AWWA WQTC55172

In 2000, the State of California proposed a public health goal of 2.5 ug/L in drinking water for total chromium, based on health assessments for hexavalent chromium (Cr-6) from the Office of Environmental Health Hazard Assessment (OEHHA). The OEHHA indicated that the level of interest for Cr-6 was 0.2 ug/L. The 2.5 ug/L total chromium public health goal was based on the presumption that 7% of the total chromium occurred as Cr-6. Thus there is a strong need for an accurate, low-level analysis of both total chromium and Cr-6 to assess the occurrence of Cr-6 and to determine the percentage of total chromium existing as Cr-6. If the 7% fraction is not reflective of most drinking waters, it is critical to be able to accurately measure Cr-6 directly at sub ug/L levels. In this paper the authors present data pertinent to accurate analysis of both total chromium and Cr-6 at low levels based on the testing of over 2,000 samples from across the State of California. It is demonstrated that, for California drinking waters, typically more than 90% of the chromium is present as hexavalent chromium and that the chromium speciation is stable over an extended period of time, eliminating the need to analyze samples within 24 hours. Includes 6 references, figures.