Malin, 1983, et al. (författare)
  • Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE): a prospective birth cohort in northern Sweden
  • 2018
  • Ingår i: BMJ Open. - : BMJ. - 2044-6055 .- 2044-6055. ; 8:10
  • Tidskriftsartikel (refereegranskat)abstract
    • © Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. INTRODUCTION: Prenatal and neonatal environmental factors, such as nutrition, microbes and toxicants, may affect health throughout life. Many diseases, such as allergy and impaired child development, may be programmed already in utero or during early infancy. Birth cohorts are important tools to study associations between early life exposure and disease risk. Here, we describe the study protocol of the prospective birth cohort, 'Nutritional impact on Immunological maturation during Childhood in relation to the Environment' (NICE). The primary aim of the NICE cohort is to clarify the effect of key environmental exposures-diet, microbes and environmental toxicants-during pregnancy and early childhood, on the maturation of the infant's immune system, including initiation of sensitisation and allergy as well as some secondary outcomes: infant growth, obesity, neurological development and oral health.METHODS AND ANALYSIS: The NICE cohort will recruit about 650 families during mid-pregnancy. The principal inclusion criterion will be planned birth at the Sunderby Hospital in the north of Sweden, during 2015-2018. Questionnaires data and biological samples will be collected at 10 time-points, from pregnancy until the children reach 4 years of age. Samples will be collected primarily from mothers and children, and from fathers. Biological samples include blood, urine, placenta, breast milk, meconium, faeces, saliva and hair. Information regarding allergic heredity, diet, socioeconomic status, lifestyle including smoking, siblings, pet ownership, etc will be collected using questionnaires. Sensitisation to common allergens will be assessed by skin prick testing and allergic disease will be diagnosed by a paediatrician at 1 and 4 years of age. At 4 years of age, the children will also be examined regarding growth, neurobehavioural and neurophysiological status and oral health.ETHICS AND DISSEMINATION: The NICE cohort has been approved by the Regional Ethical Review Board in Umeå, Sweden (2013/18-31M). Results will be disseminated through peer-reviewed journals and communicated on scientific conferences.
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  • Bhattacharya, Prosun, 1962-, et al. (författare)
  • Editors’ foreword
  • 2016
  • Ingår i: Arsenic Research and Global Sustainability. - London : CRC Press. - 9781315629438 ; , s. xlv-xlvi, s. xlvii-xlviii
  • Konferensbidrag (refereegranskat)
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18.
  • Bhattacharya, Prosun, et al. (författare)
  • Temporal and seasonal variability of arsenic in drinking water wells in Matlab, southeastern Bangladesh : A preliminary evaluation on the basis of a 4 year study
  • 2011
  • Ingår i: Journal of Environmental Science and Health. Part A. - : Informa UK Limited. - 1093-4529 .- 1532-4117. ; 46:11, s. 1177-1184
  • Tidskriftsartikel (refereegranskat)abstract
    • Temporal and seasonal variability of As concentrations in groundwater were evaluated in As-affected areas of Matlab, southeastern Bangladesh. Groundwater samples from 61 randomly selected tubewells were analyzed for As concentrations over a period of three years and four months (from July 2002 to November 2005) and monitored seasonally (three times a year). The mean As concentrations in the sampled tubewells decreased from 153 to 123 mu g/L during July 2002 to November 2005. Such changes were pronounced in tubewells with As concentration >50 mu g/L than those with As concentrations <50 mu g/L. Similarly, individual wells revealed temporal variability, for example some wells indicated a decreasing trend, while some other wells indicated stable As concentration during the monitoring period. The mean As concentrations were significantly higher in Matlab North compared with Matlab South. The spatial variations in the mean As concentrations may be due to the differences in local geological conditions and groundwater flow patterns. The variations in mean As concentrations were also observed in shallow (<40 m) and deep (>40 m) wells. However, to adequately evaluate temporal and seasonal variability of As concentration, it is imperative to monitor As concentrations in tubewells over a longer period of time. Such long-term monitoring will provide important information for the assessment of human health risk and the sustainability of safe drinking water supplies.
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19.
  • Broberg Palmgren, Karin, et al. (författare)
  • Lithium in Drinking Water and Thyroid Function
  • 2011
  • Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 119:6, s. 827-830
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: High concentrations of lithium in drinking water were previously discovered in the Argentinean Andes Mountains. Lithium is used worldwide for treatment of bipolar disorder and treatment-resistant depression. One known side effect is altered thyroid function. OBJECTIVES: We assessed associations between exposure to lithium from drinking water and other environmental sources and thyroid function. METHODS: Women (n = 202) were recruited in four Andean villages in northern Argentina. Lithium exposure was assessed based on concentrations in spot urine samples, measured by inductively coupled plasma mass spectrometry. Thyroid function was evaluated by plasma free thyroxine (T-4) and pituitary gland thyroid-stimulating hormone (TSH), analyzed by routine immuno metric methods. RESULTS: The median urinary lithium concentration was 3,910 mu g/L (5th, 95th percentiles, 270 mu g/L, 10,400 mu g/L). Median plasma concentrations (5th, 95th percentiles) of T-4 and TSH were 17 pmol/L (13 pmol/L, 21 pmol/L) and 1.9 mIU/L, (0.68 mIU/L, 4.9 mIU/L), respectively. Urine lithium was inversely associated with T-4 [beta for a 1,000-mu g/L increase = -0.19; 95% confidence interval (CI), -0.31 to -0.068; p = 0.002] and positively associated with TSH (beta = 0.096; 95% CI, 0.033 to 0.16; p = 0.003). Both associations persisted after adjustment (for T-4, beta = -0.17; 95% CI, -0.32 to -0.015; p = 0.032; for TSH: beta = 0.089; 95% CI, 0.024 to 0.15; p = 0.007). Urine selenium was positively associated with T-4 (adjusted T-4 for a 1 mu g/L increase: beta = 0.041; 95% CI, 0.012 to 0.071; p = 0.006). CONCLUSIONS: Exposure to lithium via drinking water and other environmental sources may affect thyroid function, consistent with known side effects of medical treatment with lithium. This stresses the need to screen for lithium in all drinking water sources.
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20.
  • Concha, Gabriela, et al. (författare)
  • High-Level Exposure to Lithium, Boron, Cesium, and Arsenic via Drinking Water in the Andes of Northern Argentina.
  • 2010
  • Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 44:17, s. 6875-6880
  • Tidskriftsartikel (refereegranskat)abstract
    • Elevated concentrations of arsenic in drinking water are common worldwide, however, little is known about the presence of other potentially toxic elements. We analyzed 31 different elements in drinking water collected in San Antonio de los Cobres and five surrounding Andean villages in Argentina, and in urine of the inhabitants, using ICP-MS. Besides confirmation of elevated arsenic concentrations in the drinking water (up to 210 mug/L), we found remarkably high concentrations of lithium (highest 1000 mug/L), cesium (320 mug/L), rubidium (47 mug/L), and boron (5950 mug/L). Similarly elevated concentrations of arsenic, lithium, cesium, and boron were found in urine of the studied women (N = 198): village median values ranged from 26 to 266 mug/L of arsenic, 340 to 4550 mug/L of lithium, 34 to 531 mug/L of cesium, and 2980 to 16 560 mug/L of boron. There is an apparent risk of toxic effects of long-term exposure to several of the elements, and studies on associations with adverse human health effects are warranted, particularly considering the combined, life-long exposure. Because of the observed wide range of concentrations, all water sources used for drinking water should be screened for a large number of elements; obviously, this applies to all drinking water sources globally.
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21.
  • De Loma, Jessica, et al. (författare)
  • Human adaptation to arsenic in Bolivians living in the Andes
  • 2022
  • Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 301
  • Tidskriftsartikel (refereegranskat)abstract
    • Humans living in the Andes Mountains have been historically exposed to arsenic from natural sources, including drinking water. Enzymatic methylation of arsenic allows it to be excreted more efficiently by the human body. Adaptation to high-arsenic environments via enhanced methylation and excretion of arsenic was first reported in indigenous women in the Argentinean Andes, but whether adaptation to arsenic is a general phenomenon across native populations from the Andes Mountains remains unclear. Therefore, we evaluated whether adaptation to arsenic has occurred in the Bolivian Andes by studying indigenous groups who belong to the Aymara-Quechua and Uru ethnicities and have lived in the Bolivian Andes for generations. Our population genetics methods, including genome-wide selection scans based on linkage disequilibrium patterns and allele frequency differences, in combination with targeted and whole-genome sequencing and genotype-phenotype association analyses, detected signatures of positive selection near the gene encoding arsenite methyltransferase (AS3MT), the main arsenic methylating enzyme. This was among the strongest selection signals (top 0.5% signals via locus-specific branch length and extended haplotype homozygosity tests) at a genome-wide level in the Bolivian study groups. We found a large haplotype block of 676 kb in the AS3MT region and identified candidate functional variants for further analysis. Moreover, our analyses revealed associations between AS3MT variants and the fraction of monomethylated arsenic in urine and showed that the Bolivian study groups had the highest frequency of alleles associated with more efficient arsenic metabolism reported so far. Our data support the idea that arsenic exposure has been a driver for human adaptation to tolerate arsenic through more efficient arsenic detoxification in different Andean populations.
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22.
  • Donat-Vargas, Carolina, et al. (författare)
  • Urinary phosphate is associated with cardiovascular disease incidence.
  • 2023
  • Ingår i: Journal of Internal Medicine. - 0954-6820 .- 1365-2796. ; 294:3, s. 358-369
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: Elevated phosphate (P) in urine may reflect a high intake of inorganic P salts from food additives. Elevated P in plasma is linked to vascular dysfunction and calcification.OBJECTIVE: To explore associations between P in urine as well as in plasma and questionnaire-estimated P intake, and incidence of cardiovascular disease (CVD).METHODS: We used the Swedish Mammography Cohort-Clinical, a population-based cohort study. At baseline (2004-2009), P was measured in urine and plasma in 1625 women. Dietary P was estimated via a food-frequency questionnaire. Incident CVD was ascertained via register-linkage. Associations were assessed using Cox proportional hazards regression.RESULTS: After a median follow-up of 9.4 years, 164 composite CVD cases occurred (63 myocardial infarctions [MIs] and 101 strokes). Median P (percentiles 5-95) in urine and plasma were 2.4 (1.40-3.79) mmol/mmol creatinine and 1.13 (0.92-1.36) mmol/L, respectively, whereas dietary P intake was 1510 (1148-1918) mg/day. No correlations were observed between urinary and plasma P (r = -0.07) or dietary P (r = 0.10). Urinary P was associated with composite CVD and MI. The hazard ratio of CVD comparing extreme tertiles was 1.57 (95% confidence interval 1.05, 2.35; P trend 0.037)-independently of sodium excretion, the estimated glomerular filtration rate, both P and calcium in plasma, and diuretic use. Association with CVD for plasma P was 1.41 (0.96, 2.07; P trend 0.077).CONCLUSION: Higher level of urinary P, likely reflecting a high consumption of highly processed foods, was linked to CVD. Further investigation is needed to evaluate the potential cardiovascular toxicity associated with excessive intake of P beyond nutritional requirements.
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23.
  • Engstrom, Annette, et al. (författare)
  • Associations between dietary cadmium exposure and bone mineral density and risk of osteoporosis and fractures among women
  • 2012
  • Ingår i: Bone. - : Elsevier BV. - 8756-3282 .- 1873-2763. ; 50:6, s. 1372-1378
  • Tidskriftsartikel (refereegranskat)abstract
    • Osteoporosis and its main health outcome, fragility fractures, are large and escalating public health problems. Cadmium, a widespread food contaminant, is a proposed risk factor; still the association between estimated dietary cadmium exposure and bone mineral density (BMD) has never been assessed. Within a sub-cohort of the Swedish Mammography Cohort, we assessed dietary cadmium exposure based on a food frequency questionnaire (1997) and urinary cadmium (2004-2008) in relation to total-body BMD and risk of osteoporosis and fractures (1997-2009) among 2676 women (aged 56-69 years). In multivariable-adjusted linear regression, dietary cadmium was inversely associated with BMD at the total body and lumbar spine. After further adjustment for dietary factors important for bone health and cadmium bioavailability-calcium, magnesium, iron and fiber, the associations became more pronounced. A 32% increased risk of osteoporosis (95% Cl: 2-71%) and 31% increased risk for any first incident fracture (95% Cl; 2-69%) were observed comparing high dietary cadmium exposure (>= 13 mu g/day, median) with lower exposures (<13 mu g/day). By combining high dietary with high urinary cadmium (>= 0.50 mu g/g creatinine), odds ratios among never-smokers were 2.65 (95% Cl: 1.43-4.91) for osteoporosis and 3.05 (95% Cl; 1.66-5.59) for fractures. In conclusion, even low-level cadmium exposure from food is associated with low BMD and an increased risk of osteoporosis and fractures. The partial masking of the associations by essential nutrients indicates important interplay between dietary factors and contaminants present in food. In separate analyses, dietary and urinary cadmium underestimated the association with bone effects.
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24.
  • Engstrom, Annette, et al. (författare)
  • Cadmium-induced bone effect is not mediated via low serum 1,25-dihydroxy vitamin D
  • 2009
  • Ingår i: Environmental Research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 109:2, s. 188-192
  • Tidskriftsartikel (refereegranskat)abstract
    • Cadmium is a widespread environmental pollutant, which is associated with increased risk of osteoporosis. It has been proposed that cadmium's toxic effect on bone is exerted via impaired activation of vitamin D, secondary to the kidney effects. To test this, we assessed the association of cadmium-induced bone and kidney effects with serum 1,25-dihydroxyvitamin D (1,25(OH)(2)D); measured by enzyme immunoassay. For the assessment, we selected 85 postmenopausal women, based on low (0.14-0.39 mu g/L) or high (0.66-2.1 mu g/L) urinary cadmium, within a cross-sectional population-based women's health survey in Southern Sweden. We also measured 25-hydroxy vitamin D. cadmium in blood, bone mineral density and several markers of bone remodeling and kidney effects. Although there were clear differences in both kidney and bone effect markers between women with low and high cadmium exposure, the 1,25(OH)(2)D concentrations were not significantly different (median, 111 pmol/L (5-95th percentile, 67-170 pmol/L) in low- and 125 pmol/L (66-200 pmol/L) in high-cadmium groups; p = 0.08). Also, there was no association between 1,25(OH)(2)D and markers of bone or kidney effects. It is concluded that the low levels of cadmium exposure present in the studied women, although high enough to be associated with lower bone mineral density and increased bone resorption, were not associated with lower serum concentrations of 1,25(OH)(2)D. Hence, decreased circulating levels of 1,25(OH)(2)D are unlikely to be the proposed link between cadmium-induced effects on kidney and bone. (C) 2008 Elsevier Inc. All rights reserved.
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25.
  • Engstrom, Annette, et al. (författare)
  • Retinol May Counteract the Negative Effect of Cadmium on Bone
  • 2011
  • Ingår i: Journal of Nutrition. - : Elsevier BV. - 1541-6100 .- 0022-3166. ; 141:12, s. 2198-2203
  • Tidskriftsartikel (refereegranskat)abstract
    • Cadmium and high vitamin A intake are both proposed risk factors for low bone mineral density (BMD), but potential interactions have not been studied. Within the Women's Health in the Lund Area, a population-based study in southern Sweden, we measured retinol in serum among 606 women aged 54-64 y. Data on BMD were measured by DXA at the distal forearm. Parathyroid hormone (PTH), bone alkaline phosphatase (bALP), and osteocalcin in serum and deoxypyridinoline (DPD) and cadmium in urine were available. Associations were evaluated using multivariable-adjusted linear regression analysis. Serum retinol concentrations (median, 1.9; range, 0.97-4.3 mu mol/L) were inversely associated with the bone formation markers bALP and osteocalcin (P <= 0.04) and with PTH (P = 0.07) and tended to be positively associated with BMD (P = 0.08) but not with the bone resorption marker DPD, indicating different effects on bone compared to urinary cadmium (median, 0.66; range, 0.12-3.6 nmol/mmol creatinine). Women with serum retinol less than the median and cadmium greater than the median had lower BMD than those with retinol greater than the median and cadmium less than the median (P = 0.016 among all women and P = 0.010 among never-smokers). Our findings suggest that adequate vitamin A status may counteract the adverse association between cadmium and BMD. J. Nutr. 141: 2198-2203, 2011.
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26.
  • Engström, Annette, et al. (författare)
  • Long-term cadmium exposure and the association with bone mineral density and fractures in a population-based study among women
  • 2011
  • Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 26:3, s. 486-495
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND:: All people are exposed to cadmium (Cd) via food, smokers are additionally exposed. High Cd exposure is associated with severe bone damage, but the public health impact in relation to osteoporosis and fractures at low environmental exposure remains to be clarified. METHODS:: Within the population-based Swedish Mammography Cohort, we assessed urinary Cd (U-Cd, mug/g creatinine, cr) as a marker of life-time exposure and bone mineral density (BMD) by DXA among 2,688 women. Register-based information on fractures was retrieved from 1997 to 2009. Associations were evaluated by multivariable regression analyses. RESULTS:: In linear regression U-Cd was inversely associated with BMD at the total body (p<0.001), femoral neck (p=0.025), total hip (p=0.004), lumbar spine (p=0.088), and volumetric femoral neck (p=0.013). In comparison to women with U-Cd <0.50 mug/g cr, those with U-Cd >/=0.75 mug/g cr had OR 2.45 (95% CI, 1.51-3.97) and 1.97 (95% CI, 1.24-3.14) for osteoporosis at the femoral neck and lumbar spine, respectively. Among never-smokers, the corresponding ORs were 3.45 (95% CI, 1.46-8.23) and 3.26 (95% CI, 1.44-7.38). For any first fracture (n=395) OR was 1.16 (95% CI, 0.89-1.50) comparing U-Cd >/=0.5 mug/g cr with lower levels. Among never-smokers, the ORs (95% CIs) were 2.03 (1.33-3.09) for any first fracture, 2.06 (1.28-3.32) for first osteoporotic fracture, 2.18 (1.20-3.94) for first distal forearm fracture and 1.89 (1.25-2.85) for multiple incident fractures. CONCLUSIONS:: U-Cd at low environmental exposure from food in a general population of women showed modest but significant association with both BMD and fractures especially in never smokers indicating a larger concern than previously known.
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27.
  • Engström, Karin, et al. (författare)
  • Arsenic metabolism is influenced by polymorphisms in genes involved in one-carbon metabolism and reduction reactions.
  • 2009
  • Ingår i: Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis. - : Elsevier BV. - 1879-2871 .- 0027-5107. ; 667, s. 4-14
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: The susceptibility to arsenic (As)-induced diseases differs greatly between individuals, probably to a large extent due to genetic differences in arsenic metabolism. The aim for this study was to identify genetic variants affecting arsenic metabolism. METHODS: We evaluated the association between urinary metabolite pattern and polymorphisms in three gene-groups related to arsenic metabolism: (1) methyltransferases, (2) other genes involved in one-carbon metabolism and (3) genes involved in reduction reactions. Forty-nine polymorphisms were successfully genotyped in indigenous women (N=104) from northern Argentina, exposed to approximately 200mug/L of arsenic in drinking water, with a unique metabolism with low percent monomethylated arsenic (%MMA) and high percent dimethylated As (%DMA). RESULTS: Genetic factors affecting arsenic metabolite pattern included two polymorphisms in arsenic (+III) methyltransferase (AS3MT) (rs3740400, rs7085104), where carriers had lower %MMA and higher %DMA. These single nucleotide polymorphisms (SNPs) were in strong linkage disequilibrium (LD) with three intronic AS3MT SNPs, previously reported to be associated with arsenic metabolism, indicating the existence of a strongly methylating, population-specific haplotype. The CYP17A1 rs743572, 27kilobasepairs (kbs) upstream of AS3MT, was in strong LD with the AS3MT SNPs and thus had similar effects on the metabolite profile. Smaller effects were also seen for one-carbon metabolism genes choline dehydrogenase (CHDH) (rs9001, rs7626693) and 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) (rs1801394) and genes involved in reduction reactions, glutaredoxin (GLRX) (rs3822751) and peroxiredoxin 2 (PRDX2) (rs10427027, rs12151144). Genotypes associated with more beneficial arsenic metabolite profile (low %MMA and/or high %DMA in urine) were more common in this population, which has been exposed to arsenic in drinking water for thousands of years. CONCLUSIONS: Polymorphisms in AS3MT and in genes involved in one-carbon metabolism and reduction reactions affects arsenic metabolism.
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28.
  • Engström, Karin, et al. (författare)
  • Chronic exposure to cadmium and arsenic strongly influences concentrations of 8-oxo-7,8-dihydro-2'-deoxyguanosine in urine.
  • 2010
  • Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 48:9, s. 1211-1217
  • Tidskriftsartikel (refereegranskat)abstract
    • Exposure to arsenic (As), cadmium (Cd) and lead (Pb) may generate oxidative stress, which can be assessed by 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in urine, a sensitive marker of oxidatively damaged DNA. We have evaluated oxidative stress induced by mixed chronic exposure to As, Cd, Pb, as well as the influence of As metabolism and nutritional status, i.e. ferritin (Ft), selenium (Se), zinc (Zn), manganese (Mn) and body weight. 8-oxodG was measured in urine from 212 women in early pregnancy from Matlab, rural Bangladesh, using LC-MS/MS. Cd and Pb were analyzed in urine and erythrocytes, while Se, Mn and Zn were analyzed in erythrocytes, all by ICPMS. As and As metabolites were analyzed in urine by HPLC-ICPMS. Ferritin was analyzed in plasma by radioimmunoassay. Median concentration of 8-oxodG was 8.3 nmol/L (adjusted for specific gravity), range 1.2-43, corresponding to a median of 4.7 mug/g creatinine, range 1.8-32. 8-oxodG was positively associated with urinary Cd (ss=0.32, p<0.001), urinary As (ss=0.0007, p=0.001), fraction of the monomethylated arsenic metabolite (MMA) in urine (ss=0.0026, p=0.004) and plasma Ft (ss = 0.20, p<0.001). A joint effect was seen for U-Cd and U-As, but whether this effect was additive or multiplicative was difficult to discern.
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29.
  • Engström, Karin, et al. (författare)
  • Efficient Arsenic Metabolism - The AS3MT Haplotype Is Associated with DNA Methylation and Expression of Multiple Genes Around AS3MT.
  • 2013
  • Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Arsenic is a very potent toxicant. One major susceptibility factor for arsenic-related toxicity is the efficiency of arsenic metabolism. The efficiency, in turn, is associated with non-coding single nucleotide polymorphisms (SNPs) in the arsenic methyltransferase AS3MT on chromosome 10q24. However, the mechanism of action for these SNPs is not yet clarified. Here, we assessed the influence of genetic variation in AS3MT on DNA methylation and gene expression within 10q24, in people exposed to arsenic in drinking water. DNA was extracted from peripheral blood from women in the Argentinean Andes (N = 103) and from cord blood from new-borns in Bangladesh (N = 127). AS3MT SNPs were analyzed with Sequenom or Taqman assays. Whole genome epigenetic analysis with Infinium HumanMethylation450 BeadChip was performed on bisulphite-treated DNA. Whole genome gene expression analysis was performed with Illumina DirectHyb HumanHT-12 v4.0 on RNA from peripheral blood. Arsenic exposure was assessed by HPLC-ICPMS. In the Argentinean women, the major AS3MT haplotype, associated with more efficient arsenic metabolism, showed increased methylation of AS3MT (p = 10(-6)) and also differential methylation of several other genes within about 800 kilobasepairs: CNNM2 (p<10(-16)), NT5C2 (p<10(-16)), C10orf26 (p = 10(-8)), USMG5 (p = 10(-5)), TRIM8 (p = 10(-4)), and CALHM2 (p = 0.038) (adjusted for multiple comparisons). Similar, but weaker, associations between AS3MT haplotype and DNA methylation in 10q24 were observed in cord blood (Bangladesh). The haplotype-associated altered CpG methylation was correlated with reduced expression of AS3MT and CNNM2 (r(s) = -0.22 to -0.54), and with increased expression of NT5C2 and USMG5 (r(s) = 0.25 to 0.58). Taking other possibly influential variables into account in multivariable linear models did only to a minor extent alter the strength of the associations. In conclusion, the AS3MT haplotype status strongly predicted DNA methylation and gene expression of AS3MT as well as several genes in 10q24. This raises the possibility that several genes in this region are important for arsenic metabolism.
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30.
  • Engström, Karin, et al. (författare)
  • Genetic polymorphisms influencing arsenic metabolism: evidence from Argentina.
  • 2007
  • Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 115:4, s. 599-605
  • Tidskriftsartikel (refereegranskat)abstract
    • The susceptibility to arsenic-induced diseases differs greatly between individuals, possibly due to interindividual variations in As metabolism that affect retention and distribution of toxic metabolites. To elucidate the role of genetic factors in As metabolism, we studied how polymorphisms in six genes affected the urinary metabolite pattern in a group of indigenous women (n = 147) in northern Argentina who were exposed to approximately 200 mu g/L As in drinking water. These women had low urinary percentages of monomethylated As (MMA) and high percentages of dimethylated As (DMA). MMA has been associated with adverse health effects, and DMA has the lowest body retention of the metabolites. The genes studied were arsenic(+ 111) methyltransferase (AS3MT), glutathione S-transferase omega 1 (GSTO1), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), methylenetetrahydrofolate reductase (MTHFR), and glutathione S-transferases mu I (GSTM1) and theta I (GSTT1). We found three intronic polymorphisms in AS3MT (G12390C, C14215T, and G35991A) associated with a lower percentage of MMA (%MMA) and a higher percentage of DMA (%DMA) in urine. The variant homozygotes showed approximately half the %MMA compared with wild-type homozygotes. These polymorphisms were in strong linkage, with high allelic frequencies (72-76%) compared with other populations. We also saw minor effects of other polymorphisms in the multivariate regression analysis with effect modification for the deletion genotypes for GSTM1 (affecting %MMA) and GSTT1 (affecting %MMA and %DMA). For pregnant women, effect modification was seen for the folate-metabolizing genes MTR and MTHFA In conclusion, these findings indicate that polymorphisms in AS3MT-and possibly GSTM1, GSTT1, MTR, and MTHFR-are responsible for a large part of the interindividual variation in As metabolism and susceptibility.
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31.
  • Engström, Karin, et al. (författare)
  • Genetic variation in arsenic (+3 oxidation state) methyltransferase (AS3MT), arsenic metabolism and risk of basal cell carcinoma in a European population.
  • 2015
  • Ingår i: Environmental and Molecular Mutagenesis. - : Wiley. - 1098-2280 .- 0893-6692. ; 56:1, s. 60-69
  • Tidskriftsartikel (refereegranskat)abstract
    • Exposure to inorganic arsenic increases the risk of basal cell carcinoma (BCC). Arsenic metabolism is a susceptibility factor for arsenic toxicity, and specific haplotypes in arsenic (+3 oxidation state) methyltransferase (AS3MT) have been associated with increased urinary fractions of the most toxic arsenic metabolite, methylarsonic acid (MMA). The aim of this study is to elucidate the association of AS3MT haplotypes with arsenic metabolism and the risk of BCC. Four AS3MT polymorphisms were genotyped in BCC cases (N = 529) and controls (N = 533) from Eastern Europe with low to moderate arsenic exposure (lifetime average drinking water concentration: 1.3 µg/L, range 0.01-167 µg/L). Urinary metabolites [inorganic arsenic (iAs), MMA, dimethylarsinic acid (DMA)] were analyzed by HPLC-ICPMS. Five AS3MT haplotypes (based on rs3740400 A/C, rs3740393 G/C, rs11191439 T/C and rs1046778 T/C) had frequencies >5%. Individuals with the CCTC haplotype had lower %iAs (P = 0.032) and %MMA (P = 0.020) in urine, and higher %DMA (P = 0.033); individuals with the CGCT haplotype had higher %MMA (P < 0.001) and lower %DMA (P < 0.001). All haplotypes showed increased risk of BCC with increasing arsenic exposure through drinking water (ORs 1.1-1.4, P values from <0.001 to 0.082), except for the CCTC haplotype (OR 1.0, CI 0.9-1.2, P value 0.85). The results suggest that carriage of AS3MT haplotypes associated with less-efficient arsenic methylation, or lack of AS3MT haplotypes associated with a more-efficient arsenic methylation, results in higher risk of arsenic-related BCC. The fact that AS3MT haplotype status modified arsenic metabolism, and in turn the arsenic-related BCC risk, supports a causal relationship between low-level arsenic exposure and BCC. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc.
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32.
  • Engström, Karin, et al. (författare)
  • Low 8-oxo-7,8-dihydro-2'-deoxyguanosine levels and influence of genetic background in an Andean population exposed to high levels of arsenic.
  • 2010
  • Ingår i: Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis. - : Elsevier BV. - 1879-2871 .- 0027-5107. ; 683:1-2, s. 98-105
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Arsenic (As) causes oxidative stress through generation of reactive oxygen species. 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a sensitive marker of oxidative DNA damage, has been associated with As exposure in some studies, but not in others, possibly due to population-specific genetic factors. OBJECTIVES: To evaluate the association between As and 8-oxodG in urine in a population with a low urinary monomethylated As (%MMA) and high dimethylated As (%DMA), as well as the genetic impact on (a) 8-oxodG concentrations and (b) the association between As and 8-oxodG. MATERIALS AND METHODS: Women (N=108) in the Argentinean Andes were interviewed and urine was analyzed for arsenic metabolites (ICPMS) and 8-oxodG (LC-MS/MS). Twenty-seven polymorphisms in genes related to oxidative stress and one in As(+III)methyltransferase (AS3MT) were studied. RESULTS: Median concentration of 8-oxodG was 4.7nmol/L (adjusted for specific weight; range 1.6-13, corresponding to 1.7mug/g creatinine, range 0.57-4.8) and of total urinary As metabolites (U-As) 290mug/L (range 94-720; 380mug/g creatinine, range 140-1100). Concentrations of 8-oxodG were positively associated with %MMA (strongest association, p=0.013), and weakly associated with U-As (positively) and %DMA (negatively). These associations were strengthened when taking ethnicity into account, possibly reflecting genetic differences in As metabolism and genes regulating oxidative stress and DNA maintenance. A genetic influence on 8-oxodG concentrations was seen for polymorphisms in apurinic/apyrimidinic endonuclease 1 (APEX1), DNA-methyltransferases 1 and 3b (DNMT1, DNMT3B), thioredoxin reductase 1 (TXNRD1) and 2 (TXNRD2) and glutaredoxin (GLRX). CONCLUSION: Despite high As exposure, the concentrations of 8-oxodG in this population were low compared with other As-exposed populations studied. The strongest association was found for %MMA, stressing that some inconsistencies between As and 8-oxodG partly depend on population variations in As metabolism. We found evidence of genetic impact on 8-oxodG concentrations.
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33.
  • Engström, Karin, et al. (författare)
  • Polymorphisms in Arsenic(+III)methyltransferase (AS3MT) Predict Gene Expression of AS3MT as well as Arsenic Metabolism.
  • 2011
  • Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 119, s. 182-188
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Arsenic is mono- (MMA) and dimethylated (DMA) in humans and the methylation pattern demonstrates large inter-individual differences. The fraction of urinary MMA is a marker for susceptibility to arsenic-related diseases. Objectives: The impact of polymorphisms in five methyltransferase genes on arsenic metabolism was evaluated in two populations, one in South America, one in southeast Asia. The methyltransferase genes were arsenic(+III)methyltransferase (AS3MT), DNAmethyltransferase 1a and 3b (DNMT1a, DNMT3b), phosphatidylethanolamine Nmethyltransferase (PEMT) and betaine-homocysteine methyltransferase (BHMT). AS3MT expression was analyzed in peripheral blood. Methods: Subjects were women, exposed to arsenic in drinking water in the Argentinean Andes (N=172; median urinary arsenic 200 μg/L) and in rural Bangladesh (N=361; 100 μg/L, all in early pregnancy). Urinary arsenic metabolites were measured by HPLC-ICPMS. Polymorphisms (N=22) were genotyped with Sequenom™. AS3MT expression was measured with qPCR using TaqMan® expression assays. Results: Six AS3MT polymorphisms were significantly associated with arsenic metabolite patterns in both populations (p-values ≤0.01). The most frequent AS3MT haplotype in Bangladesh was associated with higher %MMA, and the most frequent in Argentina with lower %MMA and higher %DMA. Four polymorphisms in the DNMTs were associated with metabolite patterns in Bangladesh. Non-coding AS3MT polymorphisms affected gene expression of AS3MT in peripheral blood, demonstrating that one functional impact of AS3MT polymorphisms may be altering levels of gene expression. Conclusions: Polymorphisms in AS3MT significantly predicted As metabolism across these two very different populations, suggesting that AS3MT may have an impact on As metabolite patterns in populations worldwide.
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34.
  • Engström, Karin, et al. (författare)
  • Prenatal lead exposure is associated with decreased cord blood DNA methylation of the glycoprotein VI gene involved in platelet activation and thrombus formation
  • 2015
  • Ingår i: Environmental epigenetics. - : Oxford University Press (OUP). - 2058-5888. ; 1:1, s. 1-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Early-life lead exposure impairs neurodevelopment and later exposure affects the cardiovascular system. Lead has been associated with reduced global 5-methylcytosine DNA methylation, suggesting that lead toxicity acts through epigenetic mechanisms. The objective of this study is to clarify how early-life lead exposure alters DNA methylation of specific genes, using an epigenomic approach. We measured lead concentrations in urine [gestational week (GW), 8] and erythrocytes (GW 14), using inductively coupled plasma mass spectrometry, for 127 pregnant mothers recruited in the MINIMat food and supplementation cohort in rural Bangladesh. Cord blood DNA methylation was analyzed with the Infinium HumanMethylation450K BeadChip, and top sites were validated by methylation-sensitive high-resolution melt curve analysis. Maternal urinary lead concentrations (divided into quartiles) showed significant (after adjustment for false discovery rate) inverse associations with methylation at nine CpGs. Three of these sites were in the 5'-end, including the promoter, of glycoprotein IV (GP6); cg18355337 (q = 0.029, β = -0.30), cg25818583 (q = 0.041, β = -0.18), and cg23796967 (q = 0.047, β = -0.17). The methylation in another CpG site in GP6 was close to significant (cg05374025, q = 0.057, β = - 0.23). The erythrocyte lead concentrations (divided into quartiles) were also inversely associated with CpG methylation in GP6, although this was not statistically significant after false discovery rate adjustments. Eight CpG sites in GP6 constituted a differentially methylated region in relation to urinary lead (P = 0.005, q = 0.48) and erythrocyte lead (P = 0.007, q = 0.46). In conclusion, we found that moderate prenatal lead exposure appears to epigenetically affect GP6, a key component of platelet aggregation and thrombus formation, suggesting a novel link between early lead exposure and cardiovascular disease later in life.
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35.
  • Engström, Karin, et al. (författare)
  • Transcriptomics and methylomics of CD4-positive T cells in arsenic-exposed women
  • 2017
  • Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 91:5, s. 2067-2078
  • Tidskriftsartikel (refereegranskat)abstract
    • Arsenic, a carcinogen with immunotoxic effects, is a common contaminant of drinking water and certain food worldwide. We hypothesized that chronic arsenic exposure alters gene expression, potentially by altering DNA methylation of genes encoding central components of the immune system. We therefore analyzed the transcriptomes (by RNA sequencing) and methylomes (by target-enrichment next-generation sequencing) of primary CD4-positive T cells from matched groups of four women each in the Argentinean Andes, with fivefold differences in urinary arsenic concentrations (median concentrations of urinary arsenic in the lower- and high-arsenic groups: 65 and 276 mu g/l, respectively). Arsenic exposure was associated with genome-wide alterations of gene expression; principal component analysis indicated that the exposure explained 53% of the variance in gene expression among the top variable genes and 19% of 28,351 genes were differentially expressed (false discovery rate < 0.05) between the exposure groups. Key genes regulating the immune system, such as tumor necrosis factor alpha and interferon gamma, as well as genes related to the NF-kappa-beta complex, were significantly downregulated in the high-arsenic group. Arsenic exposure was associated with genome-wide DNA methylation; the high-arsenic group had 3% points higher genome-wide full methylation (> 80% methylation) than the lower-arsenic group. Differentially methylated regions that were hyper-methylated in the high-arsenic group showed enrichment for immune-related gene ontologies that constitute the basic functions of CD4-positive T cells, such as isotype switching and lymphocyte activation and differentiation. In conclusion, chronic arsenic exposure from drinking water was related to changes in the transcriptome and methylome of CD4-positive T cells, both genome wide and in specific genes, supporting the hypothesis that arsenic causes immunotoxicity by interfering with gene expression and regulation.
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36.
  • Gardner, Renee M., et al. (författare)
  • Arsenic methylation efficiency increases during the first trimester of pregnancy independent of folate status
  • 2011
  • Ingår i: Reproductive Toxicology. - : Elsevier BV. - 0890-6238 .- 1873-1708. ; 31:2, s. 210-218
  • Tidskriftsartikel (refereegranskat)abstract
    • Exposure to inorganic arsenic during pregnancy may negatively influence the offspring, though efficient metabolism of arsenic to dimethylarsinic acid (DMA) likely reduces the health risks. This study aimed to evaluate methylation of arsenic over the entire pregnancy and the influence of nutritional status. We studied longitudinally the arsenic metabolite pattern in the urine of 324 pregnant women exposed to arsenic via drinking water and food in rural Bangladesh. Metabolism of arsenic to DMA increased markedly over the course of pregnancy, with the greatest improvement occurring in the first trimester, along with a marked decrease in the most risk-associated monomethylated metabolite. This improvement in methylation was not associated with nutritional status, including vitamin B(12) and folate. Efficient methylation to DMA was associated with improved urinary excretion of arsenic, relative to blood arsenic concentrations, indicating that micronutrient-independent up-regulation of arsenic metabolism already in early pregnancy may provide protection for the fetus.
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37.
  • Gardner, Renee M, et al. (författare)
  • Pregnancy and the methyltransferase genotype independently influence the arsenic methylation phenotype.
  • 2012
  • Ingår i: Pharmacogenetics & Genomics. - 1744-6872 .- 1744-6880. ; 22:7, s. 508-516
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: The methyltransferase genotype and pregnancy both influence the arsenic metabolism phenotype, but it is unknown whether these factors interact, explaining the drastic changes in the efficiency of arsenic metabolism observed among pregnant women. The aim of this study was to evaluate the relative contribution of the methyltransferase genotype and pregnancy to the arsenic metabolism phenotype. METHODS: We studied longitudinally the arsenic metabolite pattern in urine (at approximately gestational weeks 8, 14, and 30) of 303 women exposed to arsenic through drinking water and food in rural Bangladesh. Urinary arsenic metabolites were measured by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Data were available on genotypes for 16 polymorphisms, combined as haplotypes, in three methyltransferases: arsenic(+III)methyltransferase (AS3MT) and DNA-methyltransferases 1a and 3b (DNMT1a and DNMT3b). Changes in the arsenic metabolite pattern over time were evaluated by haplotype using logistic quantile regression. RESULTS: All four AS3MT haplotypes and all three DNMT1a haplotypes significantly influenced the metabolite pattern in the pregnant women, with consistent effects of genotype over the entire course of pregnancy. No interaction was found between the haplotypes and pregnancy-related changes in the arsenic metabolism phenotype. DNMT3b haplotypes did not significantly influence the metabolite pattern. We observed a pregnancy-attributable decrease of 5.7% in the most risk-associated monomethylated metabolite, methylarsonic acid, whereas changes between 1.6 and 5.3% of methylarsonic acid could be attributed to haplotypes of AS3MT and DNMT1a. CONCLUSION: Independent of the genotype, the efficiency of arsenic methylation increased markedly over the course of pregnancy. The effect of pregnancy on the metabolite pattern during the observational period was greater than the effect of genotype.
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38.
  • Gliga, Anda R., et al. (författare)
  • Maternal exposure to cadmium during pregnancy is associated with changes in DNA methylation that are persistent at 9 years of age
  • 2022
  • Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 163
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Cadmium (Cd) exposure during gestation has been associated with altered DNA methylation at birth, but it is not known if the changes in methylation persist into childhood. Objectives: To evaluate whether gestational Cd-related changes of DNA methylation persist from birth to 9 years of age. Methods: We studied mother–child dyads in a longitudinal cohort in rural Bangladesh. Cadmium concentrations in maternal blood (erythrocyte fraction; Ery-Cd) at gestational week 14 and in child urine (U-Cd, long-term exposure marker) at 9 years were measured using inductively coupled plasma mass spectrometry. The epigenome-wide DNA methylation was measured in mononuclear cells (PBMCs) prepared from cord blood and peripheral blood at 9 years in 71 children (hereafter referred to as the explorative group) by Infinium HumanMethylation450K BeadChip. Replication of one differentially methylated region (DMR; 9 CpG sites) was performed in PBMCs of 160 9-year-old children (validation group) by EpiTyper MALDI-TOF mass spectrometry. Results: The median maternal Ery-Cd concentration was 1.24 µg/kg (range 0.35, 4.55) in the explorative group and 0.83 µg/kg (0.08, 2.97) in the validation group. The median U-Cd concentration in the 9-year-old children was 0.26 µg/L (0.09, 1.06) in the explorative group and 0.32 µg/L (0.07, 1.33) in the validation group. In the explorative group, we identified ten DMRs, both in cord blood and in PBMCs at 9 years, that were associated with maternal Ery-Cd. Eight out of the ten DMRs were hypomethylated and three of the hypomethylated DMRs were located in the HLA region on chromosome 6. One of the DMRs (hypomethylated) in the HLA region (upstream of the zinc finger protein 57 homolog, ZFP57 gene) was replicated in the validation group, and we found that it was hypomethylated in relation to maternal Ery-Cd, but not child U-Cd. Conclusion: Gestational exposure to Cd appears to be associated with regional changes, especially hypomethylated, in DNA methylation that linger from birth up to prepubertal age.
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39.
  • Gliga, Anda R, et al. (författare)
  • Prenatal arsenic exposure is associated with increased plasma IGFBP3 concentrations in 9-year-old children partly via changes in DNA methylation
  • 2018
  • Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 92:8, s. 2487-2500
  • Tidskriftsartikel (refereegranskat)abstract
    • Exposure to inorganic arsenic (As), a carcinogen and epigenetic toxicant, has been associated with lower circulating levels of insulin-like growth factor 1 (IGF1) and impaired growth in children of pre-school age. The aim of this study was to assess the potential impact of exposure to As on IGF1 and insulin-like growth factor-binding protein 3 (IGFBP3) as well as DNA methylation changes in 9-year-old children. To this end, we studied 9-year-old children from a longitudinal mother-child cohort in rural Bangladesh (n = 551). Prenatal and concurrent exposure to As was assessed via concentrations in maternal urine at gestational week 8 and in child urine at 9 years, measured by HPLC-HG-ICPMS. Plasma IGF1 and IGFBP3 concentrations were quantified with immunoassays. DNA methylation was measured in blood mononuclear cells at 9 years in a sub-sample (n = 113) using the Infinium HumanMethylation450K BeadChip. In multivariable-adjusted linear regression models, prenatal As (natural log-transformed), but not children's concurrent urinary As, was positively associated with IGFBP3 concentrations (β = 76, 95% CI 19, 133). As concentrations were not associated with IGF1. DNA methylation analysis revealed CpGs associated with both prenatal As and IGFBP3. Mediation analysis suggested that methylation of 12 CpG sites for all children was mediator of effect for the association between prenatal As and IGFBP3. We also found differentially methylated regions, generally hypermethylated, that were associated with both prenatal As and IGFBP3. In all, our study revealed that prenatal exposure to As was positively associated with IGFBP3 concentrations in children at 9 years, independent of IGF1, and this association may, at least in part, be epigenetically mediated.
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40.
  • Grundeken, Marijke, et al. (författare)
  • Toxic metals and essential trace elements in placenta and their relation to placental function
  • 2024
  • Ingår i: Environmental Research. - : Elsevier. - 0013-9351 .- 1096-0953. ; 248
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction: Placental function is essential for fetal development, but it may be susceptible to malnutrition and environmental stressors. Objective: To assess the impact of toxic and essential trace elements in placenta on placental function. Methods: Toxic metals (cadmium, lead, mercury, cobalt) and essential elements (copper, manganese, zinc, selenium) were measured in placenta of 406 pregnant women in northern Sweden using ICP-MS. Placental weight and birth weight were obtained from hospital records and fetoplacental weight ratio was used to estimate placental efficiency. Placental relative telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) were determined by quantitative PCR (n = 285). Single exposure-outcome associations were evaluated using linear or spline regression, and joint associations and interactions with Bayesian kernel machine regression (BKMR), all adjusted for sex, maternal smoking, and age or BMI. Results: Median cadmium, mercury, lead, cobalt, copper, manganese, zinc, and selenium concentrations in placenta were 3.2, 1.8, 4.3, 2.3, 1058, 66, 10626, and 166 μg/kg, respectively. In the adjusted regression, selenium (>147 μg/kg) was inversely associated with placental weight (B: −158; 95 % CI: −246, −71, per doubling), as was lead at low selenium (B: −23.6; 95 % CI: −43.2, −4.0, per doubling). Manganese was positively associated with placental weight (B: 41; 95 % CI: 5.9, 77, per doubling) and inversely associated with placental efficiency (B: −0.01; 95 % CI: −0.019, −0.004, per doubling). Cobalt was inversely associated with mtDNAcn (B: −11; 95 % CI: −20, −0.018, per doubling), whereas all essential elements were positively associated with mtDNAcn, individually and joint. Conclusion: Among the toxic metals, lead appeared to negatively impact placental weight and cobalt decreased placental mtDNAcn. Joint essential element concentrations increased placental mtDNAcn. Manganese also appeared to increase placental weight, but not birth weight. The inverse association of selenium with placental weight may reflect increased transport of selenium to the fetus in late gestation.
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41.
  • Gustin, Klara, et al. (författare)
  • Assessment of Joint Impact of Iodine, Selenium, and Zinc Status on Women's Third-Trimester Plasma Thyroid Hormone Concentrations
  • 2022
  • Ingår i: Journal of Nutrition. - : Elsevier BV. - 1541-6100 .- 0022-3166. ; 152:7, s. 1737 -1746
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Iodine is essential for synthesizing thyroid hormones, but other micronutrients are also required for optimal thyroid function. However, there is a lack of data on combined micronutrient status in relation to thyroid hormones in pregnancy. Objectives We aimed to assess the joint associations of iodine, selenium, and zinc status with plasma concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) in pregnancy. Methods We included 531 pregnant women (aged 22-40 y) participating in a Swedish birth cohort who provided blood and spot urine samples in gestational weeks 27-33 (mean: 29). Associations of urinary iodine concentration (UIC), plasma selenium concentration, and plasma zinc concentration (measured by inductively coupled plasma mass spectrometry) with plasma hormone concentrations [total and free thyroxine (tT4, fT4), total and free triiodothyronine (tT3, fT3), and TSH] were explored with Bayesian kernel machine regression (BKMR; n = 516; outliers excluded) and multivariable-adjusted linear regression (n = 531; splined for nonlinear associations). Results Median (IQR) micronutrient concentrations were 112 mu g/L (80-156 mu g/L) for UIC, 67 mu g/L (58-76 mu g/L) for plasma selenium, and 973 mu g/L (842-1127 mu g/L) for plasma zinc; the former 2 median values were below recommended concentrations (150 mu g/L and 70 mu g/L, respectively). Mean +/- SD TSH concentration was 1.7 +/- 0.87 mIU/L, with 98% < 4 mIU/L. BKMR showed a positive trend of joint micronutrient concentrations in relation to TSH. Plasma zinc was most influential for all hormones but tT3, for which plasma selenium was most influential. In adjusted linear regression models, zinc was positively associated with tT4, tT3, and TSH, and <1200 mu g/L also with fT4 and fT3. Selenium was inversely associated with fT3, and Conclusions Pregnant women's plasma TSH concentrations in the early third trimester increased with increasing joint status of iodine, selenium, and zinc. Zinc and selenium were more influential than iodine for the hormone concentrations. Multiple micronutrients need consideration in future studies of thyroid hormone status.
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42.
  • Gustin, Klara, et al. (författare)
  • Low-level maternal exposure to cadmium, lead, and mercury and birth outcomes in a Swedish prospective birth-cohort
  • 2020
  • Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 265
  • Tidskriftsartikel (refereegranskat)abstract
    • Observational studies have indicated that low-to-moderate exposure to cadmium (Cd), lead (Pb), and mercury (Hg) adversely affects birth anthropometry, but results are inconclusive. The aim of this study was to elucidate potential impact on birth anthropometry of exposure to Cd, Pb, and Hg in pregnant women, and to identify the main dietary sources. In the NICE (Nutritional impact on Immunological maturation during Childhood in relation to the Environment) birth-cohort in northern Sweden, blood and urine were collected from pregnant women in early third trimester. Cd, Pb and Hg were measured in erythrocytes (n = 584), and Cd also in urine (n = 581), by inductively coupled plasma mass spectrometry. Dietary data were collected through a semi-quantitative food frequency questionnaire administered in mid-third trimester. Birth anthropometry data were extracted from hospital records. In multivariable-adjusted spline regression models, a doubling of maternal erythrocyte Cd (median: 0.29 μg/kg) above the spline knot of 0.50 μg/kg was associated with reduced birth weight (B: −191 g; 95% CI: −315, −68) and length (−0.67 cm; −1.2, −0.14). The association with birth weight remained when the analysis was restricted to never-smokers. Likewise, a doubling of erythrocyte Hg (median 1.5 μg/kg, mainly MeHg) above 1.0 μg/kg, was associated with decreased birth weight (−59 g; −115, −3.0), and length (−0.29 cm; −0.54, −0.047). Maternal Pb (median 11 μg/kg) was unrelated to birth weight and length. Erythrocyte Cd was primarily associated with intake of plant derived foods, Pb with game meat, tea and coffee, and Hg with fish. The results indicated that low-level maternal Cd and Hg exposure were associated with poorer birth anthropometry. Further prospective studies in low-level exposed populations are warranted.
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43.
  • Gustin, Klara, et al. (författare)
  • Mediation by Thyroid Hormone in the Relationships Between Gestational Exposure to Methylmercury and Birth Size
  • 2024
  • Ingår i: Exposure and Health. - : Springer. - 2451-9685 .- 2451-9766. ; 16:2, s. 357-368
  • Tidskriftsartikel (refereegranskat)abstract
    • Our previous studies have linked gestational methylmercury exposure, originating from seafood, to changes in maternal thyroid hormones and infant birth size in a Swedish birth cohort. Herein we aimed to determine associations between maternal thyroid hormones and infant birth size and elucidate if maternal hormones could mediate the relationship between methylmercury and lower birth size. In 515 women, without known thyroid disease, we assessed metal exposure by erythrocyte mercury concentrations (mainly methylmercury, reflecting exposure over the past months) in early third trimester measured with inductively coupled plasma-mass spectrometry. Plasma concentrations of total and free thyroxine (tT4 and fT4) and triiodothyronine (tT3 and fT3), and thyroid-stimulating hormone (TSH) were measured at an accredited clinical laboratory. In multivariable-adjusted linear regression models, maternal tT3 (per 1 nmol/L increase) was positively associated with birth weight (B: 125 g; 95% CI 36, 214) and length (B: 0.59 cm; 95% CI 0.21, 0.97). Maternal fT4 was inversely associated with birth weight (B: − 33 g; 95% CI − 57, − 9.5), driven by obese women (n = 76). Causal mediation analyses suggested that a doubling of erythrocyte mercury (> 1 µg/kg; n = 374) was associated with a mean tT3-mediated decrease in birth weight of 11 g (95% CI − 25, − 1.6) and in birth length of 0.1 cm (95% CI − 0.12, − 0.01), both equivalent to about 12% of the total effect. To conclude, tT3 was positively associated with infant birth size. Reduced tT3 levels appeared to mediate a minor part of the inverse association between methylmercury exposure and birth size.
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44.
  • Gustin, Klara, et al. (författare)
  • Thyroid hormones in relation to toxic metal exposure in pregnancy, and potential interactions with iodine and selenium
  • 2021
  • Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 157
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Several endocrine-disrupting metals may affect thyroid function, but the few available studies of exposure during pregnancy and thyroid hormones are inconclusive. Objective: To explore if environmental exposure to cadmium (Cd), lead (Pb), and methylmercury (MeHg) impacts thyroid function in pregnancy, and interacts with iodine and selenium status. Methods: Women in a Swedish birth cohort provided blood and urine samples in early third trimester. Concentrations of erythrocyte Cd, Pb, and Hg (n = 544), urinary Cd and iodine (n = 542) and plasma selenium (n = 548) were measured using inductively coupled plasma-mass spectrometry. Free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH), were measured in plasma (n = 548) with electrochemiluminescence immunoassays. Metal-hormone associations were assessed in regression models, and metal mixture effects and metal-nutrient interactions were explored in Bayesian kernel machine regression (BKMR). Results: In multivariable-adjusted regression models, a doubling of urinary Cd was associated with a mean increase in tT4 of 2.7 nmol/L (95% CI: 0.78, 4.6), and in fT3 and tT3 of 0.06 pmol/L (0.02, 0.10) and 0.09 nmol/L (0.05, 0.13), respectively. A doubling of urinary Cd was associated with a −0.002 (−0.003, −0.001) and −0.03 (−0.05, −0.02) decrease in the fT4:tT4 and fT3:tT3 ratio, respectively. A doubling of erythrocyte Hg (>1 µg/kg) was associated with a decrease in fT3 and tT3 by −0.11 pmol/L (−0.16, −0.05) and −0.11 nmol/L (−0.16, −0.06), respectively, and a −0.013 (−0.02, −0.01) decrease in the fT3:fT4 ratio. BKMR did not indicate any mixture effect of toxic metals or interactions between metals and iodine or selenium in relation to the hormones. Conclusion: Our findings suggest that exposure to Cd and Hg, at levels globally prevalent through the diet, may affect thyroid function during pregnancy, independently of iodine and selenium levels. Further studies on potential implications for maternal and child health are warranted.
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45.
  • Harari, Florencia, et al. (författare)
  • N-6-Adenine-Specific DNA Methyltransferase 1 (N6AMT1) Polymorphisms and Arsenic Methylation in Andean Women
  • 2013
  • Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 121:7, s. 797-803
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: In humans, inorganic arsenic is metabolized to methylated metabolites mainly by arsenic (+3 oxidation state) methyltransferase (AS3MT). AS3MT polymorphisms are associated with arsenic metabolism efficiency. Recently, a putative N-6-adenine-specific DNA methyltransferase 1 (N6AMT1) was found to methylate arsenic in vitro. OBJECTIVE: We evaluated the role of N6AMT1 polymorphisms in arsenic methylation efficiency in humans. METHODS: We assessed arsenic methylation efficiency in 188 women exposed to arsenic via drinking water (similar to 200 mu g/L) in the Argentinean Andes by measuring the relative concentrations of arsenic metabolites in urine [inorganic arsenic, methylarsonic acid (MMA), and dimethylarsinic acid] by high-performance liquid chromatography coupled with hydride generation and inductively coupled plasma mass spectrometry. We performed genotyping for N6AMT1 and AS3MT polymorphisms by Taqman assays, and gene expression (in blood; n = 63) with Illumina HumanHT-12 v4.0. RESULTS: Five N6AMT1 single nucleotide polymorphisms (SNPs; rs1997605, rs2205449, rs2705671, rs16983411, and rs1048546) and two N6AMT1 haplotypes were significantly associated with the percentage of MMA (%MMA) in urine, even after adjusting for AS3MT haplotype. %MMA increased monotonically according to the number of alleles for each SNP (e. g., for rs1048546, mean %MMA was 7.5% for GG, 8.8% for GT, and 9.7% for TT carriers). Three SNPs were in linkage disequilibrium (R-2 > 0.8). Estimated associations for joint effects of N6AMT1 (haplotype 1) and AS3MT (haplotype 2) were generally consistent with expectations for additive effects of each haplotype on %MMA. Carriers of N6AMT1 genotypes associated with lower %MMA showed the lowest N6AMT1 expression, but associations were monotonic according to copy number for only one genotype and one haplotype. CONCLUSIONS: N6AMT1 polymorphisms were associated with arsenic methylation in Andean women, independent of AS3MT. N6AMT1 polymorphisms may be susceptibility markers for arsenic-related toxic effects.
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46.
  • Hawkesworth, Sophie, et al. (författare)
  • Early exposure to toxic metals has a limited effect on blood pressure or kidney function in later childhood, rural Bangladesh
  • 2013
  • Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 42:1, s. 176-185
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Chronic exposure to toxic metals such as arsenic and cadmium has been implicated in the development of kidney and cardiovascular diseases but few studies have directly measured exposure during in utero and early child development. Methods We investigated the impact of exposure to arsenic (mainly in drinking water) and cadmium (mainly in rice) during pregnancy on blood pressure and kidney function at 4.5 years of age in rural Bangladesh. The effect of arsenic exposure in infancy was also assessed. Results Within a cohort of 1887 children recruited into the MINIMat study, exposure to arsenic (maternal urinary arsenic, U-As), but not cadmium, during in utero development was associated with a minimal increase in blood pressure at 4.5 years. Each 1 mg/l increase in pregnancy U-As was associated with 3.69 mmHg (95% CI: 0.74, 6.63; P: 0.01) increase in child systolic and a 2.91 mmHg (95% CI: 0.41, 5.42; P: 0.02) increase in child diastolic blood pressure. Similarly, a 1 mg/l increase in child U-As at 18 months of age was associated with a 8.25 mmHg (95% CI: 1.37, 15.1; P: 0.02) increase in systolic blood pressure at 4.5 years. There was also a marginal inverse association between infancy U-As and glomerular filtration rate at 4.5 years (-33.4 ml/min/1.72 m(2); 95% CI: -70.2, 3.34; P: 0.08). No association was observed between early arsenic or cadmium exposure and kidney volume at 4.5 years assessed by ultrasound. Conclusions These modest effect sizes provide some evidence that arsenic exposure in early life has long-term consequences for blood pressure and maybe kidney function.
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47.
  • Hore, Samar Kumar, et al. (författare)
  • Detecting arsenic-related skin lesions : Experiences from a large community-based survey in Bangladesh
  • 2007
  • Ingår i: International Journal of Environmental Health Research. - : Informa UK Limited. - 0960-3123 .- 1369-1619. ; 17:2, s. 141-149
  • Tidskriftsartikel (refereegranskat)abstract
    • A cross-sectional survey was conducted in Matlab, Bangladesh, to determine the prevalence of skin lesions (a three-step procedure) associated with arsenic exposure and discuss validity and feasibility in relation to recommended screening algorithms. Cases with skin lesions were identified by screening above 4 years of age (n = 166,934). Trained field teams conducted a careful house-to-house screening and identified 1682 individuals with skin lesions, who were referred to physicians for confirmation. Physicians diagnosed 579 cases as probable and documented all these with digital photographs. Two experts inspected all photographs for consensus agreement that was reached for 504 cases. Using the experts' opinions as reference, the positive predictive value of the physicians' diagnosis was 87% (male = 82% vs. female = 94%; p < 0.01). The physicians had difficulties in separating arsenic-induced keratosis from differential diagnoses, while probability for correct diagnosis was high for arsenic-related pigmentation changes. Including information on current arsenic concentration in drinking water (which was masked at time of skin examination) or urine in the diagnostic algorithm should have increased the number of false negative cases. In the present transition of drinking water sources these markers of current exposure levels provide no information on past exposure. A 2 - 3 step procedure with house-to-house screening and clinic-based confirmation of arsenic-induced skin lesions is a feasible approach. Information on arsenic concentration in current water sources or in urine should not have improved the precision in the diagnosis. These results may have policy implications for community screening of arsenic-related skin lesions in Bangladesh and elsewhere.
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48.
  • Hossain, Bakhtiar, et al. (författare)
  • Environmental arsenic exposure and DNA methylation of the tumor suppressor gene p16 and the DNA repair gene MLH1: effect of arsenic metabolism and genotype.
  • 2012
  • Ingår i: Metallomics. - : Oxford University Press (OUP). - 1756-5901 .- 1756-591X. ; 4:11, s. 1167-1175
  • Tidskriftsartikel (refereegranskat)abstract
    • Arsenic is carcinogenic, possibly partly through epigenetic mechanisms. We evaluated the effects of arsenic exposure and metabolism on DNA methylation. Arsenic exposure and methylation efficiency in 202 women in the Argentinean Andes were assessed from concentrations of arsenic metabolites in urine (inorganic arsenic, methylarsonic acid [MMA], and dimethylarsinic acid [DMA]), measured by HPLC-ICPMS. Methylation of CpGs of the tumor suppressor gene p16, the DNA repair gene MLH1, and the repetitive elements LINE1 was measured by PCR pyrosequencing of blood DNA. Genotyping (N = 172) for AS3MT was performed using Sequenom™, and gene expression (N = 90) using Illumina DirectHyb HumanHT-12 v3.0. Median arsenic concentration in urine was 230 μg L(-1) (range 10.1-1251). In linear regression analysis, log(2)-transformed urinary arsenic concentrations were positively associated with methylation of p16 (β = 0.14, P = 0.0028) and MLH1 (β = 0.28, P = 0.0011), but not with LINE1. Arsenic concentrations were of borderline significance negatively correlated with expression of p16 (r(s) = -0.20; P = 0.066)), but not with MLH1. The fraction of inorganic arsenic was positively (β = 0.026; P = 0.010) and DMA was negatively (β = -0.017, P = 0.043) associated with p16 methylation with no effect of MMA. Carriers of the slow-metabolizing AS3MT haplotype were associated with more p16 methylation (P = 0.022). Arsenic exposure was correlated with increased methylation, in blood, of genes encoding enzymes that suppress carcinogenesis, and the arsenic metabolism efficiency modified the degree of epigenetic alterations.
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49.
  • Hossain, Mohammad Bakhtiar, et al. (författare)
  • Low-Level Environmental Cadmium Exposure is Associated with DNA Hypomethylation in Argentinean Women.
  • 2012
  • Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 120:6, s. 879-884
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Cadmium, a common food pollutant, alters DNA methylation in vitro. Epigenetic effects might therefore partly explain cadmium's toxicity, including carcinogenicity, but human data on epigenetic effects are lacking. Objectives: To evaluate effects of dietary cadmium exposure on DNA methylation, considering other environmental exposures, genetic predisposition, and gene expression. Methods: Concentrations of cadmium, arsenic, selenium and zinc in blood and urine of nonsmoking women (N=202) from the Northern Argentinean Andes were measured by ICP-MS. Methylation in CpG islands of LINE1 (proxy for global DNA methylation) and promoter regions of p16 (CDKN2A) and MLH1 in peripheral blood were measured by bisulfite PCR pyrosequencing. Genotyping (N=172) for DNMT1 (rs10854076, rs2228611) and DNMT3B (rs2424913, rs2424932) was performed with SequenomTM; and gene expression (N=90) with DirectHyb HumanHT-12 v3.0. Results: Cadmium exposure was low: median concentrations in blood and urine were 0.36 and 0.23 µg/L, respectively. Urinary cadmium (ln transformed) was inversely associated with LINE1 methylation (β=-0.50, p=0.0070; β=-0.44, p=0.026 adjusted for age and coca chewing), but not with p16 or MLH1 methylation. Both DNMT1 rs10854076 and DNMT1 rs2228611 polymorphisms modified associations between urinary cadmium and LINE1 (p-values for interaction in adjusted models were 0.045 and 0.064, respectively). The rare genotypes demonstrated stronger hypomethylation with increasing urinary cadmium concentrations. Cadmium was inversely associated with DNMT3B (rs -0.28, p=0.0086), but not with DNMT1 expression (rs -0.075, p=0.48). Conclusion: Environmental cadmium exposure was associated with DNA hypomethylation in peripheral blood and DNMT1 genotypes modified this association. The role of epigenetic modifications in cadmium-associated diseases needs clarification.
  •  
50.
  • Igra, Annachiara Malin, et al. (författare)
  • Early Life Environmental Exposure to Cadmium, Lead, and Arsenic and Age at Menarche : A Longitudinal Mother-Child Cohort Study in Bangladesh
  • 2023
  • Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 131:2
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Several metals act as endocrine disruptors, but there are few large longitudinal studies about associations with puberty onset.OBJECTIVES: We evaluated whether early life cadmium, lead, and arsenic exposure was associated with timing of menarche. METHODS: In a mother-child cohort in rural Bangladesh (n = 935), the exposure was assessed by concentrations in maternal erythrocytes in early pregnancy and in girls' urine at 5 and 10 years of age using inductively coupled plasma mass spectrometry. The girls were interviewed twice, at aver-age ages 13.3 [standard deviation eth SD THORN = 0.43] and 13.8 (SD = 0.43) y, and the date of menarche, if present, was recorded. Associations were assessed using Kaplan-Meier analysis and multivariable-adjusted Cox regression.RESULTS: In total, 77% of the girls (n = 717) had reached menarche by the second follow-up. The median age of menarche among all girls was 13.0 y (25th-75th percentiles: 12.4-13.7 y). At 10 years of age, median urinary cadmium was 0.25 mu g/L (5th-95th percentiles: 0.087-0.72 mu g/L), lead 1.6 mu g/L (0.70-4.2 mu g/L), and arsenic 54 mu g/L (19-395 mu g/L). Given the same age, girls in the highest quartile of urinary cadmium at 5 and 10 years of age had a lower rate of menarche than girls in the lowest quartile, with an adjusted hazard ratio of (HR) 0.80 (95% CI: 0.62, 1.01) at 5 years of age, and 0.77 (95% CI: 0.60, 0.98) at 10 years of age. This implies that girls in the highest cadmium exposure quartile during childhood had a higher age at menarche. Comparing girls in the highest to the lowest quartile of urinary lead at 10 years of age, the former had a higher rate of menarche [adjusted HR = 1.23 (95% CI: 0.97, 1.56)], implying lower age at menarche, whereas there was no association with urinary lead at 5 years of age. Girls born to mothers in the highest quartile of erythrocyte arsenic during pregnancy were less likely to have attained menarche than girls born to mothers in the low-est quartile [adjusted HR = 0.79 (95% CI: 0.62, 0.99)]. No association was found with girls' urinary arsenic exposure.DISCUSSION: Long-term childhood cadmium exposure was associated with later menarche, whereas the associations with child lead exposure were inconclusive. Maternal exposure to arsenic, but not cadmium or lead, was associated with later menarche. https://doi.org/10.1289/EHP11121
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