Chromium

Abstract

Chromium occurs primarily in the trivalent state (III), which is the most stable form, or in the hexavalent state (VI), which is a strong oxidizing agent. Elemental chromium (0) does not occur naturally on earth. Trivalent chromium (III) is an essential trace metal necessary for the formation of glucose tolerance factor and for the metabolism of insulin. Commercial applications of chromium compounds include tanning (III), corrosion inhibition, plating, glassware-cleaning solutions, wood preservatives (VI), manufacture of safety matches, metal finishing (VI), and the production of pigments (III, VI). Hexavalent chromium (VI) contaminated local soil when chromium waste slag was part of the fill material present in residential, public, and industrial areas. In some urban areas, about two-thirds of the chromium in air results from the emission of hexavalent chromium from fossil fuel combustion and steel production. The remaining chromium in air is the trivalent form. The residence time of chromium in air is < 10 days, depending on the particle size. Trivalent compounds generally have low toxicity and the gastrointestinal tract poorly absorbs these compounds. Hexavalent chromium is a skin and mucous membrane irritant and some of these hexavalent compounds are strong corrosive agents. Hexavalent chromium compounds also produce an allergic contact dermatitis characterized by eczema. Sensitivity to trivalent compounds is much less frequent, but some workers may react to high concentrations of these compounds. Hexavalent chromium is recognized by the International Agency for Research on Cancer and by the US Toxicology Program as a pulmonary carcinogen. The increased risk of lung cancer occurs primarily in workers exposed to hexavalent chromium dust during the refining of chromite ore and the production of chromate pigments. Although individual studies suggest the possibility of an excess incidence of cancer at sites outside the lung, the results from these studies are inconsistent.

A Review of the Occupational and Environmental Health Hazards of Bauxite Mining in Malaysia

“…Long term intake of these metals causes organ toxicity and increases cancer risk (Barceloux, 1999;Ratnaike, 2003;Nawrot et. al, 2006;Hashim, 2016).…”

“…The other hazard is leaching of heavy metals and bauxite products into water; exerting chronic effects on adults and children, such as nerve and renal toxicity, cardiovascular conditions and delayed nerve development with high risk of cancer and death (Barceloux, 1999;Ratnaike, 2003;Nawrot et. al, 2006;Hashim, 2016).…”

“…These comprise lead, arsenic, mercury, cadmium, chromium, manganese and nickel and cause central and peripheral nerve harm. They affect nervous and cognitive functions, increases renal toxicity, with hypertension, cardiovascular problems, skin sensitivity and high mortality (Barceloux, 1999;Satoh, 2000;Lustberg and Silbergeld, 2002;Ratnaike, 2003;Crossgrove, 2004;Nawrot et. al, 2006;Das et.…”

Effect of Turmeric Oil in Reproductive Efficiency of Immature Female Rats Exposed to Oxidative Stress Induced by Potassium Dichromate

“…Chromium (Cr) exist in a series of oxidation states from -2 to + 6 valences, the most important stable states are elemental metal (0), trivalent (Cr III) and hexavalent (Cr VI) compounds (Barceloux, 1999;Shi et al, 2004;Zhitkovich, 2005;Valko et al, 2006). Cr (VI) is commonly used in multi-industrial processes, asbestos, cement, as well as in tobacco and food additives (Nriagu, 1988).…”

“…1980. Cr (VI) can traverse the placental barrier in rodents (Tipton and Shafer, 1964;Barceloux, 1999), and within the pregnant uterus Cr (VI) alters early development of blastocyst (Jacquet and Draye, 1982), decreases the number of implantation sites and viable fetuses . ; Kamath et al, 1997;Kanojia et al, 1998), produces embryo-toxic and fetotoxic effects and increase conceptus resorption in rodents.…”