Heavy metal toxicity cobalt

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... 

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. 

Heavy metals stimulate or inhibit a wide variety of enzyme systems (16, 71, 72), sometimes for protracted periods (71, 73). These effects may be so sensitive as to precede overt toxicity as in the case of lead-induced inhibition of 8 ALA dehydrase activity with consequential interference of heme and porphyrin synthesis (15, 16). Urinary excretion of 8 ALA is also a sensitive indicator of lead absorption (74). Another erythrocytic enzyme, glucose-6-phosphatase, when present in abnormally low amounts, may increase susceptibility to lead intoxication (75), and for this reason, screens to detect such affected persons in lead-related injuries have been suggested (76). Biochemical bases for trace element toxicity have been described for the heavy metals (16), selenium (77), fluoride (78), and cobalt (79). Heavy metal metabolic injury, in addition to producing primary toxicity, can adversely alter drug detoxification mechanisms (80, 81), with possible secondary consequences for that portion of the population on medication. 

The metals of most concern are the heavy metals, especially cadmium, lead, and mercury. Although it is a metalloid with characteristics of both metals and nonmetals, arsenic is commonly classified as a heavy metal for a discussion of its toxicity. Though not particularly toxic, zinc is abundant and may reach toxic levels in some cases. For example, zinc accumulates in sewage sludge and crop productivity has been lowered on land fertilized with sludge because of zinc accumulation. Copper may be toxic to plants. Aluminum, a natural constituent of soil, may be leached from soil by polluted acidic rainwater and reach levels that are toxic to plants. Other metals that may be of concern because of their toxicides include chromium, cobalt, iron, nickel, and vanadium. Radium, a radioactive alpha particle-emitting metal, can be very toxic at even very low levels in water or food. 

The metabolism of zinc is influenced by hormones, stress situations, lipopolysaccharides, toxins, oxygen radicals, lipid peroxidations, etc. This may lead to fluctuations in the zinc concentration, mainly due to the induction of metallothioneine (MT), which is a transport and intracellular depot protein. One third of this protein consists of cysteine, which binds zinc, copper, cadmium, cobalt and mercury. This protects the body from toxic heavy metal... 

Relatively few studies are available on cobalt removal from waters even though it is an important industrial material and may be toxic (though not as much as some of the other heavy metals). The dominant species in aqueous solutions is Co- [123]. The mononuclear hydrolysis products of Co(II) from CoOH to... 

Artistic inks and dyes, as well as those used in textiles are generally nontoxic, though occasionally irritating or allergenic to some. They are known to have high contents of heavy metals, such as cobalt, lead, mercury, and others, many of which are common skin irritants, and some of which are carcinogens and reproductive toxicants therefore large and frequent... 

Cobalt as a heavy metal has toxic problems and aromatic amines are also suspect. The quantities used are quite small (<1,000 ppm) and remain in the plastic... 

The issue of the so-called heavy metals has caused concern within the chemical industry for some time. While the term heavy metal might have been derived originally on the basis of density, this property alone does not necessarily relate directly to toxicity or environmental behaviour. In fact, certain metals, for example iron, zinc, manganese, copper, chromium, molybdenum and cobalt, might technically be described as heavy , yet they are essential for life. The term has come to be used to represent those metals that are regarded as detrimental to the environment when a certain concentration is... 

Heavy metals ate potentially dangerous toxicants which are the destabilizing factor in the ecological system of established biocoenosis. lead, cadmium, meicuiy, cobalt, and other heavy metals may be inducers of the oxidative stress, which is based on formation of excessive quantity of free radicals [1, 2], Their reactivity is extremely high and initiates chain oxidation reaction. Free radicals become the reason for serious functional disorders, because various cell components are damaged [3]. Initiation of hpid peroxidation in biological membranes is an example and promotes disturbance of their structure and penetrability increase. Specialized enzymatic and nonenzymatic antioxidant systerrrs are protection against free radicals [4]. 

At one time, cobalt chloride, a salt of the metal cobalt, was added to beer in the USA as a foam stabilizer. Such salts had been used to treat people with anaemia at doses of 300 mg per day without any apparent problems. However, heavy beer drinkers, who drank about 10 litres per day, suffered effects on the heart, known as cardiomyopathy, a degeneration of the heart muscle, which was eventually ascribed to the cobalt. It transpired that, while cobalt alone was apparently not toxic to the heart, even at single doses many times higher than the exposure from the additive in beer, in the exceptionally heavy drinkers the toxic effects of cobalt were greatly increased. It turned out that the victims were malnourished individuals and deficient in particular amino acids, which was an important factor in increasing the toxicity of the cobalt. Furthermore, the excessive alcohol intake was itself an additional factor. The potentiation of the toxicity of cobalt was unexpected and so had not been taken into account in the safety assessment. This illustrates the difficulty of anticipating all possible circumstances in safety evaluation. 

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