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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]
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 ]
Average hexavalent chromium levels in Hinkley were recorded as 1.19 parts-per-billion (ppb), with an estimated peak of 20 ppb. Based on the PG&E Background Study, the PG&E Topock Compressor Station averaged 7.8 ppb and peaked at 31.8 ppb. [33] The proposed California health goal for hexavalent chromium was 0.02 ppb in 2011. [34]
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 ...
In this compound, as in all chromates and dichromates, chromium is in a +6 oxidation state, commonly known as hexavalent chromium. It is a salt consisting of ammonium ions and dichromate ions. Ammonium dichromate is sometimes known as Vesuvian Fire , because of its use in demonstrations of tabletop "volcanoes". [ 2 ]
Exposure to the coplanar stereoisomer 3,3',4,4',5,5'-hexabromobiphenyl (but not the non-coplanar stereoisomer) in genetically susceptible mice is known to cause immunotoxicity and disorders related to the central nervous system, and even at doses as low as 2.5 mg/kg, excess neonatal fatalities are observed (LD 50 is from 5–10 mg/kg). [1]
The EPA has been successful in restricting five chemicals using section 6 authority (PCBs, chlorofluorocarbons, dioxin, asbestos, and hexavalent chromium) in its 38-year history, [39] with the ban on asbestos being partially overturned in 1991. [40] EPA has restricting some existing chemicals using Section 5 SNURs. [41] [42]
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 ...