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Rahbar MH, Samms-Vaughan M, Zhao Y, Saroukhani S, Bressler J, Hessabi M, Grove ML, Shakespeare-Pellington S, Loveland KA. Interactions between Environmental Factors and Glutathione S-Transferase (GST) Genes with Respect to Detectable Blood Aluminum Concentrations in Jamaican Children. Genes (Basel) 2022; 13:genes13101907. [PMID: 36292793 PMCID: PMC9601654 DOI: 10.3390/genes13101907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/13/2022] [Accepted: 10/18/2022] [Indexed: 11/16/2022] Open
Abstract
Aluminum (Al) is a metallic toxicant at high concentrations following natural or unnatural exposures. Dietary intake is considered as the main source of aluminum exposure in children. We used data from 366 typically developing (TD) children (ages 2−8 years) who participated as controls in an age- and sex-matched case−control study in Jamaica. We investigated additive and interactive associations among environmental factors and children’s genotypes for glutathione S-transferase (GST) genes (GSTT1, GSTM1, GSTP1), in relation to having a detectable blood aluminum concentration (BAlC) of >5.0 μg/L, using multivariable logistic regression models. Findings from interactive models revealed that the odds of having a detectable BAlC was significantly higher among children who ate string beans (p ≤ 0.01), whereas about 40% lower odds of having a detectable BAlC was observed in children with higher parental education level, (p = 0.02). A significant interaction between consumption of saltwater fish and GSTP1 in relation to having a detectable BAlC using either co-dominant or dominant genetic models (overall interaction p = 0.02 for both models) indicated that consumption of saltwater fish was associated with higher odds of having a detectable BAlC only among children with the GSTP1 Ile105Val Ile/Ile genotype using either co-dominant or dominant models [OR (95% CI) = 2.73 (1.07, 6.96), p = 0.04; and OR (95% CI) = 2.74 (1.08, 6.99), p = 0.03]. Since this is the first study from Jamaica that reports such findings, replication in other populations is warranted.
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Affiliation(s)
- Mohammad H. Rahbar
- Department of Epidemiology, Human Genetics, and Environmental Sciences (EHGES), School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Biostatistics/Epidemiology/Research Design (BERD) Component, Center for Clinical and Translational Sciences (CCTS), The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Division of Clinical and Translational Sciences, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-713-500-7901; Fax: +1-713-500-0766
| | - Maureen Samms-Vaughan
- Department of Child & Adolescent Health, The University of the West Indies (UWI), Mona Campus, Kingston 7, Jamaica
| | - Yuansong Zhao
- Biostatistics/Epidemiology/Research Design (BERD) Component, Center for Clinical and Translational Sciences (CCTS), The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Department of Biostatistics & Data Science, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Sepideh Saroukhani
- Biostatistics/Epidemiology/Research Design (BERD) Component, Center for Clinical and Translational Sciences (CCTS), The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Division of Clinical and Translational Sciences, Department of Internal Medicine, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Jan Bressler
- Department of Epidemiology, Human Genetics, and Environmental Sciences (EHGES), School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Manouchehr Hessabi
- Biostatistics/Epidemiology/Research Design (BERD) Component, Center for Clinical and Translational Sciences (CCTS), The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Megan L. Grove
- Department of Epidemiology, Human Genetics, and Environmental Sciences (EHGES), School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | | | - Katherine A. Loveland
- Louis A Faillace, MD, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
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Methylmercury and Polycyclic Aromatic Hydrocarbons in Mediterranean Seafood: A Molecular Anthropological Perspective. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app112311179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Eating seafood has numerous health benefits; however, it constitutes one of the main sources of exposure to several harmful environmental pollutants, both of anthropogenic and natural origin. Among these, methylmercury and polycyclic aromatic hydrocarbons give rise to concerns related to their possible effects on human biology. In the present review, we summarize the results of epidemiological investigations on the genetic component of individual susceptibility to methylmercury and polycyclic aromatic hydrocarbons exposure in humans, and on the effects that these two pollutants have on human epigenetic profiles (DNA methylation). Then, we provide evidence that Mediterranean coastal communities represent an informative case study to investigate the potential impact of methylmercury and polycyclic aromatic hydrocarbons on the human genome and epigenome, since they are characterized by a traditionally high local seafood consumption, and given the characteristics that render the Mediterranean Sea particularly polluted. Finally, we discuss the challenges of a molecular anthropological approach to this topic.
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Parajuli RP, Goodrich JM, Chan HM, Lemire M, Ayotte P, Hegele RA, Basu N. Variation in biomarker levels of metals, persistent organic pollutants, and omega-3 fatty acids in association with genetic polymorphisms among Inuit in Nunavik, Canada. ENVIRONMENTAL RESEARCH 2021; 200:111393. [PMID: 34062203 DOI: 10.1016/j.envres.2021.111393] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 05/13/2021] [Accepted: 05/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Biomarker measures of contaminant exposure and nutrient status can help increase understanding of the risks and benefits associated with the consumption of traditional foods by Inuit. While gene-environment and gene-nutrient interactions may help explain variations in biomarker measures, the role of genetic polymorphisms is largely understudied especially for vulnerable sub-populations. OBJECTIVE The aim of this study was to characterize the relationship between single nucleotide polymorphisms (SNPs) in key genes and blood concentrations of environmental chemicals and nutrients among Inuit. METHODS Blood samples from 665 individuals who participated in the Qanuippitaa Survey (Nunavik, Canada) in 2004 were analyzed for toxicants and nutrients. DNA was extracted and 140 SNPs in classes relevant to the toxicokinetics and/or toxicodynamics of the target contaminants and nutrients, and/or are involved in cardiovascular health and lipid metabolism were genotyped using the Sequenom iPLEX Gold platform. RESULTS Geometric means (μg/L) of mercury (Hg), cadmium (Cd), lead (Pb), DDE, PCB-153, and selenium (Se) were 11.1, 2.8, 39.9, 2.9, 1.1 and 301.2, respectively. Red blood cell membrane levels of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 5.1%/total fatty acid (TFA) and 1.3%/TFA respectively. Out of 106 SNPs which met our inclusion criteria, biomarker levels for Hg, Cd, Pb, DDE, PCB-153, DHA, and EPA differed (p < 0.05) by genotype for 20, 13, 12, 19, 21, 9 and 8 SNPs, respectively. Following Bonferroni correction (p < 0.0005), only 9 SNPs remained significant (rs2274976 in MTHFR, rs174602 in FADS2, rs7115739 and rs74771917 in FADS3, rs713041 in GPX4, rs2306283 and rs4149056 in SLCO1B1, rs1885301 in ABCC2/MRP2, and rs4244285 in CYP2C19; 5 associated with Hg, 2 with Pb, 2 with DDE, 4 with PCB-153, 1 with DHA). CONCLUSIONS The findings suggest that polymorphisms in environmentally-responsive genes can influence biomarker levels of key toxicants and nutrients. While there are no immediate clinical or public health implications of these findings, we believe that such gene-environment and gene-nutrient studies provide a foundation that will inform and provide direction to future studies.
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Affiliation(s)
- Rajendra Prasad Parajuli
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada; Department of Zoology, Tribhuvan University, Kathmandu, Nepal
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - Hing Man Chan
- Department of Biology, University of Ottawa, ON, Canada
| | - Melanie Lemire
- Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, QC, Canada
| | - Pierre Ayotte
- Département de Médecine Sociale et Préventive, Faculté de Médecine, Université Laval, QC, Canada
| | - Robert A Hegele
- Department of Medicine and Robarts Research Institute, Western University, ON, Canada
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada.
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Gundacker C, Graf-Rohrmeister K, Gencik M, Hengstschläger M, Holoman K, Rosa P, Kroismayr R, Offenthaler I, Plichta V, Reischer T, Teufl I, Raffesberg W, Scharf S, Köhler-Vallant B, Delissen Z, Weiß S, Uhl M. Gene Variants Determine Placental Transfer of Perfluoroalkyl Substances (PFAS), Mercury (Hg) and Lead (Pb), and Birth Outcome: Findings From the UmMuKi Bratislava-Vienna Study. Front Genet 2021; 12:664946. [PMID: 34220941 PMCID: PMC8242356 DOI: 10.3389/fgene.2021.664946] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 05/17/2021] [Indexed: 12/14/2022] Open
Abstract
Prenatal exposure to perfluoroalkyl substances (PFAS), bisphenol A (BPA), lead (Pb), total mercury (THg), and methylmercury (MeHg) can affect fetal development. Factors influencing placental transfer rate of these toxins are poorly investigated. Whether prenatal exposure to pollutants has an effect on birth weight is incompletely understood. We therefore aimed (1) to determine placental transfer rates of PFAS, BPA, Pb, THg, and MeHg, (2) to analyze relationships between fetal exposure and birth outcome and (3) to analyze gene variants as mediators of placental transfer rates and birth outcome. Two hundred healthy pregnant women and their newborns participated in the study. BPA, 16 PFAS, THg, MeHg, and Pb were determined using HPLCMS/MS (BPA, PFAS), HPLC-CV-ICPMS (MeHg), CV-AFS (THg), and GF-AAS (Pb). Questionnaires and medical records were used to survey exposure sources and birth outcome. 20 single nucleotide polymorphisms and two deletion polymorphisms were determined by real-time PCR from both maternal and newborn blood. Genotype-phenotype associations were analyzed by categorical regression and logistic regression analysis. Specific gene variants were associated with altered placental transfer of PFAS (ALAD Lys59Asn, ABCG2 Gln141Lys), THg (UGT Tyr85Asp, GSTT1del, ABCC1 rs246221) and Pb (GSTP1 Ala114Val). A certain combination of three gene polymorphisms (ABCC1 rs246221, GCLM rs41303970, HFE His63Asp) was over-represented in newborns small for gestational age. 36% of Austrian and 75% of Slovakian mothers had levels exceeding the HBM guidance value I (2 μg/L) of the German HBM Commission for PFOA. 13% of newborns and 39% of women had Ery-Pb levels above 24 μg/kg, an approximation for the BMDL01 of 12 μg/L set by the European Food Safety Authority (EFSA). Our findings point to the need to minimize perinatal exposures to protect fetal health, especially those genetically predisposed to increased transplacental exposure.
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Affiliation(s)
- Claudia Gundacker
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | | | | | | | - Karol Holoman
- University Hospital Bratislava-Ružinov, Bratislava, Slovakia
| | - Petra Rosa
- University Hospital Bratislava-Ružinov, Bratislava, Slovakia
| | - Renate Kroismayr
- Department of Biochemical Engineering, University of Applied Sciences Technikum Wien, Vienna, Austria.,Environment Agency Austria, Vienna, Austria
| | | | - Veronika Plichta
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria.,Austrian Agency for Food and Health Safety, Vienna, Austria
| | - Theresa Reischer
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | - Isabella Teufl
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria
| | | | | | | | - Zoja Delissen
- Institute of Medical Genetics, Medical University of Vienna, Vienna, Austria.,Medgene, Bratislava, Slovakia
| | | | - Maria Uhl
- Environment Agency Austria, Vienna, Austria
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Medina Pérez OM, Flórez-Vargas O, Rincón Cruz G, Rondón González F, Rocha Muñoz L, Sánchez Rodríguez LH. Glutathione-related genetic polymorphisms are associated with mercury retention and nephrotoxicity in gold-mining settings of a Colombian population. Sci Rep 2021; 11:8716. [PMID: 33888803 PMCID: PMC8062595 DOI: 10.1038/s41598-021-88137-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/08/2021] [Indexed: 11/09/2022] Open
Abstract
Mercury (Hg) vapor can produce kidney injury, where the proximal tubule region of the nephron is the main target of the Hg-induced oxidative stress. Hg is eliminated from the body as a glutathione conjugate. Thus, single nucleotide polymorphisms (SNPs) in glutathione-related genes might modulate the negative impact of this metal on the kidneys. Glutathione-related SNPs were tested for association with levels of Hg and renal function biomarkers between occupationally exposed (n = 160) and non-exposed subjects (n = 121). SNPs were genotyped by TaqMan assays in genomic DNA samples. Total mercury concentration was measured in blood, urine and hair samples. Regression analyses were performed to estimate the effects of SNPs on quantitative traits. Alleles GCLM rs41303970-T and GSTP1 rs4147581-C were significantly overrepresented in the exposed compared with the non-exposed group (P < 0.01). We found significant associations for GCLM rs41303970-T with higher urinary clearance rate of Hg (β = 0.062, P = 0.047), whereas GCLC rs1555903-C was associated with lower levels of estimated glomerular filtration rate in the non-exposed group (eGFR, β = − 3.22, P = 0.008) and beta-2-microglobulin in the exposed group (β-2MCG, β = − 19.32, P = 0.02). A SNP-SNP interaction analysis showed significant epistasis between GSTA1 rs3957356-C and GSS rs3761144-G with higher urinary levels of Hg in the exposed (β = 0.13, P = 0.04) but not in the non-exposed group. Our results suggest that SNPs in glutathione-related genes could modulate the pathogenesis of Hg nephrotoxicity in our study population by modulating glutathione concentrations in individuals occupationally exposed to this heavy metal.
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Affiliation(s)
- Olga Marcela Medina Pérez
- Departamento de Ciencias Básicas, Universidad Industrial de Santander, Bucaramanga, Colombia.,Laboratorio de Toxicología Ambiental y Toxicogenética, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Oscar Flórez-Vargas
- Laboratorio de Toxicología Ambiental y Toxicogenética, Universidad Industrial de Santander, Bucaramanga, Colombia.,Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, USA
| | - Giovanna Rincón Cruz
- Grupo de Inmunología y Epidemiología Molecular, Escuela de Microbiología, Universidad Industrial de Santander, Carrera 32 No. 29-31; Building Roberto Serpa, Floor 5, Office 5, Bucaramanga, Colombia
| | - Fernando Rondón González
- Grupo de Investigación en Microbiología y Genética, Escuela de Biología, Universidad Industrial de Santander, Bucaramanga, Colombia
| | - Linda Rocha Muñoz
- Grupo de Investigación CienciaUDES, Universidad de Santander, Bucaramanga, Colombia
| | - Luz Helena Sánchez Rodríguez
- Grupo de Inmunología y Epidemiología Molecular, Escuela de Microbiología, Universidad Industrial de Santander, Carrera 32 No. 29-31; Building Roberto Serpa, Floor 5, Office 5, Bucaramanga, Colombia. .,Laboratorio de Toxicología Ambiental y Toxicogenética, Universidad Industrial de Santander, Bucaramanga, Colombia.
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Associations of Metabolic Genes ( GSTT1, GSTP1, GSTM1) and Blood Mercury Concentrations Differ in Jamaican Children with and without Autism Spectrum Disorder. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18041377. [PMID: 33546147 PMCID: PMC7913200 DOI: 10.3390/ijerph18041377] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 12/12/2022]
Abstract
We investigated interactive roles of three metabolic glutathione S-transferase (GST) genes (GSTP1, GSTT1, and GSTM1) and autism spectrum disorder (ASD) status in relation to blood Hg concentrations (BHC) of Jamaican children. We used data from 266 children (2-8 years) with ASD and their 1:1 age- and sex-matched typically developing (TD) controls. After adjusting General Linear Models for child’s age, socioeconomic status, consumption of leafy vegetables, fried plantain, canned fish, and the interaction between GSTP1 and GSTT1, we found significant interactions between GSTP1 and ASD status in relation to BHC either in a co-dominant or dominant genetic model for GSTP1(P < 0.001, P = 0.007, respectively). In the co-dominant model for the Ile105Val GSTP1 polymorphism, geometric mean (GM) BHC in ASD cases with genotype Ile/Ile were significantly higher than in cases with the Ile/Val genotype (0.73 vs. 0.48 µg/L, P = 0.01). In contrast, in TD controls with the Ile/Val genotype GM BHC were significantly higher than in those with the Ile/Ile genotype (0.72 vs. 0.49 µg/L, P = 0.03) or the Val/Val genotype (0.72 vs. 0.51 µg/L, P = 0.04). Although our findings are consistent with the role of GSTP1 in detoxification of Hg, replication in other populations is warranted.
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Ralston NV, Raymond LJ. Soft electrophile inhibition of selenoenzymes in disease pathologies. Toxicology 2021. [DOI: 10.1016/b978-0-12-819092-0.00040-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Chan PHY, Chan KYY, Schooling CM, Hui LL, Chan MHM, Li AM, Cheung RCK, Lam HS. Association between genetic variations in GSH-related and MT genes and low-dose methylmercury exposure in children and women of childbearing age: a pilot study. ENVIRONMENTAL RESEARCH 2020; 187:109703. [PMID: 32480025 DOI: 10.1016/j.envres.2020.109703] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/17/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Genetic variations in glutathione (GSH)-related and metallothionein (MT) genes, which are involved in producing enzymes in the methylmercury (MeHg) metabolism pathway, have been proposed as one of the reasons for the individual variability in MeHg toxicokinetics. OBJECTIVE To investigate the impact of genetic variations in MT and GSH-related genes on the association of fish consumption with body burden of MeHg, as measured by hair Hg concentrations among young children and women of childbearing age. METHODS A total of 179 unrelated children and 165 mothers with either high or low fish consumption were recruited from the community. Their hair total Hg (tHg) and MeHg levels and genotypes for SNPs located on the GCLC, GCLM, GPX1, GSTA1, GSTP1, MT1A, MT2A, and MT4 genes were determined. Based on their 14-day food records, the amounts of fish consumed and their MeHg intakes were estimated. The impact of genetic variations on hair Hg concentrations was examined by using Mann-Whitney tests and multivariable linear regression analyses. RESULTS The presence of minor alleles of GCLC-129 (rs17883901), GPX1-198 (rs1050450) and MT1M (rs9936741) were associated with significantly lower hair tHg levels in mothers whereas mothers with minor alleles of GSTP1-105(rs1695) and MT1M (rs2270836) have significantly higher hair tHg levels. After adjustment for fish consumption and other confounding factors, apart from MT1M (rs2270836), all of the above SNPs remain significant in the multivariable linear regression models. CONCLUSIONS Our results in a group of children and women show that genetic variants of GSH-related and MT genes are associated with hair Hg concentrations. These genetic variations are likely to significantly affect MeHg metabolism and thus influence the accumulation of Hg in the human body.
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Affiliation(s)
- Peggy Hiu Ying Chan
- Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
| | - Kathy Yuen Yee Chan
- Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
| | - Catherine Mary Schooling
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region; CUNY School of Public Health and Health Policy, NY, USA.
| | - Lai Ling Hui
- Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
| | - Michael Ho Ming Chan
- Department of Chemical Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
| | - Albert Martin Li
- Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
| | - Robert Chi Keung Cheung
- Department of Chemical Pathology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region
| | - Hugh Simon Lam
- Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
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Yang L, Zhang Y, Wang F, Luo Z, Guo S, Strähle U. Toxicity of mercury: Molecular evidence. CHEMOSPHERE 2020; 245:125586. [PMID: 31881386 DOI: 10.1016/j.chemosphere.2019.125586] [Citation(s) in RCA: 173] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 11/28/2019] [Accepted: 12/08/2019] [Indexed: 05/25/2023]
Abstract
Minamata disease in Japan and the large-scale poisoning by methylmercury (MeHg) in Iraq caused wide public concerns about the risk emanating from mercury for human health. Nowadays, it is widely known that all forms of mercury induce toxic effects in mammals, and increasing evidence supports the concern that environmentally relevant levels of MeHg could impact normal biological functions in wildlife. The information of mechanism involved in mercurial toxicity is growing but knowledge gaps still exist between the adverse effects and mechanisms of action, especially at the molecular level. A body of data obtained from experimental studies on mechanisms of mercurial toxicity in vivo and in vitro points to that disruption of the antioxidant system may play an important role in the mercurial toxic effects. Moreover, the accumulating evidence indicates that signaling transduction, protein or/and enzyme activity, and gene regulation are involving in mediating toxic and adaptive response to mercury exposure. We conducted here a comprehensive review of mercurial toxic effects on wildlife and human, in particular synthesized key findings of molecular pathways involved in mercurial toxicity from the cells to human. We discuss the molecular evidence related mercurial toxicity to the adverse effects, with particular emphasis on the gene regulation. The further studies relying on Omic analysis connected to adverse effects and modes of action of mercury will aid in the evaluation and validation of causative relationship between health outcomes and gene expression.
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Affiliation(s)
- Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China; Center for Global Health, School of Public Health, Nanjing Medical University, 211166, Nanjing, China.
| | - Yuanyuan Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Feifei Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Zidie Luo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Shaojuan Guo
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012, Beijing, China
| | - Uwe Strähle
- Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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Joneidi Z, Mortazavi Y, Memari F, Roointan A, Chahardouli B, Rostami S. The impact of genetic variation on metabolism of heavy metals: Genetic predisposition? Biomed Pharmacother 2019; 113:108642. [DOI: 10.1016/j.biopha.2019.108642] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/25/2019] [Accepted: 01/28/2019] [Indexed: 02/08/2023] Open
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11
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Jirau-Colón H, González-Parrilla L, Martinez-Jiménez J, Adam W, Jiménez-Velez B. Rethinking the Dental Amalgam Dilemma: An Integrated Toxicological Approach. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16061036. [PMID: 30909378 PMCID: PMC6466133 DOI: 10.3390/ijerph16061036] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/21/2019] [Accepted: 03/04/2019] [Indexed: 01/06/2023]
Abstract
Mercury (Hg) has been identified as one of the most toxic nonradioactive materials known to man. Although mercury is a naturally occurring element, anthropogenic mercury is now a major worldwide concern and is an international priority toxic pollutant. It also comprises one of the primary constituents of dental amalgam fillings. Even though dental mercury amalgams have been used for almost two centuries, its safety has never been tested or proven in the United States by any regulatory agency. There has been an ongoing debate regarding the safety of its use since 1845, and many studies conclude that its use exposes patients to troublesome toxicity. In this review, we present in an objective way the danger of dental amalgam to human health based on current knowledge. This dilemma is addressed in terms of an integrated toxicological approach by focusing on four mayor issues to show how these interrelate to create the whole picture: (1) the irrefutable constant release of mercury vapor from dental amalgams which is responsible for individual chronic exposure, (2) the evidence of organic mercury formation from dental amalgam in the oral cavity, (3) the effect of mercury exposure on gene regulation in human cells which supports the intrinsic genetic susceptibility to toxicant and, finally, (4) the availability of recent epidemiological data supporting the link of dental amalgams to diseases such as Alzheimer’s and Parkinson.
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Affiliation(s)
- Hector Jirau-Colón
- Department of Biochemistry, School of Medicine, Medical Sciences Campus, University of Puerto Rico, Main Building B210, San Juan 00936, Puerto Rico.
- Center for Environmental and Toxicological Research, San Juan 00936, Puerto Rico.
| | - Leonardo González-Parrilla
- Department of Biochemistry, School of Medicine, Medical Sciences Campus, University of Puerto Rico, Main Building B210, San Juan 00936, Puerto Rico.
- Center for Environmental and Toxicological Research, San Juan 00936, Puerto Rico.
| | - Jorge Martinez-Jiménez
- Department of Biochemistry, School of Medicine, Medical Sciences Campus, University of Puerto Rico, Main Building B210, San Juan 00936, Puerto Rico.
- Center for Environmental and Toxicological Research, San Juan 00936, Puerto Rico.
| | - Waldemar Adam
- Department of Chemistry, Rio Piedras Campus, University of Puerto Rico, Av. Dr. José N. Gándara, San Juan 00936, Puerto Rico.
| | - Braulio Jiménez-Velez
- Department of Biochemistry, School of Medicine, Medical Sciences Campus, University of Puerto Rico, Main Building B210, San Juan 00936, Puerto Rico.
- Center for Environmental and Toxicological Research, San Juan 00936, Puerto Rico.
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Farina M, Aschner M. Glutathione antioxidant system and methylmercury-induced neurotoxicity: An intriguing interplay. Biochim Biophys Acta Gen Subj 2019; 1863:129285. [PMID: 30659883 DOI: 10.1016/j.bbagen.2019.01.007] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/09/2018] [Accepted: 01/09/2019] [Indexed: 01/20/2023]
Abstract
Methylmercury (MeHg) is a toxic chemical compound naturally produced mainly in the aquatic environment through the methylation of inorganic mercury catalyzed by aquatic microorganisms. MeHg is biomagnified in the aquatic food chain and, consequently, piscivorous fish at the top of the food chain possess huge amounts of MeHg (at the ppm level). Some populations that have fish as main protein's source can be exposed to exceedingly high levels of MeHg and develop signs of toxicity. MeHg is toxic to several organs, but the central nervous system (CNS) represents a preferential target, especially during development (prenatal and early postnatal periods). Though the biochemical events involved in MeHg-(neuro)toxicity are not yet entirely comprehended, a vast literature indicates that its pro-oxidative properties explain, at least partially, several of its neurotoxic effects. As result of its electrophilicity, MeHg interacts with (and oxidize) nucleophilic groups, such as thiols and selenols, present in proteins or low-molecular weight molecules. It is noteworthy that such interactions modify the redox state of these groups and, therefore, lead to oxidative stress and impaired function of several molecules, culminating in neurotoxicity. Among these molecules, glutathione (GSH; a major thiol antioxidant) and thiol- or selenol-containing enzymes belonging to the GSH antioxidant system represent key molecular targets involved in MeHg-neurotoxicity. In this review, we firstly present a general overview concerning the neurotoxicity of MeHg. Then, we present fundamental aspects of the GSH-antioxidant system, as well as the effects of MeHg on this system.
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Affiliation(s)
- Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, USA
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McCaulley ME. Autism spectrum disorder and mercury toxicity: use of genomic and epigenetic methods to solve the etiologic puzzle. Acta Neurobiol Exp (Wars) 2019. [DOI: 10.21307/ane-2019-010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Kuras R, Reszka E, Wieczorek E, Jablonska E, Gromadzinska J, Malachowska B, Kozlowska L, Stanislawska M, Janasik B, Wasowicz W. Biomarkers of selenium status and antioxidant effect in workers occupationally exposed to mercury. J Trace Elem Med Biol 2018; 49:43-50. [PMID: 29895371 DOI: 10.1016/j.jtemb.2018.04.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/21/2018] [Accepted: 04/24/2018] [Indexed: 12/14/2022]
Abstract
The present observation based research was designed to evaluate the influence of occupational human exposure to metallic mercury (Hg°) vapor on the biomarkers of selenium status involved in the antioxidant defense system. For this purpose we determined Hg and selenium (Se) concentrations in body fluids, the markers of antioxidant effect measured as an activity of Se-dependent enzymes (red blood cell and plasma glutathione peroxidase: GPx1-RBC and GPx3-P), concentration of selenoprotein P in the plasma (SeP-P) and total antioxidant activity in the plasma (TAA-P) in 131 male workers from a chloralkali plant exposed to Hg° and 67 non-exposed males (control group). The mRNA expression levels of glutathione peroxidases (GPX1, GPX3), selenoprotein P (SEPP1), thioredoxin reductase 1 (TRXR1), thioredoxin 1 (TRX1), peroxiredoxins (PRDX1, PRDX2) were also examined in the leukocytes of peripheral blood. Hg concentration in the blood (Hg-B) and urine (Hg-U) samples was determined using the thermal decomposition amalgamation/atomic absorption spectrometry (TDA-AAS) method and Se concentrations in plasma (Se-P) and urine (Se-U) using the inductively coupled plasma mass spectrometry (ICP-MS) method. Activities of GPx1-RBC, GPx3-P and TAA-P were determined using the kinetic and spectrophotometric method, respectively. Gene expression analysis was performed using the quantitative Real-Time PCR. The results showed significant higher Hg levels among the Hg°-exposed workers in comparison to control group (12-times higher median for Hg-B and almost 74-times higher median for Hg-U concentration in chloralkali workers). Se-P was also significantly higher (Me (median): 82.85 μg/L (IQR (interquartile range) 72.03-90.28 μg/L) for chloralkali workers vs. Me: 72.74 μg/L (IQR 66.25-80.14 μg/L) for control group; p = 0.0001) but interestingly correlated inversely with Hg-U in chloralkali workers suggesting depletion of the Se protection among the workers with the highest Hg-U concentration. The mRNA level for GPX1, PRXD1 were markedly but significantly higher in the workers compared to the control group. Moreover, concentrations of Hg-B and Hg-U among the workers were significantly positively correlated with the levels of selenoprotein P at both the mRNA and selenoprotein levels. In the multivariate model, after adjusting to cofounders (dental amalgam fillings, age, BMI, job seniority time, smoking), we confirmed that Hg-U concentration was inversely correlated with genes expression of TRXR1. This is the first comprehensive assessment of the impact of occupational exposure of workers to Hg° at both the mRNA and selenoprotein levels, with investigation of fish intake obtained by means of a questionnaire. These findings suggest that exposure to Hg° alters gene expression of the antioxidant enzymes and the level of Se-containing selenoproteins.
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Affiliation(s)
- Renata Kuras
- Nofer Institute of Occupational Medicine, Department of Biological and Environmental Monitoring, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Edyta Reszka
- Nofer Institute of Occupational Medicine, Department of Molecular Genetics and Epigenetics, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Edyta Wieczorek
- Nofer Institute of Occupational Medicine, Department of Molecular Genetics and Epigenetics, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Ewa Jablonska
- Nofer Institute of Occupational Medicine, Department of Molecular Genetics and Epigenetics, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Jolanta Gromadzinska
- Nofer Institute of Occupational Medicine, Department of Biological and Environmental Monitoring, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Beata Malachowska
- Medical University of Lodz, Department of Biostatistics and Translational Medicine, Mazowiecka 15 Street, 92-215 Lodz, Poland.
| | - Lucyna Kozlowska
- Department of Dietetics, Faculty of Human Nutrition and Consumer Sciences, University of Life Sciences, Nowoursynowska 159c Street, Warsaw, Poland.
| | - Magdalena Stanislawska
- Nofer Institute of Occupational Medicine, Department of Biological and Environmental Monitoring, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Beata Janasik
- Nofer Institute of Occupational Medicine, Department of Biological and Environmental Monitoring, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
| | - Wojciech Wasowicz
- Nofer Institute of Occupational Medicine, Department of Biological and Environmental Monitoring, Sw. Teresy 8 Street, 91-348 Lodz, Poland.
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Parajuli RP, Goodrich JM, Chan LHM, Ayotte P, Lemire M, Hegele RA, Basu N. Genetic polymorphisms are associated with exposure biomarkers for metals and persistent organic pollutants among Inuit from the Inuvialuit Settlement Region, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 634:569-578. [PMID: 29635199 DOI: 10.1016/j.scitotenv.2018.03.331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/12/2018] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Inuit are exposed to some of the highest levels of contaminants worldwide. Studies suggest that several genes that mediate the metabolism of these contaminants are polymorphic. We hypothesize that single nucleotide polymorphisms (SNPs) in such genes may underline differences in biomarker concentrations and/or modify exposure-biomarker associations. METHODS Members from the Inuvialuit Settlement Region (Canada) were recruited. Blood concentrations of mercury (Hg), cadmium (Cd), lead (Pb), dichlorodiphenyldichloroethylene (DDE), and polychlorinated biphenyl (PCB-153) were measured. SNPs from pathways such as glutathione, metallothionein, oxidative stress, and xenobiotic transport were genotyped in 281 participants, and data from 112 SNPs were included in the analyses. Surveys were administered to obtain information on demographics, and key sources of Hg (diet) and Cd (smoking) exposure. ANOVA and linear regressions were used for data analyses. RESULTS Geometric mean concentrations of metals were 4.6μg/L for Hg, 1.3μg/L for Cd, and 32.2μg/L for Pb. Concentrations of organic pollutants were 2.0μg/L for DDE and 0.6μg/L for PCB-153. Biomarker levels for Hg, Cd, Pb, DDE, and PCB-153 differed (p<0.05) by genotype for 4, 3, 4, 3, and 3 SNPs, respectively. In multivariable analyses (for Pb, DDE, PCB-153) adjusting age, sex and body mass index (BMI), only 2 associations (one for Pb and one for DDE) remained significant. In multivariable analyses accounting for sources of Hg or Cd exposure, 24 SNPs (9 for Hg, 15 for Cd with 4 overlapping) had significant (p<0.05) main effects on biomarker levels and/or modified exposure-biomarker associations. CONCLUSION The findings suggest that polymorphisms in key environmentally responsive genes can influence biomarker levels and/or modify exposure-biomarker associations for contaminants of concern to Arctic populations. Consideration of such gene-environment results may help improve the ability to conduct exposure (and ultimately risk) assessments of country foods and Inuit health.
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Affiliation(s)
- Rajendra Prasad Parajuli
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec H9X 3V9, Canada
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | | | - Pierre Ayotte
- Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, Université Laval, QC, Canada; Centre de toxicologie du Québec, Institut national de santé publique du Québec, QC, Canada
| | - Melanie Lemire
- Axe santé des populations et pratiques optimales en santé, Centre de recherche du CHU de Québec, Université Laval, QC, Canada
| | | | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec H9X 3V9, Canada; Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
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Wahlberg K, Love TM, Pineda D, Engström K, Watson GE, Thurston SW, Yeates AJ, Mulhern MS, McSorley EM, Strain JJ, Smith TH, Davidson PW, Shamlaye CF, Myers GJ, Rand MD, van Wijngaarden E, Broberg K. Maternal polymorphisms in glutathione-related genes are associated with maternal mercury concentrations and early child neurodevelopment in a population with a fish-rich diet. ENVIRONMENT INTERNATIONAL 2018; 115:142-149. [PMID: 29573653 PMCID: PMC5970067 DOI: 10.1016/j.envint.2018.03.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/11/2018] [Accepted: 03/11/2018] [Indexed: 05/05/2023]
Abstract
INTRODUCTION Glutathione (GSH) pathways play a key role the metabolism and elimination of the neurotoxicant methylmercury (MeHg). We hypothesized that maternal genetic variation linked to GSH pathways could influence MeHg concentrations in pregnant mothers and children and thereby also affect early life development. METHODS The GCLM (rs41303970, C/T), GCLC (rs761142, T/G) and GSTP1 (rs1695, A/G) polymorphisms were genotyped in 1449 mothers in a prospective study of the Seychellois population with a diet rich in fish. Genotypes were analyzed in association with maternal hair and blood Hg, fetal blood Hg (cord blood Hg), as well as children's mental (MDI) and motor development (PDI; MDI and PDI assessed by Bayley Scales of Infant Development at 20 months). We also examined whether genotypes modified the association between Hg exposure and developmental outcomes. RESULTS GCLC rs761142 TT homozygotes showed statistically higher mean maternal hair Hg (4.12 ppm) than G carriers (AG 3.73 and GG 3.52 ppm) (p = 0.037). For the combination of GCLC rs761142 and GCLM rs41303970, double homozygotes TT + CC showed higher hair Hg (4.40 ppm) than G + T carriers (3.44 ppm; p = 0.018). No associations were observed between GSTP1 rs1695 and maternal hair Hg or between any genotypes and maternal blood Hg or cord blood Hg. The maternal GSTP1 rs1695 rare allele (G) was associated with a lower MDI among children (β = -1.48, p = 0.048). We also observed some interactions: increasing Hg in maternal and cord blood was associated with lower PDI among GCLC rs761142 TT carriers; and increasing Hg in hair was associated with lower MDI among GSTP1 rs1695 GG carriers. CONCLUSIONS Maternal genetic variation in genes involved in GSH synthesis is statistically associated with Hg concentrations in maternal hair, but not in maternal or fetal blood. We observed interactions that suggest maternal GSH genetics may modify associations between MeHg exposure and neurodevelopmental outcomes.
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Affiliation(s)
- Karin Wahlberg
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22185 Lund, Sweden
| | - Tanzy M Love
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Daniela Pineda
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22185 Lund, Sweden
| | - Karin Engström
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22185 Lund, Sweden
| | - Gene E Watson
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Sally W Thurston
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Alison J Yeates
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - Maria S Mulhern
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - Emeir M McSorley
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - J J Strain
- Nutrition Innovation Centre for Food and Health (NICHE), Ulster University, Cromore Road, Coleraine BT52 1SA, Co. Londonderry, UK
| | - Tristram H Smith
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22185 Lund, Sweden
| | - Philip W Davidson
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | | | - G J Myers
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Matthew D Rand
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Edwin van Wijngaarden
- University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Rochester, NY 14642, USA
| | - Karin Broberg
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, 22185 Lund, Sweden; Institute of Environmental Medicine, Metals and Health, Box 210, 171 77 Stockholm, Sweden.
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Moodley R, Naidoo S, Wyk JV. The prevalence of occupational health-related problems in dentistry: A review of the literature. J Occup Health 2018; 60:111-125. [PMID: 29213011 PMCID: PMC5886878 DOI: 10.1539/joh.17-0188-ra] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/13/2017] [Indexed: 01/03/2023] Open
Abstract
The study was conducted to report on the scope and prevalence of occupational health related-problems experienced by dentists, dental therapists, and oral hygienists in their practice of dentistry. BACKGROUND Professional practice and dental training have many risk factors, and the dental team should be able to recognize these factors to protect themselves. The prevalence of conditions related to the musculoskeletal system, stress, percutaneous injuries, ears, and eyes are of concern. The dental team should also not forget hepatitis B, hepatitis C, and HIV as risks in practice. Dental practitioners should protect themselves by self-recognizing risk factors and by maintaining proper working conditions. METHODS The study targeted all empirical research, case studies, and systematic literature reviews written in English. All articles selected were subjected to a data analysis process. Data were captured on an Excel spreadsheet and reported in a comprehensive table. RESULTS The literature addressing occupational health among dental practitioners included mainly cross-sectional studies and review papers (2001-2016). Forty-nine studies were included in the review. Musculoskeletal disorders remain the most researched occupational health-related problems in dentistry. Eye protection compliance was low among practitioners. Percutaneous injuries especially among young dentists and students were still a concern. CONCLUSION Occupational health-related problems are still prevalent in current dentistry practice, despite changes in equipment and surgery design. The reported prevalence of occupational related-health problems and other findings of investigative studies highlight the need for continuous professional education and a need to improve clinical practice aspects of dentistry curricula.
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Affiliation(s)
- Rajeshree Moodley
- Discipline of Dentistry, School of Health Sciences, University of KwaZulu-Natal
| | - Saloshni Naidoo
- Discipline of Public Health Medicine, School of Nursing and Public Health, University of KwaZulu-Natal
| | - Jacqueline van Wyk
- Discipline of Clinical and Professional Practice, School of Clinical Medicine, College of Health Sciences, University of KwaZulu-Natal
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Fields CA, Borak J, Louis ED. Mercury-induced motor and sensory neurotoxicity: systematic review of workers currently exposed to mercury vapor. Crit Rev Toxicol 2017; 47:811-844. [PMID: 28718354 PMCID: PMC5931703 DOI: 10.1080/10408444.2017.1342598] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 05/12/2017] [Accepted: 06/11/2017] [Indexed: 01/08/2023]
Abstract
The neurotoxicity of elemental mercury (Hg0) is well-recognized, but it is uncertain whether and for how long neurotoxicity persists; among studies that evaluated previously exposed workers, only one examined workers during and also years after exposure ceased. The aim of this review is to document the type, frequency, and dose-relatedness of objective neurological effects in currently exposed mercury workers and thereby provide first approximations of the effects one would have expected in previously exposed workers evaluated during exposure. We systematically reviewed studies of neurotoxicity in currently exposed mercury workers identified by searching MEDLINE (1950-2015), government reports, textbook chapters, and references cited therein; dental cohorts were not included. Outcomes on physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies were extracted and evaluated for consistency and dose-relatedness. Forty-five eligible studies were identified, comprising over 3000 workers chronically exposed to a range of Hg0 concentrations (0.002-1.7 mg/m3). Effects that demonstrated consistency across studies and increased frequency across urine mercury levels (<50; 50-99; 100-199; ≥200 μg/L) included tremor, impaired coordination, and abnormal reflexes on PE, and reduced performance on NB tests of tremor, manual dexterity and motor speed. The data suggest response thresholds of UHg ≈275 μg/L for PE findings and ≈20 μg/L for NB outcomes. These results indicate that PE is of particular value for assessing workers with UHg >200 μg/L, while NB testing is more appropriate for those with lower UHg levels. They also provide benchmarks to which findings in workers with historical exposure can be compared.
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Affiliation(s)
- Cheryl A. Fields
- Department of Environmental Health Sciences, Yale School of Public Health, New Haven, Connecticut, USA
| | - Jonathan Borak
- Departments of Medicine and Epidemiology & Public Health, Yale School of Medicine, New Haven, Connecticut, USA
| | - Elan D. Louis
- Department of Neurology, Yale School of Medicine, and Department of Chronic Disease Epidemiology, Yale School of Public Health, New Haven, Connecticut, USA
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The Putative Role of Environmental Mercury in the Pathogenesis and Pathophysiology of Autism Spectrum Disorders and Subtypes. Mol Neurobiol 2017; 55:4834-4856. [DOI: 10.1007/s12035-017-0692-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 07/13/2017] [Indexed: 01/28/2023]
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Vorojeikina D, Broberg K, Love TM, Davidson PW, van Wijngaarden E, Rand MD. Editor's Highlight: Glutathione S-Transferase Activity Moderates Methylmercury Toxicity During Development in Drosophila. Toxicol Sci 2017; 157:211-221. [PMID: 28184905 PMCID: PMC5837650 DOI: 10.1093/toxsci/kfx033] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Glutathione (GSH) pathways play a central role in methylmercury (MeHg) metabolism and elimination, largely due to formation of a more readily transported MeHg-GSH conjugate. Glutathione S-transferases (GSTs) have therefore been proposed to facilitate MeHg elimination by catalyzing MeHg-GSH conjugation. A role for human GSTP1 in MeHg disposition is suggested by the association of two common polymorphisms in the coding region (Ile105Val and Ala114Val) with Hg levels in either blood or hair. In this study, we investigated a functional role for GSTs in modulating MeHg toxicity during development. Using the Drosophila model to execute targeted manipulations of both endogenous GSTs and introduced human GSTP1 variants we correlate gene and protein expression levels with GST activity and also with MeHg body burden and developmental outcomes. RNAi knockdown of endogenous GSTD1, GSTE1, or GSTS1, individually, increased susceptibility to MeHg during pupal development resulting in a reduced rate of adult eclosion. Exogenous expression of human GSTP1 in developing flies resulted in increased MeHg tolerance relative to control flies as seen with elevated eclosion rates when reared on MeHg containing food. Furthermore, the GSTP1105 and GSTP1114 variants showed a reduced enzyme activity relative to wild-type GSTP1 (GSTP1wt). Finally, we observed a trend whereby Hg body burden was inversely related to the levels of GST activity. However, in some instances GSTP1 expression resulted in increased eclosion rates without reducing Hg body burden suggesting that GSTs interact with MeHg via both toxicokinetic and toxicodynamic mechanisms. These findings indicate that GSTs moderate MeHg toxicity during development in our experimental model.
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Affiliation(s)
| | - Karin Broberg
- The Institute of Environmental Medicine, Unit of Metals & Health, Karolinska Institute, Stockholm, Sweden
- Department of Laboratory Medicine, Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden
| | - Tanzy M. Love
- Department of Pediatrics
- Department of Biostatistics and Computational Biology
| | | | - Edwin van Wijngaarden
- Department of Environmental Medicine
- Department of Pediatrics
- Department of Public Health SciencesDepartment of Dentistry, University of Rochester School of Medicine and Dentistry, Rochester, New York
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Branco V, Caito S, Farina M, Teixeira da Rocha J, Aschner M, Carvalho C. Biomarkers of mercury toxicity: Past, present, and future trends. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2017; 20:119-154. [PMID: 28379072 PMCID: PMC6317349 DOI: 10.1080/10937404.2017.1289834] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Mercury (Hg) toxicity continues to represent a global health concern. Given that human populations are mostly exposed to low chronic levels of mercurial compounds (methylmercury through fish, mercury vapor from dental amalgams, and ethylmercury from vaccines), the need for more sensitive and refined tools to assess the effects and/or susceptibility to adverse metal-mediated health risks remains. Traditional biomarkers, such as hair or blood Hg levels, are practical and provide a reliable measure of exposure, but given intra-population variability, it is difficult to establish accurate cause-effect relationships. It is therefore important to identify and validate biomarkers that are predictive of early adverse effects prior to adverse health outcomes becoming irreversible. This review describes the predominant biomarkers used by toxicologists and epidemiologists to evaluate exposure, effect and susceptibility to Hg compounds, weighing on their advantages and disadvantages. Most importantly, and in light of recent findings on the molecular mechanisms underlying Hg-mediated toxicity, potential novel biomarkers that might be predictive of toxic effect are presented, and the applicability of these parameters in risk assessment is examined.
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Affiliation(s)
- Vasco Branco
- a Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia , Universidade de Lisboa , Lisboa , Portugal
| | - Sam Caito
- b Department of Molecular Pharmacology , Albert Einstein College of Medicine , Bronx , New York , USA
| | - Marcelo Farina
- c Departamento de Bioquímica, Centro de Ciências Biológicas , Universidade Federal de Santa Catarina , Florianópolis , Brazil
| | - João Teixeira da Rocha
- d Departamento Bioquímica e Biologia Molecular , Universidade Federal de Santa Maria , Santa Maria , RS , Brazil
| | - Michael Aschner
- b Department of Molecular Pharmacology , Albert Einstein College of Medicine , Bronx , New York , USA
| | - Cristina Carvalho
- a Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia , Universidade de Lisboa , Lisboa , Portugal
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Genetic Aspects of Susceptibility to Mercury Toxicity: An Overview. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14010093. [PMID: 28106810 PMCID: PMC5295343 DOI: 10.3390/ijerph14010093] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 12/16/2016] [Accepted: 01/12/2017] [Indexed: 12/12/2022]
Abstract
Human exposure to mercury is still a major public health concern. In this context, children have a higher susceptibility to adverse neurological mercury effects, compared to adults with similar exposures. Moreover, there exists a marked variability of personal response to detrimental mercury action, in particular among population groups with significant mercury exposure. New scientific evidence on genetic backgrounds has raised the issue of whether candidate susceptibility genes can make certain individuals more or less vulnerable to mercury toxicity. In this review, the aim is to evaluate a new genetic dimension and its involvement in mercury risk assessment, focusing on the important role played by relevant polymorphisms, located in attractive gene targets for mercury toxicity. Existing original articles on epidemiologic research which report a direct link between the genetic basis of personal vulnerability and different mercury repercussions on human health will be reviewed. Based on this evidence, a careful evaluation of the significant markers of susceptibility will be suggested, in order to obtain a powerful positive “feedback” to improve the quality of life. Large consortia of studies with clear phenotypic assessments will help clarify the “window of susceptibility” in the human health risks due to mercury exposure.
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Ha E, Basu N, Bose-O'Reilly S, Dórea JG, McSorley E, Sakamoto M, Chan HM. Current progress on understanding the impact of mercury on human health. ENVIRONMENTAL RESEARCH 2017; 152:419-433. [PMID: 27444821 DOI: 10.1016/j.envres.2016.06.042] [Citation(s) in RCA: 208] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 06/22/2016] [Accepted: 06/25/2016] [Indexed: 05/18/2023]
Abstract
Mercury pollution and its impacts on human health is of global concern. The authors of this paper were members of the Plenary Panel on Human Health in the 12th International Conference on Mercury as a Global Pollutant held in Korea in June 2015. The Panel was asked by the conference organizers to address two questions: what is the current understanding of the impacts of mercury exposure on human health and what information is needed to evaluate the effectiveness of the Minamata Convention in lowering exposure and preventing adverse effects. The authors conducted a critical review of the literature published since January 2012 and discussed the current state-of-knowledge in the following areas: environmental exposure and/or risk assessment; kinetics and biomonitoring; effects on children development; effects on adult general populations; effects on artisanal and small-scale gold miners (ASGM); effects on dental workers; risk of ethylmercury in thimerosal-containing vaccines; interactions with nutrients; genetic determinants and; risk communication and management. Knowledge gaps in each area were identified and recommendations for future research were made. The Panel concluded that more knowledge synthesis efforts are needed to translate the research results into management tools for health professionals and policy makers.
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Affiliation(s)
- Eunhee Ha
- Ewha Womans University, College of Medicine, Department of Preventive Medicine, South Korea
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Canada
| | - Stephan Bose-O'Reilly
- University Hospital Munich, Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, WHO Collaborating Centre for Occupational Health, Germany; University for Health Sciences, Medical Informatics and Technology (UMIT), Department of Public Health, Health Services Research and Health Technology Assessment, Austria
| | - José G Dórea
- Department of Nutrition, University of Brasília, Brasília, Brazil
| | - Emeir McSorley
- Northern Ireland Centre for Food and Health, Ulster University, United Kingdom
| | - Mineshi Sakamoto
- Department of Epidemiology, National Institute for Minamata Disease, Japan
| | - Hing Man Chan
- Department of Biology, University of Ottawa, Canada.
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Rocha AV, Rita Cardoso B, Zavarize B, Almondes K, Bordon I, Hare DJ, Teixeira Favaro DI, Franciscato Cozzolino SM. GPX1 Pro198Leu polymorphism and GSTM1 deletion do not affect selenium and mercury status in mildly exposed Amazonian women in an urban population. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 571:801-808. [PMID: 27450956 DOI: 10.1016/j.scitotenv.2016.07.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 07/08/2016] [Accepted: 07/08/2016] [Indexed: 06/06/2023]
Abstract
Mercury is potent toxicant element, but its toxicity can be reduced by forming a complex with selenium for safe excretion. Considering the impact of mercury exposure in the Amazon region and the possible interaction between these two elements, we aimed to assess the effects of Pro198Leu polymorphism to GPX1 and GSTM1 deletion, on mercury levels in a population from Porto Velho, an urban locality in the Brazilian Amazon region. Two hundred women from the capital city of Rondônia state were recruited for this study with 149 deemed suitable to participate. We assessed dietary intake using 24-hour recall. Selenium levels in plasma and erythrocytes were measured using hydride generation quartz tube atomic absorption spectroscopy and total hair mercury using cold vapor atomic absorption spectrometry. Oxidative stress parameters (GPx activity, oxygen radical absorbency capacity [ORAC] and malondialdehyde [MDA]) were also analyzed. All participants were genotyped for Pro198Leu polymorphism and GSTM1 deletion. We observed that this population presented high prevalence of selenium deficiency, and also low levels of mercury, likely due to food habits that did not include selenium-rich food sources or significant consumption of fish (mercury biomagnifiers) regularly. Univariate statistical analysis showed that Pro198Leu and GSTM1 genotypes did not affect selenium and mercury levels in this population. Pro198Leu polymorphism and GSTM1 deletion had no effect on mercury levels in mildly exposed people, suggesting these genetic variants impact mercury levels only in highly exposed populations.
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Affiliation(s)
- Ariana V Rocha
- Faculty of Pharmaceutical Sciences, Department of Food and Experimental Nutrition, University of São Paulo, São Paulo, Brazil
| | - Bárbara Rita Cardoso
- Faculty of Pharmaceutical Sciences, Department of Food and Experimental Nutrition, University of São Paulo, São Paulo, Brazil; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, Victoria 3052, Australia.
| | - Bruna Zavarize
- Faculty of Pharmaceutical Sciences, Department of Food and Experimental Nutrition, University of São Paulo, São Paulo, Brazil
| | - Kaluce Almondes
- Faculty of Pharmaceutical Sciences, Department of Food and Experimental Nutrition, University of São Paulo, São Paulo, Brazil
| | - Isabella Bordon
- Laboratory of Instrumental Neutron Activation Analysis (INAA), Research Reactor Centre, IPEN - Nuclear and Energy Research Institute, São Paulo, Brazil
| | - Dominic J Hare
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, Victoria 3052, Australia; Elemental Bio-Imaging Facility, University of Technology Sydney, Broadway, New South Wales, Australia
| | - Déborah Inês Teixeira Favaro
- Laboratory of Instrumental Neutron Activation Analysis (INAA), Research Reactor Centre, IPEN - Nuclear and Energy Research Institute, São Paulo, Brazil
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25
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Genetics of the human placenta: implications for toxicokinetics. Arch Toxicol 2016; 90:2563-2581. [DOI: 10.1007/s00204-016-1816-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/04/2016] [Indexed: 10/21/2022]
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26
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Parajuli RP, Goodrich JM, Chou HN, Gruninger SE, Dolinoy DC, Franzblau A, Basu N. Genetic polymorphisms are associated with hair, blood, and urine mercury levels in the American Dental Association (ADA) study participants. ENVIRONMENTAL RESEARCH 2016; 149:247-258. [PMID: 26673400 PMCID: PMC4897752 DOI: 10.1016/j.envres.2015.11.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 05/21/2023]
Abstract
BACKGROUND/AIMS Mercury (Hg) is a potent toxicant of concern to the general public. Recent studies suggest that several genes that mediate Hg metabolism are polymorphic. We hypothesize that single nucleotide polymorphisms (SNPs) in such genes may underline inter-individual differences in exposure biomarker concentrations. METHODS Dental professionals were recruited during the American Dental Association (ADA) 2012 Annual Meeting. Samples of hair, blood, and urine were collected for quantifying Hg levels and genotyping (88 SNPs in classes relevant to Hg toxicokinetics including glutathione metabolism, selenoproteins, metallothioneins, and xenobiotic transporters). Questionnaires were administrated to obtain information on demographics and sources of Hg exposure (e.g., fish consumption and use of dental amalgam). Here, we report results for 380 participants with complete genotype and Hg biomarker datasets. ANOVA and linear regressions were used for statistical analysis. RESULTS Mean (geometric) Hg levels in hair (hHg), blood (bHg), urine (uHg), and the average estimated Hg intake from fish were 0.62µg/g, 3.75µg/L, 1.32µg/L, and 0.12µg/kg body weight/day, respectively. Out of 88 SNPs successfully genotyped, Hg biomarker levels differed by genotype for 25 SNPs, one of which remained significant following Bonferroni correction in ANOVA. When the associations between sources of Hg exposure and SNPs were analyzed with respect to Hg biomarker concentrations, 38 SNPs had significant main effects and/or gene-Hg exposure source interactions. Twenty-five, 23, and four SNPs showed significant main effects and/or interactions for hHg, bHg, and uHg levels, respectively (p<0.05), and six SNPs (in GCLC, MT1M, MT4, ATP7B, and BDNF) remained significant following Bonferroni correction. CONCLUSION The findings suggest that polymorphisms in environmentally-responsive genes can influence Hg biomarker levels. Hence, consideration of such gene-environment factors may improve the ability to assess the health risks of Hg more precisely.
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Affiliation(s)
- Rajendra Prasad Parajuli
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada.
| | - Jaclyn M Goodrich
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
| | | | | | - Dana C Dolinoy
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA; Department of Nutritional Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA.
| | - Alfred Franzblau
- Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
| | - Niladri Basu
- Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada; Department of Environmental Health Sciences, Unisiversity of Michigan School of Public Health, Ann Arbor, MI, USA.
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27
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Shinde V, Hoelting L, Srinivasan SP, Meisig J, Meganathan K, Jagtap S, Grinberg M, Liebing J, Bluethgen N, Rahnenführer J, Rempel E, Stoeber R, Schildknecht S, Förster S, Godoy P, van Thriel C, Gaspar JA, Hescheler J, Waldmann T, Hengstler JG, Leist M, Sachinidis A. Definition of transcriptome-based indices for quantitative characterization of chemically disturbed stem cell development: introduction of the STOP-Tox ukn and STOP-Tox ukk tests. Arch Toxicol 2016; 91:839-864. [PMID: 27188386 PMCID: PMC5306084 DOI: 10.1007/s00204-016-1741-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/04/2016] [Indexed: 01/08/2023]
Abstract
Stem cell-based in vitro test systems can recapitulate specific phases of human development. In the UKK test system, human pluripotent stem cells (hPSCs) randomly differentiate into cells of the three germ layers and their derivatives. In the UKN1 test system, hPSCs differentiate into early neural precursor cells. During the normal differentiation period (14 days) of the UKK system, 570 genes [849 probe sets (PSs)] were regulated >fivefold; in the UKN1 system (6 days), 879 genes (1238 PSs) were regulated. We refer to these genes as 'developmental genes'. In the present study, we used genome-wide expression data of 12 test substances in the UKK and UKN1 test systems to understand the basic principles of how chemicals interfere with the spontaneous transcriptional development in both test systems. The set of test compounds included six histone deacetylase inhibitors (HDACis), six mercury-containing compounds ('mercurials') and thalidomide. All compounds were tested at the maximum non-cytotoxic concentration, while valproic acid and thalidomide were additionally tested over a wide range of concentrations. In total, 242 genes (252 PSs) in the UKK test system and 793 genes (1092 PSs) in the UKN1 test system were deregulated by the 12 test compounds. We identified sets of 'diagnostic genes' appropriate for the identification of the influence of HDACis or mercurials. Test compounds that interfered with the expression of developmental genes usually antagonized their spontaneous development, meaning that up-regulated developmental genes were suppressed and developmental genes whose expression normally decreases were induced. The fraction of compromised developmental genes varied widely between the test compounds, and it reached up to 60 %. To quantitatively describe disturbed development on a genome-wide basis, we recommend a concept of two indices, 'developmental potency' (D p) and 'developmental index' (D i), whereby D p is the fraction of all developmental genes that are up- or down-regulated by a test compound, and D i is the ratio of overrepresentation of developmental genes among all genes deregulated by a test compound. The use of D i makes hazard identification more sensitive because some compounds compromise the expression of only a relatively small number of genes but have a high propensity to deregulate developmental genes specifically, resulting in a low D p but a high D i. In conclusion, the concept based on the indices D p and D i offers the possibility to quantitatively express the propensity of test compounds to interfere with normal development.
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Affiliation(s)
- Vaibhav Shinde
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | - Lisa Hoelting
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Box: M657, 78457, Constance, Germany.,Konstanz Graduate School Chemical Biology KORS-CB, University of Konstanz, 78457, Constance, Germany
| | - Sureshkumar Perumal Srinivasan
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | - Johannes Meisig
- Institute of Pathology, Charité Universitätsmedizin, 10117, Berlin, Germany.,Integrative Research Institute for the Life Sciences, Institute for Theoretical Biology, Humboldt Universität, 10115, Berlin, Germany
| | - Kesavan Meganathan
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | - Smita Jagtap
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | | | - Julia Liebing
- Leibniz Research Centre for Working Environment and Human Factors at the Technical, University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany
| | - Nils Bluethgen
- Institute of Pathology, Charité Universitätsmedizin, 10117, Berlin, Germany.,Integrative Research Institute for the Life Sciences, Institute for Theoretical Biology, Humboldt Universität, 10115, Berlin, Germany
| | | | - Eugen Rempel
- Department of Statistics, TU Dortmund University, Dortmund, Germany.,Centre for Organismal Studies, Heidelberg University, 69120, Heidelberg, Germany
| | - Regina Stoeber
- Leibniz Research Centre for Working Environment and Human Factors at the Technical, University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany
| | - Stefan Schildknecht
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Box: M657, 78457, Constance, Germany
| | - Sunniva Förster
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Box: M657, 78457, Constance, Germany
| | - Patricio Godoy
- Leibniz Research Centre for Working Environment and Human Factors at the Technical, University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany
| | - Christoph van Thriel
- Leibniz Research Centre for Working Environment and Human Factors at the Technical, University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany
| | - John Antonydas Gaspar
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | - Jürgen Hescheler
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany
| | - Tanja Waldmann
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Box: M657, 78457, Constance, Germany
| | - Jan G Hengstler
- Leibniz Research Centre for Working Environment and Human Factors at the Technical, University of Dortmund (IfADo), Ardeystrasse 67, 44139, Dortmund, Germany.
| | - Marcel Leist
- Doerenkamp-Zbinden Chair for In Vitro Toxicology and Biomedicine, University of Konstanz, Box: M657, 78457, Constance, Germany.
| | - Agapios Sachinidis
- Institute of Neurophysiology and Centre for Molecular Medicine Cologne (CMMC), University of Cologne (UKK), Robert-Koch-Str. 39, 50931, Cologne, Germany.
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Karimi R, Vacchi-Suzzi C, Meliker JR. Mercury exposure and a shift toward oxidative stress in avid seafood consumers. ENVIRONMENTAL RESEARCH 2016; 146:100-107. [PMID: 26745733 PMCID: PMC6191849 DOI: 10.1016/j.envres.2015.12.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 05/29/2023]
Abstract
Mechanisms of mercury (Hg) toxicity at low doses from seafood consumption, the most common exposure route, are not well understood. We tested the hypothesis that seafood Hg exposure is related to a shift in redox status, indicated by a decrease in the ratio of reduced to oxidized glutathione (GSH:GSSG) in blood, or increase in redox potential (Eh). We also examined whether key seafood nutrients (selenium (Se), omega-3 fatty acids) confound or modify this shift. We measured blood concentrations of total Hg, Se, GSH, GSSG, and the Omega-3 Index (% omega-3s of total fatty acids in red blood cell membranes) in seafood consumers in Long Island, NY. We examined relationships between Hg, GSH:GSSG ratio and Eh. Elevated blood Hg (>5.8µgL(-1)) was associated with lower GSH:GSSG (β=-116.73, p=0.01), with no evidence of confounding by Se or Omega-3 Index. However, in models stratified by Omega-3 Index levels, Hg-GSH:GSSG associations were weakened among those with high Omega-3 Index levels (>6% of fatty acids, β=-63.46, p=0.28), and heightened among those with low Omega-3 Index (β=-182.53, p<0.01). We observed comparable patterns for Eh in relation to Hg. These results support the hypothesis that Hg exposure from seafood is linked to a shift in redox status toward oxidative stress, modified by omega-3 fatty acids in this population. Further work should examine the role of different seafood nutrients and Hg-induced shifts in redox status in the diverse health effects associated with elevated Hg exposure.
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Affiliation(s)
- Roxanne Karimi
- Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook, NY 11794-5000, USA.
| | | | - Jaymie R Meliker
- Stony Brook University, Department of Preventive Medicine, Stony Brook, NY, USA; Stony Brook University, Program in Public Health, Stony Brook, NY, USA
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29
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Goodrich JM, Chou HN, Gruninger SE, Franzblau A, Basu N. Exposures of dental professionals to elemental mercury and methylmercury. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2016; 26:78-85. [PMID: 26329138 PMCID: PMC4689636 DOI: 10.1038/jes.2015.52] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 07/28/2015] [Indexed: 05/03/2023]
Abstract
Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms--methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Hg levels in biomarkers of elemental Hg (urine) and methylmercury (hair and blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general US population. Geometric means (95% CI) were 1.28 (1.19-1.37) μg/l in urine, 0.60 (0.54-0.67) μg/g in hair and 3.67 (3.38-3.98) μg/l in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours and sex. Fish consumption patterns predicted hair and blood Hg levels, which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish--swordfish, fresh tuna, white canned tuna, whitefish and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure.
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Affiliation(s)
- Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | | | | | - Alfred Franzblau
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA
| | - Niladri Basu
- Department of Agriculture and Environmental Sciences, McGill University, Montreal, Quebec, Canada
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30
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Li P, Feng X, Chan HM, Zhang X, Du B. Human Body Burden and Dietary Methylmercury Intake: The Relationship in a Rice-Consuming Population. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:9682-9689. [PMID: 26189659 DOI: 10.1021/acs.est.5b00195] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Rice can be the main route of methylmercury (MeHg) exposure for rice-consuming populations living in area where mercury (Hg) is mined. However, the current risk assessment paradigm for MeHg exposure is based on epidemiological data collected from fish-consuming populations. This study was designed to evaluate the relationship between dietary MeHg intake and human body burden in a rice -consuming population from the Wanshan Hg mining area in China. Hair MeHg concentrations averaged 2.07 ± 1.79 μg/g, and the average blood MeHg concentration across the study area ranged from 2.20 to 9.36 μg/L. MeHg constituted 52.8 ± 17.5% and 71.7 ± 18.2% of total Hg (THg) on average in blood and hair samples, respectively. Blood and hair MeHg concentrations, rather than THg, can be used as a proxy of human MeHg exposure. Hair MeHg levels showed no significant monthly variation; however, hair THg can be impacted by inorganic Hg exposure. The toxicokinetic model of MeHg exposure based on fish consumption underestimated the human hair MeHg levels, and this may be a consequence of the high hair-to-blood MeHg ratio (361 ± 105) in the studied rice-consuming population. The use of risk assessment models based on fish consumption may not be appropriate for inland mining areas where rice is the staple food.
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Affiliation(s)
- Ping Li
- †State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Xinbin Feng
- †State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Hing-Man Chan
- ‡Centre for Advanced Research in Environmental Genomics, University of Ottawa, Ottawa, K1N 6N5, Canada
| | - Xiaofeng Zhang
- §Department of Toxicology, Public Health College, Harbin Medical University, Harbin, 150081, China
| | - Buyun Du
- †State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- !!University of Chinese Academy of Sciences, Beijing, 100049, China
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31
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Maccani JZJ, Koestler DC, Lester B, Houseman EA, Armstrong DA, Kelsey KT, Marsit CJ. Placental DNA Methylation Related to Both Infant Toenail Mercury and Adverse Neurobehavioral Outcomes. ENVIRONMENTAL HEALTH PERSPECTIVES 2015; 123:723-9. [PMID: 25748564 PMCID: PMC4492267 DOI: 10.1289/ehp.1408561] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 03/04/2015] [Indexed: 05/19/2023]
Abstract
BACKGROUND Prenatal mercury (Hg) exposure is associated with adverse child neurobehavioral outcomes. Because Hg can interfere with placental functioning and cross the placenta to target the fetal brain, prenatal Hg exposure can inhibit fetal growth and development directly and indirectly. OBJECTIVES We examined potential associations between prenatal Hg exposure assessed through infant toenail Hg, placental DNA methylation changes, and newborn neurobehavioral outcomes. METHODS The methylation status of > 485,000 CpG loci was interrogated in 192 placental samples using Illumina's Infinium HumanMethylation450 BeadArray. Hg concentrations were analyzed in toenail clippings from a subset of 41 infants; neurobehavior was assessed using the NICU Network Neurobehavioral Scales (NNNS) in an independent subset of 151 infants. RESULTS We identified 339 loci with an average methylation difference > 0.125 between any two toenail Hg tertiles. Variation among these loci was subsequently found to be associated with a high-risk neurodevelopmental profile (omnibus p-value = 0.007) characterized by the NNNS. Ten loci had p < 0.01 for the association between methylation and the high-risk NNNS profile. Six of 10 loci reside in the EMID2 gene and were hypomethylated in the 16 high-risk profile infants' placentas. Methylation at these loci was moderately correlated (correlation coefficients range, -0.33 to -0.45) with EMID2 expression. CONCLUSIONS EMID2 hypomethylation may represent a novel mechanism linking in utero Hg exposure and adverse infant neurobehavioral outcomes.
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Affiliation(s)
- Jennifer Z J Maccani
- Penn State Tobacco Center of Regulatory Science, Department of Public Health Sciences, College of Medicine, Penn State University, Hershey, Pennsylvania, USA
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32
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Omanwar S, Fahim M. Mercury Exposure and Endothelial Dysfunction: An Interplay Between Nitric Oxide and Oxidative Stress. Int J Toxicol 2015; 34:300-7. [PMID: 26060268 DOI: 10.1177/1091581815589766] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular endothelium plays a vital role in the organization and function of the blood vessel and maintains homeostasis of the circulatory system and normal arterial function. Functional disruption of the endothelium is recognized as the beginning event that triggers the development of consequent cardiovascular disease (CVD) including atherosclerosis and coronary heart disease. There is a growing data associating mercury exposure with endothelial dysfunction and higher risk of CVD. This review explores and evaluates the impact of mercury exposure on CVD and endothelial function, highlighting the interplay of nitric oxide and oxidative stress.
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Affiliation(s)
- Swati Omanwar
- School of Sciences, Indira Gandhi National Open University, New Delhi, India
| | - M Fahim
- Hamdard Institute of Medical Science and Research, Hamdard University, New Delhi, India
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33
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Llop S, Ballester F, Broberg K. Effect of Gene-Mercury Interactions on Mercury Toxicokinetics and Neurotoxicity. Curr Environ Health Rep 2015; 2:179-94. [DOI: 10.1007/s40572-015-0047-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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34
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Zendehdel R. Oxidative Damage Modeling by Biomonitoring of Exposure to Metals for Manual Metal Arc Welders. HEALTH SCOPE 2014. [DOI: 10.17795/jhealthscope-16440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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35
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Woods JS, Heyer NJ, Russo JE, Martin MD, Farin FM. Genetic polymorphisms affecting susceptibility to mercury neurotoxicity in children: summary findings from the Casa Pia Children's Amalgam clinical trial. Neurotoxicology 2014; 44:288-302. [PMID: 25109824 DOI: 10.1016/j.neuro.2014.07.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 12/15/2022]
Abstract
Mercury (Hg) is neurotoxic, and children may be particularly susceptible to this effect. A current major challenge is identification of children who may be uniquely susceptible to Hg toxicity because of genetic predisposition. We examined the possibility that common genetic variants that are known to affect neurologic functions or Hg handling in adults would modify the adverse neurobehavioral effects of Hg exposure in children. Three hundred thirty subjects who participated as children in the recently completed Casa Pia Clinical Trial of Dental Amalgams in Children were genotyped for 27 variants of 13 genes that are reported to affect neurologic functions and/or Hg disposition in adults. Urinary Hg concentrations, reflecting Hg exposure from any source, served as the Hg exposure index. Regression modeling strategies were employed to evaluate potential associations between allelic status for individual genes or combinations of genes, Hg exposure, and neurobehavioral test outcomes assessed at baseline and for 7 subsequent years during the clinical trial. Among boys, significant modification of Hg effects on neurobehavioral outcomes over a broad range of neurologic domains was observed with variant genotypes for 4 of 13 genes evaluated. Modification of Hg effects on a more limited number of neurobehavioral outcomes was also observed for variants of another 8 genes. Cluster analyses suggested some genes interacting in common processes to affect Hg neurotoxicity. In contrast, significant modification of Hg effects on neurobehavioral functions among girls with the same genotypes was substantially more limited. These observations suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children, particularly boys, with genetic variants that are relatively common to the general human population. These findings advance public health goals to identify factors underlying susceptibility to Hg toxicity and may contribute to strategies for preventing adverse health risks associated with Hg exposure.
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Affiliation(s)
- James S Woods
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
| | - Nicholas J Heyer
- Battelle Centers for Public Health Research and Evaluation, Seattle, WA, USA
| | - Joan E Russo
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA
| | - Michael D Martin
- Departments of Oral Medicine and Epidemiology, University of Washington, Seattle, WA, USA
| | - Federico M Farin
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
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36
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Basu N, Goodrich JM, Head J. Ecogenetics of mercury: from genetic polymorphisms and epigenetics to risk assessment and decision-making. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:1248-58. [PMID: 24038486 DOI: 10.1002/etc.2375] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/10/2013] [Accepted: 08/08/2013] [Indexed: 05/20/2023]
Abstract
The risk assessment of mercury (Hg), in both humans and wildlife, is made challenging by great variability in exposure and health effects. Although disease risk arises following complex interactions between genetic ("nature") and environmental ("nurture") factors, most Hg studies thus far have focused solely on environmental factors. In recent years, ecogenetic-based studies have emerged and have started to document genetic and epigenetic factors that may indeed influence the toxicokinetics or toxicodynamics of Hg. The present study reviews these studies and discusses their utility in terms of Hg risk assessment, management, and policy and offers perspectives on fruitful areas for future research. In brief, epidemiological studies on populations exposed to inorganic Hg (e.g., dentists and miners) or methylmercury (e.g., fish consumers) are showing that polymorphisms in a number of environmentally responsive genes can explain variations in Hg biomarker values and health outcomes. Studies on mammals (wildlife, humans, rodents) are showing Hg exposures to be related to epigenetic marks such as DNA methylation. Such findings are beginning to increase understanding of the mechanisms of action of Hg, and in doing so they may help identify candidate biomarkers and pinpoint susceptible groups or life stages. Furthermore, they may help refine uncertainty factors and thus lead to more accurate risk assessments and improved decision-making.
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Affiliation(s)
- Niladri Basu
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA; Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
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Abstract
Mercury (Hg) is a highly toxic, non-essential, naturally occurring metal with a variety of uses. Mercury is not required for any known biological process and its presence in the human body may be detrimental, especially to the nervous system. Both genetic and behavioral studies suggest that mercury levels, age (both of exposure and at testing), and genetic background determine disease processes and outcome. The metal receptors and genes responsible for mercury metabolism also appear to play a pivotal role in the etiology of mercury-induced pathology. This review presents information about the latest advances in mercury research, with particular focus on low-level exposures and the contribution of genetics to toxic outcome. Future studies should address the contribution of genetics and low-level mercury exposure to disease, namely gene x environment interactions, taking into consideration age of exposure as developing animals are exquisitely more sensitive to this metal. In addition to recent advances in understanding the pathology associated with mercury exposure, the review highlights transport mechanisms, cellular distribution and detoxification of mercury species in the body.
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Affiliation(s)
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Hellwege JN, Palmer ND, Ziegler JT, Langefeld CD, Lorenzo C, Norris JM, Takamura T, Bowden DW. Genetic variants in selenoprotein P plasma 1 gene (SEPP1) are associated with fasting insulin and first phase insulin response in Hispanics. Gene 2013; 534:33-9. [PMID: 24161883 DOI: 10.1016/j.gene.2013.10.035] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 10/15/2013] [Indexed: 10/26/2022]
Abstract
CONTEXT Insulin resistance is not fully explained on a molecular level, though several genes and proteins have been tied to this defect. Knockdowns of the SEPP1 gene, which encodes the selenoprotein P (SeP) protein, have been shown to increase insulin sensitivity in mice. SeP is a liver-derived plasma protein and a major supplier of selenium, which is a proposed insulin mimetic and antidiabetic agent. OBJECTIVE SEPP1 single nucleotide polymorphisms (SNPs) were selected for analysis with glucometabolic measures. PARTICIPANTS AND MEASURES The study included1424 Hispanics from families in the Insulin Resistance Atherosclerosis Family Study (IRASFS). Additionally, the multi-ethnic Insulin Resistance Atherosclerosis Study was used. A frequently sampled intravenous glucose tolerance test was used to obtain precise measures of acute insulin response (AIR) and the insulin sensitivity index (SI). DESIGN 21 SEPP1 SNPs (tagging SNPs (n=12) from HapMap, 4 coding variants and 6 SNPs in the promoter region) were genotyped and analyzed for association. RESULTS Two highly correlated (r(2)=1) SNPs showed association with AIR (rs28919926; Cys368Arg; p=0.0028 and rs146125471; Ile293Met; p=0.0026) while rs16872779 (intronic) was associated with fasting insulin levels (p=0.0097). In the smaller IRAS Hispanic cohort, few of the associations seen in the IRASFS were replicated, but meta-analysis of IRASFS and all 3 IRAS cohorts (N=2446) supported association of rs28919926 and rs146125471 with AIR (p=0.013 and 0.0047, respectively) as well as rs7579 with SI (p=0.047). CONCLUSIONS Overall, these results in a human sample are consistent with the literature suggesting a role for SEPP1 in insulin resistance.
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Affiliation(s)
- Jacklyn N Hellwege
- Molecular Genetics and Genomics Program, Wake Forest School of Medicine, Winston-Salem, NC, USA; Center for Genomics and Personalized Medicine Research, Wake Forest School of Medicine, Winston-Salem, NC, USA; Center for Diabetes Research, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Dutton DJ, Fyie K, Faris P, Brunel L, Emery JH. The association between amalgam dental surfaces and urinary mercury levels in a sample of Albertans, a prevalence study. J Occup Med Toxicol 2013; 8:22. [PMID: 23984857 PMCID: PMC3766055 DOI: 10.1186/1745-6673-8-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 08/27/2013] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE The objective of this study was to quantify the relationship between number of dental amalgam surfaces and urinary mercury levels. METHODS This study uses participant data from a large philanthropic chronic disease prevention program in Calgary, Alberta, Canada. Urine samples were analysed for mercury levels (measured in μg/g-creatinine). T-tests were used to determine if differences in urine mercury were statistically significant between persons with no dental amalgam surfaces and one or more dental amalgam surfaces. Linear regression was used to estimate the change in urinary mercury per amalgam surface. RESULTS Urinary mercury levels were statistically significantly higher in participants with amalgam surfaces, with an average difference of 0.55 μg/g-creatinine. Per amalgam surface, we estimated an expected increase of 0.04 μg/g-creatinine. Measured urinary mercury levels were also statistically significantly higher in participants with dental amalgam surfaces following the oral administration of 2,3-dimercaptopropane-l-sulfonate (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) which are used to mobilize mercury from the blood and tissues. DISCUSSION Our estimates indicate that an individual with seven or more dental amalgam surfaces has 30% to 50% higher urinary mercury levels than an individual without amalgams. This is consistent with past literature that has identified seven amalgam surfaces as an unsafe level of exposure to mercury vapor. Our analysis suggests that continued use of silver amalgam dental fillings for restorative dentistry is a non-negligible, unnecessary source of mercury exposure considering the availability of composite resin alternatives.
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Affiliation(s)
- Daniel J Dutton
- Department of Community Health Sciences, University of Calgary, 3rd Floor, TRW Building, 3280 Hospital Drive NW, Calgary, AB T2N 4Z6, Canada.
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Woods JS, Heyer NJ, Russo JE, Martin MD, Pillai PB, Farin FM. Modification of neurobehavioral effects of mercury by genetic polymorphisms of metallothionein in children. Neurotoxicol Teratol 2013; 39:36-44. [PMID: 23827881 DOI: 10.1016/j.ntt.2013.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Revised: 06/13/2013] [Accepted: 06/19/2013] [Indexed: 01/02/2023]
Abstract
Mercury (Hg) is neurotoxic, and children may be particularly susceptible to this effect. A current major challenge is the identification of children who may be uniquely susceptible to Hg toxicity because of genetic disposition. We examined the hypothesis that genetic variants of metallothionein (MT) that are reported to affect Hg toxicokinetics in adults would modify the neurotoxic effects of Hg in children. Five hundred seven children, 8-12 years of age at baseline, participated in a clinical trial to evaluate the neurobehavioral effects of Hg from dental amalgam tooth fillings. Subjects were evaluated at baseline and at 7 subsequent annual intervals for neurobehavioral performance and urinary Hg levels. Following the completion of the clinical trial, we performed genotyping assays for variants of MT isoforms MT1M (rs2270837) and MT2A (rs10636) on biological samples provided by 330 of the trial participants. Regression modeling strategies were employed to evaluate associations between allelic status, Hg exposure, and neurobehavioral test outcomes. Among girls, few significant interactions or independent main effects for Hg exposure and either of the MT gene variants were observed. In contrast, among boys, numerous significant interaction effects between variants of MT1M and MT2A, alone and combined, with Hg exposure were observed spanning multiple domains of neurobehavioral function. All dose-response associations between Hg exposure and test performance were restricted to boys and were in the direction of impaired performance. These findings suggest increased susceptibility to the adverse neurobehavioral effects of Hg among children with relatively common genetic variants of MT, and may have important public health implications for future strategies aimed at protecting children and adolescents from the potential health risks associated with Hg exposure. We note that because urinary Hg reflects a composite exposure index that cannot be attributed to a specific source, these findings do not support an association between Hg in dental amalgams specifically and the adverse neurobehavioral outcomes observed.
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Affiliation(s)
- James S Woods
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
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Shachar BZ, Carmichael SL, Stevenson DK, Shaw GM. Could genetic polymorphisms related to oxidative stress modulate effects of heavy metals for risk of human preterm birth? Reprod Toxicol 2013; 42:24-6. [PMID: 23811355 DOI: 10.1016/j.reprotox.2013.06.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/03/2013] [Accepted: 06/12/2013] [Indexed: 01/13/2023]
Abstract
Human preterm birth (PTB) is a complex medical outcome influenced by a combination of genetic and environmental factors. Research on the causative factors of PTB has mostly focused on demographic, socio-behavioral and environmental risk factors. Recent studies turn the spotlight on the effects of heavy metals exposure on adverse pregnancy outcomes. Here we present and evaluate the hypothesis that heavy metals may cause PTB through oxidative stress, and that this effect may be modified by polymorphisms in genes related to oxidative stress. Indeed, accumulating data suggest that the risk of PTB is correlated with polymorphisms in genes involved in detoxification, oxidative stress and lipid metabolism. These and other polymorphisms have independently been associated with susceptibility to the adverse effects of heavy metals.
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Affiliation(s)
- Bat Zion Shachar
- Stanford University School of Medicine, Department of Pediatrics, United States.
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Sherman LS, Blum JD, Franzblau A, Basu N. New insight into biomarkers of human mercury exposure using naturally occurring mercury stable isotopes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:3403-9. [PMID: 23463943 DOI: 10.1021/es305250z] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Human exposure to methylmercury (MeHg) and elemental mercury vapor (Hg(0)(g)) are often estimated using total Hg concentrations in hair and urine, respectively. We investigated whether Hg stable isotopes could be used to better distinguish between exposure to Hg(0)(g) versus MeHg. We found that hair from North American dental professionals was characterized by high positive Δ(199)Hg values (mean = 1.86‰, 1 SD = 0.12‰, n = 11). This confirms that among people who regularly consume fish, total Hg concentrations in hair reflect exposure to MeHg. In contrast, we found that urine from the same individuals was characterized by a range of Δ(199)Hg values (0.29 to 1.77‰, 2 SD = 0.06‰, n = 12) that were significantly correlated to the number of dental amalgams in each individual's mouth. We hypothesize that fish-derived MeHg is demethylated within the body, causing mass-dependent fractionation and the excretion of inorganic Hg in urine. Mercury in urine therefore represents a mixture of demethylated fish-derived MeHg and amalgam-derived inorganic Hg. We estimate that the majority (>70%) of Hg in urine from individuals with <10 dental amalgams is derived from ingestion of MeHg in fish. These data suggest that within populations that consume fish, urine total Hg concentrations may overestimate Hg exposure from personal dental amalgams.
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Affiliation(s)
- Laura S Sherman
- Department of Earth and Environmental Sciences, University of Michigan, 1100 N University Ave, Ann Arbor, Michigan 48109, United States.
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Goodrich JM, Basu N, Franzblau A, Dolinoy DC. Mercury biomarkers and DNA methylation among Michigan dental professionals. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2013; 54:195-203. [PMID: 23444121 PMCID: PMC3750961 DOI: 10.1002/em.21763] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 05/19/2023]
Abstract
Modification of the epigenome may be a mechanism underlying toxicity and disease following chemical exposure. Animal and human data suggest that mercury (Hg) impacts DNA methylation. We hypothesize that methylmercury and inorganic Hg exposures from fish consumption and dental amalgams, respectively, may be associated with altered DNA methylation at global repetitive elements (long interspersed elements, LINE-1) and candidate genes related to epigenetic processes (DNMT1) and protection against Hg toxicity (SEPW1, SEPP1). Dental professionals were recruited at Michigan Dental Association (MDA) meetings in 2009 and 2010. Subjects (n=131) provided survey data (e.g. exposure sources, demographics) and biological samples for Hg measurement and epigenetic analysis. Total Hg was quantified via atomic absorption spectrophotometry in hair and urine, indicative of methylmercury and inorganic Hg exposures, respectively. Global repetitive and candidate gene methylation was quantified via pyrosequencing of bisulfite converted DNA isolated from buccal mucosa. Hair Hg (geometric mean (95% CI): 0.37 (0.31-0.44) µg/g) and urine Hg (0.70 (0.60-0.83) µg/L) were associated with sources of exposure (fish consumption and dental amalgams, respectively). Multivariable linear regression revealed a trend of SEPP1 hypomethylation with increasing hair Hg levels, and this was significant (P<0.05) among males. The trend remained when excluding non-dentists. No significant relationships between urine Hg and DNA methylation were observed. Thus, in a limited cohort, we identified an association between methylmercury exposure and hypomethylation of a potentially labile region of the genome (SEPP1 promoter), and this relationship was gender specific.
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Affiliation(s)
- Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA.
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Goodrich JM, Wang Y, Gillespie B, Werner R, Franzblau A, Basu N. Methylmercury and elemental mercury differentially associate with blood pressure among dental professionals. Int J Hyg Environ Health 2013; 216:195-201. [PMID: 22494934 PMCID: PMC3727420 DOI: 10.1016/j.ijheh.2012.03.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 02/25/2012] [Accepted: 03/08/2012] [Indexed: 02/07/2023]
Abstract
Methylmercury-associated effects on the cardiovascular system have been documented though discrepancies exist, and most studied populations experience elevated methylmercury exposures. No paper has investigated the impact of low-level elemental (inorganic) mercury exposure on cardiovascular risk in humans. The purpose of this study was to increase understanding of the association between mercury exposure (methylmercury and elemental mercury) and blood pressure measures in a cohort of dental professionals that experience background exposures to both mercury forms. Dental professionals were recruited during the 2010 Michigan Dental Association Annual Convention. Mercury levels in hair and urine samples were analyzed as biomarkers of methylmercury and elemental mercury exposure, respectively. Blood pressure (systolic, diastolic) was measured using an automated device. Distribution of mercury in hair (mean, range: 0.45, 0.02-5.18 μg/g) and urine (0.94, 0.03-5.54 μg/L) correspond well with the US National Health and Nutrition Examination Survey. Linear regression models revealed significant associations between diastolic blood pressure (adjusted for blood pressure medication use) and hair mercury (n=262, p=0.02). Urine mercury results opposed hair mercury in many ways. Notably, elemental mercury exposure was associated with a significant systolic blood pressure decrease (n=262, p=0.04) that was driven by the male population. Associations between blood pressure and two forms of mercury were found at exposure levels relevant to the general population, and associations varied according to type of mercury exposure and gender.
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Affiliation(s)
- Jaclyn M. Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Yi Wang
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Brenda Gillespie
- Department of Biostatistics, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Robert Werner
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
- Department of Physical Medicine and Rehabilitation, University of Michigan, 325 E. Eisenhower Parkway Suite 100, Ann Arbor, MI 48108, USA
| | - Alfred Franzblau
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
| | - Niladri Basu
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA
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Fretham SJ, Caito S, Martinez-Finley EJ, Aschner M. Mechanisms and Modifiers of Methylmercury-Induced Neurotoxicity. Toxicol Res (Camb) 2012; 1:32-38. [PMID: 27795823 DOI: 10.1039/c2tx20010d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The neurotoxic consequences of methylmercury (MeHg) exposure have long been known, however a complete understanding of the mechanisms underlying this toxicity is elusive. Recent epidemiological and experimental studies have provided many mechanistic insights, particularly into the contribution of genetic and environmental factors that interact with MeHg to modify toxicity. This review will outline cellular processes directly and indirectly affected by MeHg, including oxidative stress, cellular signaling and gene expression, and discuss genetic, environmental and nutritional factors capable of modifying MeHg toxicity.
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Affiliation(s)
- Stephanie Jb Fretham
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Samuel Caito
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Ebany J Martinez-Finley
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Michael Aschner
- Department of Pediatrics and Department of Pharmacology, and the Kennedy Center for Research on Human Development, Vanderbilt University Medical Center, Nashville, TN, USA
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Wang Y, Goodrich JM, Gillespie B, Werner R, Basu N, Franzblau A. An investigation of modifying effects of metallothionein single-nucleotide polymorphisms on the association between mercury exposure and biomarker levels. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:530-4. [PMID: 22233731 PMCID: PMC3339459 DOI: 10.1289/ehp.1104079] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 01/09/2012] [Indexed: 05/19/2023]
Abstract
BACKGROUND Recent studies have suggested that several genes that mediate mercury metabolism are polymorphic in humans. OBJECTIVE We hypothesized that single-nucleotide polymorphisms (SNPs) in metallothionein (MT) genes may underlie interindividual differences in mercury biomarker levels. We studied the potential modifying effects of MT SNPs on mercury exposure-biomarker relationships. METHODS We measured total mercury in urine and hair samples of 515 dental professionals. We also surveyed occupational and personal exposures to dental amalgam and dietary fish consumption, from which daily methylmercury (MeHg) intake was estimated. Log-transformed urine and hair levels were modeled in multivariable linear regression separately against respective exposure surrogates, and the effect modification of 13 MT SNPs on exposure was investigated. RESULTS The mean mercury levels in urine (1.06 μg/L) and hair (0.51 μg/g) were not significantly different from the U.S. general population (0.95 μg/L and 0.47 μg/g, respectively). The mean estimated daily MeHg intake was 0.084 μg/kg/day (range, 0-0.98 μg/kg/day), with 25% of study population intakes exceeding the current U.S. Environmental Protection Agency reference dose of 0.1 μg/kg/day. Multivariate regression analysis showed that subjects with the MT1M (rs2270837) [corrected] AA genotype (n = 10) or the MT2A (rs10636) CC genotype (n = 42) had lower urinary mercury levels than did those with the MT1M or MT2A GG genotype (n = 329 and 251, respectively) after controlling for exposure and potential confounders. After controlling for MeHg intake, subjects with MT1A (rs8052394) GA and GG genotypes (n = 24) or the MT1M (rs9936741) TT genotype (n = 459) had lower hair mercury levels than did subjects with MT1A AA (n = 113) or MT1M TC and CC genotypes (n = 15), respectively. CONCLUSION Our findings suggest that some MT genetic polymorphisms may influence mercury biomarker concentrations at levels of exposure relevant to the general population.
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Affiliation(s)
- Yi Wang
- Department of Environmental Health Sciences, University of Michigan, Ann Arbor, Michigan 48109-2029, USA
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Goodrich JM, Basu N. Variants of glutathione s-transferase pi 1 exhibit differential enzymatic activity and inhibition by heavy metals. Toxicol In Vitro 2012; 26:630-5. [PMID: 22401947 DOI: 10.1016/j.tiv.2012.02.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 02/18/2012] [Accepted: 02/20/2012] [Indexed: 11/17/2022]
Abstract
Nonsynonymous single nucleotide polymorphisms in glutathione s-transferase pi 1 (GSTP1; Ile/Val 105, Ala/Val 114) have been associated with altered toxicant metabolism in epidemiological cohorts. We explored the impact of GSTP1 genotype on enzyme kinetics and heavy metal inhibition in vitro. Four GSTP1 allozymes (105/114: Ile/Ala, Val/Ala, Ile/Val, Val/Val) were expressed in and purified from Escherichia coli. Enzyme activity assays quantifying the rate of glutathione conjugation with 1-chloro-2,4-dinitrobenzene (CDNB) revealed significant differences in kinetic parameters depending on genotype (p<0.01). Allozymes with Ile105 had better catalytic efficiency and greater affinity for CDNB (mean ± SEM: Ile105 Ala114 K(m)=0.33 ± 0.07 mM vs. Val105 Ala114 K(m)=1.15 ± 0.07 mM). Inhibition of GSTP1 activity by heavy metals was assessed following treatment with mercury (inorganic-HgCl(2), methylmercury-MeHg), selenium, cadmium, lead, arsenic, and manganese. All allozymes were inhibited by HgCl(2) (IC(50) range: 24.1-172 μM), MeHg (93.9-480 μM), and selenium (43.7-62.8 μM). Genotype significantly influenced the potency of mercury with GSTP1 Ile105 Val114 the least sensitive and Val105 Ala114 the most sensitive to inhibition by HgCl(2) and MeHg. Overall, genotype of two nonsynonymous polymorphisms in GSTP1 influenced enzyme kinetics pertaining to an electrophilic substrate and inhibition by two mercury species.
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Affiliation(s)
- Jaclyn M Goodrich
- Department of Environmental Health Sciences, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
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Wang Y, Goodrich JM, Werner R, Gillespie B, Basu N, Franzblau A. An investigation of modifying effects of single nucleotide polymorphisms in metabolism-related genes on the relationship between peripheral nerve function and mercury levels in urine and hair. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 417-418:32-8. [PMID: 22236634 PMCID: PMC3299006 DOI: 10.1016/j.scitotenv.2011.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 11/30/2011] [Accepted: 12/06/2011] [Indexed: 05/24/2023]
Abstract
Mercury (Hg) is a potent neurotoxicant. We hypothesized that single nucleotide polymorphisms (SNPs) in genes coding glutathione-related proteins, selenoproteins and metallothioneins may modify the relationship of mercury biomarkers with changes in peripheral nerve function. Dental professionals (n=515) were recruited in 2009 and 2010. Sensory nerve function (onset latency, peak latency and amplitude) of the median, ulnar and sural nerves was recorded. Samples of urine, hair and DNA were collected. Covariates related to demographics, nerve function and elemental and methyl-mercury exposure were also collected. Subjects included 244 dentists (47.4%) and 269 non-dentists (52.2%; mostly dental hygienists and dental assistants). The mean mercury levels in urine (1.06 μg/L) and hair (0.51 μg/g) were not significantly different from the US general population (0.95 μg/L and 0.47 μg/g, respectively). In multivariate linear models predicting nerve function adjusting for covariates, only 3 out of a total of 504 models showed stable and statistically significant interaction of SNPs with mercury biomarkers. Overall, given the possibility of false positives, the results suggested little evidence of effect modification of the SNPs on the relationship between mercury biomarkers with peripheral nerve function at exposure levels that are relevant to the general US population.
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Affiliation(s)
- Yi Wang
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
| | - Jaclyn M. Goodrich
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
| | - Robert Werner
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
- Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
| | - Brenda Gillespie
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
| | - Niladri Basu
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
| | - Alfred Franzblau
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI USA 48109
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