Metal toxicity cobalt

The algal requirements for three essential trace metals—Fe, Mn and Zn—appear to determine trace metal toxicity in marine phytoplankton. Other essential metals such as copper or cobalt are sufficiently abundant that they more commonly function as toxicants than as limiting elements. Zinc presents the pecularity that it can both be limiting or toxic in most phytoplankters, the thresholds of Zn + limitation and toxicity are fairly close to each other, leaving a relatively narrow range of conditions that result in optimal growth. 

Cobalt, Co, is a metallic element. Cobalt 59 is the only stable isotope. Common isotopes are cobalt 57, cobalt 58, and the most common, cobalt 60. Cobalt is a steel-gray, shining, hard, ductile, and somewhat malleable metal. It has magnetic properties and corrodes readily in air. Cobalt dust is flammable and toxic by inhalation, with a TLV of 0.05 mg/m of air. It is an important trace element in soils and animal nutrition. Cobalt 57 is radioactive. It has a half-life of 267 days. It is a radioactive poison and is used in biological research. Cobalt 58 is also radioactive and has a half-life of 72 days. It is a radioactive poison, and it is used in biological and medical research. Cobalt 60 is one of the most common radioisotopes. It has a half-life of... 

Cobalt is one of the heavy metal toxic pollutants that is present in trace amounts in natural waters, the amount usually being less than 1 g/L. Consequently, its removal by adsorption using suitable adsorbents has been studied by a number of... 

The carbonyls of cobalt, like other metal carbonyls [see NilCOlJ, are the most toxic cobalt compounds. Co2(CO)8, Co4(CO),2 and Co6(CO)i6 are solid substances which are prepared from cobalt and carbon monoxide using elevated temperature and pressure. 

Cobalt difluoride, used primarily for the manufacture of cobalt trifluoride, CoF, is available from Advance Research Chemicals, Inc., Aldrich Chemicals, and PCR in the United States, Fluorochem in the UK, and Schuhardt in Germany. The 1993 price varied from 60 to 200/kg depending on the quantity and the price of cobalt metal. C0F2 is shipped as a corrosive and toxic material in DOT-approved containers. 

Trace metals can serve as essential nutrients and as toxic substances (Sunda et al, 1991 Frausto da Silva and Williams, 1991). For example, cobalt is a component of vitamin B-12. This vitamin is essential for nitrogen fixing algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and... 

In a different way, metallic-core nanoparticles [346-349] (prepared cf. Section 3.10) equipped with biocompatible coats such as L-cysteine or dextrane may be exploited for highly efficient and cell-specific cancer cell targeting, i.e., for improving diagnosis and therapy of human cancer. In a recent proof-of-principle experiment an unexpectedly low toxicity of the L-cysteine-covered cobalt nanoparticles was demonstrated [433] For diagnostic purposes, it is expected to use the advantageous magnetic properties of the metallic-core nanoparticles to obtain a contrast medium for MRI with considerably increased sensitivity, capable to detect micro-metastases in the environment of healthy tissues [434 37]. 

Coprecipitation is a partitioning process whereby toxic heavy metals precipitate from the aqueous phase even if the equilibrium solubility has not been exceeded. This process occurs when heavy metals are incorporated into the structure of silicon, aluminum, and iron oxides when these latter compounds precipitate out of solution. Iron hydroxide collects more toxic heavy metals (chromium, nickel, arsenic, selenium, cadmium, and thorium) during precipitation than aluminum hydroxide.38 Coprecipitation is considered to effectively remove trace amounts of lead and chromium from solution in injected wastes at New Johnsonville, Tennessee.39 Coprecipitation with carbonate minerals may be an important mechanism for dealing with cobalt, lead, zinc, and cadmium. 

Cyanide s binding to metallic ions is also employed in a reaction with cobalt-containing compounds that yields cyanocobalamin (see Section 2.6). Cobalt compounds generally are not used because of their toxicity however, Co2EDTA (Klimmek et al. 1983) and hydroxocobalamin (Benabid et al. 1987 Mengel et al. 1989 Mushett et al. 1952) have been used as antidotes both in clinical and laboratory trials. Cardiac toxicity from Co2EDTA use under clinical conditions has raised caution in its clinical use, as the cardiac... 

The corrosion rate of Pb02 - often enhanced by mechanical erosion - is relatively high and may be a problem due to the toxicity of lead. Pb02 can be stabilized by modification with, for example, silver, antimony, tin, cobalt oxides (or by alloying of the lead base metal with these metals, respectively) [29]. 

Like catalytic cracking, hydrocracking processes generate toxic metal compounds, many of which are present in spent catalyst sludge and catalyst fines generated from catalytic cracking and hydrocracking. These include metals such as nickel, cobalt, and molybdenum. 

Metals are extremely important not only for chemical reactions but also for the health and welfare of plants and animals. Some examples of metals required for good nutrition, even in trace amounts, are iron, copper, cobalt, potassium, sodium, and zinc. Other metals—for example, mercury, lead, cadmium, barium, beryllium, radium, and uranium—are very toxic. Some metals at the atomic and ionic levels are crucial for the oxidation process that metabolizes carbohydrates for all living cells. 

The dust and powder of cobalt metal, ores, and some compounds, such as cobaltous nitrate [ColNOfljT bH O], are flammable and toxic if inhaled. Cobaltous acetate [ColCjHjOjlj dHjO], which is soluble in water, is not allowed to be used in food products because of its toxicity. 

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