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California Proposes New Standard for Hexavalent Chromium

The California Department of Public Health (CDPH) has proposed a Maximum Contaminant Level (MCL) of 10 µg/L (or ppb) for hexavalent chromium, also called chromium 6.  Currently in California, hexavalent chromium does not have its own MCL but is regulated as a part of the MCL for total chromium which is set at 50 µg/L by the state.  EPA, and other states, also do not have a separate MCL but include consideration of hexavalent chromium under the federal total chromium standard of 100 µg/L.

State legislation in 2001 required the CDPH to set a hexavalent chromium MCL.  In 2011, California established a Public Health Goal (PHG) of 0.02 µg/L for hexavalent chromium.  The Public Health Goal is the state equivalent of EPA’s Maximum Contaminant Level Goal (MCLG).  EPA does not have a separate MCLG for hexavalent chromium but the Total Chromium MCLG is currently 100 µg/L, the same as the MCL.  California is required to set the MCL as close to the PHG as technically and economically feasible.  The cost of treatment was cited as a major factor in setting the MCL at 10 µg/L in California, instead of some lower number closer to 0.02 µg/L.  According to an LA Times article, some water systems in the state are already treating chromium 6 to half the proposed MCL, and environmental groups have been pushing for a much lower number for the standard.  With the number of systems impacted and the level of interest in chromium 6, it’s safe to assume there will be many comments on the MCL proposal during the comment period which runs until October 11, 2013.  A final MCL could be issued sometime in 2014.

See the CDPH news release and the publication of the proposed standard for additional details.  There is also extensive background information on hexavalent chromium on the CDPH chromium 6 website, including a fact sheet, information about chromium 6 monitoring results in California, and links to other resources on chromium 6.