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Kang B, Wang J, Guo S, Yang L. Mercury-induced toxicity: Mechanisms, molecular pathways, and gene regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 943:173577. [PMID: 38852866 DOI: 10.1016/j.scitotenv.2024.173577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/01/2024] [Accepted: 05/25/2024] [Indexed: 06/11/2024]
Abstract
Mercury is a well-known neurotoxicant for humans and wildlife. The epidemic of mercury poisoning in Japan has clearly demonstrated that chronic exposure to methylmercury (MeHg) results in serious neurological damage to the cerebral and cerebellar cortex, leading to the dysfunction of the central nervous system (CNS), especially in infants exposed to MeHg in utero. The occurrences of poisoning have caused a wide public concern regarding the health risk emanating from MeHg exposure; particularly those eating large amounts of fish may experience the low-level and long-term exposure. There is growing evidence that MeHg at environmentally relevant concentrations can affect the health of biota in the ecosystem. Although extensive in vivo and in vitro studies have demonstrated that the disruption of redox homeostasis and microtube assembly is mainly responsible for mercurial toxicity leading to adverse health outcomes, it is still unclear whether we could quantitively determine the occurrence of interaction between mercurial and thiols and/or selenols groups of proteins linked directly to outcomes, especially at very low levels of exposure. Furthermore, intracellular calcium homeostasis, cytoskeleton, mitochondrial function, oxidative stress, neurotransmitter release, and DNA methylation may be the targets of mercury compounds; however, the primary targets associated with the adverse outcomes remain to be elucidated. Considering these knowledge gaps, in this article, we conducted a comprehensive review of mercurial toxicity, focusing mainly on the mechanism, and genes/proteins expression. We speculated that comprehensive analyses of transcriptomics, proteomics, and metabolomics could enhance interpretation of "omics" profiles, which may reveal specific biomarkers obviously correlated with specific pathways that mediate selective neurotoxicity.
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Affiliation(s)
- Bolun Kang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China
| | - Jinghan Wang
- 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
| | - Lixin Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, China.
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Nascimento TS, Pinto DV, Dias RP, Raposo RS, Nunes PIG, Roque CR, Santos FA, Andrade GM, Viana JL, Fostier AH, Sussulini A, Alvarez-Leite JI, Fontes-Ribeiro C, Malva JO, Oriá RB. Chronic Methylmercury Intoxication Induces Systemic Inflammation, Behavioral, and Hippocampal Amino Acid Changes in C57BL6J Adult Mice. Int J Mol Sci 2022; 23:13837. [PMID: 36430321 PMCID: PMC9697706 DOI: 10.3390/ijms232213837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/12/2022] Open
Abstract
Methylmercury (MeHg) is highly toxic to the human brain. Although much is known about MeHg neurotoxic effects, less is known about how chronic MeHg affects hippocampal amino acids and other neurochemical markers in adult mice. In this study, we evaluated the MeHg effects on systemic lipids and inflammation, hippocampal oxidative stress, amino acid levels, neuroinflammation, and behavior in adult male mice. Challenged mice received MeHg in drinking water (2 mg/L) for 30 days. We assessed weight gain, total plasma cholesterol (TC), triglycerides (TG), endotoxin, and TNF levels. Hippocampal myeloperoxidase (MPO), malondialdehyde (MDA), acetylcholinesterase (AChE), amino acid levels, and cytokine transcripts were evaluated. Mice underwent open field, object recognition, Y, and Barnes maze tests. MeHg-intoxicated mice had higher weight gain and increased the TG and TC plasma levels. Elevated circulating TNF and LPS confirmed systemic inflammation. Higher levels of MPO and MDA and a reduction in IL-4 transcripts were found in the hippocampus. MeHg-intoxication led to increased GABA and glycine, reduced hippocampal taurine levels, delayed acquisition in the Barnes maze, and poor locomotor activity. No significant changes were found in AChE activity and object recognition. Altogether, our findings highlight chronic MeHg-induced effects that may have long-term mental health consequences in prolonged exposed human populations.
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Affiliation(s)
- Tyciane S. Nascimento
- Neuroscience and Behavior Laboratory, Drug Research and Development Center, Federal University of Ceará, Fortaleza 60430-275, Brazil
| | - Daniel V. Pinto
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Ronaldo P. Dias
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Ramon S. Raposo
- Experimental Biology Core, Health Sciences Center, University of Fortaleza, Fortaleza 60812-020, Brazil
| | - Paulo Iury G. Nunes
- Natural Products Laboratory, Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Cássia R. Roque
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Flávia A. Santos
- Natural Products Laboratory, Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza 60430-270, Brazil
| | - Geanne M. Andrade
- Neuroscience and Behavior Laboratory, Drug Research and Development Center, Federal University of Ceará, Fortaleza 60430-275, Brazil
| | - José Lucas Viana
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Anne H. Fostier
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Alessandra Sussulini
- Department of Analytical Chemistry, Institute of Chemistry, University of Campinas—UNICAMP, Campinas 13083-862, Brazil
| | - Jacqueline I. Alvarez-Leite
- Laboratory of Atherosclerosis and Nutritional Biochemistry, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Carlos Fontes-Ribeiro
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Institute of Pharmacology and Experimental Therapeutics and Center for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - João O. Malva
- Coimbra Institute for Clinical and Biomedical Research (iCBR), Institute of Pharmacology and Experimental Therapeutics and Center for Innovative Biomedicine and Biotechnology (CIBB), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Reinaldo B. Oriá
- Laboratory of Tissue Healing, Ontogeny, and Nutrition, Department of Morphology and Institute of Biomedicine, School of Medicine, Federal University of Ceará, Fortaleza 60430-270, Brazil
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Marić Đ, Bonderović V, Javorac D, Baralić K, Bulat Z, Đukić-Ćosić D, Mandić-Rajčević S, Žarković M, Buha-Đorđević A. Exposure to mercury and thyroid function: Is there a connection? ARHIV ZA FARMACIJU 2022. [DOI: 10.5937/arhfarm72-40122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mercury (Hg) is one of the most important environmental pollutants with endocrinedisrupting properties. There is little data from epidemiological studies describing the doseresponse relationship between toxic metal levels and hormone levels. The aim of this study was to use the nearest neighbor matching analysis to determine the difference in Hg concentration in healthy/sick subjects with thyroid disease and to use Benchmark modeling to determine the doseresponse relationship between Hg levels in the blood and thyroid-stimulating hormone (TSH) and thyroid hormones in serum. Blood samples were collected and used for Hg measurement using the ICP-MS method, and separated serum was used for hormone analysis. The study showed the existence of a statistically significant difference in Hg levels measured in healthy and sick subjects and the existence of a dose-response relationship between Hg and all measured hormones, with a narrow interval obtained for the Hg-TSH pair. The results of this research support the use of the Benchmark dose approach for the purpose of analyzing data from human studies, and our further research will be focused on examining the impact of low doses on animal models in order to determine more precise effects of low doses on the organism.
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Gustin K, Barman M, Skröder H, Jacobsson B, Sandin A, Sandberg AS, Wold AE, Vahter M, Kippler M. Thyroid hormones in relation to toxic metal exposure in pregnancy, and potential interactions with iodine and selenium. ENVIRONMENT INTERNATIONAL 2021; 157:106869. [PMID: 34530290 DOI: 10.1016/j.envint.2021.106869] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 09/03/2021] [Accepted: 09/05/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Several endocrine-disrupting metals may affect thyroid function, but the few available studies of exposure during pregnancy and thyroid hormones are inconclusive. OBJECTIVE To explore if environmental exposure to cadmium (Cd), lead (Pb), and methylmercury (MeHg) impacts thyroid function in pregnancy, and interacts with iodine and selenium status. METHODS Women in a Swedish birth cohort provided blood and urine samples in early third trimester. Concentrations of erythrocyte Cd, Pb, and Hg (n = 544), urinary Cd and iodine (n = 542) and plasma selenium (n = 548) were measured using inductively coupled plasma-mass spectrometry.Free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH), were measured in plasma (n = 548) with electrochemiluminescence immunoassays. Metal-hormone associations were assessed in regression models, and metal mixture effects and metal-nutrient interactions were explored in Bayesian kernel machine regression (BKMR). RESULTS In multivariable-adjusted regression models, a doubling of urinary Cd was associated with a mean increase in tT4 of 2.7 nmol/L (95% CI: 0.78, 4.6), and in fT3 and tT3 of 0.06 pmol/L (0.02, 0.10) and 0.09 nmol/L (0.05, 0.13), respectively. A doubling of urinary Cd was associated with a -0.002 (-0.003, -0.001) and -0.03 (-0.05, -0.02) decrease in the fT4:tT4 and fT3:tT3 ratio, respectively. A doubling of erythrocyte Hg (>1 µg/kg) was associated with a decrease in fT3 and tT3 by -0.11 pmol/L (-0.16, -0.05) and -0.11 nmol/L (-0.16, -0.06), respectively, and a -0.013 (-0.02, -0.01) decrease in the fT3:fT4 ratio. BKMR did not indicate any mixture effect of toxic metals or interactions between metals and iodine or selenium in relation to the hormones. CONCLUSION Our findings suggest that exposure to Cd and Hg, at levels globally prevalent through the diet, may affect thyroid function during pregnancy, independently of iodine and selenium levels. Further studies on potential implications for maternal and child health are warranted.
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Affiliation(s)
- Klara Gustin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Malin Barman
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Helena Skröder
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Bo Jacobsson
- Department of Obstetrics and Gynecology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Genetics and Bioinformatics, Domain of Health Data and Digitalisation, Institute of Public Health Oslo, Norway
| | - Anna Sandin
- Department of Clinical Sciences, Unit of Pediatrics, Sunderby Research Unit, Umeå University, Umeå, Sweden
| | - Ann-Sofie Sandberg
- Food and Nutrition Science, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Agnes E Wold
- Institute of Biomedicine, Dept, of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Marie Vahter
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Maria Kippler
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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Zheng Y, Wei L, Duan L, Yang F, Huang G, Xiao T, Wei M, Liang Y, Yang H, Li Z, Wang D. Rapid field testing of mercury pollution by designed fluorescent biosensor and its cells-alginate hydrogel-based paper assay. J Environ Sci (China) 2021; 106:161-170. [PMID: 34210432 DOI: 10.1016/j.jes.2021.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/24/2020] [Accepted: 01/06/2021] [Indexed: 06/13/2023]
Abstract
With increasing industrial activities, mercury has been largely discharged into environment and caused serious environmental problems. The growing level of mercury pollution has become a huge threat to human health due to its significant biotoxicity. Therefore, the simple and fast means for on-site monitoring discharged mercury pollution are highly necessary to protect human beings from its pernicious effects in time. Herein, a "turn off" fluorescent biosensor (mCherry L199C) for sensing Hg2+ was successfully designed based on direct modification of the chromophore environment of fluorescent protein mCherry. For rapid screening and characterization, the designed variant of mCherry (mCherry L199C) was directly expressed on outer-membrane of Escherichia coli cells by cell surface display technique. The fluorescent biosensor was characterized to have favorable response to Hg2+ at micromole level among other metal ions and over a broad pH range. Further, the cells of the fluorescent biosensor were encapsulated in alginate hydrogel to develop the cells-alginate hydrogel-based paper. The cells-alginate hydrogel-based paper could detect mercury pollution in 5 min with simple operation process and inexpensive equipment, and it could keep fluorescence and activity stable at 4 °C for 24 hr, which would be a high-throughput screening tool in preliminarily reporting the presence of mercury pollution in natural setting.
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Affiliation(s)
- Yanan Zheng
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Liudan Wei
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Linwei Duan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‑Bioresources, Guangxi University, Nanning 530004, China
| | - Fangfang Yang
- Guangxi-ASEAN Food Inspection and Testing Center, China
| | - Guixiang Huang
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Tianyi Xiao
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Min Wei
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Yanling Liang
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Huiting Yang
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China
| | - Zhipeng Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro‑Bioresources, Guangxi University, Nanning 530004, China.
| | - Dan Wang
- College of Chemistry and Materials, Guangxi Key Laboratory of Natural Polymer Chemistry and Physics, Nanning Normal University, Nanning 530001, China.
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Babić Leko M, Gunjača I, Pleić N, Zemunik T. Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels. Int J Mol Sci 2021; 22:6521. [PMID: 34204586 PMCID: PMC8234807 DOI: 10.3390/ijms22126521] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 01/09/2023] Open
Abstract
Thyroid hormones are necessary for the normal functioning of physiological systems. Therefore, knowledge of any factor (whether genetic, environmental or intrinsic) that alters the levels of thyroid-stimulating hormone (TSH) and thyroid hormones is crucial. Genetic factors contribute up to 65% of interindividual variations in TSH and thyroid hormone levels, but many environmental factors can also affect thyroid function. This review discusses studies that have analyzed the impact of environmental factors on TSH and thyroid hormone levels in healthy adults. We included lifestyle factors (smoking, alcohol consumption, diet and exercise) and pollutants (chemicals and heavy metals). Many inconsistencies in the results have been observed between studies, making it difficult to draw a general conclusion about how a particular environmental factor influences TSH and thyroid hormone levels. However, lifestyle factors that showed the clearest association with TSH and thyroid hormones were smoking, body mass index (BMI) and iodine (micronutrient taken from the diet). Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels. Among the pollutants analyzed, most studies observed a decrease in thyroid hormone levels after exposure to perchlorate. Future studies should continue to analyze the impact of environmental factors on thyroid function as they could contribute to understanding the complex background of gene-environment interactions underlying the pathology of thyroid diseases.
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Affiliation(s)
| | | | | | - Tatijana Zemunik
- Department of Medical Biology, School of Medicine, University of Split, Šoltanska 2, 21000 Split, Croatia; (M.B.L.); (I.G.); (N.P.)
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Kim MJ, Kim S, Choi S, Lee I, Moon MK, Choi K, Park YJ, Cho YH, Kwon YM, Yoo J, Cheon GJ, Park J. Association of exposure to polycyclic aromatic hydrocarbons and heavy metals with thyroid hormones in general adult population and potential mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 762:144227. [PMID: 33373756 DOI: 10.1016/j.scitotenv.2020.144227] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 06/12/2023]
Abstract
Air pollution and fuel emissions are the common sources of human exposure to polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Several studies have suggested potential associations between PAHs/heavy metals and thyroid hormones, however, reports have been inconsistent. In this study, we employed a subpopulation of the adults (n = 1254) who participated in the Korean National Environmental Health Survey 2015-2017, and investigated the association of PAHs and major heavy metals with thyroid hormones, and explored the underlying mechanisms of thyroid disruption. Four PAH metabolites and three heavy metals of lead (Pb), mercury (Hg), and cadmium (Cd) were measured either in urine or in total blood. In addition, thyroid hormones (T3 and T4), TSH, thyroxine-binding globulin (TBG), and thyroid autoantibodies were measured, and peripheral deiodinase activity (GD) and thyroid's secretory capacity (GT) were calculated. Urinary Hg was negatively associated with total T3 in both males and females, while it was positively associated with total T4 among females only. Urinary Hg was related to decreased GD and increased GT in both sexes. In contrast, urinary Cd was positively associated with total T3 and GD in both male and female populations. Urinary Cd also showed a positive association with thyroid autoantibodies, but only in males. A multi-factor model considering co-exposure to multiple chemicals also resulted in similar associations. Among the measured PAH metabolites, only urinary 1-hydroxypyrene showed a negative association with total T3 in males. However, this association was marginal, and disappeared in a multi-chemical model. The present observations are suggestive that exposures to Hg and Cd might disrupt thyroid hormones, possibly through an alteration of deiodinase activity. Association of PAH exposure with thyroid hormone appears to be insignificant.
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Affiliation(s)
- Min Joo Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Republic of Korea
| | - Sunmi Kim
- School of Public Health, Seoul National University, Seoul, Republic of Korea; Chemical Safety Research Center, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
| | - Sohyeon Choi
- Department of Environmental Health Sciences, Soonchunhyang University, Asan, Republic of Korea
| | - Inae Lee
- School of Public Health, Seoul National University, Seoul, Republic of Korea
| | - Min Kyong Moon
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Division of Endocrinology, Department of Internal Medicine, Seoul National University Boramae Medical Center, Seoul, Republic of Korea
| | - Kyungho Choi
- School of Public Health, Seoul National University, Seoul, Republic of Korea
| | - Young Joo Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Republic of Korea
| | - Yoon Hee Cho
- Center for Environmental Health Sciences, Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA
| | - Young Min Kwon
- Environmental Health Research Division, National Institute of Environmental Research, Ministry of Environment, Incheon, Republic of Korea
| | - Jiyoung Yoo
- Environmental Health Research Division, National Institute of Environmental Research, Ministry of Environment, Incheon, Republic of Korea
| | - Gi Jeong Cheon
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jeongim Park
- Department of Environmental Health Sciences, Soonchunhyang University, Asan, Republic of Korea.
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Berlin M. Mercury in dental amalgam: a risk analysis. Neurotoxicology 2020; 81:382-386. [DOI: 10.1016/j.neuro.2020.09.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Evaluation of the effects of chronic occupational exposure to metallic mercury on the thyroid parenchyma and hormonal function. Int Arch Occup Environ Health 2019; 93:491-502. [PMID: 31832764 DOI: 10.1007/s00420-019-01499-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 11/28/2019] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Experiments in animals exposed to mercury (Hg) in different chemical states have shown thyroid parenchymal and hormone alterations. However, these experiments did not allow the establishment of dose-response curves or provide an understanding of whether these Hg effects on the thyroid parenchyma occur in humans. OBJECTIVE To evaluate the association between chronic occupational exposure to metallic Hg and alterations in thyroid hormones and gland parenchyma 14 years after the last exposure. METHODS A cross-sectional study including 55 males exposed in the past to metallic Hg and 55 non-exposed males, paired by age, was conducted in the Hospital das Clínicas (Brazil) from 2016 to 2017. Serum concentrations of total and free triiodothyronine (TT3 and FT3), free thyroxine (FT4), thyrotropin (TSH), reverse T3 (RT3), selenium and antithyroid antibody titers were obtained. The Hg and iodine concentrations were measured in urine. The thyroid parenchyma was evaluated by B-mode ultrasonography with Doppler. The nodules with aspects suspicious for malignancy were submitted to aspiration puncture with a thin needle, and the cytology assessment was classified by the Bethesda system. The t test or Mann-Whitney test, Chi-square test and Spearman correlation were used to compare the exposed and non-exposed groups and examine the relationships between the variables. Univariate and multivariate logistic regression models were used to trace determinants of the risk of thyroid hormone alteration. Statistical significance was defined by p < 0.05. RESULTS The urinary Hg average was significantly higher in the exposed group than in the non-exposed group (p < 0.01). The mean TSH serum concentration in the exposed group was higher, with a statistically significant difference between the groups (p = 0.03). Serum concentrations of TSH exceeded the normality limit (4.20 µIU/ml) in 13 exposed individuals (27.3%) and 4 non-exposed individuals (7.3%), with a statistically significant association between the hormonal increase and exposure to Hg (p = 0.02). In the logistic regression model, exposure to Hg (yes or no) showed an odds ratio = 4.86 associated with an increase of TSH above the normal limit (p = 0.04). The serum concentrations of RT3 showed a statistically borderline difference between the groups (p = 0.06). There was no statistically significant difference between the mean TT3, FT3 and FT4 serum concentrations in the Hg-exposed group compared to the non-exposed group. The proportions of the echogenicity alterations were higher in the exposed group compared to the non-exposed group (27.3% versus 9.1%; p = 0.03). Papillary carcinomas were documented in three exposed individuals and one non-exposed individual. A follicular carcinoma was recorded in one non-exposed individual. CONCLUSIONS Due to the higher serum TSH concentration and the prevalence of parenchymal alterations in the Hg-exposed group, even after cessation of exposure, it is recommended that the thyroid status of exposed workers be followed for a long period.
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Khan R, Ali S, Mumtaz S, Andleeb S, Ulhaq M, Tahir HM, Khan MKA, Khan MA, Shakir HA. Toxicological effects of toxic metals (cadmium and mercury) on blood and the thyroid gland and pharmacological intervention by vitamin C in rabbits. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:16727-16741. [PMID: 30989610 DOI: 10.1007/s11356-019-04886-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/15/2019] [Indexed: 05/25/2023]
Abstract
Cadmium and mercury are non-biodegradable toxic metals that may cause many detrimental effects to the thyroid gland and blood. Vitamin C has been found to be a significant chain-breaking antioxidant and enzyme co-factor against metal toxicity and thus make them less available for animals. The current study was performed to find the effect of individual metals (cadmium and mercury), their co-administration, and the ameliorative effects of vitamin C on some of the parameters that indicate oxidative stress and thyroid dysfunction. Cadmium chloride (1.5 mg/kg), mercuric chloride (1.2 mg/kg), and vitamin C (150 mg/kg of body weight) were orally administered to eight treatment groups of the rabbits (1. control; 2. Vit C; 3. CdCl2; 4. HgCl2; 5. Vit C + CdCl2; 6. Vit C + HgCl2; 7. CdCl2 + HgCl2, and 8. Vit C + CdCl2 + HgCl2). After the biometric measurements of all experimental rabbits, biochemical parameters viz. triidothyronine (T3), thyroxine (T4), thyroid-stimulating hormone (TSH), and triglycerides were measured using commercially available kits. The results exhibited significant decline (p < 0.05) in mean hemoglobin, corpuscular hemoglobin, packed cell volume, T3 (0.4 ± 0.0 ng/ml), and T4 (26.3 ± 1.6 ng/ml) concentration. While, TSH (0.23 ± 0.01 nmol/l) and triglyceride (4.42 ± 0.18 nmol/l) were significantly (p < 0.05) increased but chemo-treatment with Vit C reduces the effects of Cd, Hg, and their co-administration but not regained the values similar to those of controls. This indicates that Vit C had a shielding effect on the possible metal toxicity. The Cd and Hg also found to accumulate in vital organs when measured by atomic absorption spectrophotometer. The metal concentration trend was observed as follows: kidney > liver > heart > lungs. It was concluded that Cd and Hg are toxic and tended to bioaccumulate in different organs and their toxic action can be subdued by vitamin C in biological systems.
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Affiliation(s)
- Rida Khan
- Department of Zoology, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Shaukat Ali
- Department of Zoology, Government College University, Lahore, Pakistan.
| | - Shumaila Mumtaz
- Department of Zoology, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Saiqa Andleeb
- Department of Zoology, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
| | - Mazhar Ulhaq
- Department of Veterinary Biomedical Sciences, PMAS Arid Agriculture University, Rawalpindi, PK-46300, Pakistan
| | | | | | - Muhammad Adeeb Khan
- Department of Zoology, The University of Azad Jammu and Kashmir, Muzaffarabad, Pakistan
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Carter M, Abdi A, Naz F, Thabet F, Vyas A. A Mercury Toxicity Case Complicated by Hyponatremia and Abnormal Endocrinological Test Results. Pediatrics 2017; 140:peds.2016-1402. [PMID: 28701428 DOI: 10.1542/peds.2016-1402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/10/2017] [Indexed: 11/24/2022] Open
Abstract
Mercury (Hg) poisoning is considered a rare disease by the National Institutes of Health and the diagnosis can present great challenges to clinicians. Children who are exposed to Hg can present with a wide variety of symptoms, including acrodynia, tremor, excessive salivation, and psychiatric symptoms, including insomnia. However, endocrinologic manifestations from Hg exposure are less well known. This is a case report of a 12-year-old boy who presented with body rash, irritability, insomnia, and profuse sweating after returning from a summer camp. The child was initially managed in the outpatient setting, and the investigation was mainly targeted toward infectious etiology, including Rocky Mountain spotted fever and Lyme disease. He was eventually admitted to the hospital with altered mental status and was noted to have hyponatremia with serum sodium of 121 mEq/L. Thyroid studies also revealed elevated free thyroxine levels in the presence of normal triiodothyronine and thyrotropin. The patient developed hypertension and tachycardia, and was found to have elevated 24-hour vanillylmandelic acid and metanephrines. Finally, heavy metal measurements revealed a blood Hg level that was greater than the reference values of 0 to 9 ng/mL. Chelation treatment with 2,3-dimercaptopropane-1-sulfonate was subsequently initiated and over a period of 8 months his symptoms resolved and his thyroid function test returned to normal. This case highlights some of the challenges commonly encountered in identifying Hg exposure. More importantly, it illustrates that exposure to Hg should be considered in children who present with the symptoms and abnormal endocrinologic test results described in this report.
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Affiliation(s)
- Matthew Carter
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, Michigan
| | - Abdul Abdi
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, Michigan
| | - Fareeha Naz
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, Michigan
| | - Farouq Thabet
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, Michigan
| | - Arpita Vyas
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, East Lansing, Michigan .,Department of Pediatrics, Texas Tech University, Odessa, Texas
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Fu D, Leef M, Nowak B, Bridle A. Thyroid hormone related gene transcription in southern sand flathead (Platycephalus bassensis) is associated with environmental mercury and arsenic exposure. ECOTOXICOLOGY (LONDON, ENGLAND) 2017; 26:600-612. [PMID: 28353161 DOI: 10.1007/s10646-017-1793-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/18/2017] [Indexed: 06/06/2023]
Abstract
Arsenic (As) and mercury (Hg) are ubiquitous elements known to disrupt thyroid function in vertebrates. To explore the underlying mechanisms of Hg and As on the fish thyroid system, we investigated the associations between muscle concentrations of Hg and As with thyroid-related gene transcription in flathead (Platycephalus bassensis) from a contaminated estuary. We sampled fish at several sites to determine the hepatic expression of genes including deiodinases (D1 and D2), transthyretin (TTR), thyroid hormone receptors (TRα and TRβ) and related them to Hg and As levels in the same individuals. Negative correlations were observed between Hg levels and D2, TTR, TRα and TRβ, whereas positive associations were found between As concentrations and TTR and TRβ. These results suggest that Hg and As exposures from environmental pollution affect the regulation of genes important for normal thyroid function in fish. These thyroid-related genes could be used as biomarkers for monitoring environmental thyroid-hormone disrupting chemicals.
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Affiliation(s)
- Dingkun Fu
- Institute for Marine and Antarctic Studies, University of Tasmania, Locked Bag 1370, Launceston, TAS, 7250, Australia.
| | - Melanie Leef
- Institute for Marine and Antarctic Studies, University of Tasmania, Locked Bag 1370, Launceston, TAS, 7250, Australia
| | - Barbara Nowak
- Institute for Marine and Antarctic Studies, University of Tasmania, Locked Bag 1370, Launceston, TAS, 7250, Australia
| | - Andrew Bridle
- Institute for Marine and Antarctic Studies, University of Tasmania, Locked Bag 1370, Launceston, TAS, 7250, Australia
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13
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Schumacher L, Abbott LC. Effects of methyl mercury exposure on pancreatic beta cell development and function. J Appl Toxicol 2016; 37:4-12. [PMID: 27594070 DOI: 10.1002/jat.3381] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/29/2016] [Accepted: 07/31/2016] [Indexed: 12/31/2022]
Abstract
Methyl mercury is an environmental contaminant of worldwide concern. Since the discovery of methyl mercury exposure due to eating contaminated fish as the underlying cause of the Minamata disaster, the scientific community has known about the sensitivity of the developing central nervous system to mercury toxicity. Warnings are given to pregnant women and young children to limit consumption of foods containing methyl mercury to protect the embryonic, fetal and postnatally developing central nervous system. However, evidence also suggests that exposure to methyl mercury or various forms of inorganic mercury may also affect development and function of other organs. Numerous reports indicate a worldwide increase in diabetes, particularly type 2 diabetes. Quite recently, methyl mercury has been shown to have adverse effects on pancreatic beta (β) cell development and function, resulting in insulin resistance and hyperglycemia and may even lead to the development of diabetes. This review discusses possible mechanisms by which methyl mercury exposure may adversely affect pancreatic β cell development and function, and the role that methyl mercury exposure may have in the reported worldwide increase in diabetes, particularly type 2 diabetes. While additional information is needed regarding associations between mercury exposure and specific mechanisms of the pathogenesis of diabetes in the human population, methyl mercury's adverse effects on the body's natural sources of antioxidants suggest that one possible therapeutic strategy could involve supplementation with antioxidants. Thus, it is important that additional investigation be undertaken into the role of methyl mercury exposure and reduced pancreatic β cell function. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Lauren Schumacher
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, TX, 77843-4458, USA
| | - Louise C Abbott
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, TX, 77843-4458, USA
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Benvenga S, Antonelli A, Vita R. Thyroid nodules and thyroid autoimmunity in the context of environmental pollution. Rev Endocr Metab Disord 2015; 16:319-40. [PMID: 26825072 DOI: 10.1007/s11154-016-9327-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Evidence suggests that in most industrialized countries autoimmune disorders, including chronic lymphocytic thyroiditis, are increasing. This increase parallels the one regarding differentiated thyroid cancer, the increment of which is mainly due to the papillary histotype. A number of studies have pointed to an association between chronic lymphocytic thyroiditis and differentiated thyroid cancer. The upward trend of these two thyroid diseases is sustained by certain environmental factors, such as polluting substances acting as endocrine disrupting chemicals. Herein we will review the experimental and clinical literature that highlights the effects of environmental and occupational exposure to polluting chemicals in the development of autoimmune thyroid disease or differentiated thyroid cancer. Stakeholders, starting from policymarkers, should become more sensitive to the consequences for the thyroid resulting from exposure to EDC. Indeed, the economic burden resulting from such consequences has not been quantified thus far.
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Affiliation(s)
- Salvatore Benvenga
- Department of Clinical and Experimental Medicine, University of Messina, Policlinico G. Martino, Padiglione H, 4 piano, via Consolare Valeria, 98125, Messina, Italy.
- Master Program on Childhood, Adolescent and Women's Endocrine Health, University of Messina School of Medicine, Messina, Italy.
- Interdepartmental Program of Molecular and Clinical Endocrinology, and Women's Endocrine Health, University Hospital Policlinico G. Martino, Messina, Italy.
| | - Alessandro Antonelli
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Roberto Vita
- Department of Clinical and Experimental Medicine, University of Messina, Policlinico G. Martino, Padiglione H, 4 piano, via Consolare Valeria, 98125, Messina, Italy
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Llop S, Lopez-Espinosa MJ, Murcia M, Alvarez-Pedrerol M, Vioque J, Aguinagalde X, Julvez J, Aurrekoetxea JJ, Espada M, Santa-Marina L, Rebagliato M, Ballester F. Synergism between exposure to mercury and use of iodine supplements on thyroid hormones in pregnant women. ENVIRONMENTAL RESEARCH 2015; 138:298-305. [PMID: 25749125 DOI: 10.1016/j.envres.2015.02.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/16/2015] [Accepted: 02/23/2015] [Indexed: 06/04/2023]
Abstract
OBJECTIVE To evaluate the association between mercury exposure and thyroid-stimulating hormone (TSH), total triiodothyronine (TT3) and free thyroxine (FT4) levels during pregnancy as well as to explore if there is any synergic action between mercury and intake of iodine from different sources. METHODS The study population was 1407 pregnant women participating in the Spanish INMA birth cohort study. Total mercury concentrations were analyzed in cord blood. Thyroid hormones (THs) were measured in serum samples collected at 13.2±1.5 weeks of gestation. The association between mercury and TH levels was evaluated with multivariate linear regression models. Effect modification caused by iodine intake from supplements and diet was also evaluated. RESULTS The geometric means of TSH, TT3, FT4 and mercury were 1.1μU/L, 2.4nmol/L, 10.5pmol/L and 7.7μg/L, respectively. Mercury levels were marginally significantly associated with TT3 (β: -0.05; 95%CI: -0.10, 0.01), but were neither associated with TSH nor FT4. The inverse association between mercury and TT3 levels was stronger among the iodine supplement consumers (-0.08; 95%CI: -0.15, -0.02, interaction p-value=0.07). The association with FT4 followed the same pattern, albeit not significant. CONCLUSION Prenatal mercury exposure was inversely associated with TT3 levels among women who took iodine supplements during pregnancy. These results could be of public health concern, although further research is needed.
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Affiliation(s)
- Sabrina Llop
- FISABIO-Universitat de València-Universitat Jaume I Joint Research Unit of Epidemiology and Environmental Health, Av. Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain.
| | - Maria-Jose Lopez-Espinosa
- FISABIO-Universitat de València-Universitat Jaume I Joint Research Unit of Epidemiology and Environmental Health, Av. Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - Mario Murcia
- FISABIO-Universitat de València-Universitat Jaume I Joint Research Unit of Epidemiology and Environmental Health, Av. Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - Mar Alvarez-Pedrerol
- Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader 88, 08003 Barcelona, Spain; Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Jesús Vioque
- Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Universidad Miguel Hernandez, Avenida de Alicante KM 87, 03550 Sant Joan d´Alacant, Spain
| | - Xabier Aguinagalde
- Laboratorio de Salud Pública de Alava, Santiago 11, 01002 Vitoria Gasteiz, Spain
| | - Jordi Julvez
- Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader 88, 08003 Barcelona, Spain; Municipal Institute of Medical Research (IMIM-Hospital del Mar), Doctor Aiguader 88, 08003 Barcelona, Spain
| | - Juan J Aurrekoetxea
- Departamento de Sanidad Gobierno Vasco, Subdirección de Salud Pública de Gipuzkoa, Avenida de Navarra 4, 20013 San Sebastián, Spain; Biodonostia, Instituto de Investigación Biomédica, Doctor Begiristain, s/n, 20014 San Sebastián, Spain; Departamento de Medicina Preventiva y Salud Pública, University of the Basque Country (UPV/EHU), Apartado 1599, 20014 San Sebastian, Spain
| | - Mercedes Espada
- Laboratorio de Salud Pública de Bizkaia, Departamento de Salud del Gobierno Vasco, Parque Tecnológico de Bizkaia, C/Ibaizabal, Edificio 502, 1ª Pt, 48160 Derio, Spain
| | - Loreto Santa-Marina
- Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Departamento de Sanidad Gobierno Vasco, Subdirección de Salud Pública de Gipuzkoa, Avenida de Navarra 4, 20013 San Sebastián, Spain; Biodonostia, Instituto de Investigación Biomédica, Doctor Begiristain, s/n, 20014 San Sebastián, Spain
| | - Marisa Rebagliato
- FISABIO-Universitat de València-Universitat Jaume I Joint Research Unit of Epidemiology and Environmental Health, Av. Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain; Universitat Jaume I, Av. de Vicent Sos Baynat, s/n, 12071 Castelló de la Plana, Spain
| | - Ferran Ballester
- FISABIO-Universitat de València-Universitat Jaume I Joint Research Unit of Epidemiology and Environmental Health, Av. Catalunya 21, 46020 Valencia, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Madrid, Spain
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Chen A, Kim SS, Chung E, Dietrich KN. Thyroid hormones in relation to lead, mercury, and cadmium exposure in the National Health and Nutrition Examination Survey, 2007-2008. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:181-6. [PMID: 23164649 PMCID: PMC3569681 DOI: 10.1289/ehp.1205239] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 11/15/2012] [Indexed: 05/25/2023]
Abstract
BACKGROUND Heavy metals, such as lead (Pb), mercury (Hg), and cadmium (Cd), are known toxicants, but their associations with the thyroid axis have not been well quantified at U.S. background levels. OBJECTIVES We investigated the relationships between thyroid hormones (total and free thyroxine [TT4 and FT4], total and free triiodothyronine [TT3 and FT3], thyroid-stimulating hormone [TSH], and thyroglobulin [Tg]) and levels of Pb, Hg, and Cd in blood and Cd in urine. METHODS We separately analyzed a sample of 1,109 adolescents (12-19 years of age) and a sample of 4,409 adults from the U.S. National Health and Nutrition Examination Survey (NHANES) 2007-2008. We estimated associations after adjusting for age, sex, race, urinary iodine, body mass index, and serum cotinine. RESULTS The geometric mean (GM) levels of blood Pb (BPb), total Hg, and Cd were 0.81 µg/dL, 0.47 µg/L, and 0.21 µg/L in adolescents and 1.43 µg/dL, 0.96 µg/L, and 0.38 µg/L in adults, respectively. The GMs of urinary Cd were 0.07 and 0.25 µg/g creatinine in adolescents and adults, respectively. No consistent pattern of metal and thyroid hormone associations was observed in adolescents. In adults, blood Hg was inversely related to TT4, TT3, and FT3 and urinary Cd was positively associated with TT4, TT3, FT3, and Tg, but there were no associations with Pb. Associations were relatively weak at an individual level, with about 1-4% change in thyroid hormones per interquartile range increase in Hg or Cd. CONCLUSIONS Our analysis suggests an inverse association between Hg exposure and thyroid hormones, and a positive association between Cd exposure and thyroid hormones in adults.
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Affiliation(s)
- Aimin Chen
- Department of Environmental Health, Division of Epidemiology and Biostatistics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
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17
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Ursinyova M, Uhnakova I, Serbin R, Masanova V, Husekova Z, Wsolova L. The relation between human exposure to mercury and thyroid hormone status. Biol Trace Elem Res 2012; 148:281-91. [PMID: 22426797 DOI: 10.1007/s12011-012-9382-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
Abstract
The aim of this study was to investigate total mercury (THg) and methylmercury (MeHg) exposure of 75 mother-child pairs in relation to their thyroid hormone status (thyroid-stimulating hormone (TSH), triiodothyronine (T3), free triiodothyronine (fT3), thyroxine (T4), and free thyroxine (fT4)). THg and MeHg in blood samples were measured by atomic absorption spectrometry and gas chromatography-inductively coupled plasma-mass spectrometry, respectively. The median THg and MeHg levels in maternal blood, cord blood, and blood of 6-month-old children were 0.50, 0.53, and 0.32 and 0.22, 0.32, and 0.08 μg/L, respectively. There were significant correlations between paired maternal-cord blood levels for THg and MeHg, with a greater transplacental transport of MeHg compared with THg (mean cord/maternal blood ratio, 1.80 vs. 1.24). The maternal blood THg was found to be a better predictor of TSH levels in children than their current THg exposure. There was a positive correlation between maternal THg and children's TSH. T3 and fT3 levels in children were negatively related to cord blood THg in the majority (Caucasian) subgroup, whereas these associations were positive in the Roma subgroup. Mothers with dental amalgam fillings had significantly lower T4 and fT4 levels. Moreover, fT4 in the mothers of boys negatively correlated with maternal THg levels. MeHg exposure lowered T3 levels in the mothers of girls. Our results suggest that low-level exposure to Hg can affect thyroid hormone status during prenatal and early postnatal exposure depending on the form of Hg, gender, ethnicity, lifestyle, or socioeconomic status (dental amalgam fillings).
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Affiliation(s)
- Monika Ursinyova
- Department of Metallomics, Slovak Medical University, Limbova 14, 83303 Bratislava, Slovakia
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18
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The effects of chronic ingestion of mercuric chloride on fertility and testosterone levels in male Sprague Dawley rats. J Biomed Biotechnol 2012; 2012:815186. [PMID: 22829750 PMCID: PMC3398687 DOI: 10.1155/2012/815186] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/06/2012] [Indexed: 11/25/2022] Open
Abstract
Although male infertility is well researched, the effects of inorganic mercury on male reproduction and fertility are less well known. Studies pertaining to mercury and male fertility identified reduced concentration of testosterone in the serum of male workers, a toxic influence on fertility of organic mercury compounds within concentrations at the workplace, and increased days to pregnancy. We evaluated the effect of chronic mercuric chloride (HgCl2) exposure in male rats on reproductive endpoints. Thirty-day old male Sprague Dawley rats (n = 31) were exposed to 0.0, 1.0, or 2.0 mg/kg/day of HgCl2 via gavage. After 60 days exposure, they were housed with nonexposed females for 21 days. A survivor analysis revealed the exposed animals took longer to impregnate the females and had a lower rate of impregnation. Further statistical analysis revealed a lower correlation between testicular testosterone levels and days to impregnate, and also lower sperm counts in the epididymis head and body of the exposed males. The results indicate that HgCl2 exposure had significant adverse effects on male rat reproduction endpoints including fertility at a dose that was not clinically toxic.
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Bernhoft RA. Mercury toxicity and treatment: a review of the literature. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2011; 2012:460508. [PMID: 22235210 PMCID: PMC3253456 DOI: 10.1155/2012/460508] [Citation(s) in RCA: 492] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/01/2011] [Indexed: 11/30/2022]
Abstract
Mercury is a toxic heavy metal which is widely dispersed in nature. Most human exposure results from fish consumption or dental amalgam. Mercury occurs in several chemical forms, with complex pharmacokinetics. Mercury is capable of inducing a wide range of clinical presentations. Diagnosis of mercury toxicity can be challenging but can be obtained with reasonable reliability. Effective therapies for clinical toxicity have been described.
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Affiliation(s)
- Robin A Bernhoft
- Bernhoft Center for Advanced Medicine, Suite 208, 11677 San Vicente Boulevard, Los Angeles, CA 90049, USA.
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20
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Novembrino C, De Giuseppe R, Bamonti F, Pigatto PD, Guzzi G. Graves' orbitopathy and oxidative stress. Orbit 2011; 30:63. [PMID: 20919814 DOI: 10.3109/01676830.2010.497576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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Holmes P, James KAF, Levy LS. Is low-level environmental mercury exposure of concern to human health? THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 408:171-82. [PMID: 19850321 DOI: 10.1016/j.scitotenv.2009.09.043] [Citation(s) in RCA: 231] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 09/17/2009] [Accepted: 09/24/2009] [Indexed: 05/24/2023]
Abstract
Mercury has long been recognised as toxic, principally in relation to its effects on humans following acute or prolonged high-level occupational exposures and, in the latter half of the last century, from a number of environmental incidents. Recognised target organs are the kidneys, central nervous system and thyroid glands. Recently concern has grown about the potential risks to the human population from current background environmental levels, leading bodies such as the World Health Organisation to call for the reduction or, wherever possible, elimination of the use of mercury. This review considers the strength of the epidemiological evidence on the effects of prolonged low-level exposure to the various forms of mercury. The limited research base suggests that several of the potential targets of long-term environmental exposure to mercury are similar to those occurring from occupational exposure including the renal, cardiovascular and immune systems. However, the evidence also suggests that, particularly in the case of organic mercury compounds, the most sensitive endpoint is central nervous system toxicity, especially in relation to exposure during the in utero period and childhood. It also appears that those human populations which have traditionally consumed diets high in seafoods are at greatest risk. While the extent of risk to the general population that may arise from existing environmental exposure levels appears limited, this conclusion is based on an incomplete dataset and therefore the general consensus view that exposure to mercury in its various forms should be minimised where practical, appears to be justified. A number of potential areas of further research are suggested as being pre-requisite to the development of a more rigorous risk assessment.
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Affiliation(s)
- P Holmes
- Institute of Environment and Health, Cranfield Health, First Floor Building 63, Cranfield University, Cranfield, Bedfordshire, MK43 0AL, UK.
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22
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Wada H, Cristol DA, McNabb FMA, Hopkins WA. Suppressed adrenocortical responses and thyroid hormone levels in birds near a mercury-contaminated river. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:6031-6038. [PMID: 19731714 DOI: 10.1021/es803707f] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Much of the research on sublethal, adverse effects of mercury (Hg) has focused on impairment of neurological function and reproduction in fish and fish-eating vertebrates. Here we examined the associations between Hg and endocrine function (adrenocortical responses and plasma thyroid hormone concentrations) of insectivorous tree swallow nestlings adjacent to a Hg-contaminated river and nearby reference rivers in Virginia. Nestlings from the contaminated sites had blood Hg concentrations that exceeded those from the reference sites by more than an order of magnitude (354 +/- 22 vs 17 +/- 1 ppb wet weight). A regression of age and Hg concentrations suggested dietary Hg at the contaminated sites exceeded the nestlings' capacity to eliminate Hg through deposition into growing feathers. Although blood Hg concentrations among nestlings at the contaminated sites were lower than those typically associated with abnormal behavior or altered physiology in young birds, adrenocortical responses, plasma triiodothyronine, and thyroxin concentrations were suppressed, relative to reference levels, by the end of the nestling period. These results suggest that (1) Hg may disrupt endocrine systems of terrestrial avian young and (2) adverse effects of Hg on endocrine systems may be most evident once endocrine axes are fully developed.
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Affiliation(s)
- Haruka Wada
- Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, 100 Cheatham Hall, Blacksburg, Virginia 24061, USA.
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23
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Tan SW, Meiller JC, Mahaffey KR. The endocrine effects of mercury in humans and wildlife. Crit Rev Toxicol 2009; 39:228-69. [DOI: 10.1080/10408440802233259] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Iavicoli I, Fontana L, Bergamaschi A. The effects of metals as endocrine disruptors. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2009; 12:206-23. [PMID: 19466673 DOI: 10.1080/10937400902902062] [Citation(s) in RCA: 295] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
This review reports current knowledge regarding the roles that cadmium (Cd), mercury (Hg), arsenic (As), lead (PB), manganese (Mn), and zinc (Zn) play as endocrine-disrupting chemicals (EDCs). The influence of these metals on the endocrine system, possible mechanisms of action, and consequent health effects were correlated between experimental animals and humans. Analysis of the studies prompted us to identify some critical issues related to this area and showed the need for more rigorous and innovative studies. Consequently, it was recommended that future studies need to: (1) identify the mechanisms of action, because at the present time only a few have been elucidated-in this context, the possible presence of hormesis need to be determined, as currently this was reported only for exposure Cd and As; (2) study the possible additive, synergistic, or antagonistic effects on the endocrine system following exposure to a mixture of metals since there is a lack of these studies available, and in general or occupational environments, humans are simultaneously exposed to different classes of xenobiotics, including metals, but also to organic compounds that might also be EDCs; (3) assess the potential adverse effects on the endocrine system of low-level exposures to metals, as most of the information currently available on EDCs originates from studies in which exposure levels were particularly high; and (4) assess the effects on the endocrine and reproductive systems of other metals that are present in the general and occupational environment that have not yet been evaluated.
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Affiliation(s)
- Ivo Iavicoli
- Institute of Occupational Medicine, Universita Cattolica del Sacro Cuore, Rome, Italy.
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Garnier R. Risque de cancer dans l’industrie de production du chlore et de soude caustique par électrolyse ? ARCH MAL PROF ENVIRO 2009. [DOI: 10.1016/j.admp.2008.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abdelouahab N, Mergler D, Takser L, Vanier C, St-Jean M, Baldwin M, Spear PA, Chan HM. Gender differences in the effects of organochlorines, mercury, and lead on thyroid hormone levels in lakeside communities of Quebec (Canada). ENVIRONMENTAL RESEARCH 2008; 107:380-392. [PMID: 18313043 DOI: 10.1016/j.envres.2008.01.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 10/29/2007] [Accepted: 01/03/2008] [Indexed: 05/26/2023]
Abstract
Environmental chemicals can disrupt endocrine balance and in particular thyroid hormone (TH) homeostasis. However, studies differ with respect to thyroid profile changes and gender differences are rarely examined. This study investigated the THs, triodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH), in relation to serum organochlorines (OCs), bioindicators of mercury (Hg) and blood lead (Pb) in 211 freshwater fish consumers (124 men and 87 women) from two communities in Canada. Thyroid hormones were within the normal range and the bioindicators of exposure were low compared to other reports on fish consumers. Stratified analysis showed that for women, serum T3 concentrations were negatively related to serum concentrations of PCB 138, PCB 153, the non-coplanar congeners, Arochlor 1260, and SigmaPCB, as well as p,p'-DDE. No relations were observed between T4 and any of the chemicals measured, but TSH was negatively related to blood Pb. For men, serum T4 was inversely related to PCB 138, non-ortho-substituted (dioxin-like) PCBs and SigmaPCB. A significant positive relationship was observed between serum TSH and different PCB congeners (PCB 138, PCB 180, non-coplanar congeners, mono-ortho coplanar congeners, dioxin-like PCBs), as well as SigmaPCB. Serum TSH increased with hair and blood Hg concentrations and was highest among those in the highest 50th percentile for both Hg and dioxin-like PCB congeners compared to the others. No associations were observed for T3 in men. These findings suggest that even at low concentrations, these environmental contaminants can interfere with thyroid status and effects may differ by gender.
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Affiliation(s)
- Nadia Abdelouahab
- Centre de Recherche Interdisciplinaire en Biologie, Santé, Société et Environnement CINBIOSE, Université du Québec à Montréal, Montréal, Québec, Canada.
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Bal-Price AK, Suñol C, Weiss DG, van Vliet E, Westerink RH, Costa LG. Application of in vitro neurotoxicity testing for regulatory purposes: Symposium III summary and research needs. Neurotoxicology 2008; 29:520-31. [DOI: 10.1016/j.neuro.2008.02.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Revised: 02/14/2008] [Accepted: 02/14/2008] [Indexed: 01/14/2023]
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Román GC. Autism: transient in utero hypothyroxinemia related to maternal flavonoid ingestion during pregnancy and to other environmental antithyroid agents. J Neurol Sci 2007; 262:15-26. [PMID: 17651757 DOI: 10.1016/j.jns.2007.06.023] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The incidence and prevalence of autism have increased during the past two decades. Despite comprehensive genetic studies the cause of autism remains unknown. This review emphasizes the potential importance of environmental factors in its causation. Alterations of cortical neuronal migration and cerebellar Purkinje cells have been observed in autism. Neuronal migration, via reelin regulation, requires triiodothyronine (T3) produced by deiodination of thyroxine (T4) by fetal brain deiodinases. Experimental animal models have shown that transient intrauterine deficits of thyroid hormones (as brief as 3 days) result in permanent alterations of cerebral cortical architecture reminiscent of those observed in brains of patients with autism. I postulate that early maternal hypothyroxinemia resulting in low T3 in the fetal brain during the period of neuronal cell migration (weeks 8-12 of pregnancy) may produce morphological brain changes leading to autism. Insufficient dietary iodine intake and a number of environmental antithyroid and goitrogenic agents can affect maternal thyroid function during pregnancy. The most common causes could include inhibition of deiodinases D2 or D3 from maternal ingestion of dietary flavonoids or from antithyroid environmental contaminants. Some plant isoflavonoids have profound effects on thyroid hormones and on the hypothalamus-pituitary axis. Genistein and daidzein from soy (Glycine max) inhibit thyroperoxidase that catalyzes iodination and thyroid hormone biosynthesis. Other plants with hypothyroid effects include pearl millet (Pennisetum glaucum) and fonio millet (Digitaria exilis); thiocyanate is found in Brassicae plants including cabbage, cauliflower, kale, rutabaga, and kohlrabi, as well as in tropical plants such as cassava, lima beans, linseed, bamboo shoots, and sweet potatoes. Tobacco smoke is also a source of thiocyanate. Environmental contaminants interfere with thyroid function including 60% of all herbicides, in particular 2,4-dichlorophenoxyacetic acid (2,4-D), acetochlor, aminotriazole, amitrole, bromoxynil, pendamethalin, mancozeb, and thioureas. Other antithyroid agents include polychlorinated biphenyls (PCBs), perchlorates, mercury, and coal derivatives such as resorcinol, phthalates, and anthracenes. A leading ecological study in Texas has correlated higher rates of autism in school districts affected by large environmental releases of mercury from industrial sources. Mercury is a well known antithyroid substance causing inhibition of deiodinases and thyroid peroxidase. The current surge of autism could be related to transient maternal hypothyroxinemia resulting from dietary and/or environmental exposure to antithyroid agents. Additional multidisciplinary epidemiological studies will be required to confirm this environmental hypothesis of autism.
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Affiliation(s)
- Gustavo C Román
- University of Texas Health Sciences Center at San Antonio, San Antonio, TX, USA.
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Costa LG, Fattori V, Giordano G, Vitalone A. An in vitro approach to assess the toxicity of certain food contaminants: Methylmercury and polychlorinated biphenyls. Toxicology 2007; 237:65-76. [PMID: 17553607 DOI: 10.1016/j.tox.2007.05.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 04/24/2007] [Accepted: 05/01/2007] [Indexed: 12/27/2022]
Abstract
Methylmercury (MeHg) and polychlorinated biphenyls (PCBs) are widespread environmental pollutants and food contaminants, and known developmental neurotoxicants. Aim of this study was to evaluate the effects of MeHg, PCB 126 and PCB 153 in a battery of in vitro cell systems. A total of 17 cell types were utilized, including nervous system (neuronal and astroglial) and non-nervous system cells. End-points measured included MTT reduction, Trypan blue exclusion and (3)H-thymidine incorporation into DNA. Results indicate that this approach would identify these three compounds as neurotoxicants, and would also point out to the thyroid (for PCB 126 and MeHg) and the prostate (for both PCBs) as important additional targets. Tests of binary combinations of MeHg and PCBs indicated no interaction and an additive response, in agreement with other recent reports. Cerebellar granule neurons from mice with genetically determined low glutathione levels were more sensitive than wild-type neurons to the toxicity of all three compounds, supporting a role for oxidative stress in their neurotoxicity. These findings provide initial evidence that a relatively rapid in vitro screening approach can be developed, that would provide initial information useful for assessing neurotoxicity, as well as indication on potential other targets of biological action or toxicity.
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Affiliation(s)
- Lucio G Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA; Department of Human Anatomy, Pharmacology and Forensic Sciences, University of Parma Medical School, Parma, Italy.
| | - Vittorio Fattori
- Department of Pharmacology and Human Physiology, University of Bari Medical School, Bari, Italy
| | - Gennaro Giordano
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Annabella Vitalone
- Department of Human Anatomy, Pharmacology and Forensic Sciences, University of Parma Medical School, Parma, Italy
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Abstract
This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."
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Affiliation(s)
- Thomas W Clarkson
- Department of Environmental Medicine, University of Rochester School of Medicine, New York, USA.
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Windham GC, Zhang L, Gunier R, Croen LA, Grether JK. Autism spectrum disorders in relation to distribution of hazardous air pollutants in the san francisco bay area. ENVIRONMENTAL HEALTH PERSPECTIVES 2006; 114:1438-44. [PMID: 16966102 PMCID: PMC1570060 DOI: 10.1289/ehp.9120] [Citation(s) in RCA: 268] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
OBJECTIVE To explore possible associations between autism spectrum disorders (ASD) and environmental exposures, we linked the California autism surveillance system to estimated hazardous air pollutant (HAP) concentrations compiled by the U.S. Environmental Protection Agency. METHODS Subjects included 284 children with ASD and 657 controls, born in 1994 in the San Francisco Bay area. We assigned exposure level by census tract of birth residence for 19 chemicals we identified as potential neurotoxicants, developmental toxicants, and/or endocrine disruptors from the 1996 HAPs database. Because concentrations of many of these were highly correlated, we combined the chemicals into mechanistic and structural groups, calculating summary index scores. We calculated ASD risk in the upper quartiles of these group scores or individual chemical concentrations compared with below the median, adjusting for demographic factors. RESULTS The adjusted odds ratios (AORs) were elevated by 50% in the top quartile of chlorinated solvents and heavy metals [95% confidence intervals (CIs) , 1.1-2.1], but not for aromatic solvents. Adjusting for these three groups simultaneously led to decreased risks for the solvents and increased risk for metals (AORs for metals: fourth quartile = 1.7 ; 95% CI, 1.0-3.0 ; third quartile = 1.95 ; 95% CI, 1.2-3.1) . The individual compounds that contributed most to these associations included mercury, cadmium, nickel, trichloroethylene, and vinyl chloride. CONCLUSIONS Our results suggest a potential association between autism and estimated metal concentrations, and possibly solvents, in ambient air around the birth residence, requiring confirmation and more refined exposure assessment in future studies.
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Affiliation(s)
- Gayle C Windham
- Division of Environmental and Occupational Disease Control, California Department of Health Services, Richmond, California, USA.
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Takser L, Mergler D, Baldwin M, de Grosbois S, Smargiassi A, Lafond J. Thyroid hormones in pregnancy in relation to environmental exposure to organochlorine compounds and mercury. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:1039-45. [PMID: 16079076 PMCID: PMC1280346 DOI: 10.1289/ehp.7685] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Polychlorinated biphenyls (PCBs), chlorinated pesticides, and mercury are global environmental contaminants that can disrupt the endocrine system in animals and humans. However, there is little evidence that they can interfere with endocrine status in pregnant women and neonates at low levels of exposure. The aim of this study was to examine thyroid hormone levels during pregnancy and in cord blood in relation to blood concentrations of organochlorine compounds (OCs) and Hg in healthy women recruited during pregnancy. We found a significant negative correlation between maternal total triiodothyronine levels and three non-coplanar congeners (PCB-138, PCB-153, and PCB-180), three pesticides (p,p -DDE, cis-nanochlor, and hexachlorobenzene), and inorganic Hg independently, without any other changes in thyroid status. No significant relationships were observed between OCs and cord serum thyroid hormones. Cord serum free thyroxin was negatively correlated with inorganic Hg. These results suggest that at even low levels of exposure, persistent environmental contaminants can interfere with thyroid status during pregnancy.
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Affiliation(s)
- Larissa Takser
- Laboratoire de Physiologie Materno-foetale, Université du Quebec à Montréal, Montréal, Quebec, Canada
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Brownawell AM, Berent S, Brent RL, Bruckner JV, Doull J, Gershwin EM, Hood RD, Matanoski GM, Rubin R, Weiss B, Karol MH. The Potential Adverse Health Effects of Dental Amalgam. ACTA ACUST UNITED AC 2005; 24:1-10. [PMID: 16042501 DOI: 10.2165/00139709-200524010-00001] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
There is significant public concern about the potential health effects of exposure to mercury vapour (Hg(0)) released from dental amalgam restorations. The purpose of this article is to provide information about the toxicokinetics of Hg(0), evaluate the findings from the recent scientific and medical literature, and identify research gaps that when filled may definitively support or refute the hypothesis that dental amalgam causes adverse health effects. Dental amalgam is a widely used restorative dental material that was introduced over 150 years ago. Most standard dental amalgam formulations contain approximately 50% elemental mercury. Experimental evidence consistently demonstrates that Hg(0) is released from dental amalgam restorations and is absorbed by the human body. Numerous studies report positive correlations between the number of dental amalgam restorations or surfaces and urine mercury concentrations in non-occupationally exposed individuals. Although of public concern, it is currently unclear what adverse health effects are caused by the levels of Hg(0) released from this restoration material. Historically, studies of occupationally exposed individuals have provided consistent information about the relationship between exposure to Hg(0) and adverse effects reflecting both nervous system and renal dysfunction. Workers are usually exposed to substantially higher Hg(0) levels than individuals with dental amalgam restorations and are typically exposed 8 hours per day for 20-30 years, whereas persons with dental amalgam restorations are exposed 24 hours per day over some portion of a lifetime. This review has uncovered no convincing evidence pointing to any adverse health effects that are attributable to dental amalgam restorations besides hypersensitivity in some individuals.
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Affiliation(s)
- Amy M Brownawell
- Life Sciences Research Office, Bethesda, Maryland 20814-3998, USA.
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