Knowra Hexavalent chromium Hexavalent chromium Hexavalent chromium is chromium in the +6 oxidation state, usually present in chromate or dichromate compounds. Many such compounds are toxic, and some cause cancer after inhalation.
Chromate : Chromate is the tetrahedral oxyanion CrO₄²⁻, in which chromium has oxidation state +6. Chromate is a common dissolved form of hexavalent chromium in water.
Electroplating : Electroplating uses electric current to deposit a metal coating onto a conductive surface. Some plating baths use chromium(VI) compounds to produce hard, corrosion-resistant coatings.
Lung cancer : Lung cancer is a malignant growth arising in the tissues of the lungs. Inhaled chromium(VI) compounds are established occupational causes of lung cancer.
Chromium : Chromium is a metallic chemical element with atomic number 24 and several common oxidation states. Hexavalent chromium is one chemical state of this element, not a synonym for all chromium.
Dichromate : Dichromate is the orange oxyanion Cr₂O₇²⁻, containing two chromium(VI) atoms. Acidic conditions shift chromate toward this form, used in some industrial processes.
Chromate conversion coating : A chromate conversion coating is a protective surface layer formed by treating metal with chromate-containing solutions. This corrosion-control treatment has historically used hexavalent chromium on aluminum and other metals.
Occupational exposure : Occupational exposure is contact with chemical, physical, or biological hazards during work. Workers in plating, welding, and related industries can encounter airborne chromium(VI).
Trivalent chromium : Trivalent chromium is chromium in the +3 oxidation state, found in compounds with substantially different chemistry and toxicity from chromium(VI). Its lower toxicity and different biological behavior make it a key comparison.
Chromium(III) : Chromium(III) is chromium in the +3 oxidation state, a more stable and generally less toxic form than chromium(VI). Reduction of chromium(VI) to chromium(III) is central to its biological toxicity and remediation.
Stainless steel welding : Stainless steel welding joins corrosion-resistant steel by heating and fusing its components. Welding fumes can contain chromium(VI) formed from chromium in the steel.
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