Silver
描述
Silver is widely distributed in the earth's crust and is found in soil, fresh and sea water, and the air. It is readily absorbed into the human body with food and drink and through inhalation, but the low levels of silver commonly present in the bloodstream (< 2.3 b.mu g/L) and in key tissues like liver and kidney have not been associated with any disease or disability. Silver is not an acknowledged trace element in the human body and fulfills no physiological or biochemical role in any tissue even though it interacts with several essential elements including zinc and calcium. Physiologically, it exists as an ion in the body. Silver has a long history in the treatment of human diseases, including epilepsy, neonatal eye disease, venereal diseases, and wound infections. It has been employed in water purification and is currently used to safeguard hospital hot water systems against Legionella infections. Principle routes of human exposure to silver nowadays are through its widespread use as an antimicrobial agent in wound care products and medical devices, including in-dwelling catheters, bone cements, cardiac valves and prostheses, orthopedic pins, and dental devices. In each case, the antimicrobial properties of silver are dependent upon release of biologically active silver ion (Ag*) from metallic silver (including nanocrystalline forms), silver nitrate, silver sulfadiazine, and other silver compounds incorporated in the various devices, and its lethal effect on pathogenic organisms. Experience has shown that a large proportion of the silver ion released from medical devices not required for antimicrobial action is disseminated into tissue fluids and exudates, where it combines with albumins and macroglobulins. These silver-protein complexes are absorbed into the systemic circulation to be deposited in key soft tissues, including the skin, liver, kidney, spleen, lungs, and brain. As a xenobiotic material, silver must be presumed to present a health risk to exposed persons under some circumstances. Unlike the well-documented neurotoxic metals including lead and mercury, silver does not appear to be a cumulative poison and is eliminated from the body through the urine and feces. Excretion of silver by these routes may be a measure of mean daily intake, but since this view is based largely on the clinical use of silver nitrate and silver sulfadiazine used in burn wound therapy, its true relevance in the metabolism of silver used in the wider context of medical devices is questionable. Argyria is the most widely publicized clinical condition associated with silver accumulation in blood and soft tissues. It commonly occurs in individuals exposed to high levels of silver occupationally (metallurgy, photography, and mining industries), or consuming or inhaling silver hygiene products (including colloidal silver products) for long periods. Silver is absorbed into the body and deposited in the perivascular regions of the skin and other soft tissues as black granules of silver sulfide or silver selenide. The resulting slate grey discoloration of the skin occasionally associated with melanogenic changes, is semipermanent and cosmetically undesirable but is not known to be life-threatening. (A7730).
类别
"Household Toxin", "Industrial/Workplace Toxin", "Pollutant", "Food Toxin", "Natural Toxin"
同义词
"Ag", "Ag(1+)", "Ag+", "Argentum", "Silver cation", "Silver ion (1+)", "Silver metal", "Silver(0)", "Silver(1+)", "Silver(1+) ion", "Silver(I) cation"
InChI 标识符
InChI=1S/Ag/q+1
键
InChIKey=FOIXSVOLVBLSDH-UHFFFAOYSA-N
化合物类型
Inorganic compounds
大分类
Homogeneous metal compounds
类型
Homogeneous transition metal compounds
直接大类
Homogeneous transition metal compounds
取代基
"Homogeneous transition metal"
外部描述符
"a cation", "elemental silver", "monoatomic monocation", "monovalent inorganic cation", "silver cation"
地位
Detected and Not Quantified
蜂窝位置
"Cytoplasm", "Extracellular"
熔点/沸点/溶解度
960.5°C/2212°C (4013.6°F)/
暴露途径
Oral (L808) ; inhalation (L808) ; dermal (L808)
毒性机制
Metallic silver is oxidized and may deposit in the tissues, causing arygria. The silver ion is known to inhibit glutathione peroxidase and NA+,K+-ATPase activity, respectively disrupting selenium-catalyzed sulfhydryl oxidation-reduction reactions and intracellular ion concentrations. Silver nanoparticles are believed to disrupt the mitochondrial respiratory chain, causing oxidative stress, reduced ATP synthesis, and DNA damage. (L808, A243, A244, A245, A246)
代谢
Silver and its compounds can be absorbed via inhalation, orally and dermally. It distributes throughout the body, particularily to the liver. Insoluble silver salts are transformed into soluble silver sulfide albuminates, bind to amino or carboxyl groups in RNA, DNA, and proteins, or are reduced to metallic silver by ascorbic acid or catecholamines. Metallic silver is oxidized and may deposit in the tissues, causing arygria. Silver is eliminated primarily in the faeces. (L808)
毒性值
LD50: 100 mg/kg (Oral, Mouse) (T34)
用途/来源
Most silver is produced as a by-product of copper, gold, lead, and zinc refining. Silver is a precious metal used to make ornaments, jewelry, silverware, and currency coins. It is also used in electrical equipment, mirrors, dental fillings, and brazing alloys and solders. Silver compounds are used in photographic film and as antibacterial agents. (L808, L809)
健康影响
Silver itself is not toxic to humans, but most silver salts are. In large doses, silver and compounds containing it can be absorbed into the circulatory system and become deposited in various body tissues, leading to argyria, which results in a blue-grayish pigmentation of the skin, eyes, and mucous membranes. Argyria is rare, and although, so far as known, this condition does not otherwise harm a person's health, it is disfiguring and usually permanent. Mild forms of argyria are sometimes mistaken for cyanosis. (L809)
症状
Exposure to high levels of silver for a long period of time may result in a condition called arygria, a blue-gray discoloration of the skin and other body tissues. Argyria is a permanent effect but does not appear to be harmful to health. Exposure to high levels of silver in the air has resulted in breathing problems, lung and throat irritation, and stomach pains. Skin contact with silver can cause mild allergic reactions such as rash, swelling, and inflammation in some people. (L808)
维基百科链接
http://en.wikipedia.org/wiki/Silver
创建于
2009-03-06 18:58:18 UTC
更新于
2014-12-24 20:21:20 UTC