Last Update: August 22, 2013
Here are significant events associated with development of a maximum contaminant level (MCL) for chromium-6 (hexavalent chromium) in drinking water:
September 2000: The Governor signed SB 2127 (Schiff) into law. It requires CDHS to determine the levels of chromium-6 in drinking water supplied by public water systems in the San Fernando Basin aquifer, and, in consultation with OEHHA, assess the associated exposures and risks to the public.
January 2001: With adoption of a regulation identifying chromium-6 as an unregulated chemical requiring monitoring, CDHS began receiving sampling results.
March 2001: Cal/EPA asked the University of California to convene an expert panel to address the carcinogenicity of ingested chromium-6, and CDHS requested OEHHA to prepare a PHG for chromium-6. A PHG is needed for the development of a chromium-6-specific MCL.
July 2001: UC expert panel meets regarding carcinogenicity of ingested chromium-6.
August 2001: The expert panel's report (PDF)is released. Among its findings, the panel considered the mouse study providing the basis for the PHG's 0.2-µg/L de minimis cancer risk for ingested chromium-6 to be unsuitable for such use. The panel also concluded that the current total chromium MCL (50 µg/L) provides adequate public health protection, pending the completion of the NTP studies.
October 2001: The Governor signed SB 351 (Ortiz) (Health and Safety Code Section 116365.5, Chapter 602, Statutes of 2001) into law. It requires CDHS to adopt a chromium-6 MCL by January 1, 2004.
November 2001: OEHHA announced its withdrawal of the total chromium PHG. A chromium-6-specific PHG will be developed by OEHHA.
April 2003: At a legislative hearing in Sacramento on April 2, Cal/EPA announced it would not use the expert panel's report in the chromium-6 PHG—citing concerns about panelists' possible conflicts of interest—and OEHHA indicated the draft PHG would not be available until later that year.
August 2005: OEHHA released comments of peer reviewers (PDF) of a "pre-release" draft PHG for chromium-6.
May 2007: NTP's reports on studies on the carcinogenesis of chromium-6 (dichromate dihydrate) in drinking water—which found there to be sufficient evidence of carcinogenicity in rodents—are reviewed and approved by the Board of Scientific Counselors Technical Reports Review Subcommittee.
August 2009: OEHHA releases a draft PHG for chromium-6.
September 2010: OEHHA releases comments of peer reviewers of the August 2009 draft PHG.
September 2010: US EPA's IRIS releases its Toxicological Review of Hexavalent Chromium (External Review Draft) - now archived.
December 2010: OEHHA releases a revised draft PHG for chromium-6.
January 2011: US EPA releases its recommendations for enhanced chromium-6 monitoring for public water systems.
July 2011: OEHHA releases the final PHG for chromium-6.
August 2013: CDPH proposes an MCL for chromium--6.
Current status: See status of the MCL for chromium-6.
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