![]() ![]() Hexavalent Cr compounds have varied uses in industry and are often used for their anti-corrosive properties in metal coatings, protective paints, dyes and pigments. ![]() Studies have shown that Cr(III) is not toxic and non-carcinogenic. Trivalent chromium, Cr(III), which is the most stable form of chromium, is found in trace amounts in the human body and is believed to be necessary for sugar metabolism. Chromium has oxidation states ranging from -2 to +6, of which the divalent (+2, chromous), trivalent (+3, Chromic) and hexavalent (+6) are the most important. The toxicity of hexavalent Cr arises from its ability to bind to cellular macromolecules. The US Environmental Protection Agency has classified Cr(VI) compounds as ‘Group A carcinogens’, while the International Agency for Research on Cancer (IARC) as ‘known human carcinogens by inhalation (Group 1)’. Hexavalent Cr or Cr(VI) is one of the oxidation states of the element Cr and is the toxic form that poses a health risk to workers exposed to it. The presence of Cr in the +6 oxidation state (Cr) is still observed in ambient air samples in California despite steps taken to reduce emissions from plating operations, welding and other types of ‘hot work’ on stainless steel and other metals that contain Cr, and spray paints and coatings. The toxic effects of certain chromium (Cr) compounds in air have been recognized for a long time. In particular, as the profile of metals as toxic air pollutants has grown in recent years, so the air quality infrastructure put in place to make measurements of these pollutants has similarly increased. Air quality remains a concern to governments, regulators, and the public because of the detrimental effect that air pollutants can have on human health and environmental sustainability.
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