Path to Cr6 MCL


State of California—Health and Human Services Agency California Department of Public Health – NOTICE OF PROPOSED RULEMAKING: HEXAVALENT CHROMIUM MCL (DPH-11-005)


Hexavalent Chromium (Chromium-6) Maximum Contaminant Level (MCL) (DPH-11-005)

On August 23, 2013, CDPH announced in the California Regulatory Notice Register the availability of the proposed 0.010-milligram per liter MCL for hexavalent chromium (chromium-6) for public comment. The public comment period begins on August 23 and ends at 5:00 pm on October 11, 2013. CDPH will hold public hearings in Sacramento and in Los Angeles on October 11, 2013, to receive comments on the proposed regulations. Written comments may be submitted to the Office of Regulations (OOR) (see information on submitting comments). As required by the Administrative Procedure Act, all comments, whether written or presented at the public hearings, will be responded to in the final statement of reasons. Follow this link to OOR for the notice of proposed rulemaking (which includes times and locations of the hearings), the text of the proposed regulations, the initial statement of reasons, and other pertinent information.

Here is the CDPH press release announcing the availability of the proposed regulation.

Information about chromium-6 in drinking water and its regulation is available in our Fact Sheet (PDF) Opens in new window..

Current MCL for Total Chromium

Chromium-6 (hexavalent chromium) is currently regulated under the 50-micrograms per liter (µg/L) primary drinking water standard (maximum contaminant level, MCL} for total chromium. California’s MCL for total chromium was established in 1977, when we adopted what was then a “National Interim Drinking Water Standard” for chromium. The total chromium MCL was established to address exposures to chromium-6, the more toxic form of chromium. Chromium-3 (trivalent chromium) is a required nutrient.

The US Environmental Protection Agency (EPA) adopted the same 50-µg/L standard tor total chromium, but in 1991 raised the federal MCL to 100 µg/L. California did not follow US EPA’s change and stayed with its 50-µg/L standard.

A Specific MCL for Chromium-6

In 1999, as part of the process of reviewing MCLs in response to public health goals (PHGs), CDPH’s precursor, the California Department of Health Services (CDHS), identified the chromium MCL as one for review. In particular, we sought to determine whether or not an MCL that is specific for chromium-6 would be appropriate. Subsequently, events primarily between 1999-2001 and concerns about chromium-6’s potential carcinogenicity when ingested resulted in a state law that requires CDPH to adopt a chromium-6-specific MCL (see chromium-6 timeline).

California’s Health and Safety Code guides the development of an MCL for chromium-6: §116365.5 requires the adoption of an MCL for chromium-6 by January 1, 2004. In addition, Health and Safety Code §116365(a) requires CDPH to establish an MCL at a level as close as is technically and economically feasible to the contaminant’s PHG, which is the concentration of a contaminant in drinking water that does not pose a significant risk to health. PHGs are developed by Cal/EPA’s Office of Environmental Health Hazard Assessment (OEHHA).

In July 2011 OEHHA established a PHG for chromium-6 of 0.02 µg/L. The PHG represents a de minimis lifetime cancer risk from exposure to chromium-6 in drinking water, based on studies in laboratory animals. OEHHA has also prepared a PHG fact sheet.

The availability of the chromium-6 PHG enabled CDPH to proceed with setting a primary drinking water standard (see the MCL process), and on August 23, 2013, CDPH proposed a chromium-6-specific MCL of 0.010 milligram per liter (equivalent to 10 µg/L). Completion of the rulemaking process may take up to 12 months after the proposal. In the absence of any major delays, an enforceable MCL is anticipated to be established in 2014.

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Readers interested in the levels of chromium in their drinking water should refer to their water systems’ annual Consumer Confidence Reports (CCRs). Many CCRs for California water systems are available on the US EPA’s CCR website.

Source: Chromium-6 in Drinking Water: MCL Update