As the bioavailability of a particular chemical species can produce detrimental human health effects, trace element speciation in groundwater, surface water and drinking waters has been of major concern in the natural environment for decades. Many states, as well as the U. S. EPA, have only regulated total chromium levels in drinking water, with the total chromium standard (including Trivalent Chromium or the Chromium-3 chemical species) being 50 ppb and 100 ppb, respectively. The state of California has now established a “groundbreaking” drinking water regulation for Hexavalent Chromium, or the Chromium-6 chemical species (a known carcinogen), at a maximum contaminant level of 10 ppb. Information concerning this new regulation can be found below:
Groundwater Information Sheet – Hexavalent Chromium [State Water Resources Control Board (SWRCB); May 2014]
http://www.swrcb.ca.gov/gama/docs/coc_hexchromcr6.pdf
Chromium-6 in Drinking Water Sources: Sampling Results [California Department of Public Health (CDPH); Updated March 2014]
http://www.cdph.ca.gov/certlic/drinkingwater/pages/chromium6sampling.aspx
Hexavalent Chromium Maximum Contaminant Limit (MCL), DPH-11-005; March 14, 2014 (Title 22 California Code of Regulations, Division 4, Chapter 14, Article 3)
Chromium in Drinking Water
[World Health Organization (WHO), 2003]
http://www.who.int/water_sanitation_health/dwq/chemicals/chromium.pdf
U. S. EPA Methods
EPA Method 218.7: Determination of Hexavalent Chromium in Drinking Water by Ion Chromatography with Post-Column Derivatization and UV-Visible Spectroscopic Detection
http://water.epa.gov/scitech/drinkingwater/labcert/upload/EPA_Method_218-7.pdf
EPA Method 200.8: Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma –Mass Spectrometry
http://water.epa.gov/scitech/methods/cwa/bioindicators/upload/2007_07_10_methods_method_200_8.pdf
N. B.: The New California Regulatory Drinking Water Standard for Hexavalent Chromium at 10 ppb will go into effect on July 1, 2014!
C. Mei-Ling HAMILTON - Environmental Geochemistry Issues 