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Tungsten is a naturally occurring, high tensile strength element that has been used in a number of consumer products. Tungsten has been detected in soil, waterways, groundwater, and human tissue and body fluids. Elevated levels of tungsten in urine were reported for populations exposed to tungstate in drinking water in areas where natural tungsten formations were prevalent. Published reports indicated that sodium tungstate may modulate hematopoiesis, immune cell populations, and immune responses in rodent models. The objective of this study was to assess potential immunotoxicity of sodium tungstate dihydrate (STD), a drinking water contaminant. Female B6C3F1/N mice received 0–2000 mg STD/L in their drinking water for 28 days, and were evaluated for effects on immune cell populations in spleen and bone marrow, and humoral-mediated, cell-mediated, and innate immunity. Three different parameters of cell-mediated immunity were similarly affected at 1000 mg STD/L. T-cell proliferative responses against allogeneic leukocytes and anti-CD3 were decreased 32%, and 21%, respectively. Cytotoxic T-lymphocyte activity was decreased at all effector:target cell ratios examined. At 2000 mg STD/L, the absolute numbers of CD3+ T-cell progenitor cells in bone marrow were increased 86%, but the alterations in B-lymphocyte and other progenitor cells were not significant. There were no effects on bone marrow DNA synthesis or colony forming capabilities. STD-induced effects on humoral-mediated immunity, innate immunity, and splenocyte sub-populations were limited. Enhanced histopathology did not detect treatment-related lesions in any of the immune tissues. These data suggest exposure to STD in drinking water may adversely effect cell-mediated immunity.
Tungsten is a naturally occurring, high tensile strength element that has been used in a number of consumer products. Tungsten has been detected in soil, waterways, groundwater, and human tissue and body fluids. Elevated levels of tungsten in urine were reported for populations exposed to tungstate in drinking water in areas where natural tungsten formations were prevalent. Published reports indicated that sodium tungstate may modulate hematopoiesis, immune cell populations, and immune responses in rodent models. The objective of this study was to assess potential immunotoxicity of sodium tungstate dihydrate (STD), a drinking water contaminant. Female B6C3F1/N mice received 0–2000 mg STD/L in their drinking water for 28 days, and were evaluated for effects on immune cell populations in spleen and bone marrow, and humoral-mediated, cell-mediated, and innate immunity. Three different parameters of cell-mediated immunity were similarly affected at 1000 mg STD/L. T-cell proliferative responses against allogeneic leukocytes and anti-CD3 were decreased 32%, and 21%, respectively. Cytotoxic T-lymphocyte activity was decreased at all effector:target cell ratios examined. At 2000 mg STD/L, the absolute numbers of CD3+ T-cell progenitor cells in bone marrow were increased 86%, but the alterations in B-lymphocyte and other progenitor cells were not significant. There were no effects on bone marrow DNA synthesis or colony forming capabilities. STD-induced effects on humoral-mediated immunity, innate immunity, and splenocyte sub-populations were limited. Enhanced histopathology did not detect treatment-related lesions in any of the immune tissues. These data suggest exposure to STD in drinking water may adversely effect cell-mediated immunity.
Tungsten is a rare metal with numerous applications, most notably in machine tools, catalysts, and superalloys. The physical and chemical properties of tungsten and its compounds of commercial importance (such as sodium tungstate, ammonium meta ‐ and para ‐tungstate, tungsten metal, tungsten carbide, and tungsten oxides), as well as tungsten industrialization, recycling, occupational exposure, and biomonitoring are discussed. Between 1970 and 1990, most tungsten toxicological investigations concerned the toxicity and health effects of cemented carbides, also known as hard metal, rather than tungsten and its compounds themselves. However, within the last decade a diversity of studies on the toxicity of the water soluble and bioavailable sodium tungstate, have been conducted to fill several toxicity knowledge gaps. Acute toxicity studies on several soluble (sodium tungstate, ammonium para ‐ and meta ‐tungstate) and sparingly water‐soluble (tungsten metal, tungsten oxides, tungsten carbide) substances reported low acute oral, dermal, and inhalation toxicity, as well as a lack of eye and dermal irritation and sensitization potential. Studies published within the last 5–7 years on sodium tungstate include oral repeated exposure, reproductive, developmental, neurotoxicological, and immunotoxicological endpoints. Several reports have incorrectly associated repeated exposure toxicity of hard metals with pure tungsten carbide. As the toxicity of hard metal does not represent the intrinsic toxicity of tungsten substances so it is discussed separately within this chapter.
The article contains sections titled: 1. Introduction 2. Properties 2.1. Physical Properties 2.2. Chemical Properties 3. Raw Materials 3.1. Natural Resources 3.2. Tungsten Scrap 4. Production 4.1. Mining and Ore Beneficiation 4.2. Pretreatment of Ore Concentrates and Scrap 4.3. Hydrometallurgy 4.3.1. Digestion 4.3.2. Purification 4.3.3. Conversion of Sodium Tungstate Solution to Ammonium Tungstate Solution 4.3.4. Crystallization of Ammonium Paratungstate (APT) 4.4. Production of Tungsten Oxides 4.5. Production of Tungsten Metal Powder 4.6. Production of High‐Purity Tungsten Metal (99.999 ‐ 99.9999%) 4.7. Powder Metallurgy (PM) 4.8. Metal Injection Molding 4.8.1 MIM Process Overview 4.8.2 General Guidelines 4.8.3 MIM of Tungsten, Tungsten Alloys, Tungsten–Copper Composites, Tungsten Heavy Alloy, and Cemented Carbide 4.9. Additive Manufacturing of Tungsten and Cemented Carbides (WC–Co) 4.10. Fabrication of Wrought PM Tungsten 4.10.1. Shaping–Mill Products 4.10.2 Mechanical Bonding of Tungsten to Tungsten and Other Metals 4.11. Surface Treatment 4.12. Melting 5. Tungsten Alloys 5.1. Single‐Phase Solid‐Solution Alloys 5.2. Multiphase Alloys 5.2.1 Tungsten Heavy Metals 5.2.2. Tungsten–Copper and Tungsten–Silver Composites 5.2.3. Non‐Sag Tungsten 5.2.4 Alloys with Oxide Dispersions 5.2.5 Porous, Infiltrated Tungsten 6. Uses of Tungsten 6.1. Tungsten and Tungsten Alloys 6.2. Cemented Carbides (WC–Co) 6.3. Tungsten Coatings 7. Tungsten in Melting Metallurgy of Steel and Superalloys 7.1. Tungsten in Steel 7.2. Tungsten in Superalloys 7.3. Master Alloys 7.3.1 Ferrotungsten 7.3.2. Tungsten Melting Base 7.3.3. Master Alloys for Superalloys 7.4. Production of Master Alloys 7.4.1. Production of Ferrotungsten 7.4.2. Production of Tungsten Melting Base 7.4.3. Production of Master Alloys for Superalloys 8. Tungsten Compounds and Their Application 8.1. Tungsten Chemistry 8.2. Aqueous Solutions of Tungsten 8.3. Intermetallic Compounds 8.4. Compounds with Nonmetals 8.4.1. Tungsten–Boron Compounds 8.4.2. Tungsten–Carbon Compounds 8.4.3. Tungsten–Silicon Compounds 8.4.4. Tungsten–Group 15 Compounds 8.4.5. Tungsten–Oxygen Compounds 8.4.6. Tungsten–Chalcogenide Compounds 8.4.7. Tungsten–Halogenide Compounds 9. Tungsten in Catalysis 10. Tungsten Recycling 10.1. Direct Recycling 10.2. Semi‐Direct Methods 10.3. Hydrometallurgy 10.4. Melting Metallurgy 11. Analysis 11.1. Raw Materials 11.2. High Purity Intermediate Products, Tungsten Powder and Sintered Tungsten Metal 11.3 Trace Elements in High‐Purity Tungsten Metal 12. Economic Aspects 12.1. Production 12.2. Consumption 12.3 Price 13. Toxicology and Occupational Health 13.1. Toxicokinetics 13.2. Acute Toxicity 13.3. Subchronic and Chronic Toxicity 13.4. Genotoxicity 13.5. Carcinogenicity 13.6. Reproductive Toxicity 13.7. Developmental Toxicity 13.8. Immunotoxicity 13.9. Human Biomonitoring Data 13.10. Occupational Health 14. Acknowledgements
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