- Cadmium (Cd) is a German scientist discovered in 1817, ranked No. 48 Cadmium in the periodic table of chemical elements D.I.Mendeleev scientist (1834-1907). From reviews of scientific researchers, indicates Cadmium is one of the three metals that endanger human lives the most, two remaining types is Lead and Mercury.- Cadmium may be grouped in the following categories: releases from natural sources, in other words, releases resulting from natural mobilization of naturally occurring cadmium from the Earth's crust and mantle, such as volcanic activity and weathering of rocks; current anthropogenic releases from the mobilization of cadmium impurities in raw materials such as phosphate minerals, fossil fuels and other extracted, treated and recycled metals - particularly zinc and copper; current anthropogenic releases of cadmium used in products and processes, as a result of use, disposal, recycling, reclamation, open burning or incineration; releases from municipal installations; and the mobilization of historical anthropogenic and natural cadmium releases previously deposited in soils, sediments, landfills and waste or tailings piles ( united nations environment programme, Chemicals Branch, DTIE )- Cadmium is an element that occurs naturally in the earth’s crust. It usually combines with other elements such as oxygen, chlorine or sulphur to form cadmium oxide, cadmium chloride or cadmium sulphate. Cadmium oxide is most commonly found in the air whereas cadmium chloride and cadmium sulphate dissolve in water. The type of cadmium is important when assessing the risk of adverse health effects (Prepared by S Bull CHAPD HQ, HPA 2010 Version 3 ) - Cadmium containing products are rarely re-cycled, but frequently dumped together with household waste, thereby contaminating the environment, especially if the waste is incinerated. Natural as well as anthropogenic sources of cadmium, including industrial emissions and the application of fertilizer and sewage sludge to farm land, may lead to contamination of soils, and to increased cadmium uptake by crops and vegetables, grown for human consumption ( Lars Järup, Department of Epidemiology and Public Health, Imperial College, London, UK )- The main route of cadmium exposure in the occupational setting is via the respiratory tract. Air concentrations of cadmium fumes or dust vary considerably between different industries, such as smelters, pigment plants and battery factories (Järup et al., 1998a)- Cd enters the body through cigarette smoke, paint, and contaminated foods and refined grains in particular. This is a heavy metal present in the soil, rarely in the form of essences, often combined with other ingredients to produce various types, such as: cadmium oxide, cadmium chloride, cadmium sulfate, cadmium sulfide. Soil, sand, stone, coal, phosphate fertilizers contain cadmium.- In soil, the chemistry of cadmium is to a great extent controlled by pH. Cadmium may be adsorbed on clay minerals, carbonates or hydrous oxides of iron and manganese or may be precipitated as cadmium carbonate, hydroxide, and phosphate. Under acidic conditions cadmium solubility increases, and very little adsorption of cadmium by soil colloids, hydrous oxides, and organic matter takes place. Both toxicity and bioavailability of cadmium are influenced by soil characteristics (ECB, 2005). Soil characteristics influence cadmium sorption and therefore its bioavailability and toxicity (ECB, 2005). Cadmium mobility and bioavailability are higher in noncalcareous than in calcareous soils (Thornton 1992, as cited by ATSDR, 1999). Liming of soil raises the pH, increasing cadmium adsorption to the soil and reducing bioavailability (He and Singh 1994; Thornton 1992, as cited by ATSDR, 1999)
-
- Cd survive and thrive in the human body from 10-30 years cause disease silently and prolonged, and there are currently no effective treatment methods caused by Cd. So we need to avoid poisoning prevention Cd, avoid creating environmental pollutants, and if there is exposure to Cd, the need to take measures to prevent, not to have the opportunity Cd enters human body.
- In soil, the chemistry of cadmium is to a great extent controlled by pH. Cadmium may be adsorbed on clay minerals, carbonates or hydrous oxides of iron and manganese or may be precipitated as cadmium carbonate, hydroxide, and phosphate. Under acidic conditions cadmium solubility increases, and very little adsorption of cadmium by soil colloids, hydrous oxides, and organic matter takes place. Both toxicity and bioavailability of cadmium are influenced by soil characteristics (ECB, 2005). Soil characteristics influence cadmium sorption and therefore its bioavailability and toxicity (ECB, 2005). Cadmium mobility and bioavailability are higher in noncalcareous than in calcareous soils (Thornton 1992, as cited by ATSDR, 1999). Liming of soil raises the pH, increasing cadmium adsorption to the soil and reducing bioavailability (He and Singh
đang được dịch, vui lòng đợi..