Toxicity from Heavy Metals Dissertation Example | Topics and Well Written Essays - 5000 words

Toxicity from Heavy Metals - Dissertation Example Heavy metals occur naturally in the crust of the Earth. These metals depict remarkable stability, and resist any attempt at degradation or destruction. As a consequence, heavy metals accumulate in sediments and soils. Some of the heavy metals have undergone drastic change in their biochemical and geological cycles, due to human activity (Department for Environment Food and Rural Affairs, 2008). Some of the primary man – made sources of heavy metals are the mines, smelters, foundries, traffic and by products of combustion. Heavy metals that are comparatively more volatile tend to be dispersed over vast areas through the atmosphere. In several cases, such heavy metals have been deposited thousands of miles from the site of their initial release into the atmosphere (Department for Environment Food and Rural Affairs, 2008). The suspension in the atmosphere of heavy metal particles, in general, depends on their size and lightness. Thus, heavy metal particles that are larger than 10 micro meters (Â µm) in diameter settle to the ground, under the influence of gravity. This takes a few hours for completion. However, the heavy metal particles that are less than 1Â µm in diameter persist in the atmosphere for weeks. Such particles are usually removed from the atmosphere, by precipitation (Department for Environment Food and Rural Affairs, 2008). ... However, the heavy metal particles that are less than 1Â µm in diameter persist in the atmosphere for weeks. Such particles are usually removed from the atmosphere, by precipitation (Department for Environment Food and Rural Affairs, 2008). A useful definition of heavy metals is given below. Heavy metals are chemical elements that have a specific gravity that is ? 5 times the specific gravity of water. At 40C the specific gravity is deemed to be 1, by convention. As such, specific gravity is the ration of the density of a substance to the density of water (LifeExtension, 2013). Toxicity in Heavy Metals Some of the toxic metals, whose specific gravity exceeds 5 times that of water are; arsenic with a specific gravity of 5.7, cadmium with a specific gravity of 8.65, iron with a specific gravity of 7.9, lead with a specific gravity of 11.34, and mercury with a specific gravity of 13.546 (LifeExtension, 2013). Heavy metals that cannot be metabolised by the human body accumulate in the s oft tissues and become toxic. The entry of heavy metals into the human body is via air, food, water; and cutaneous absorption due to agricultural activity; exposure during manufacturing, industrial or pharmaceutical activity; or residential exposure (LifeExtension, 2013). With regard to adults, the entry of toxic heavy metals is frequently on account of industrial exposure to these substances. Among children, ingestion is the most common reason for the entry of toxic heavy metals. It has been determined that normal hand to mouth activity could lead to the development of toxic levels of heavy metals among children. The infrequent or rare routes of toxic heavy metal entry into the human body include radiological procedures, incorrect dosing or monitoring during intravenous nutrition, a