Chromium
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Chromium can exist in a number of oxidation states of which trivalent chromium (chromium III) or hexavalent chromium (chromium VI) are most predominant.
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The toxicity of chromium is dictated by the oxidation state of the chromium, and can also be compound specific.
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Small amounts of trivalent chromium (chromium III) are essential for our well being.
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Neither hexavalent nor trivalent chromium compounds are particularly well absorbed after ingestion.
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The most important route of exposure for hexavalent chromium is by inhalation.
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Upon absorption into the body, the majority of Chromium VI is rapidly reduced to Chromium III which will accumulate predominantly in the kidneys, lungs, bone marrow, liver, testes, spleen and lymph nodes.
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Trivalent chromium and hexavalent chromium are common forms, and unlike metallic chromium (oxidation state of zero) are known to cause allergic reactions. In the body it is believed that hexavalent chromium is reduced to trivalent chromium, which acts as a hapten binding with cellular proteins and triggering an allergic reaction.
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The prevalence of chromium contact allergies in the general population varies and it has been estimated that in the European population it is about 1%.
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The IARC (International Agency for Research on Cancer) has classified Chromium [VI] as carcinogenic to humans (Group 1). Chromium and chromium [III] compounds are not classifiable as to their carcinogenicity to humans (Group 3).
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The motion picture “Erin Brockovich” was a film about hexavalent chromium that was found in drinking water in the American town of Hinkley, and the resulting health effects.