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CAS Number: 7440-47-3
Synonyms: Chromium (III), Chromium (VI), Cr (III), Cr (VI), Hexavalent Chromium, Trivalent Chromium
Contaminant Type: Chemical

Chromium and its compounds are used in metal alloys such as stainless steel, protective coatings on metal, magnetic tapes, and pigments for paints, cement paper, rubber, composition floor covering and other materials. Other users includes: chemical intermediate for wood preservatives, organic chemical synthesis, photochemical processing and industrial water treatment.  In medicine, chromium compounds are used in astringents and antiseptics.  They also are used in cooling waters, and in the leather tanning industry, in catalytic manufacture, and fungicides, as an algaecide against slime forming bacteria and yeasts in brewery processing water and brewery warmer water. [1381,1398,1414]

Chromium is not likely to migrate to groundwater.  A field trial on the application of wastewater treatment slude to soil found movement of heavy metals, including chromium, from the soil surface to a depth of 10 cm, but most of the metals (mean 87%) remained in the upper 5 cm of soil.  Uptake by plants is generally low, it was found to be greater from ultrabasic soils by a factor of 5-40 than on calcareous or silica-based soils.[1419]

Chromium compounds are very persistant in water.  Most of the chromium in surface waters may be present in particulate form as sediments.  Some of the particulate chromium would remain as suspended matter and ultimately be deposited in sediments. The exact chemical form of chromium in surface waters are not well defined.  Although most of the soluble chromium in surface waters may be present as Cr (VI), a small amount may be present as Cr (III) organic complexes.[1419]

EPA has found chromium to potentially cause the skin irritation or ulceration related health effects from acute exposures at levels above the MCL. Chromium has the potential to damage liver, kidney circulatory and nerve tissues, and dermatitis  from long-term exposures at levels above the MCL.  In late 2010 EPA noted recent risk assessment of chromium-6 as a likely human carcinogen by ingestion and that it was considering tightening the chromium drinking water standard in 2011. 

EPA has set an MCL of 100 ug/L for total chromium.  Background levels in water average 1 ug/L while municipal drinking water contain 0.1 - 35 ug/L.  The higher values of chromium can be related to source of anthropogenic pollution.  A survey of 3834 tap waters reported the concentrations of chromium to range from 0.4 - 8 ug/L.  The reported chromium concentrations in this study may be a little higher than the actual values due to inadequate flushing of tap water before collection of samples.  This indicates that the concentrations of chromium in household tap water have potential to increase due to house plumbing materials.[1419]

Total chromium is regulated in drinking water in the US with a MCL of 0.10 mg/L or 100 ug/L based on the total concentration of the trivalent and hexavalent forms of dissolved chromium.  USEPA has identified several teatment processes as Best Available Technologies (BATs) for control of chromium in drinkign water.  They are: Coagulation/filtration, ion exchange, reverse osmosis, and lime softening.[1419]

Date of Literature Search: March 2010


1381 Eary, L. E., Rai, D.; 1988; Chromate removal from aqueous wastes by reduction with ferrous ion; Environ. Sci. Technol.; 22(8): 972-977
1392 Kozlowski, C. A., Walkowiak, W.; 2002; Removal of chromium(VI) from aqueous solution by polymer inclusion membranes; Wat. Res.; 36: 4870-4876
1398 Natraj, S. K., Hosamani, K. M., Aminabhavi, T. M.; 2007; Potential application of an electrodialysis pilot plant containing ion-exchange membranes in chromium removal; Desalination; 217: 181-190
1414 U. S. Department of Health and Human Services; 2008; Draft toxicological profile for chromium; Draft Toxicological Profile for chromium; Agency for Toxic Substances and Disease Registry
1419 USEPA; 2010; Technical factsheet on: Chromium; USEPA;