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Thomas DJ, Rainbow J, Bartley LE. Correction: The rapid-tome, a 3D-printed microtome, and an updated hand-sectioning method for high-quality plant sectioning. Plant Methods 2024; 20:58. [PMID: 38689307 PMCID: PMC11059604 DOI: 10.1186/s13007-024-01164-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Affiliation(s)
- D J Thomas
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - J Rainbow
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - L E Bartley
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA.
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Chevallier MA, Fantuzzi E, Hajek M, Mayer S, Tanner R, Thomas DJ, Vanhavere F. Analysis of EURADOS neutron intercomparison results according to new ISO standards criteria. Radiat Prot Dosimetry 2023; 199:1729-1734. [PMID: 37819341 DOI: 10.1093/rpd/ncad003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/04/2022] [Accepted: 12/06/2022] [Indexed: 10/13/2023]
Abstract
The European Radiation Dosimetry Group has carried out several different types of intercomparison (IC) exercises in the past that qualify as proficiency tests for different dosimetry systems and types of radiation. The first neutron dosemeter IC was held in 2012 (IC2012n) and was followed by a second in 2017/2018 (IC2017n). In sum, 31 Individual Monitoring Services (IMSs) entered 34 dosimetry systems in IC2012n, and 32 IMSs entered 33 dosimetry systems for IC2017n. Such exercises provided a rare opportunity to see how neutron dosemeters perform. For the IC2012n exercise, there were no applicable performance standards for neutron personal dosemeters. ISO/TC85/SC2 updated the ISO Standard 14146 in 2018 (ISO 14146:2018. Radiation protection-Criteria and performance limits for the periodic evaluation of dosimetry services) to include neutron dosimetry. It was thus possible to analyse the IC2017n exercise in accordance with the requirements given by this new standard. It is now of interest to reanalyse the results of IC2012n to quantify any modifications to the conclusions.
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Affiliation(s)
- M-A Chevallier
- Dosimetry Research Department, Institut de Radioprotection et de Sûreté Nucléaire, 92260 Fontenay-aux-Roses, France
| | - E Fantuzzi
- Radiation Protection Institute, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), 40136 Bologna, Italy
| | - M Hajek
- Division of Radiation, Transport and Waste Safety, International Atomic Energy Agency (IAEA), 1400 Vienna, Austria
| | - S Mayer
- Department of Radiation Safety and Security, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland
| | - R Tanner
- Dosimetry Services Department, UK Health Security Agency (UKHSA), Didcot, Oxon OX11 0RQ, UK
| | - D J Thomas
- Nuclear Metrology Group, National Physical Laboratory (NPL), Teddington TW11 0LW, UK
| | - F Vanhavere
- Radiation Protection Dosimetry and Calibration, SCK-CEN, Belgian Nuclear Research Centre, 2400 Mol, Belgium
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Söhngen C, Thomas DJ, Skowron MA, Bremmer F, Eckstein M, Stefanski A, Driessen MD, Wakileh GA, Stühler K, Altevogt P, Theodorescu D, Klapdor R, Schambach A, Nettersheim D. CD24 targeting with NK-CAR immunotherapy in testis, prostate, renal and (luminal-type) bladder cancer and identification of direct CD24 interaction partners. FEBS J 2023; 290:4864-4876. [PMID: 37254618 DOI: 10.1111/febs.16880] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 04/26/2023] [Accepted: 05/26/2023] [Indexed: 06/01/2023]
Abstract
Alternative therapeutic options targeting urologic malignancies, such as germ cell tumours, as well as urothelial, renal and prostate carcinomas, are still urgently needed. The membrane protein CD24 represents a promising immunotherapeutical approach. The present study aimed to decipher the molecular function of CD24 in vitro and evaluate the cytotoxic capacity of a third-generation natural killer (NK) cell chimeric antigen receptor (CAR) against CD24 in urologic tumour cell lines. Up to 20 urologic tumour cell lines and several non-malignant control cells were included. XTT viability assays and annexin V/propidium iodide flow cytometry analyses were performed to measure cell viability and apoptosis rates, respectively. Co-immunoprecipitation followed by mass spectrometry analyses identified direct interaction partners of CD24. Luciferase reporter assays were used to functionally validate transactivation of CD24 expression by SOX2. N- and O-glycosylation of CD24 were evaluated by enzymatic digestion and mass spectrometry. The study demonstrates that SOX2 transactivates CD24 expression in embryonal carcinoma cells. In cells of different urological origins, CD24 interacted with proteins involved in cell adhesion, ATP binding, phosphoprotein binding and post-translational modifications, such as histone acetylation and ubiquitination. Treatment of urological tumour cells with NK-CD24-CAR cells resulted in a decreased cell viability and apoptosis induction specifically in CD24+ tumour cells. Limitations of the study include the in vitro setting, which still has to be confirmed in vivo. In conclusion, we show that CD24 is a promising novel target for immune therapeutic approaches targeting urologic malignancies.
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Affiliation(s)
- Christian Söhngen
- Department of Urology, Urological Research Laboratory, Translational UroOncology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Germany
| | - David J Thomas
- Department of Urology, Urological Research Laboratory, Translational UroOncology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Germany
| | - Margaretha A Skowron
- Department of Urology, Urological Research Laboratory, Translational UroOncology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Germany
| | - Felix Bremmer
- Institute of Pathology, University Medical Center Goettingen, Germany
| | - Markus Eckstein
- Institute of Pathology, Friedrich Alexander University Erlangen-Nürnberg, University Hospital, Germany
| | - Anja Stefanski
- Molecular Proteomics Laboratory, Heinrich-Heine-University Düsseldorf, Germany
| | - Marc D Driessen
- Molecular Proteomics Laboratory, Heinrich-Heine-University Düsseldorf, Germany
| | - Gamal A Wakileh
- Department of Urology, Urological Research Laboratory, Translational UroOncology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Germany
- Department of Urology, University Hospital Ulm, Germany
| | - Kai Stühler
- Molecular Proteomics Laboratory, Heinrich-Heine-University Düsseldorf, Germany
| | - Peter Altevogt
- Skin Cancer Unit, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, Ruprecht-Karl University Heidelberg, Germany
| | - Dan Theodorescu
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Rüdiger Klapdor
- Department of Gynecology and Obstetrics, Hannover Medical School, Germany
| | - Axel Schambach
- Department of Gynecology and Obstetrics, Hannover Medical School, Germany
- Institute for Experimental Hematology, Hannover Medical School, Germany
| | - Daniel Nettersheim
- Department of Urology, Urological Research Laboratory, Translational UroOncology, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Germany
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Douillet C, Miller M, Cable PH, Shi Q, El-Masri H, Matoušek T, Koller BH, Thomas DJ, Stýblo M. Fate of arsenicals in mice carrying the human AS3MT gene exposed to environmentally relevant levels of arsenite in drinking water. Sci Rep 2023; 13:3660. [PMID: 36871058 PMCID: PMC9985638 DOI: 10.1038/s41598-023-30723-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Although mice are widely used to study adverse effects of inorganic arsenic (iAs), higher rates of iAs methylation in mice than in humans may limit their utility as a model organism. A recently created 129S6 mouse strain in which the Borcs7/As3mt locus replaces the human BORCS7/AS3MT locus exhibits a human-like pattern of iAs metabolism. Here, we evaluate dosage dependency of iAs metabolism in humanized (Hs) mice. We determined tissue and urinary concentrations and proportions of iAs, methylarsenic (MAs), and dimethylarsenic (DMAs) in male and female Hs and wild-type (WT) mice that received 25- or 400-ppb iAs in drinking water. At both exposure levels, Hs mice excrete less total arsenic (tAs) in urine and retain more tAs in tissues than WT mice. Tissue tAs levels are higher in Hs females than in Hs males, particularly after exposure to 400-ppb iAs. Tissue and urinary fractions of tAs present as iAs and MAs are significantly greater in Hs mice than in WT mice. Notably, tissue tAs dosimetry in Hs mice resembles human tissue dosimetry predicted by a physiologically based pharmacokinetic model. These data provide additional support for use of Hs mice in laboratory studies examining effects of iAs exposure in target tissues or cells.
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Affiliation(s)
- Christelle Douillet
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7461, USA
| | - Madison Miller
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7461, USA
| | - Peter H Cable
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7461, USA
| | - Qing Shi
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7461, USA
| | - Hisham El-Masri
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - Tomáš Matoušek
- Institute of Analytical Chemistry of the Czech Academy of Sciences, v. v. i., Veveří 97, 602 00, Brno, Czech Republic
| | - Beverly H Koller
- Department of Genetics, School of Medicine, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - David J Thomas
- Dinkey Creek Consulting, LLC, Chapel Hill, NC, 27517, USA
| | - Miroslav Stýblo
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599-7461, USA.
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Thomas DJ, Rainbow J, Bartley LE. The rapid-tome, a 3D-printed microtome, and an updated hand-sectioning method for high-quality plant sectioning. Plant Methods 2023; 19:12. [PMID: 36739429 PMCID: PMC9898918 DOI: 10.1186/s13007-023-00986-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 01/21/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Microscopic analysis of plant anatomy is a common procedure in biology to study structure and function that requires high-quality sections for accurate measurements. Hand sectioning of specimens is typically limited to moderately soft tissue while harder samples prohibit sectioning by hand and/or result in inconsistent thicknesses. RESULTS Here we present both a clearly described hand-sectioning method and a novel microtome design that together provide the means to section a variety of plant sample types. The described hand-sectioning method for herbaceous stems works well for softer subjects but is less suitable for samples with secondary growth (e.g., wood production). Instead, the "Rapid-Tome" is a novel tool for sectioning both soft and tougher high-aspect-ratio samples, such as stems and roots, with excellent sample control. The Rapid-Tome can be 3D-printed in approximately 18 h on a mid-quality printer common at university maker spaces. After printing and trimming, Rapid-Tome assembly takes a few minutes with five metal parts common at hardware stores. Users sectioned a variety of plant samples including the hollow internodes of switchgrass (Panicum virgatum), fibrous switchgrass roots containing aerenchyma, and woody branches of eastern red cedar (Juniperus virginiana) and American sycamore (Platanus occidentalis). A comparative analyses with Rapid-Tome-produced sections readily revealed a significant difference in seasonal growth of sycamore xylem vessel area in spring (49%) vs. summer (23%). Additionally, high school students with no prior experience produced sections with the Rapid-Tome adequate for comparative analyses of various plant samples in less than an hour. CONCLUSIONS The described hand-sectioning method is suitable for softer tissues, including hollow-stemmed grasses and similar samples. In addition, the Rapid-Tome provides capacity to safely produce high-quality sections of tougher plant materials at a fraction of the cost of traditional microtomes combined with excellent sample control. The Rapid-Tome features rapid sectioning, sample advancement, blade changes, and sample changes; it is highly portable and can be used easily with minimal training making production of thin sections accessible for classroom and outreach use, in addition to research.
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Affiliation(s)
- David J Thomas
- Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Jordan Rainbow
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Laura E Bartley
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA.
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George SE, Devereux R, James J, Wan Y, Diamond GL, Bradham KD, Thomas DJ. Dietary lead modulates the mouse intestinal microbiome: Subacute exposure to lead acetate and lead contaminated soil. Ecotoxicol Environ Saf 2023; 249:114430. [PMID: 37192935 PMCID: PMC10181873 DOI: 10.1016/j.ecoenv.2022.114430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The effect of dietary lead on the intestinal microbiome has not been fully elucidated. To determine if there was an association between microflora modulation, predicted functional genes, and Pb exposure, mice were provided diets amended with increasing concentrations of a single lead compound, lead acetate, or a well characterized complex reference soil containing lead, i.e. 6.25-25 mg/kg Pb acetate (PbOAc) or 7.5-30 mg/kg Pb in reference soil SRM 2710a having 0.552 % Pb among other heavy metals such as Cd. Feces and ceca were collected following 9 days of treatment and the microbiome analyzed by 16 S rRNA gene sequencing. Treatment effects on the microbiome were observed in both feces and ceca of mice. Changes in the cecal microbiomes of mice fed Pb as Pb acetate or as a constituent in SRM 2710a were statistically different except for a few exceptions regardless of dietary source. This was accompanied by increased average abundance of functional genes associated with metal resistance, including those related to siderophore synthesis and arsenic and/or mercury detoxification. Akkermansia, a common gut bacterium, was the highest ranked species in control microbiomes whereas Lactobacillus ranked highest in treated mice. Firmicutes/Bacteroidetes ratios in the ceca of SRM 2710a treated mice increased more than with PbOAc, suggestive of changes in gut microbiome metabolism that promotes obesity. Predicted functional gene average abundance related to carbohydrate, lipid, and/or fatty acid biosynthesis and degradation were greater in the cecal microbiome of SRM 2710a treated mice. Bacilli/Clostridia increased in the ceca of PbOAc treated mice and may be indicative of increased risk of host sepsis. Family Deferribacteraceae also was modulated by PbOAc or SRM 2710a possibly impacting inflammatory response. Understanding the relationship between microbiome composition, predicted functional genes, and Pb concentration, especially in soil, may provide new insights into the utility of various remediation methodologies that minimize dysbiosis and modulate health effects, thus assisting in the selection of an optimal treatment for contaminated sites.
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Affiliation(s)
- S. Elizabeth George
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, Gulf Breeze, FL 32561, United States
| | - Richard Devereux
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, Gulf Breeze, FL 32561, United States
| | - Joseph James
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, Gulf Breeze, FL 32561, United States
| | - Yongshan Wan
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, Gulf Breeze, FL 32561, United States
| | | | - Karen D. Bradham
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Environmental Measurement & Modeling, Research Triangle Park, NC 27711, United States
| | - David J. Thomas
- U. S. Environmental Protection Agency, Office of Research & Development, Center for Computational Toxicology & Exposure, Chemical Characterization & Exposure Division, Research Triangle Park, NC 27711, United States
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Diamond GL, Thomas DJ, Bradham KD. Evaluating the mouse model for estimation of arsenic bioavailability: Comparison of estimates of absolute bioavailability of inorganic arsenic in mouse, humans, and other species. J Toxicol Environ Health A 2022; 85:815-825. [PMID: 35791284 PMCID: PMC9431397 DOI: 10.1080/15287394.2022.2095314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Accurate assessment of adverse health effects attributable to ingestion of inorganic arsenic (As) present in contaminated soils requires determination of the internal dose of metal provided by ingested soil. This calculation requires estimation of the oral bioavailability of soil-borne (As). Animal models to assess the bioavailability of soil (As) are frequently used as surrogates for determination of this variable in humans. A mouse assay has been widely applied to estimate the bioavailability of As in soils at sites impacted by mining, smelting, and pesticides. In the mouse assay, the relative bioavailability (RBA) of soil (As) is determined as the ratio of the fraction of the ingested arsenic dose excreted in urine after consumption of diets containing a test soil or the soluble reference compound, sodium arsenate. The aim of the current study was to compare (As) bioavailability measured in the mouse assay with reported estimates in humans. Here, a pharmacokinetic model based on excretion of arsenic in urine and feces was used to estimate the absolute bioavailability (ABA) of As in mice that received an oral dose of sodium arsenate. Based upon this analysis, in mice that consumed diet amended with sodium arsenate, the ABA was 85%. This estimate of arsenic ABA for the mouse is comparable to estimates in humans who consumed (As) in drinking water and diet, and to estimates of ABA in monkeys and swine exposed to sodium arsenate. The concordance of estimates for ABA in mice and humans provides further support for use of the mouse model in human health risk assessment. Sodium arsenate ABA also provides a basis for estimating soil arsenic ABA from RBA estimates obtained in the mouse model.
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Affiliation(s)
| | - David J Thomas
- Dinkey Creek Consulting, LLC, Chapel Hill, NC, United States
| | - Karen D Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, United States
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Griggs JL, Chi L, Hanley NM, Kohan M, Herbin-Davis K, Thomas DJ, Lu K, Fry RC, Bradham KD. Bioaccessibility of arsenic from contaminated soils and alteration of the gut microbiome in an in vitro gastrointestinal model. Environ Pollut 2022; 309:119753. [PMID: 35835276 PMCID: PMC9667710 DOI: 10.1016/j.envpol.2022.119753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/15/2022] [Accepted: 07/08/2022] [Indexed: 05/11/2023]
Abstract
Arsenic exposure has been reported to alter the gut microbiome in mice. Activity of the gut microbiome derived from fecal microbiota has been found to affect arsenic bioaccessibility in an in vitro gastrointestinal (GI) model. Only a few studies have explored the relation between arsenic exposure and changes in the composition of the gut microbiome and in arsenic bioaccessibility. Here, we used simulated GI model system (GIMS) containing a stomach, small intestine, colon phases and microorganisms obtained from mouse feces (GIMS-F) and cecal contents (GIMS-C) to assess whether exposure to arsenic-contaminated soils affect the gut microbiome and whether composition of the gut microbiome affects arsenic bioaccessibility. Soils contaminated with arsenic did not alter gut microbiome composition in GIMS-F colon phase. In contrast, arsenic exposure resulted in the decline of bacteria in GIMS-C, including members of Clostridiaceae, Rikenellaceae, and Parabacteroides due to greater diversity and variability in microbial sensitivity to arsenic exposure. Arsenic bioaccessibility was greatest in the acidic stomach phase of GIMS (pH 1.5-1.7); except for GIMS-C colon phase exposed to mining-impacted soil in which greater levels of arsenic solubilized likely due to microbiome effects. Physicochemical properties of different test soils likely influenced variability in arsenic bioaccessibility (GIMS-F bioaccessibility range: 8-37%, GIMS-C bioaccessibility range: 2-18%) observed in this study.
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Affiliation(s)
- Jennifer L Griggs
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| | - Liang Chi
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Nancy M Hanley
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - Michael Kohan
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - Karen Herbin-Davis
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - David J Thomas
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - Kun Lu
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Rebecca C Fry
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Karen D Bradham
- Watershed and Ecosystem Characterization Division, Center for Environmental Measurement and Modelling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
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George SE, James J, Devereux R, Wan Y, Diamond GL, Bradham KD, Scheckel KG, Thomas DJ. Ingestion of remediated lead-contaminated soils affects the fecal microbiome of mice. Sci Total Environ 2022; 837:155797. [PMID: 35561906 PMCID: PMC9830667 DOI: 10.1016/j.scitotenv.2022.155797] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/12/2022] [Accepted: 05/05/2022] [Indexed: 05/08/2023]
Abstract
The relationship between ingestion of diets amended with a Pb-contaminated soil and the composition of the fecal microbiome was examined in a mouse model. Mice consumed diets amended with a Pb-contaminated soil in its native (untreated) state or after treatment for remediation with phosphoric acid or triple superphosphate alone or in combination with iron-waste material or biosolids compost. Subacute dietary exposure of mice receiving treated soil resulted in modulation of the fecal intestinal flora, which coincided with reduced relative Pb bioavailability in the bone, blood and kidney and differences in Pb speciation compared to untreated soil. Shifts in the relative abundance of several phyla including Verrucomicrobia, Tenericutes, Firmicutes, Proteobacteria, and TM7 (Candidatus Saccharibacteria) were observed. Because the phyla persist in the presence of Pb, it is probable that they are resistant to Pb. This may enable members of the phyla to bind and limit Pb uptake in the intestine. Families Ruminococcaceae, Lachnospiraceae, Erysipelotrichaceae, Verrucomicrobiaceae, Prevotellaceae, Lactobacilaceae, and Bacteroidaceae, which have been linked to health or disease, also were modulated. This study is the first to explore the relationship between the murine fecal microbiome and ingested Pb contaminated soils treated with different remediation options designed to reduce bioavailability. Identifying commonalities in the microbiome that are correlated with more positive health outcomes may serve as biomarkers to assist in the selection of remediation approaches that are more effective and pose less risk.
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Affiliation(s)
- S Elizabeth George
- Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, U.S. Environmental Protection Agency, Office of Research & Development, Gulf Breeze, FL 32561, United States.
| | - Joseph James
- Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, U.S. Environmental Protection Agency, Office of Research & Development, Gulf Breeze, FL 32561, United States
| | - Richard Devereux
- Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, U.S. Environmental Protection Agency, Office of Research & Development, Gulf Breeze, FL 32561, United States
| | - Yongshan Wan
- Center for Environmental Measurement & Modeling, Gulf Ecosystem Measurement & Modeling Division, U.S. Environmental Protection Agency, Office of Research & Development, Gulf Breeze, FL 32561, United States
| | - Gary L Diamond
- SRC, Inc., North Syracuse, New York 13212, United States
| | - Karen D Bradham
- Center for Environmental Measurement & Modeling, Watershed & Ecosystem Characterization Division, U.S. Environmental Protection Agency, Office of Research & Development, Research Triangle Park, NC 27711, United States
| | - Kirk G Scheckel
- Center for Environmental Solutions and Emergency Response, Land Remediation & Technology Division, U.S. Environmental Protection Agency, Office of Research & Development, Cincinnati, OH 45224, United States
| | - David J Thomas
- Center for Computational Toxicology & Exposure, Chemical Characterization & Exposure Division, U.S. Environmental Protection Agency, Office of Research & Development, Research Triangle Park, NC 27711, United States
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Sowers TD, Bone SE, Noerpel MR, Blackmon MD, Karna RR, Scheckel KG, Juhasz AL, Diamond GL, Thomas DJ, Bradham KD. Plumbojarosite Remediation of Soil Affects Lead Speciation and Elemental Interactions in Soil and in Mice Tissues. Environ Sci Technol 2021; 55:15950-15960. [PMID: 34806356 PMCID: PMC9606633 DOI: 10.1021/acs.est.1c06067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Lead (Pb) contamination of soils is of global concern due to the devastating impacts of Pb exposure in children. Because early-life exposure to Pb has long-lasting health effects, reducing exposure in children is a critical public health goal that has intensified research on the conversion of soil Pb to low bioavailability phases. Recently, plumbojarosite (PLJ) conversion of highly available soil Pb was found to decrease Pb relative bioavailability (RBA <10%). However, there is sparse information concerning interactions between Pb and other elements when contaminated soil, pre- and post-remediation, is ingested and moves through the gastrointestinal tract (GIT). Addressing this may inform drivers of effective chemical remediation strategies. Here, we utilize bulk and micro-focused Pb X-ray absorption spectroscopy to probe elemental interactions and Pb speciation in mouse diet, cecum, and feces samples following ingestion of contaminated soils pre- and post-PLJ treatment. RBA of treated soils was less than 1% with PLJ phases transiting the GIT with little absorption. In contrast, Pb associated with organics was predominantly found in the cecum. These results are consistent with transit of insoluble PLJ to feces following ingestion. The expanded understanding of Pb interactions during GIT transit complements our knowledge of elemental interactions with Pb that occur at higher levels of biological organization.
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Affiliation(s)
- Tyler D Sowers
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Sharon E Bone
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Matthew R Noerpel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Matthew D Blackmon
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Ranju R Karna
- Bennett Aerospace, Inc., Engineer Research and Development Center, USACE, Vicksburg, Mississippi 39183, United States
| | - Kirk G Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, United States
| | - Albert L Juhasz
- Future Industries Institute, University of South Australia, Mawson Lakes Campus, Adelaide, SA 5095, Australia
| | - Gary L Diamond
- SRC, Inc., North Syracuse, New York 13212, United States
| | - David J Thomas
- Center for Computational Toxicology & Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Karen D Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
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11
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Griggs JL, Thomas DJ, Fry R, Bradham KD. Improving the predictive value of bioaccessibility assays and their use to provide mechanistic insights into bioavailability for toxic metals/metalloids - A research prospectus. J Toxicol Environ Health B Crit Rev 2021; 24:307-324. [PMID: 34092204 PMCID: PMC8390437 DOI: 10.1080/10937404.2021.1934764] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Widespread contamination of soil, dust, and food with toxic metal(loid)s pose a significant public health concern. Only a portion of orally ingested metal(loid) contaminants are bioavailable, which is defined as the fraction of ingested metal(loid)s absorbed across the gastrointestinal barrier and into systemic circulation. Bioaccessibility tools are a class of in vitro assays used as a surrogate to estimate risk of oral exposure and bioavailability. Although development and use of bioaccessibility tools have contributed to our understanding of the factors influencing oral bioavailability of metal(loid)s, some of these assays may lack data that support their use in decisions concerning adverse health risks and soil remediation. This review discusses the factors known to influence bioaccessibility of metal(loid) contaminants and evaluates experimental approaches and key findings of SW-846 Test Method 1340, Unified BARGE Method, Simulated Human Intestinal Microbial Ecosystem, Solubility Bioaccessibility Research Consortium assay, In Vitro Gastrointestinal model, TNO-Gastrointestinal Model, and Dutch National Institute for Public Health and the Environment bioaccessibility models which are used to assess oral absolute bioavailability and relative bioavailability in solid matrices. The aim of this review was to identify emerging knowledge gaps and research needs with an emphasis on research required to evaluate these models on (1) standardization of assay techniques and methodology, and (2) use of common criteria for assessing the performance of bioaccessibility models.
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Affiliation(s)
- Jennifer L. Griggs
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599 USA
| | - David J. Thomas
- Chemical Characterization and Exposure Division, Center for Computational Toxicology & Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709 USA
| | - Rebecca Fry
- Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599 USA
| | - Karen D. Bradham
- Watershed and Ecosystem Characterization Division, Center for Environmental Measurement and Modelling, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709 USA
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Stýblo M, Venkatratnam A, Fry RC, Thomas DJ. Origins, fate, and actions of methylated trivalent metabolites of inorganic arsenic: progress and prospects. Arch Toxicol 2021; 95:1547-1572. [PMID: 33768354 DOI: 10.1007/s00204-021-03028-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 03/11/2021] [Indexed: 12/16/2022]
Abstract
The toxic metalloid inorganic arsenic (iAs) is widely distributed in the environment. Chronic exposure to iAs from environmental sources has been linked to a variety of human diseases. Methylation of iAs is the primary pathway for metabolism of iAs. In humans, methylation of iAs is catalyzed by arsenic (+ 3 oxidation state) methyltransferase (AS3MT). Conversion of iAs to mono- and di-methylated species (MAs and DMAs) detoxifies iAs by increasing the rate of whole body clearance of arsenic. Interindividual differences in iAs metabolism play key roles in pathogenesis of and susceptibility to a range of disease outcomes associated with iAs exposure. These adverse health effects are in part associated with the production of methylated trivalent arsenic species, methylarsonous acid (MAsIII) and dimethylarsinous acid (DMAsIII), during AS3MT-catalyzed methylation of iAs. The formation of these metabolites activates iAs to unique forms that cause disease initiation and progression. Taken together, the current evidence suggests that methylation of iAs is a pathway for detoxification and for activation of the metalloid. Beyond this general understanding of the consequences of iAs methylation, many questions remain unanswered. Our knowledge of metabolic targets for MAsIII and DMAsIII in human cells and mechanisms for interactions between these arsenicals and targets is incomplete. Development of novel analytical methods for quantitation of MAsIII and DMAsIII in biological samples promises to address some of these gaps. Here, we summarize current knowledge of the enzymatic basis of MAsIII and DMAsIII formation, the toxic actions of these metabolites, and methods available for their detection and quantification in biomatrices. Major knowledge gaps and future research directions are also discussed.
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Affiliation(s)
- Miroslav Stýblo
- Department of Nutrition, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
| | - Abhishek Venkatratnam
- Department of Nutrition, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Environmental Science and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Rebecca C Fry
- Department of Environmental Science and Engineering, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - David J Thomas
- Chemical Characterization and Exposure Division, Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA.
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Sowers TD, Nelson CM, Diamond GL, Blackmon MD, Jerden ML, Kirby AM, Noerpel MR, Scheckel KG, Thomas DJ, Bradham KD. High Lead Bioavailability of Indoor Dust Contaminated with Paint Lead Species. Environ Sci Technol 2021; 55:402-411. [PMID: 33307690 PMCID: PMC8204915 DOI: 10.1021/acs.est.0c06908] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
House dust and soils can be major sources of lead (Pb) exposure for children. The American Healthy Homes Survey (AHHS) was developed to estimate Pb exposure from house dust and soil, in addition to other potential household contaminants and allergens. We have combined X-ray absorption spectroscopic (XAS) fingerprinting and in vivo mouse relative bioavailability (RBA) measurements for a subset of house dust and residential soils collected in the AHHS, with the primary objective of gaining a better understanding of determinants of house dust Pb bioavailability. Lead speciation was well related to variations in RBA results and revealed that highly bioavailable Pb (hydroxy)carbonate (indicative of Pb-based paint) was the major Pb species present in house dusts. Measured Pb RBA was up to 100% and is likely driven by paint Pb. To our knowledge, this is the first report of in vivo Pb RBA for U.S. house dust contaminated in situ with paint Pb and corroborates results from a previous study that demonstrated high RBA of paint Pb added to soil. We also report a relatively low RBA (23%) in a residential soil where the major Pb species was found to be plumbojarosite, consistent with a previous report that plumbojarosite lowers Pb RBA in soils.
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Affiliation(s)
- Tyler D. Sowers
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Clay M. Nelson
- SRC, Inc., North Syracuse, New York 13212, United States
| | | | - Matt D. Blackmon
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Marissa L. Jerden
- Jacobs Technology, Inc., 109 T.W. Alexander Drive, RTP, North Carolina 27711, US
| | - Alicia M. Kirby
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, US
| | - Matthew R. Noerpel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, US
| | - Kirk G. Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio 45268, US
| | - David J. Thomas
- Center for Computational Toxicology & Exposure, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
| | - Karen D. Bradham
- Center of Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, US
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Koller BH, Snouwaert JN, Douillet C, Jania LA, El-Masri H, Thomas DJ, Stýblo M. Arsenic Metabolism in Mice Carrying a BORCS7/AS3MT Locus Humanized by Syntenic Replacement. Environ Health Perspect 2020; 128:87003. [PMID: 32779937 PMCID: PMC7418654 DOI: 10.1289/ehp6943] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
BACKGROUND Chronic exposure to inorganic arsenic (iAs) is a significant public health problem. Methylation of iAs by arsenic methyltransferase (AS3MT) controls iAs detoxification and modifies risks of iAs-induced diseases. Mechanisms underlying these diseases have been extensively studied using animal models. However, substantive differences between humans and laboratory animals in efficiency of iAs methylation have hindered the translational potential of the laboratory studies. OBJECTIVES The goal of this study was to determine whether humanization of the As3mt gene confers a human-like pattern of iAs metabolism in mice. METHODS We generated a mouse strain in which the As3mt gene along with the adjacent Borcs7 gene was humanized by syntenic replacement. We compared expression of the mouse As3mt and the human AS3MT and the rate and pattern of iAs metabolism in the wild-type and humanized mice. RESULTS AS3MT expression in mouse tissues closely modeled that of human and differed substantially from expression of As3mt. Detoxification of iAs was much less efficient in the humanized mice than in wild-type mice. Profiles for iAs and its methylated metabolites in tissues and excreta of the humanized mice were consistent with those reported in humans. Notably, the humanized mice expressed both the full-length AS3MT that catalyzes iAs methylation and the human-specific AS3MTd2d3 splicing variant that has been linked to schizophrenia. CONCLUSIONS These results suggest that AS3MT is the primary genetic locus responsible for the unique pattern of iAs metabolism in humans. Thus, the humanized mouse strain can be used to study the role of iAs methylation in the pathogenesis of iAs-induced diseases, as well as to evaluate the role of AS3MTd2d3 in schizophrenia. https://doi.org/10.1289/EHP6943.
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Affiliation(s)
- Beverly H. Koller
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - John N. Snouwaert
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Christelle Douillet
- Department of Nutrition, UNC Gillings School of Public Health, Chapel Hill, North Carolina, USA
| | - Leigh A. Jania
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Hisham El-Masri
- Chemical Characterization and Exposure Division, Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - David J. Thomas
- Chemical Characterization and Exposure Division, Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Miroslav Stýblo
- Department of Nutrition, UNC Gillings School of Public Health, Chapel Hill, North Carolina, USA
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Bradham K, Herde C, Herde P, Juhasz AL, Herbin-Davis K, Elek B, Farthing A, Diamond GL, Thomas DJ. Intra- and Interlaboratory Evaluation of an Assay of Soil Arsenic Relative Bioavailability in Mice. J Agric Food Chem 2020; 68:2615-2622. [PMID: 32027133 PMCID: PMC8190816 DOI: 10.1021/acs.jafc.9b06537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hand-to-mouth activity in children can be an important route for ingestion of soil and dust contaminated with inorganic arsenic. Estimating the relative bioavailability of arsenic present in these media is a critical element in assessing the risks associated with aggregate exposure to this toxic metalloid during their early life. Here, we evaluated the performance of a mouse assay for arsenic bioavailability in two laboratories using a suite of 10 soils. This approach allowed us to examine both intralaboratory and interlaboratory variations in assay performance. Use of a single vendor for preparation of all amended test diets and of a single laboratory for arsenic analysis of samples generated in the participating laboratories minimized contributions of these potential sources of variability in assay performance. Intralaboratory assay data showed that food and water intake and cumulative urine and feces production remained stable over several years. The stability of these measurements accounted for the reproducibility of estimates of arsenic bioavailability obtained from repeated intralaboratory assays using sodium arsenate or soils as the test material. Interlaboratory comparisons found that estimates of variables used to evaluate assay performance (recovery and urinary excretion factor) were similar in the two laboratories. For all soils, estimates of arsenic relative bioavailability obtained in the two laboratories were highly correlated (r2 = 0.94 and slope = 0.9) in a linear regression model. Overall, these findings show that this mouse assay for arsenic bioavailability provides reproducible estimates using a variety of test soils. This robust model may be adaptable for use in other laboratory settings.
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Affiliation(s)
- Karen Bradham
- Public Health Chemistry Branch, Exposure Measurements and Methods Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709 USA
| | - Carina Herde
- South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Paul Herde
- South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Albert L. Juhasz
- Future Industries Institute, University of South Australia, Adelaide, Australia
| | - Karen Herbin-Davis
- Pharmacokinetics Branch, Integrated Systems Toxicology Divison, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709 USA
| | - Brittany Elek
- Pharmacokinetics Branch, Integrated Systems Toxicology Divison, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709 USA
| | - Amy Farthing
- Pharmacokinetics Branch, Integrated Systems Toxicology Divison, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709 USA
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16
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Bradham KD, Nelson CM, Diamond GL, Thayer WC, Scheckel KG, Noerpel M, Herbin-Davis K, Elek B, Thomas DJ. Dietary Lead and Phosphate Interactions Affect Oral Bioavailability of Soil Lead in the Mouse. Environ Sci Technol 2019; 53:12556-12564. [PMID: 31557437 PMCID: PMC8188726 DOI: 10.1021/acs.est.9b02803] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Effects of dietary P level on the oral bioavailability of Pb present in soil were examined in a mouse model. Adult female C57BL/6 mice had free access to AIN-93G purified rodent diet amended with Pb as a soluble salt, Pb acetate, or in a soil matrix (NIST SRM 2710a). In these studies, the basal diet contained P at a nutritionally sufficient level (0.3% w/w) and the modified diets contained P at a lower (0.15%) or a higher (1.2%) level. For either dietary Pb source (Pb acetate or NIST SRM 2710a), low dietary P level markedly increased accumulation of Pb in bone, blood, and kidney. Tissue Pb levels in mice fed a high P in diet were not different from mice fed the basal P diet. Dietary P and Pb interacted to affect body weight change and feed efficiency in mice. The relative contribution of different Pb species in diet and feces was also affected by dietary P level. Differences in Pb species between diet and feces indicated that transformation of Pb species can occur during gastrointestinal tract transit. These interactions between Pb and P that alter Pb speciation may be important determinants of the bioavailability of Pb ingested in soil.
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Affiliation(s)
- Karen D Bradham
- Office of Research and Development , United States Environmental Protection Agency , Research Triangle Park , Durham , North Carolina 27711 , United States
| | - Clay M Nelson
- Office of Research and Development , United States Environmental Protection Agency , Research Triangle Park , Durham , North Carolina 27711 , United States
| | - Gary L Diamond
- SRC, Inc. , North Syracuse , New York 13212 , United States
| | | | - Kirk G Scheckel
- Office of Research and Development , United States Environmental Protection Agency , Cincinnati , Ohio 45224 , United States
| | - Matt Noerpel
- Office of Research and Development , United States Environmental Protection Agency , Cincinnati , Ohio 45224 , United States
| | - Karen Herbin-Davis
- Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Laboratory, ORD, US EPA, RTP, NC , Durham , North Carolina 27709 , United States
| | - Brittany Elek
- Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Laboratory, ORD, US EPA, RTP, NC , Durham , North Carolina 27709 , United States
| | - David J Thomas
- Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Laboratory, ORD, US EPA, RTP, NC , Durham , North Carolina 27709 , United States
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Bilinsky LM, Thomas DJ, Fisher JW. Using mathematical modeling to infer the valence state of arsenicals in tissues: A PBPK model for dimethylarsinic acid (DMA V) and dimethylarsinous acid (DMA III) in mice. J Theor Biol 2019; 461:215-229. [PMID: 30393109 PMCID: PMC6296760 DOI: 10.1016/j.jtbi.2018.10.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/10/2018] [Accepted: 10/25/2018] [Indexed: 10/28/2022]
Abstract
Chronic exposure to inorganic arsenic (iAs), a contaminant of water and food supplies, is associated with many adverse health effects. A notable feature of iAs metabolism is sequential methylation reactions which produce mono- and di-methylated arsenicals that can contain arsenic in either the trivalent (III) or pentavalent (V) valence states. Because methylated arsenicals containing trivalent arsenic are more potent toxicants than their pentavalent counterparts, the ability to distinguish between the +3 and +5 valence states is a crucial property for physiologically based pharmacokinetic (PBPK) models of arsenicals to possess if they are to be of use in risk assessment. Unfortunately, current analytic techniques for quantifying arsenicals in tissues disrupt the valence state; hence, pharmacokinetic studies in animals, used for model calibration, only reliably provide data on the sum of the +3 and +5 valence forms of a given metabolite. In this paper we show how mathematical modeling can be used to overcome this obstacle and present a PBPK model for the dimethylated metabolite of iAs, which exists as either dimethylarsinous acid, (CH3)2AsIIIOH (abbreviated DMAIII) or dimethylarsinic acid, (CH3)2AsV(O)OH (abbreviated DMAV). The model distinguishes these two forms and sets a lower bound on how much of an organ's DMA burden is present in the more reactive and toxic trivalent valence state. We conjoin the PBPK model to a simple model for DMAIII-induced oxidative stress in liver and use this extended model to predict cytotoxicity in liver in response to the high oral dose of DMAV. The model incorporates mechanistic details derived from in vitro studies and is iteratively calibrated with lumped-valence-state PK data for intravenous or oral dosing with DMAV. Model formulation leads us to predict that orally administered DMAV undergoes extensive reduction in the gastrointestinal (GI) tract to the more toxic trivalent DMAIII.
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Affiliation(s)
- Lydia M Bilinsky
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR 72079, USA.
| | - David J Thomas
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T. W. Alexander Drive (MD-105-03), Research Triangle Park, NC 27711, USA.
| | - Jeffrey W Fisher
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR 72079, USA.
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18
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Salvador-Castiñeira P, Hambsch FJ, Göök A, Vidali M, Hawkes NP, Oberstedt S, Roberts NJ, Taylor GC, Thomas DJ. Absolute cross section measurements of 238U(n,f) and 237Np(n,f) in the neutron energy range 1-2.4 MeV. EPJ Web Conf 2019. [DOI: 10.1051/epjconf/201921103009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
New standard (n,f) cross sections other than 235U are important to study the relevant cross sections for Generation-IV power plants. A specific need for such standards is for performing new experiments with quasimonoenergetic neutron beams, such as those produced by Van de Graaf accelerators. Neutrons down-scattered to low energies in the experimental environment, so called room-return, become relevant for this type of measurements. Hence, a standard (n,f) cross section with a fission threshold is of great interest, in order to suppress the contribution from room-return background. For this reason we have performed two experiments at the VDG of the National Physical Laboratory to measure absolutely the (n,f) cross sections of 235U, 238U and 237Np in the fast neutron energy region. Our preliminary results are in agreement with the most up-to-date evaluations.
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Bradham KD, Diamond GL, Nelson CM, Noerpel M, Scheckel KG, Elek B, Chaney RL, Ma Q, Thomas DJ. Long-Term in Situ Reduction in Soil Lead Bioavailability Measured in a Mouse Model. Environ Sci Technol 2018; 52:13908-13913. [PMID: 30358995 PMCID: PMC8190820 DOI: 10.1021/acs.est.8b04684] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Effects of different treatments on the bioavailability of lead (Pb) in soil from a smelter emission contaminated site in Joplin, Missouri, were evaluated in a mouse model. Similar estimates of relative bioavailability for Pb in untreated or treated soil were obtained in mice and in the well-established juvenile swine model. In the mouse model, treatments that used phosphate (phosphoric acid or triple superphosphate) combined with iron oxide or biosolids compost significantly reduced soil Pb bioavailability. Notably, effects of these remediation procedures were persistent, given that up to 16 years had elapsed between soil treatment and sample collection. Remediation of soils was associated with changes in Pb species present in soil. Differences in Pb species in ingested soil and in feces from treated mice indicated that changes in Pb speciation occurred during transit through the gastrointestinal tract. Use of the mouse model facilitates evaluation of remediation procedures and allows monitoring of the performance of procedures under laboratory and field conditions.
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Affiliation(s)
- Karen D. Bradham
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, 27711, United States
- Corresponding author: Address: 109 T.W. Alexander Drive, MD-205-05, Research Triangle Park, NC 27711. . Phone: (919) 541-9414. Fax: (919) 541-3527
| | | | - Clay M. Nelson
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, 27711, United States
| | - Matt Noerpel
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Cincinnati, Ohio, 45224, United States
| | - Kirk G. Scheckel
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Cincinnati, Ohio, 45224, United States
| | - Brittany Elek
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Laboratory, ORD, US EPA, RTP, NC, 27709
| | - Rufus L. Chaney
- USDA-ARS-Adaptive Cropping Systems Lab, Beltsville, MD, 20705
| | - Qing Ma
- DND-CAT, Synchrotron Research Center-Northwestern University at the Advanced Photon Source, Argonne, IL 60439
| | - David J. Thomas
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Laboratory, ORD, US EPA, RTP, NC, 27709
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20
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El-Masri HA, Hong T, Henning C, Mendez W, Hudgens EE, Thomas DJ, Lee JS. Erratum: "Evaluation of a Physiologically Based Pharmacokinetic (PBPK) Model for Inorganic Arsenic Exposure Using Data from Two Diverse Human Populations". Environ Health Perspect 2018; 126:99002. [PMID: 30392381 PMCID: PMC6375391 DOI: 10.1289/ehp4370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/30/2018] [Indexed: 06/08/2023]
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21
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Hawkes NP, Kolkowski P, Roberts NJ, Salvador-Castiñeira P, Taylor GC, Thomas DJ. ADDITIONAL CHARACTERISATION OF THE THERMAL NEUTRON PILE AT THE NATIONAL PHYSICAL LABORATORY, UK. Radiat Prot Dosimetry 2018; 180:25-28. [PMID: 29040724 DOI: 10.1093/rpd/ncx191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Indexed: 06/07/2023]
Abstract
As part of its wide-ranging neutron metrology capabilities, the National Physical Laboratory in the UK has a thermal neutron facility in which accelerator-produced neutrons are moderated within a large assembly or pile of graphite bricks. The neutron field has previously been well characterised in terms of the fluence rate and energy spectrum at various irradiation positions. However, recent changes to the structure (e.g. enlarging the central irradiation cavity) have prompted a renewal and extension of this work. We have also used Monte Carlo modelling to improve our understanding of the pile's performance.
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Affiliation(s)
- N P Hawkes
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK
| | - P Kolkowski
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK
| | - N J Roberts
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK
| | | | - G C Taylor
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK
| | - D J Thomas
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, UK
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22
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El-Masri HA, Hong T, Henning C, Mendez W, Hudgens EE, Thomas DJ, Lee JS. Evaluation of a Physiologically Based Pharmacokinetic (PBPK) Model for Inorganic Arsenic Exposure Using Data from Two Diverse Human Populations. Environ Health Perspect 2018; 126:077004. [PMID: 30024383 PMCID: PMC6108830 DOI: 10.1289/ehp3096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 05/24/2018] [Accepted: 06/08/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Multiple epidemiological studies exist for some of the well-studied health endpoints associated with inorganic arsenic (iAs) exposure; however, results are usually expressed in terms of different exposure/dose metrics. Physiologically based pharmacokinetic (PBPK) models may be used to obtain a common exposure metric for application in dose-response meta-analysis. OBJECTIVE A previously published PBPK model for inorganic arsenic (iAs) was evaluated using data sets for arsenic-exposed populations from Bangladesh and the United States. METHODS The first data set was provided by the Health Effects of Arsenic Longitudinal Study cohort in Bangladesh. The second data set was provided by a study conducted in Churchill County, Nevada, USA. The PBPK model consisted of submodels describing the absorption, distribution, metabolism and excretion (ADME) of iAs and its metabolites monomethylarsenic (MMA) and dimethylarsenic (DMA) acids. The model was used to estimate total arsenic levels in urine in response to oral ingestion of iAs. To compare predictions of the PBPK model against observations, urinary arsenic concentration and creatinine-adjusted urinary arsenic concentration were simulated. As part of the evaluation, both water and dietary intakes of arsenic were estimated and used to generate the associated urine concentrations of the chemical in exposed populations. RESULTS When arsenic intake from water alone was considered, the results of the PBPK model underpredicted urinary arsenic concentrations for individuals with low levels of arsenic in drinking water and slightly overpredicted urinary arsenic concentrations in individuals with higher levels of arsenic in drinking water. When population-specific estimates of dietary intakes of iAs were included in exposures, the predictive value of the PBPK model was markedly improved, particularly at lower levels of arsenic intake. CONCLUSIONS Evaluations of this PBPK model illustrate its adequacy and usefulness for oral exposure reconstructions in human health risk assessment, particularly in individuals who are exposed to relatively low levels of arsenic in water or food. https://doi.org/10.1289/EHP3096.
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Affiliation(s)
- Hisham A El-Masri
- National Health and Environmental Effects Research Laboratory, Office of Research and Development (ORD), U.S. Environmental Protection Agency (EPA), Durham, North Carolina, USA
| | - Tao Hong
- ICF International, Inc., Durham, North Carolina, USA
| | - Cara Henning
- ICF International, Inc., Durham, North Carolina, USA
| | | | - Edward E Hudgens
- National Health and Environmental Effects Research Laboratory, Office of Research and Development (ORD), U.S. Environmental Protection Agency (EPA), Durham, North Carolina, USA
| | - David J Thomas
- National Health and Environmental Effects Research Laboratory, Office of Research and Development (ORD), U.S. Environmental Protection Agency (EPA), Durham, North Carolina, USA
| | - Janice S Lee
- National Center for Environmental Assessment, ORD, EPA, Durham, North Carolina, USA
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Abstract
Seventeen patients with urinary diversions present for between 10 and 17 years were examined endoscopically. The region of the anastomosis was successfully biopsied in 13 cases. Biopsy specimens were examined both histologically and cytologically. Urine was aspirated from the conduits under sterile conditions and sent for qualification of bacterial flora. Histology revealed a variable degree of villous atrophy, mucosal metaplasia, crypt hyperplasia and in one case, antral type gland metaplasia. The finding of hyperplasia was corroborated by flow cytometry which demonstrated a high percentage of cells in G2 and metaphase. The majority of cases showed a colonic type of bacterial colonization and mucin histochemistry demonstrated a colonic type of mucin.
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Affiliation(s)
- D J Thomas
- Department of Urology, Bristol Royal Infirmary
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24
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Abstract
In humans, early life exposure to inorganic arsenic is associated with adverse health effects. Inorganic arsenic in utero or in early postnatal life also produces adverse health effects in offspring of pregnant mice that consumed drinking water containing low part per billion levels of inorganic arsenic. Because aggregate exposure of pregnant mice to inorganic arsenic from both drinking water and food has not been fully evaluated in experimental studies, quantifying arsenic exposure of the developing mouse is problematic. Here, we determined levels of total arsenic and arsenic species in natural ingredient rodent diets that are composed of many plant and animal-derived foodstuffs and in a purified ingredient rodent diet that is composed of a more restricted mixture of foodstuffs. In natural ingredient diets, total arsenic levels ranged from ∼60 to ∼400 parts per billion, and in the purified ingredient diet, total arsenic level was 13 parts per billion. Inorganic arsenic was the predominant arsenic species in trifluoroacetic acid extracts of each diet. Various exposure scenarios were evaluated using information on inorganic arsenic levels in diet and drinking water and on daily food and water consumption of pregnant mice. In a scenario in which pregnant mice consumed drinking water with 10 parts per billion of inorganic arsenic and a natural ingredient diet containing 89 parts per billion of inorganic arsenic, drinking water contributed only ∼20% of inorganic arsenic intake. Quantitation of arsenic species in diets used in studies in which drinking water is the nominal source of arsenic exposure provides more accurate dosimetry and improves understanding of dose-response relations. Use of purified ingredient diets will minimize the discrepancy between the target dosage level and the actual dosage level attained in utero exposure studies designed to evaluate effects of low level exposure to inorganic arsenic.
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Affiliation(s)
- Manuela Murko
- Institute of Chemistry, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Brittany Elek
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Laboratory, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709, United States
| | - Miroslav Styblo
- Department of Nutrition, Gillings School of Global Public Health, The University of North Carolina, Chapel Hill, North Carolina 27719, United States
| | - David J. Thomas
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Laboratory, Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709, United States
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Nelson CM, Li K, Obenour DR, Miller J, Misenheimer JC, Scheckel K, Betts A, Juhasz A, Thomas DJ, Bradham KD. Relating soil geochemical properties to arsenic bioaccessibility through hierarchical modeling. J Toxicol Environ Health A 2018; 81:160-172. [PMID: 29336680 PMCID: PMC9153852 DOI: 10.1080/15287394.2018.1423798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Interest in improved understanding of relationships among soil properties and arsenic (As) bioaccessibility has motivated the use of regression models for As bioaccessibility prediction. However, limits in the numbers and types of soils included in previous studies restrict the usefulness of these models beyond the range of soil conditions evaluated, as evidenced by reduced predictive performance when applied to new data. In response, hierarchical models that consider variability in relationships among soil properties and As bioaccessibility across geographic locations and contaminant sources were developed to predict As bioaccessibility in 139 soils on both a mass fraction (mg/kg) and % basis. The hierarchical approach improved the estimation of As bioaccessibility in studied soils. In addition, the number of soil elements identified as statistically significant explanatory variables increased when compared to previous investigations. Specifically, total soil Fe, P, Ca, Co, and V were significant explanatory variables in both models, while total As, Cd, Cu, Ni, and Zn were also significant in the mass fraction model and Mg was significant in the % model. This developed hierarchical approach provides a novel tool to (1) explore relationships between soil properties and As bioaccessibility across a broad range of soil types and As contaminant sources encountered in the environment and (2) identify areas of future mechanistic research to better understand the complexity of interactions between soil properties and As bioaccessibility.
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Affiliation(s)
- Clay M Nelson
- a National Exposure Research Laboratory, Office of Research and Development , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Kevin Li
- b Department of Civil, Construction, and Environmental Engineering , North Carolina State University , Raleigh , NC , USA
| | - Daniel R Obenour
- b Department of Civil, Construction, and Environmental Engineering , North Carolina State University , Raleigh , NC , USA
| | - Jonathan Miller
- b Department of Civil, Construction, and Environmental Engineering , North Carolina State University , Raleigh , NC , USA
| | - John C Misenheimer
- c Oak Ridge Institute for Science and Education Research Participant , Research Triangle Park , NC , USA
| | - Kirk Scheckel
- d Office of Research and Development , U.S. Environmental Protection Agency , Cincinnati , OH , USA
| | - Aaron Betts
- e Department of Plant and Soil Sciences , University of Delaware , Newark , DE , USA
| | - Albert Juhasz
- f Centre for Environmental Risk Assessment and Remediation , University of South Australia , Mawson Lakes , SA Australia
| | - David J Thomas
- g National Health and Environmental Effects Research Laboratory, Office of Research and Development , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Karen D Bradham
- a National Exposure Research Laboratory, Office of Research and Development , U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
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26
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Bradham KD, Diamond GL, Burgess M, Juhasz A, Klotzbach JM, Maddaloni M, Nelson C, Scheckel K, Serda SM, Stifelman M, Thomas DJ. In vivo and in vitro methods for evaluating soil arsenic bioavailability: relevant to human health risk assessment. J Toxicol Environ Health B Crit Rev 2018; 21:83-114. [PMID: 29553912 PMCID: PMC9347188 DOI: 10.1080/10937404.2018.1440902] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Arsenic (As) is the most frequently occurring contaminant on the priority list of hazardous substances, which lists substances of greatest public health concern to people living at or near U.S. National Priorities List site. Accurate assessment of human health risks from exposure to As-contaminated soils depends on estimating its bioavailability, defined as the fraction of ingested As absorbed across the gastrointestinal barrier and available for systemic distribution and metabolism. Arsenic bioavailability varies among soils and is influenced by site-specific soil physical and chemical characteristics and internal biological factors. This review describes the state-of-the science that supports our understanding of oral bioavailability of soil As, the methods that are currently being explored for estimating soil As relative bioavailability (RBA), and future research areas that could improve our prediction of the oral RBA of soil As in humans. The following topics are addressed: (1) As soil geochemistry; (2) As toxicology; (3) in vivo models for estimating As RBA; (4) in vitro bioaccessibility methods; and (5) conclusions and research needs.
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Affiliation(s)
- Karen D Bradham
- a Public Health Chemistry Branch, Exposure Methods and Measurements Division, National Exposure Research Laboratory , Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | | | - Michele Burgess
- c Science Policy Branch, Office of Superfund Remediation and Technology Innovation, Office of Land and Emergency Management , US Environmental Protection Agency , Arlington , VA , USA
| | - Albert Juhasz
- d Future Industries Institute , University of South Australia , Adelaide , SA , Australia
| | | | - Mark Maddaloni
- e Region 2 , U.S. Environmental Protection Agency , New York , NY , USA
| | - Clay Nelson
- a Public Health Chemistry Branch, Exposure Methods and Measurements Division, National Exposure Research Laboratory , Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Kirk Scheckel
- f Land Remediation and Pollution Control Division, National Risk Management Research Laboratory , Office of Research and Development, U.S. Environmental Protection Agency , Cincinnati , Ohio
| | - Sophia M Serda
- g Region 9 , U.S. Environmental Protection Agency , San Francisco , CA , USA
| | - Marc Stifelman
- h Region 10 , U.S. Environmental Protection Agency , Seattle , WA , USA
| | - David J Thomas
- i Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory , Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
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27
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Bradham KD, Nelson CM, Kelly J, Pomales A, Scruton K, Dignam T, Misenheimer JC, Li K, Obenour DR, Thomas DJ. Relationship Between Total and Bioaccessible Lead on Children's Blood Lead Levels in Urban Residential Philadelphia Soils. Environ Sci Technol 2017; 51:10005-10011. [PMID: 28787152 PMCID: PMC5675733 DOI: 10.1021/acs.est.7b02058] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Relationships between total soil or bioaccessible lead (Pb), measured using an in vitro bioaccessibility assay, and children's blood lead levels (BLL) were investigated in an urban neighborhood in Philadelphia, PA, with a history of soil Pb contamination. Soil samples from 38 homes were analyzed to determine whether accounting for the bioaccessible Pb fraction improves statistical relationships with children's BLLs. Total soil Pb concentration ranged from 58 to 2821 mg/kg; the bioaccessible Pb concentration ranged from 47 to 2567 mg/kg. Children's BLLs ranged from 0.3 to 9.8 μg/dL. Hierarchical models were used to compare relationships between total or bioaccessible Pb in soil and children's BLLs. Total soil Pb concentration as the predictor accounted for 23% of the variability in child BLL; bioaccessible soil Pb concentration as the predictor accounted for 26% of BLL variability. A bootstrapping analysis confirmed a significant increase in R2 for the model using bioaccessible soil Pb concentration as the predictor with 99.0% of bootstraps showing a positive increase. Estimated increases of 1.3 μg/dL and 1.5 μg/dL in BLL per 1000 mg/kg Pb in soil were observed for this study area using total and bioaccessible Pb concentrations, respectively. Children's age did not contribute significantly to the prediction of BLLs.
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Affiliation(s)
- Karen D. Bradham
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, United States
| | - Clay M. Nelson
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, United States
| | - Jack Kelly
- Hazardous Site Cleanup Division, U.S. EPA Region III, Philadelphia, Pennsylvania, United States
| | - Ana Pomales
- Division of Community Health Investigations, Agency for Toxic Substances and Disease Registry, Philadelphia, Pennsylvania, United States
| | - Karen Scruton
- Division of Community Health Investigations, Agency for Toxic Substances and Disease Registry, Philadelphia, Pennsylvania, United States
| | - Tim Dignam
- Division of Environmental Hazards and Health Effects, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States
| | - John C. Misenheimer
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, United States
| | - Kevin Li
- Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina, United States
| | - Daniel R. Obenour
- Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina, United States
| | - David J. Thomas
- Office of Research and Development, United States Environmental Protection Agency (U.S. EPA), Research Triangle Park, North Carolina, United States
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28
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Salvador-Castiñeira P, Hambsch FJ, Göök A, Vidali M, Hawkes NP, Roberts NJ, Taylor GC, Thomas DJ. Absolute and relative cross section measurements of 237Np(n,f) and 238U(n,f) at the National Physical Laboratory. EPJ Web Conf 2017. [DOI: 10.1051/epjconf/201714604050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Thomas DJ, Bradham K. Role of complex organic arsenicals in food in aggregate exposure to arsenic. J Environ Sci (China) 2016; 49:86-96. [PMID: 28007183 DOI: 10.1016/j.jes.2016.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 05/07/2016] [Accepted: 06/01/2016] [Indexed: 06/06/2023]
Abstract
For much of the world's population, food is the major source of exposure to arsenic. Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here, we 2evaluate the contribution of complex organic arsenicals (arsenosugars, arsenolipids, and trimethylarsonium compounds) that are found in foods and consider their origins, metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.
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Affiliation(s)
- David J Thomas
- Pharmacokinetics Branch, Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, USA.
| | - Karen Bradham
- Public Health Chemistry Branch, Exposure Methods and Measurements Division, National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, USA
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30
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Bradham KD, Green W, Hayes H, Nelson C, Alava P, Misenheimer J, Diamond GL, Thayer WC, Thomas DJ. Estimating relative bioavailability of soil lead in the mouse. J Toxicol Environ Health A 2016; 79:1179-1182. [PMID: 27767405 DOI: 10.1080/15287394.2016.1221789] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Lead (Pb) in soil is an important exposure source for children. Thus, determining bioavailability of Pb in soil is critical in evaluating risk and selecting appropriate strategies to minimize exposure. A mouse model was developed to estimate relative bioavailability of Pb in NIST SRM 2710a (Montana 1 Soil). Based on Pb levels in tissues, the mean relative bioavailability of this metal in this soil was 0.5. Estimates of relative bioavailabilities derived from mouse compared favorably with those obtained in juvenile swine. The mouse model is thus an efficient and inexpensive method to obtain estimates of relative bioavailability of soil Pb.
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Affiliation(s)
- Karen D Bradham
- a Public Health Chemistry Branch, Exposure Methods and Measurements Division , National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA
| | - William Green
- b Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA
| | - Hunter Hayes
- b Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA
| | - Clay Nelson
- a Public Health Chemistry Branch, Exposure Methods and Measurements Division , National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA
| | - Pradeep Alava
- c National Research Associateship Programs , Research Triangle Park , North Carolina , USA
| | - John Misenheimer
- d Oak Ridge Institute for Science and Education , Research Triangle Park , North Carolina , USA
| | | | | | - David J Thomas
- b Pharmacokinetics Branch, Integrated Systems Toxicology Division , National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency , Research Triangle Park , North Carolina , USA
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31
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Chevallier MA, Fantuzzi E, Cruz-Suarez R, Luszik-Bhadra M, Mayer S, Thomas DJ, Tanner R, Vanhavere F. EURADOS IC2012N: FURTHER INFORMATION DERIVED FROM AN EURADOS INTERNATIONAL COMPARISON OF NEUTRON PERSONAL DOSEMETERS. Radiat Prot Dosimetry 2016; 170:78-81. [PMID: 26715777 DOI: 10.1093/rpd/ncv518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In 2012, the European Radiation Dosimetry Group (EURADOS) performed an intercomparison for neutron dosemeters that are intended to measure personal dose equivalent, Hp(10). A total of 31 participants registered with 34 dosimetry systems. The irradiation tests were chosen to provide the participants with useful information on their dosimetry systems, i.e. linearity, reproducibility, responses for different energies and angles and to simulated workplace fields. This paper gives details of the extensive information derived from the exercise.
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Affiliation(s)
- M-A Chevallier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17, 31 avenue de la Division Leclerc, Fontenay-aux-Roses 92260, France
| | - E Fantuzzi
- ENEA-Radiation Protection Institute, via dei Colli, 16, Bologna 40136, Italy
| | | | - M Luszik-Bhadra
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, Braunschweig D-38116, Germany
| | - S Mayer
- Paul Scherrer Institute (PSI), Villigen PSI CH-5232, Switzerland
| | - D J Thomas
- National Physical Laboratory (NPL), Hampton Road, Teddington TW11 0LW, UK
| | - R Tanner
- Public Health England, CRCE, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - F Vanhavere
- SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, Mol 2400, Belgium
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32
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Hawkes NP, Thomas DJ, Taylor GC. CORRECTIONS ASSOCIATED WITH ON-PHANTOM CALIBRATIONS OF NEUTRON PERSONAL DOSEMETERS. Radiat Prot Dosimetry 2016; 170:35-38. [PMID: 26424136 DOI: 10.1093/rpd/ncv409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The response of neutron personal dosemeters as a function of neutron energy and angle of incidence is typically measured by mounting the dosemeters on a slab phantom and exposing them to neutrons from an accelerator-based or radionuclide source. The phantom is placed close to the source (75 cm) so that the effect of scattered neutrons is negligible. It is usual to mount several dosemeters on the phantom together. Because the source is close, the source distance and the neutron incidence angle vary significantly over the phantom face, and each dosemeter may receive a different dose equivalent. This is particularly important when the phantom is angled away from normal incidence. With accelerator-produced neutrons, the neutron energy and fluence vary with emission angle relative to the charged particle beam that produces the neutrons, contributing further to differences in dose equivalent, particularly when the phantom is located at other than the straight-ahead position (0° to the beam). Corrections for these effects are quantified and discussed in this article.
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Affiliation(s)
- N P Hawkes
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | - D J Thomas
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | - G C Taylor
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
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Carlin DJ, Naujokas MF, Bradham KD, Cowden J, Heacock M, Henry HF, Lee JS, Thomas DJ, Thompson C, Tokar EJ, Waalkes MP, Birnbaum LS, Suk WA. Arsenic and Environmental Health: State of the Science and Future Research Opportunities. Environ Health Perspect 2016; 124:890-9. [PMID: 26587579 PMCID: PMC4937867 DOI: 10.1289/ehp.1510209] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 11/10/2015] [Indexed: 05/20/2023]
Abstract
BACKGROUND Exposure to inorganic and organic arsenic compounds is a major public health problem that affects hundreds of millions of people worldwide. Exposure to arsenic is associated with cancer and noncancer effects in nearly every organ in the body, and evidence is mounting for health effects at lower levels of arsenic exposure than previously thought. Building from a tremendous knowledge base with > 1,000 scientific papers published annually with "arsenic" in the title, the question becomes, what questions would best drive future research directions? OBJECTIVES The objective is to discuss emerging issues in arsenic research and identify data gaps across disciplines. METHODS The National Institutes of Health's National Institute of Environmental Health Sciences Superfund Research Program convened a workshop to identify emerging issues and research needs to address the multi-faceted challenges related to arsenic and environmental health. This review summarizes information captured during the workshop. DISCUSSION More information about aggregate exposure to arsenic is needed, including the amount and forms of arsenic found in foods. New strategies for mitigating arsenic exposures and related health effects range from engineered filtering systems to phytogenetics and nutritional interventions. Furthermore, integration of omics data with mechanistic and epidemiological data is a key step toward the goal of linking biomarkers of exposure and susceptibility to disease mechanisms and outcomes. CONCLUSIONS Promising research strategies and technologies for arsenic exposure and adverse health effect mitigation are being pursued, and future research is moving toward deeper collaborations and integration of information across disciplines to address data gaps. CITATION Carlin DJ, Naujokas MF, Bradham KD, Cowden J, Heacock M, Henry HF, Lee JS, Thomas DJ, Thompson C, Tokar EJ, Waalkes MP, Birnbaum LS, Suk WA. 2016. Arsenic and environmental health: state of the science and future research opportunities. Environ Health Perspect 124:890-899; http://dx.doi.org/10.1289/ehp.1510209.
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Affiliation(s)
- Danielle J. Carlin
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | | | - Karen D. Bradham
- Human Exposure & Atmospheric Science Division, National Exposure Research Laboratory, U.S. Environmental Protection Agency (EPA), Research Triangle Park, North Carolina, USA
| | - John Cowden
- National Center for Computational Toxicology, and
| | - Michelle Heacock
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Heather F. Henry
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
| | - Janice S. Lee
- National Center for Environmental Assessment, Office of Research and Development (ORD), U.S. EPA, Research Triangle Park, North Carolina, USA
| | - David J. Thomas
- Integrated Systems Toxicology Division, National Human and Environmental Health Effects Research Laboratory, ORD, U.S. EPA, Research Triangle Park, North Carolina, USA
| | | | - Erik J. Tokar
- National Toxicology Program, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
| | - Michael P. Waalkes
- National Toxicology Program, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
| | - Linda S. Birnbaum
- National Toxicology Program, NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
- NIEHS, NIH, DHHS, Research Triangle Park, North Carolina, USA
| | - William A. Suk
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
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Hudgens EE, Drobna Z, He B, Le XC, Styblo M, Rogers J, Thomas DJ. Biological and behavioral factors modify urinary arsenic metabolic profiles in a U.S. population. Environ Health 2016; 15:62. [PMID: 27230915 PMCID: PMC4880853 DOI: 10.1186/s12940-016-0144-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 05/16/2016] [Indexed: 05/19/2023]
Abstract
BACKGROUND Because some adverse health effects associated with chronic arsenic exposure may be mediated by methylated arsenicals, interindividual variation in capacity to convert inorganic arsenic into mono- and di-methylated metabolites may be an important determinant of risk associated with exposure to this metalloid. Hence, identifying biological and behavioral factors that modify an individual's capacity to methylate inorganic arsenic could provide insights into critical dose-response relations underlying adverse health effects. METHODS A total of 904 older adults (≥45 years old) in Churchill County, Nevada, who chronically used home tap water supplies containing up to 1850 μg of arsenic per liter provided urine and toenail samples for determination of total and speciated arsenic levels. Effects of biological factors (gender, age, body mass index) and behavioral factors (smoking, recent fish or shellfish consumption) on patterns of arsenicals in urine were evaluated with bivariate analyses and multivariate regression models. RESULTS Relative contributions of inorganic, mono-, and di-methylated arsenic to total speciated arsenic in urine were unchanged over the range of concentrations of arsenic in home tap water supplies used by study participants. Gender predicted both absolute and relative amounts of arsenicals in urine. Age predicted levels of inorganic arsenic in urine and body mass index predicted relative levels of mono- and di-methylated arsenic in urine. Smoking predicted both absolute and relative levels of arsenicals in urine. Multivariate regression models were developed for both absolute and relative levels of arsenicals in urine. Concentration of arsenic in home tap water and estimated water consumption were strongly predictive of levels of arsenicals in urine as were smoking, body mass index, and gender. Relative contributions of arsenicals to urinary arsenic were not consistently predicted by concentrations of arsenic in drinking water supplies but were more consistently predicted by gender, body mass index, age, and smoking. CONCLUSIONS These findings suggest that analyses of dose-response relations in arsenic-exposed populations should account for biological and behavioral factors that modify levels of inorganic and methylated arsenicals in urine. Evidence of significant effects of these factors on arsenic metabolism may also support mode of action studies in appropriate experimental models.
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Affiliation(s)
- Edward E Hudgens
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA
| | - Zuzana Drobna
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Bin He
- Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, T6G 2G3, Canada
| | - X C Le
- Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, T6G 2G3, Canada
| | - Miroslav Styblo
- Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - John Rogers
- Westat, 1600 Research Boulevard, Rockville, MD, 20850, USA
| | - David J Thomas
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27709, USA.
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Diamond GL, Bradham KD, Brattin WJ, Burgess M, Griffin S, Hawkins CA, Juhasz AL, Klotzbach JM, Nelson C, Lowney YW, Scheckel KG, Thomas DJ. Predicting oral relative bioavailability of arsenic in soil from in vitro bioaccessibility. J Toxicol Environ Health A 2016; 79:165-73. [PMID: 27029599 DOI: 10.1080/15287394.2015.1134038] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Several investigations have been conducted to develop in vitro bioaccessibility (IVBA) assays that reliably predict in vivo oral relative bioavailability (RBA) of arsenic (As). This study describes a meta-regression model relating soil As RBA and IVBA that is based upon data combined from previous investigations that examined the relationship between As IVBA and RBA when IVBA was determined using an extraction of soil in 0.4 M glycine at pH 1.5. Data used to develop the model included paired IVBA and RBA estimates for 83 soils from various types of sites such as mining, smelting, and pesticide or herbicide application. The following linear regression model accounted for 87% of the observed variance in RBA (R(2) = .87): RBA(%) = 0.79 × IVBA(%) + 3. This regression model is more robust than previously reported models because it includes a larger number of soil samples, and also accounts for variability in RBA and IVBA measurements made on samples collected from sites contaminated with different As sources and conducted in different labs that have utilized different experimental models for estimating RBA.
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Affiliation(s)
| | - Karen D Bradham
- b U.S. Environmental Protection Agency , Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA
| | | | - Michele Burgess
- c U.S. Environmental Protection Agency , Office of Superfund Remediation and Technology Innovation, Science Policy Branch , Washington DC , USA
| | - Susan Griffin
- d U.S. Environmental Protection Agency , Denver , Colorado , USA
| | - Cheryl A Hawkins
- c U.S. Environmental Protection Agency , Office of Superfund Remediation and Technology Innovation, Science Policy Branch , Washington DC , USA
| | - Albert L Juhasz
- e Centre for Environmental Risk Assessment and Remediation , University of South Australia , Adelaide , South Australia , Australia
| | | | - Clay Nelson
- b U.S. Environmental Protection Agency , Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park , North Carolina , USA
| | | | - Kirk G Scheckel
- g U.S. Environmental Protection Agency , Office of Research and Development, National Risk Management Research Laboratory , Cincinnati , Ohio , USA
| | - David J Thomas
- h U.S. Environmental Protection Agency , Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park , North Carolina , USA
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Bradham KD, Nelson C, Juhasz AL, Smith E, Scheckel K, Obenour DR, Miller BW, Thomas DJ. Independent data validation of an in vitro method for the prediction of the relative bioavailability of arsenic in contaminated soils. Environ Sci Technol 2015; 49:6312-6318. [PMID: 25965337 DOI: 10.1021/acs.est.5b00905] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In vitro bioaccessibility (IVBA) assays estimate arsenic (As) relative bioavailability (RBA) in contaminated soils to improve accuracy in human exposure assessments. Previous studies correlating soil As IVBA with RBA have been limited by the use of few soil types and sources of As, and the predictive value of As IVBA has not been validated using an independent set of As-contaminated soils. In this study, a robust linear model was developed to predict As RBA in mice using IVBA, and the predictive capability of the model was independently validated using a unique set of As-contaminated soils. Forty As-contaminated soils varying in soil type and contaminant source were included in this study, with 31 soils used for initial model development and nine soils used for independent model validation. The initial model reliably predicted As RBA values in the independent data set, with a mean As RBA prediction error of 5.4%. Following validation, 40 soils were used for final model development, resulting in a linear model with the equation RBA = 0.65 × IVBA + 7.8 and an R(2) of 0.81. The in vivo-in vitro correlation and independent data validation presented provide critical verification necessary for regulatory acceptance in human health risk assessment.
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Affiliation(s)
- Karen D Bradham
- †Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Clay Nelson
- †Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
| | - Albert L Juhasz
- ‡Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Euan Smith
- ‡Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Kirk Scheckel
- §Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio 45224, United States
| | - Daniel R Obenour
- ∥Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Bradley W Miller
- §Office of Research and Development, United States Environmental Protection Agency, Cincinnati, Ohio 45224, United States
| | - David J Thomas
- †Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, United States
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Thomas DJ, Willison JR. Effect of phlebotomy on cerebral blood flow and function. Bibl Haematol 2015:139-44. [PMID: 7337654 DOI: 10.1159/000402218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Wang QQ, Thomas DJ, Naranmandura H. Importance of being thiomethylated: formation, fate, and effects of methylated thioarsenicals. Chem Res Toxicol 2015; 28:281-9. [PMID: 25531277 DOI: 10.1021/tx500464t] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although inorganic arsenic has long been recognized as a potent toxicant and carcinogen in humans, recent evidence shows that at least some of its effects are mediated by methylated metabolites. Elucidating the conversion of inorganic arsenic to mono-, di-, and trimethylated species has provided insights into the enzymology of this pathway and identified genetic and environmental factors that influence the susceptibility of individuals to this metalloid's adverse health effects. Notably, almost all work on the formation, fate, and effects of methylated arsenicals has focused on oxoarsenicals in which arsenic is bound to one or more oxygen atoms. However, thioarsenicals are a class of arsenicals in which a sulfur atom has replaced one or more oxygens that are bound to arsenic. Thioarsenicals have been identified as urinary metabolites in humans and other animals following exposure to inorganic arsenic. Studies find that methylated thioarsenicals exhibit kinetic behavior and toxicological properties that distinguish them from methylated oxoarsenicals. This perspective considers that formation, fate, and effects of methylated thioarsenicals with an emphasis on examining the linkages between the molecular processes that underlie both methylation and thiolation reactions. Integrating this information will provide a more comprehensive view of the relationship between the metabolism of arsenic and the risk posed by chronic exposure to this environmental contaminant.
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Affiliation(s)
- Qian Qian Wang
- Department of Toxicology, School of Medicine and Public Health, ‡College of Pharmaceutical Sciences, Zhejiang University , Hangzhou 310058, China
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Juhasz AL, Smith E, Nelson C, Thomas DJ, Bradham K. Variability associated with as in vivo-in vitro correlations when using different bioaccessibility methodologies. Environ Sci Technol 2014; 48:11646-53. [PMID: 25157927 DOI: 10.1021/es502751z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
To evaluate the capabilities of in vitro assays to predict arsenic (As) relative bioavailability (RBA), we examined the relationship between As bioaccessibility, determined using a number of in vitro bioaccessibility (IVBA) methodologies (SBRC, IVG, PBET, DIN and UBM) and As RBA determined in a mouse assay for nine As-contaminated soils and 1 NIST reference material (2710a). Significant differences (P < 0.05) in As IVBA were observed within and between assays indicating that different IVBA methodologies may not produce congruent data, as a result of variability in the extracting medium constituents and/or differences in the pH of gastric and intestinal phases. When results of in vivo determinations of As RBA were compared with As IVBA results, there was no significant difference in slopes of the relationships (P = 0.49-0.88) when SBRC, IVG, PBET, DIN, and UBM gastric and intestinal phase data were used. A significantly (P < 0.05) smaller y-intercept was, however, determined for the in vivo-SBRC gastric phase correlation compared to SBRC, IVG, PBET, and DIN intestinal phase, a factor that may influence prediction of As RBA, especially for soils with low As RBA. When in vivo-in vitro relationships were compared to previously derived correlations from the literature, some differences were observed. These differences may be attributed to factors affecting both in vivo and in vitro data including physiological differences in animal models (e.g., mouse versus swine), which may influence As absorption, differences in the approach used to estimate As RBA, and variability arising from subtle interoperator differences in performance of in vitro assays.
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Affiliation(s)
- Albert L Juhasz
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Mawson Lakes, South Australia 5095, Australia
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Roberts NJ, Jones LN, Liu ZZ, Tagziria H, Thomas DJ. Bonner sphere measurements of 241Am-B and 241Am-F neutron energy spectra unfolded using high-resolution a priori data. Radiat Prot Dosimetry 2014; 161:225-228. [PMID: 24126487 DOI: 10.1093/rpd/nct238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
High-resolution neutron energy spectra, covering the entire energy range of interest, for two standard radionuclide neutron sources ((241)Am-B and (241)Am-F) have been derived from Bonner sphere measurements by using high-resolution a priori data in the unfolding process. In each case, two a priori spectra were used, one from a two-stage calculation and also one from a combination of the calculated spectrum with a high-resolution measured spectrum. The unfolded spectra are compared with those published elsewhere and show significant differences from the ISO- and IAEA-recommended spectra for (241)Am-B and (241)Am-F, respectively. Values for the fluence-average energy and fluence-to-dose-equivalent conversion coefficients are presented for the new spectra, and the implications of the new spectra for the emission rates of the sources when measured by the manganese bath technique are also determined.
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Affiliation(s)
- N J Roberts
- National Physical Laboratory, Hampton Road, Teddington, Middx TW11 0LW, UK
| | - L N Jones
- National Physical Laboratory, Hampton Road, Teddington, Middx TW11 0LW, UK
| | - Z Z Liu
- National Physical Laboratory, Hampton Road, Teddington, Middx TW11 0LW, UK
| | - H Tagziria
- National Physical Laboratory, Hampton Road, Teddington, Middx TW11 0LW, UK
| | - D J Thomas
- National Physical Laboratory, Hampton Road, Teddington, Middx TW11 0LW, UK
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Fantuzzi E, Chevallier MA, Cruz-Suarez R, Luszik-Bhadra M, Mayer S, Thomas DJ, Tanner R, Vanhavere F. EURADOS IC2012N: EURADOS 2012 intercomparison for whole-body neutron dosimetry. Radiat Prot Dosimetry 2014; 161:73-77. [PMID: 24578527 DOI: 10.1093/rpd/nct295] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The European Radiation Dosimetry Group (EURADOS) IC2012n intercomparison for neutron dosemeters intended to measure personal dose equivalent, Hp(10), was performed in 2012. A total of 31 participants (27 individual monitoring services from Europe, 2 from Japan, 1 from Israel and 1 from USA) registered with 34 dosimetry systems. Participation was restricted to passive or active neutron dosemeters routinely used in individual monitoring of radiation workers. The dosimetry systems were based on thermoluminescence, polyallyldiglycol carbonate, optically stimulated luminescence, fission track detection and silicon diodes (electronic devices). The irradiation tests were chosen to provide the participants with useful information on their dosimetry systems, i.e. linearity, reproducibility, responses for different energies and angles and to simulated workplace fields. The paper will report and discuss the first analysis of the results of the EURADOS IC2012n intercomparison.
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Affiliation(s)
- E Fantuzzi
- ENEA-Radiation Protection Institute, via dei Colli, 16-40136 Bologna (BO), Italy
| | - M-A Chevallier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17, 31 avenue de la Division Leclerc, 92260 Fontenay-aux-Roses, France
| | | | - M Luszik-Bhadra
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, D-38116 Braunschweig, Germany
| | - S Mayer
- Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland
| | - D J Thomas
- National Physical Laboratory (NPL), Hampton Road, Teddington TW11 0LW, UK
| | - R Tanner
- Public Health England, CRCE, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - F Vanhavere
- SCK-CEN, Belgian Nuclear Research Centre, Boeretang 200, 2400 Mol, Belgium
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Abstract
The present system of radiation protection for neutrons is reviewed with particular reference to the development of the protection quantities and their relationships with the operational quantities. Some of the shortcomings of the system are outlined, and the difficulties of measuring the operational quantities. Suggestions are made for future developments.
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Affiliation(s)
- David J Thomas
- National Physical Laboratory, NPL, Hampton Road, Teddington TW11 0LW, UK
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Atanackovic J, Thomas DJ, Roberts NJ, Witharana S, Dubeau J, Yonkeu A. Correction and verification of AECL Bonner Sphere response matrix based on mono-energetic neutron calibration performed at NPL. Radiat Prot Dosimetry 2014; 161:216-220. [PMID: 24319105 DOI: 10.1093/rpd/nct324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The AECL Bonner Sphere Spectrometer (BSS) was taken to National Physical Laboratory (NPL) for calibration in mono-energetic neutron fields and bare (252)Cf neutron fields. The mono-energetic radiations were performed using ISO-8529 prescribed neutron energies: 0.071, 0.144, 0.565, 1.2, 5 and 17 MeV. A central SP9 proportional counter was also evaluated at the NPL thermal neutron calibration facility in order to assess an effective pressure of (3)He inside the counter, i.e. number density of (3)He atoms. Based on these measurements and methods outlined by Thomas and Soochak, a new BSS response matrix was generated. The response matrix is then verified by unfolding spectra corresponding to various neutron fields. Those are NPL bare (252)Cf source, National Institute of Standards and Technology bare and heavy water moderated (252)Cf source and (241)AmBe calibration source located at National Research Council. A good agreement was observed with expected neutron fluence rates, as well as derived dosimetric quantities, such as International Commission on Radiological Protection-74 ambient dose equivalent.
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Affiliation(s)
- J Atanackovic
- Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ONT, Canada K0J 1J0
| | - D J Thomas
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | - N J Roberts
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
| | | | - J Dubeau
- DETEC, Gatineau, QC, Canada J8 T 4J1
| | - A Yonkeu
- Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ONT, Canada K0J 1J0
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Antonelli R, Shao K, Thomas DJ, Sams R, Cowden J. AS3MT, GSTO, and PNP polymorphisms: impact on arsenic methylation and implications for disease susceptibility. Environ Res 2014; 132:156-67. [PMID: 24792412 DOI: 10.1016/j.envres.2014.03.012] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 03/05/2014] [Accepted: 03/12/2014] [Indexed: 05/19/2023]
Abstract
BACKGROUND Oral exposure to inorganic arsenic (iAs) is associated with adverse health effects. Epidemiological studies suggest differences in susceptibility to these health effects, possibly due to genotypic variation. Genetic polymorphisms in iAs metabolism could lead to increased susceptibility by altering urinary iAs metabolite concentrations. OBJECTIVE To examine the impact of genotypic polymorphisms on iAs metabolism. METHODS We screened 360 publications from PubMed and Web of Science for data on urinary mono- and dimethylated arsenic (MMA and DMA) percentages and polymorphic genes encoding proteins that are hypothesized to play roles in arsenic metabolism. The genes we examined were arsenic (+3) methyltransferase (AS3MT), glutathione-s-transferase omega (GSTO), and purine nucleoside phosphorylase (PNP). Relevant data were pooled to determine which polymorphisms are associated across studies with changes in urinary metabolite concentration. RESULTS In our review, AS3MT polymorphisms rs3740390, rs11191439, and rs11191453 were associated with statistically significant changes in percent urinary MMA. Studies of GSTO polymorphisms did not indicate statistically significant associations with methylation, and there are insufficient data on PNP polymorphisms to evaluate their impact on metabolism. DISCUSSION Collectively, these data support the hypothesis that AS3MT polymorphisms alter in vivo metabolite concentrations. Preliminary evidence suggests that AS3MT genetic polymorphisms may impact disease susceptibility. GSTO polymorphisms were not associated with iAs-associated health outcomes. Additional data are needed to evaluate the association between PNP polymorphisms and iAs-associated health outcomes. Delineation of these relationships may inform iAs mode(s) of action and the approach for evaluating low-dose health effects for iAs. CONCLUSIONS Genotype impacts urinary iAs metabolite concentrations and may be a potential mechanism for iAs-related disease susceptibility.
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Affiliation(s)
- Ray Antonelli
- ORISE Fellow, Hazardous Pollutant Assessment Group, National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Kan Shao
- ORISE Fellow, Hazardous Pollutant Assessment Group, National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - David J Thomas
- Integrated Systems Toxicology Division, National Health and Environmental Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Reeder Sams
- Hazardous Pollutant Assessment Group, National Center for Environmental Assessment, Research Triangle Park Division, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - John Cowden
- Hazardous Pollutant Assessment Group, National Center for Environmental Assessment, Research Triangle Park Division, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA.
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Affiliation(s)
- David J. Thomas
- Pharmacokinetics Branch,
Integrated Systems Toxicology Division, National Health and Environmental
Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27709, United States
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Calderon RL, Hudgens EE, Carty C, He B, Le XC, Rogers J, Thomas DJ. Biological and behavioral factors modify biomarkers of arsenic exposure in a U.S. population. Environ Res 2013; 126:134-44. [PMID: 23777639 DOI: 10.1016/j.envres.2013.04.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 04/01/2013] [Accepted: 04/19/2013] [Indexed: 05/21/2023]
Abstract
Although consumption of drinking water contaminated with inorganic arsenic is usually considered the primary exposure route, aggregate exposure to arsenic depends on direct consumption of water, use of water in food preparation, and the presence in arsenicals in foods. To gain insight into the effects of biological and behavioral factors on arsenic exposure, we determined arsenic concentrations in urine and toenails in a U.S. population that uses public or private water supplies containing inorganic arsenic. Study participants were 904 adult residents of Churchill County, Nevada, whose home tap water supplies contained <3 to about 1200 µg of arsenic per liter. Biomarkers of exposure for this study were summed urinary concentrations of inorganic arsenic and its methylated metabolites (speciated arsenical), of all urinary arsenicals (total arsenical), and of all toenail arsenicals (total arsenical). Increased tap water arsenic concentration and consumption were associated with significant upward trends for urinary speciated and total and toenail total arsenical concentrations. Significant gender differences in concentrations of speciated and total arsenicals in urine and toenails reflected male-female difference in water intake. Both recent and higher habitual seafood consumption significantly increased urinary total but not speciated arsenical concentration. In a stepwise general linear model, seafood consumption significantly predicted urinary total arsenical but not urinary speciated or toenail total arsenical concentrations. Smoking behavior significantly predicted urinary speciated or total arsenical concentration. Gender, tap water arsenic concentration, and primary drinking water source significantly predicted urinary speciated and total concentrations and toenail total arsenical concentrations. These findings confirm the primacy of home tap water as a determinant of arsenic concentration in urine and toenails. However, biological and behavioral factors can modify exposure-response relations for these biomarkers. Refining estimates of the influence of these factors will permit better models of dose-response relations for this important environmental contaminant.
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Affiliation(s)
- Rebecca L Calderon
- Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, USA
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Ali AS, Vasdev N, Shanmuganathan S, Paez E, Dark JH, Manas D, Thomas DJ. The surgical management and prognosis of renal cell cancer with IVC tumor thrombus: 15-Years of experience using a multi-specialty approach at a single UK referral center. Urol Oncol 2013; 31:1298-304. [DOI: 10.1016/j.urolonc.2011.11.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 10/31/2011] [Accepted: 11/02/2011] [Indexed: 10/14/2022]
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Dodmane PR, Arnold LL, Pennington KL, Thomas DJ, Cohen SM. Effect of dietary treatment with dimethylarsinous acid (DMAIII) on the urinary bladder epithelium of arsenic (+3 oxidation state) methyltransferase (As3mt) knockout and C57BL/6 wild type female mice. Toxicology 2013; 305:130-5. [DOI: 10.1016/j.tox.2013.01.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/08/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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Simeonsson JB, Elwood SA, Ezer M, Pacquette HL, Swart DJ, Beach HD, Thomas DJ. Development of ultratrace laser spectrometry techniques for measurements of arsenic. Talanta 2013; 58:189-99. [PMID: 18968745 DOI: 10.1016/s0039-9140(02)00267-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2001] [Revised: 05/07/2002] [Indexed: 11/26/2022]
Abstract
Several techniques based on laser induced fluorescence (LIF) spectrometry and laser enhanced ionization (LEI) spectrometry have been investigated for ultratrace measurements of arsenic. Studies by our group in this area that have been published previously are reviewed here, and are presented along with the results of recent studies that have not yet been published. The techniques presented include LIF detection in the inductively coupled plasma atomizer, the electrothermal atomizer, the tungsten coil atomizer, the flame atomizer and LEI detection in the flame atomizer, and include approaches that utilize hydride generation or laser ablation sample introduction. Recent efforts have been directed towards developing speciation approaches for arsenic that utilize LIF spectrometric detection. The capabilities of each technique are summarized including the sensitivity and limits of detection, which range from sub-pg ml(-1) to ng ml(-1) levels. Selected applications of the techniques are presented to demonstrate their utility for environmental and biological samples, and areas for future investigation and further development are discussed.
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Affiliation(s)
- J B Simeonsson
- US EPA, National Health and Environmental Effects Research Laboratory, Experimental Toxicology Division, MD-74, Research Triangle Park, Durham, NC 27711, USA
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Bradham KD, Diamond GL, Scheckel KG, Hughes MF, Casteel SW, Miller BW, Klotzbach JM, Thayer WC, Thomas DJ. Mouse assay for determination of arsenic bioavailability in contaminated soils. J Toxicol Environ Health A 2013; 76:815-826. [PMID: 24028666 DOI: 10.1080/15287394.2013.821395] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A mouse assay for measuring the relative bioavailability (RBA) of arsenic (As) in soil was developed. In this study, results are presented of RBA assays of 16 soils, including multiple assays of the same soils, which provide a quantitative assessment of reproducibility of mouse assay results, as well as a comparison of results from the mouse assay with results from a swine and monkey assay applied to the same test soils. The mouse assay is highly reproducible; three repeated assays on the same soils yielded RBA estimates that ranged from 1 to 3% of the group mean. The mouse, monkey, and swine models yielded similar results for some, but not all, test materials. RBA estimates for identical soils (nine test soils and three standard reference materials [SRM]) assayed in mice and swine were significantly correlated (r = 0.70). Swine RBA estimates for 6 of the 12 test materials were higher than those from the mouse assay. RBA estimates for three standard reference materials (SRM) were not statistically different (mouse/swine ratio ranged from 0.86-1). When four test soils from the same orchard were assessed in the mouse, monkey, and swine assays, the mean soil As RBA were not statistically different. Mouse and swine models predicted similar steady state urinary excretion fractions (UEF) for As of 62 and 74%, respectively, during repeated ingestion doses of sodium arsenate, the water-soluble As form used as the reference in the calculation of RBA. In the mouse assay, the UEF for water soluble As(V) (sodium arsenate) and As(III) (sodium [meta] arsenite) were 62% and 66%, respectively, suggesting similar absolute bioavailabilities for the two As species. The mouse assay can serve as a highly cost-effective alternative or supplement to monkey and swine assays for improving As risk assessments by providing site-specific assessments of RBA of As in soils.
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Affiliation(s)
- Karen D Bradham
- a U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory , Research Triangle Park , North Carolina , USA
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