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Information and Data on Chromium-6

Last updated Oct. 12, 2017 - 8:33 am

In light of the recent media spotlight (a study released on December 20, 2010 by the Washington-based Environmental Working Group) on Hexavalent Chromium (chromium-6), the City of Raleigh Public Utilities Department is providing the following facts related to chromium-6 in its water and what the City is doing to monitor chromium-6 levels in the City of Raleigh water distribution system.

Latest news updates can be found below.

If you have additional questions, please contact our Assistant Director of Public Utilities at 919-996-3489.

Latest Updates

August 1, 2017
California’s water agency agreed to eliminate the cap on hexavalent chromium in drinking water, the toxic chemical made famous in the movie “Erin Brockovich.”

Erin Brockovich weighs in on California’s removal of limits on chemical made famous in movie

September 14, 2015
California Extends Chromium 6 Compliance Deadline

April-May 2014
EPA Takes Next Steps on Hexavalent Chromium

September 3, 2013
California Proposes Hexavalent Chromium Standard

Previous Updates

March 2, 2013
In an InsideEPA online newsletter article states that soon-to-be published risk research shows that EPA's current drinking water limit for hexavalent chromium (Cr6) is adequately protective, bolstering chemical industry efforts to push EPA to soften its controversial 2010 draft assessment that labeled the metal a human carcinogen and was expected to drive stricter regulatory standards.

Industry Says Pending Study Shows No Need To Strengthen EPA's Cr6 Limits

May 1, 2012
In an InsideEPA online newsletter posted May 1, 2012, article author David LaRoss notes that the EPA is adding hexavalent chromium (Cr6) to the list of currently unregulated contaminants for which utilities must monitor. This requires utilities to monitor both total chromium and Cr6. The rule gives large systems until October 31 to develop and submit a testing schedule to EPA. View InsideEPA Document

March 19, 2012
In an InsideEPA online newsletter posted March 13, 2012, article author David LaRoss notes. View Inside EPA Document

March 5, 2012
EPA Sets New Schedule For Hexavalent Chromium IRIS Risk Assessment
On February 28, EPA updated its schedule to complete its Integrated Risk Information System (IRIS) risk assessment of Hexavalent Chromium (Cr-VI). The draft Cr-VI IRIS assessment, focusing on oral ingestion of Cr-VI, was originally scheduled for a fall 2011 release. However, the oral risk assessment will now be combined with an inhalation exposure assessment also under development and will be released in 2013 for public and external peer review. Based on that schedule, release of a final Cr-VI IRIS assessment would not be expected until at least 2014. View AMWA Regulatory Report

February 29, 2012
The studies referenced in the February 6, 2012 AMWA Monday morning article, Studies Show Non-Linear Cr-VI Cancer Risk, are "new" in the sense that they are recent or very near completion, including peer review and publication. However, the preliminary results of the studies have been in discussion for some time and AMWA, along with other associations, has submitted comments to the EPA which should be incorporated into their IRIS risk assessment for Cr-VI . This is very likely one of the main reasons the EPA IRIS assessment for Cr-VI has been delayed. --Scott Biernat, Manager of Regulatory Affairs, AMWA

So What Do the Measured Units Mean?

Water professionals have the technology today to detect more substances at lower levels than ever before. As analytical methods improve, various compounds, including hexavalent chromium, are likely to be found at very low levels in many of our nation's lakes, rivers and streams. Current EPA standards for all types of chromium provide for a maximum contaminant limit of 100 parts per billion (ppb), with some States adopting a more stringent standard of 50 ppb of total chromium. To better illustrate the extremely low level concentrations of chromium in our drinking water supply, current contaminant limits of 100 parts per billion could be compared to:

  • 100 seconds of time in 32 years
  • 100 kernels of corn in a 45-foot high, 16-foot diameter silo
  • 100 drops of liquid in a railroad tanker car
Learn more about So What Do the Measured Units Mean?

What is the City of Raleigh Doing?

EPA's Third Unregulated Contaiminant Monitoring Rule (UCMR-3)

As recommended by EPA, the City of Raleigh undertook preliminary sampling for chromium-6 under several source water and finished water conditions. Water distribution sampling locations coincided with lead and copper sampling locations and maximum residence times within the system. The following table presents the city's results for this voluntary testing.

Chromium-6 Data 2011 through 2015

  • Finished water is water that has passed through all processes in a water treatment plant and is ready to be delivered to consumers.
  • Raw water is intake water prior to any treatment or use.

As research evolves on this subject, the City of Raleigh will continue to monitor the results and will comply with all standards adopted through implementation of new federal and state regulations. The City is committed to protecting public health and ensuring the safety of the drinking water for our customers in Raleigh and surrounding communities of Garner, Knightdale, Rolesville, Wake Forest, Wendell and Zebulon.

Is My Water Safe?

Yes, your water is safe to drink! As noted above, chromium-6 is currently regulated as part of the 'total chromium' drinking water standard under the Federal Safe Drinking Water Act (SDWA). This standard addresses all forms of chromium, including chromium-6. The current drinking water standard sets the maximum contaminant level (MCL) of total chromium allowed in drinking water at 100 parts per billion (ppb), also equivalent to 100 micrograms per liter (ug/L).

  • The water community, of which the City of Raleigh is a part, is absolutely committed to protecting public health. The advent of safe treated water supplies can be counted among the greatest public health achievements of modern society.
  • Water professionals are researching the occurrence of Hexavalent Chromium in drinking water supplies and are paying close attention to health effects research as it become available.
  • The fact that a substance is detectable does not mean the substance is harmful to humans.
  • While this metal may be detected at very low levels in source waters, people regularly consume or expose themselves to products containing this metal in much higher concentrations (i.e., chrome fixtures, metal pots and other chromed items around the home). The level in which they are found in source waters is very small in comparison.
  • The EPA maintains an active program called the Contaminant Candidate List (CCL) to identify contaminants in public drinking water that warrant detailed study. The EPA is currently evaluating Hexavalent Chromium through this and other programs.

While research has not conclusively demonstrated human health impacts from chromium-6 at the ultra-low levels found in some drinking water supplies, the ongoing debate should remind us of how precious our water resources are and of the need to protect them from harmful substances. As a society, we should encourage policies that protect source water from contaminants introduced into the environment.

Learn more about Is My Water Safe?

History of Chromium-6

Hexavalent chromium (also known as chromium-6) is currently a topic of national debate and research. As with other contaminants of concern, the U.S. Environmental Protection Agency (EPA) has begun a "rigorous and comprehensive review of the potential health effects" of ultra low level concentrations of chromium. Hexavalent chromium is one of 20 chemicals currently being reviewed by the EPA for possible further regulations. Chromium is a naturally occurring metallic element in the periodic table. It is odorless and tasteless. Chromium is found throughout nature, including in humans, other animals, plants, soils, volcanic dust and water. The three most common forms of chromium found are chromium (0), chromium-3 and chromium-6. The metal chromium or chromium (0) is used in the making of steel. Chromium-3 and chromium-6 are both used for chrome plating, dyes and tanning processes.

Learn more about History of Chromium-6

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