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Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent). [1] It has been identified as carcinogenic, which is of concern since approximately 136,000 tonnes (150,000 tons) of hexavalent chromium were produced in 1985. [ 2 ]
An example of this chemical causing adverse health issues is through a well-known hexavalent chromium (chromium 6) pollution event in Hinkley, California. Groundwater contamination in Hinkley was caused by water containing hexavalent chromium being dumped on the ground by Pacific Gas and Electric (PG&E) from 1952 to 1966. PG&E used this ...
There were an estimated 700 properties above or near the chromium groundwater contamination. The EPA found that 14 out of the 512 investigated basements had hexavalent chromium levels above acceptable; the EPA removed the chromium and installed systems to prevent further contamination in thirteen out of the fourteen basements. [1]
The chromium is oxidized to the hexavalent form, while the iron forms iron(III) oxide, Fe 2 O 3: 4 FeCr 2 O 4 + 8 Na 2 CO 3 + 7 O 2 → 8 Na 2 CrO 4 + 2 Fe 2 O 3 + 8 CO 2. Subsequent leaching of this material at higher temperatures dissolves the chromates, leaving a residue of insoluble iron oxide. Normally the chromate solution is further ...
Hexavalent chromium is the most toxic form of chromium. In the U.S., the Environmental Protection Agency regulates it heavily. The EPA lists hexavalent chromium as a hazardous air pollutant because it is a human carcinogen , a "priority pollutant" under the Clean Water Act , and a "hazardous constituent" under the Resource Conservation and ...
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[1] [2] PG&E used chromium 6, or hexavalent chromium (a cheap and efficient rust suppressor), in its compressor station for natural-gas transmission pipelines. [1] [3] Hexavalent-chromium compounds are genotoxic carcinogens. In 1993, legal clerk Erin Brockovich began an investigation into the health impacts of the contamination. A class-action ...
When you buy a bottle of vitamins from a nutrition store, you’ll probably notice a best-by date on the bottom of the jar. But that inscribed number isn’t a hard-and-fast rule—there is some ...