Hexavalent chromium, also known as Chrome-6, is a form of the element chromium that is suspected to pose a human health risk if ingested. Chrome-6 is often present at very low levels in groundwater due to its occurrence in certain geological formations. Human caused contamination can also occur due to releases from various industrial processes. The US EPA and the California Department of Public Health currently regulate Total Chromium in drinking water, which includes all forms of chromium, including Chrome-6. Total Chromium has a drinking water standard of 50 parts per billion in California.
On July 27, 2011, the California Office of Health Hazard Assessment adopted a Public Health Goal for Chrome-6 of 0.02 parts per billion (ppb). A Public Health Goal is considered to be the level in drinking water that a person could consume for an entire lifetime with little to no risk of any adverse health effects. It is not a drinking water standard, or a line of demarcation separating a “safe” level from an “unsafe” level. While any contamination below a Public Health Goal is unlikely to pose a health risk, it’s probable that levels above the Public Health Goal also do not pose a health risk.
The California Department of Public Health (CDPH) uses the Public Health Goal as the starting point for developing a drinking water standard, known as a Maximum Contaminant Level, or MCL. When developing a drinking water standard, the CDPH considers a number of practical issues, including the prevalence of a substance, treatment options, laboratory analytical capabilities, and the costs to acheive various potential MCL levels. In all, it can take several years for the development of an MCL.
Anaheim has been monitoring its water supplies for many years for Total Chromium and has rarely detected it. When Chrome-6 first became an issue following the Erin Brokovich movie, all of Anaheim’s wells were tested. Since monitoring first began in 2001, Chrome-6 has been found in most of our active production wells at levels ranging from the laboratory detection level of 0.2 parts per billion to a high of 3.3 ppb. Anaheim's groundwater has average Chrome-6 levels of approximately 0.7 ppb. Data from Orange County suggests that low levels of Chrome-6 are common in this area due to the natural geology and Anaheim’s Chrome-6 levels are similar to those found throughout the County.
Going forward, Anaheim will keep a close watch on the development of an MCL for Chrome-6 and will ensure that all of its sources meet all drinking water standards. Since the proposed Public Health Goal is below the ability of analytical detection technology, we can be certain that a drinking water standard will not be set that low. Whatever level is chosen, however, Anaheim, will only serve water that meets all State and Federal regulatory standards.
July 28, 2011