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Chromium Information

Chromium is an odorless and tasteless metallic element. Chromium is found naturally in rocks, plants, soil and volcanic dust, and animals.

The most common forms of chromium that occur in natural waters in the environment are:


  -Trivalent chromium (chromium-3)
  -Hexavalent chromium (chromium-6)

Chromium-3 is an essential human dietary element. It is found in many vegetables, fruits, meats, grains, and yeast. 

Chromium-6 occurs naturally in the environment from the erosion of natural chromium deposits. It can also be produced by industrial processes. There are demonstrated instances of chromium being released to the environment by leakage, poor storage, or inadequate industrial waste disposal practices.

Where does haxavalent chromium come from?

In addition to natural sources, hexavalent chromium enters drinking water sources through discharges of dye and paint pigments, wood preservatives, chrome plating wastes, and leaching from hazardous waste sites. Not surprisingly, communities near chromium waste disposal sites or chromium manufacturing and processing plants are at particular risk of exposure. Probably the most impacted people are workers exposed on the job.


Potential Impacts:

What are the health effects of hexavalent chromium?


Hexavalent chromium is a carcinogen and a reproductive toxicant for both males and females. As a result, it was added to California's
Proposition 65
list of toxic substances (pdf) in December 2008. Exposure to hexavalent chromium occurs through breathing, ingestion, and contact with the skin. Although most of the known health impacts are related to inhalation, there is now strong data linking ingestion of hexavalent chromium, such as through drinking water, to severe health effects. In addition to cancer and reproductive harm, short and long-term exposures can lead to eye and respiratory irritation, asthma attacks, nasal ulcers, dermal burns, anemia, acute gastroenteritis, vertigo, gastrointestinal hemorrhage, convulsions, ulcers, and damage or failure of the liver and kidneys.

 

Does trivalent chromium convert to hexavalent chromium in drinking water distribution systems? 

If an oxidant like the disinfectants used in drinking water treatment and distribution is present, trivalent chromium may be oxidized to the hexavalent form, partially or completely. A WaterRF study (Brandhuber et al, 2004) evaluated the effects of free chlorine, chloramines, potassium permanganate and hydrogen peroxide in the oxidation of trivalent chromium to the hexavalent species. Free chlorine could oxidize 50 – 65% of trivalent to hexavalent chromium at neutral or low pH conditions. However, the presence of other ions and natural organic matter may lessen the re-oxidation of Cr(III) by chlorine (Clifford and Chau, 1987). The Water Research Foundation is currently funding research to explore the fate of trivalent as well as hexavalent chromium through treatment and the distribution system. A detailed discussion of the chemistry of chromium in drinking water treatment is available through the Water Research Foundation (McNeil, 2012).


Regulations:

The current federal drinking water standard for total chromium is 0.1
mg/l mg/l or 100 ppb. Chromium-6 and chromium-3 are covered under the total chromium drinking water standard because these forms of chromium can convert back and forth in water and in the human body, depending on environmental conditions. Measuring just one form may not capture all of the chromium that is present. In order to ensure that the greatest potential risk is addressed, EPA's regulation assumes that a measurement of total chromium is 100 percent chromium-6, the more toxic form. If tap water from a public water system exceeds this federal standard, consumers will be notified.

The Village of Orland Park tested for chromium 6 under the third Unregulated Contaminant Monitoring Rule (UCMR 3) from 2013-2014.  UCMR 3 requires monitoring for 30 contaminants (28 chemicals, including chromium 6, as well as two viruses) between 2013 and 2015 using analytical methods developed by EPA, consensus organizations or both. This monitoring provides a basis for future regulatory actions to protect public health.  Orland Park’s test results for chromium 6 were all well below the USEPA maximum contaminant level of 100 parts per billion.   

 

Village of Orland Park, Test Results for Chromium 6

Collection Date

Lab Result
 (parts per billion)

Maximum Contaminant Level (parts per billion)

4/10/2013

.21

100

4/10/2013

.20

100

7/10/2013

.03

100

7/10/2013

.18

100

10/9/2013

.22

100

10/9/2013

.20

100

1/15/2014

.20

100

1/15/2014

.20

100

  

The Chicago Department of Water Management has begun quarterly monitoring for chromium-6. Federal regulators and the drinking water industry are presently researching chromium-6, also referred to as hexavalent chromium, in an attempt to discover at what levels it might pose a health risk in drinking water. Chromium-6 is a naturally occurring contaminant and an industrial chemical that has been linked to cancer.

Currently, there are no regulations or requirements to test for chromium-6 in drinking water.  The EPA did issue a guidance statement on January 11, 2011. That statement recommended surface water systems like Chicago sample the source water, plant treated water, and water in the distribution system on a quarterly basis.

The Chicago Department of Water Management is voluntarily following the EPA’s recommendations. The EPA is developing a risk assessment for chromium-6 via ingestion; results should be available later this year. The risk assessment will form the basis of any regulations that may be developed for this element. The Chicago Department of Water Management is prepared to respond, immediately to any new regulations, for chromium-6, to protect public health and meet federal and state water quality standards.

All testing for chromium performed by the City of Chicago have shown results far below the USEPA Maximum Contaminant Level of 100 ug/l.  Quarterly results can be viewed by following the link below…

https://www.cityofchicago.org/city/en/depts/water/supp_info/water_quality_resultsandreports/chromium-6.html


Removal Process:

Hexavalent chromium in water can be treated in one of two ways: 1) direct removal of hexavalent chromium, or 2) reduction of hexavalent chromium to the trivalent form, followed by removal of trivalent chromium. Two technologies have been tested and found to be successful at the demonstration-scale (Blute (2010), Blute and Wu, (2012)) and pilot-scale (McGuire et al. (2006), McGuire et al. (2007), Qin et al. (2005)) in Glendale, Calif., including reduction coagulation filtration (RCF) and single use weak base anion exchange (WBA). Strong base anion exchange (SBA) has been tested at the pilot-scale (McGuire et al., 2006). All three technologies can achieve Cr(VI) concentrations less than 1 ppb. Targeting total Cr removal with the WBA process to less than 1 ppb is very costly compared with operating to achieve Cr(VI) removal, but can be achieved. RCF with microfiltration rather than granular media filtration was necessary to target total chromium concentrations of less than 1 ppb in demonstration testing. The evaluation of removals to lower levels has continued and is still underway in Glendale. Information collected through the Glendale studies has been sufficiently detailed to support development of basic cost models for RCF and WBA (Najm, 2013) and analyze management options for residual streams from these treatment technologies (Blute and Wu, 2012).