Download or read book JV Task 96 Phase 2 Investigating the Importance of the Mercury Selenium Interaction written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to improve the understanding of the mercury issue, it is vital to study mercury's effects on selenium physiology. While mercury present in the environment or food sources may pose health risks, the protective effects of selenium have not been adequately considered in establishing regulatory policy. Numerous studies report that vulnerability to mercury toxicity is inversely proportional to selenium status or level. However, selenium status has not been considered in the development of the reference dosage levels for mercury exposure. Experimental animals fed low-selenium diets are far more vulnerable to mercury toxicity than animals fed normal selenium, and animals fed selenium-rich diets are even more resistant. Selenium-dependent enzymes in brain and endocrine tissues can be impaired by excessive mercury exposure, apparently because mercury has an extremely high binding affinity for selenium. When selenium becomes bound to mercury, it is unable to participate in the metabolic cycling of selenoprotein synthesis. Because of mercury-dependent impairments of selenoprotein synthesis, various antioxidant and regulatory functions in brain biochemistry are compromised. This report details a 2-year multiclient-funded research program designed to examine the interactions between mercury and selenium in animal models. The studies explored the effects of dietary intakes of toxic amounts of methylmercury and the protective effects of the normal dietary range of selenium in counteracting mercury toxicity. This study finds that the amounts of selenium present in ocean fish are sufficient to protect against far larger quantities of methylmercury than those present in typical seafoods. Toxic effects of methylmercury exposure were not directly proportional to mercury concentrations in blood, brain, or any other tissues. Instead, mercury toxicity was proportional to molar ratios of mercury relative to selenium. In order to accurately assess risk associated with methylmercury or mercury exposures, mercury-selenium ratios appear to be far more accurate and effective in identifying risk and protecting human and environmental health. This study also finds that methylmercury toxicity can be effectively treated by dietary selenium, preventing the death and progressive disabilities that otherwise occur in methylmercury-treated subjects. Remarkably, the positive response to selenium therapy was essentially equivalent regardless of whether or not toxic amounts of methylmercury were still administered. The findings of the Physiologically Oriented Integration of Nutrients and Toxins (POINT) models of the effects of mercury and selenium developed in this project are consistent with the hypothesis that mercury toxicity arises because of mercury-dependent inhibition of selenium availability in brain and endocrine tissues. This appears to occur through synergistic effects of mercury-dependent inhibition of selenium transport to these tissues and selective sequestration of the selenium present in the tissues. Compromised transport of selenium to the brain and endocrine tissues would be particularly hazardous to the developing fetus because the rapidly growing tissues of the child have no selenium reserves. Therefore, maternal consumption of foods with high mercury-selenium ratios is hazardous. In summation, methylmercury exposure is unlikely to cause harm in populations that eat selenium-rich diets but may cause harm among populations that consume certain foods that have methylmercury present in excess of selenium.
Download or read book JV Task 116 Selenium s Role in the Seafood Safety Issue written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Continuing studies under these three funded projects - (JV Task 77 The Health Implications of the Mercury-Selenium Interaction, JV Task 96 Investigating the Importance of the Mercury-Selenium Interaction, and JV Task 116 Selenium's Role in the Seafood Safety Issue) - were performed to determine the effects of different levels of dietary mercury and selenium on the growth and development of test animals, and related tissue analyses, to understand the protective benefits of dietary selenium in reference to low-level exposure to mercury. Maternal exposure to methylmercury from seafood has been found to cause neurodevelopmental harm in children. However, significant nutritional benefits will be lost if fish consumption is needlessly avoided. The results of these studies support the hypothesis that intracellular Se itself is the physiologically important biomolecule and that the harm of mercury toxicity arises when Hg abundance becomes great enough to bind a significant portion of intracellular Se in vulnerable tissues such as the brain. Formation of HgSe limits bioavailability of Se for synthesis of Se-dependent enzymes, particularly in brain tissues. When production of these enzymes is impaired, the loss of their numerous essential functions results in the signs and symptoms of Hg toxicity. The finding that one mole of Se protects against many moles of Hg indicates that its beneficial effect is not due to sequestration of mercury as HgSe but rather due to the biological activity of the Se. Therefore, the selenium content of seafoods must be considered along with their methylmercury contents in evaluating the effect of dietary exposure to mercury.
Download or read book Inorganic Species in Water written by Thomas B. Hoover and published by . This book was released on 1978 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stockley s Herbal Medicines Interactions written by Elizabeth M. Williamson and published by . This book was released on 2009 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains data on over 150 of the most commonly used herbal medicines, dietary supplements and nutraceuticals.
Download or read book Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms written by and published by DIANE Publishing. This book was released on 2002 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Human Health and Performance Risks of Space Exploration Missions written by Jancy C. McPhee and published by U. S. National Aeronautics & Space Administration. This book was released on 2009 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tolerable upper intake levels for vitamins and minerals written by European Commission. Scientific Committee on Food and published by . This book was released on 2006 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Water Quality Guidelines for the Protection of Aquatic Life written by Canada. Environment Canada and published by . This book was released on 2003 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Distributed by the Government of Canada Depository Services Program.
Download or read book Advances in Mercury Toxicology written by Tsuguyoshi Suzuki and published by Springer Science & Business Media. This book was released on 1991 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Aquatic Toxicology written by Mikko Nikinmaa and published by Elsevier. This book was released on 2014-07-01 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Introduction to Aquatic Toxicology is an introductory reference for all aspects of toxicology pertaining to aquatic environments. As water sources diminish, the need to understand the effects that contaminants may have on aquatic organisms and ecosystems increases in importance. This book will provide you with a solid understanding of aquatic toxicology, its past, its cutting-edge present and its likely future. An Introduction to Aquatic Toxicology will introduce you to the global issue of aquatic contamination, detailing the major sources of contamination, from where they originate, and their effects on aquatic organisms and their environment. State-of-the-art toxicological topics covered include nanotoxicology, toxicogenomics, bioinformatics, transcriptomics, metabolomics, as well as water management and the toxicological effects of major environmental issues such as algal blooms, climate change and ocean acidification. This book is intended for anyone who wants to know more about the impact of toxicants on aquatic organisms and ecosystems, or to keep up to date with recent and future developments in the field. - Provides with the latest perspectives on the impacts of toxicants on aquatic environments, such as nanotoxicology, toxicogenomics, ocean acidification and eutrophication - Offers a complete overview, beginning with the origins of aquatic toxicology and concluding with potential future challenges - Includes guidance on testing methods and a glossary of aquatic toxicology terms
Download or read book Extractive Metallurgy of Niobium written by A.K. Suri and published by Routledge. This book was released on 2017-11-13 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth and development witnessed today in modern science, engineering, and technology owes a heavy debt to the rare, refractory, and reactive metals group, of which niobium is a member. Extractive Metallurgy of Niobium presents a vivid account of the metal through its comprehensive discussions of properties and applications, resources and resource processing, chemical processing and compound preparation, metal extraction, and refining and consolidation. Typical flow sheets adopted in some leading niobium-producing countries for the beneficiation of various niobium sources are presented, and various chemical processes for producing pure forms of niobium intermediates such as chloride, fluoride, and oxide are discussed. The book also explains how to liberate the metal from its intermediates and describes the physico-chemical principles involved. It is an excellent reference for chemical metallurgists, hydrometallurgists, extraction and process metallurgists, and minerals processors. It is also valuable to a wide variety of scientists, engineers, technologists, and students interested in the topic.
Download or read book Field Manual of Wildlife Diseases written by and published by Geological Survey (USGS). This book was released on 1999 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stockley s Drug Interactions 9 written by Ivan H. Stockley and published by . This book was released on 2010 with total page 1792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guidelines for Drinking water Quality written by World Health Organization and published by World Health Organization. This book was released on 1993 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume describes the methods used in the surveillance of drinking water quality in the light of the special problems of small-community supplies, particularly in developing countries, and outlines the strategies necessary to ensure that surveillance is effective.
Download or read book Quantities Units and Symbols in Physical Chemistry written by International Union of Pure and Applied Chemistry. Physical and Biophysical Chemistry Division and published by Royal Society of Chemistry. This book was released on 2007 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prepared by the IUPAC Physical Chemistry Division this definitive manual, now in its third edition, is designed to improve the exchange of scientific information among the readers in different disciplines and across different nations. This book has been systematically brought up to date and new sections added to reflect the increasing volume of scientific literature and terminology and expressions being used. The Third Edition reflects the experience of the contributors with the previous editions and the comments and feedback have been integrated into this essential resource. This edition has been compiled in machine-readable form and will be available online.
Download or read book New Frontiers in Organoselenium Compounds written by Eder João Lenardão and published by Springer. This book was released on 2018-06-29 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents recent advances in and perspectives on the use of organoselenium compounds, primarily highlighting the new frontiers in the field of Green Chemistry, their therapeutic and biological relevance and new materials. Throughout its 200 pages, readers will find an updated and comprehensive review of new aspects of organoselenium chemistry and biochemistry. Fully referenced and written in an easy to read style, it offers readers a primary resource for including organoselenium derivatives in their projects. This book will be of interest to specialists, students and researchers involved in a broad range of fields, from synthetic green chemistry to medicinal chemistry and the chemistry of natural products. The connection between organoselenium compounds and green chemistry, despite having only recently emerged, is one of the subjects of this book. The first chapter highlights the use of Se-containing molecules as reagents and catalysts in new green protocols to access important organic transformations. The book provides a wealth of examples of bioactive Se-containing molecules, especially focusing on those with potential therapeutic uses. The second chapter focuses on the state of the art concerning the role of organoselenium compounds as antioxidants, GPx mimics, and derivatives endowed with different bioactive properties. “Organoselenium in nature” is the title of the third chapter, which equips readers with essential information on the main natural organoselenium compounds and where they are found. Selected aspects of the metabolism of selenium in plants and microorganisms are also discussed. In closing, the book includes a chapter dedicated to recent advances concerning the nonbonding interactions between organochalcogen compounds. This is currently a hot topic in selenium chemistry and biochemistry, and here readers will find key insights into the chalcogen bond and its role in the biological activity of organoselenium compounds.
Download or read book Water Quality for Ecosystem and Human Health written by Geneviève M. Carr and published by UNEP/Earthprint. This book was released on 2008 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document is intended to provide an overview of the major components of surface and ground water quality and how these relate to ecosystem and human health. Local, regional and global assessments of water quality monitoring data are used to illustrate key features of aquatic environments, and to demonstrate how human activities on the landscape can influence water quality in both positive and negative ways. Clear and concise background knowledge on water quality can serve to support other water assessments.
