In August, the California Department of Public Health (CDPH) proposed a Cr-VI maximum contaminant level (MCL) of 10 parts per billion (ppb). Based on the economic and technical feasibility of implementing the new MCL, which must be considered under California law, the proposed standard is significantly higher than the 0.02 ppb public health goal for Cr-VI in drinking water set by California’s Office of Environmental Health Hazard Assessment in 2011. As it stands, meeting the new 10 ppb MCL is estimated to cost California drinking water utilities approximately $156 million annually.
At the federal level, the evaluation of Cr-VI is moving at a much slower pace, with EPA still focused on key scientific issues and data collection and analysis expected to inform its Integrated Risk Information System (IRIS) assessment of Cr-VI and potential regulatory development efforts.
A two-day “state of the science workshop” on Cr-VI was held in September to help inform EPA’s IRIS assessment. The first day focused on gastrointestinal tract processes that affect the absorption and transmission of Cr-VI and its conversion into non-toxic trivalent chromium, especially at low doses. The second day explored exposure factors affecting susceptible human populations and life stages.
The Cr-VI data currently being collected under the third Unregulated Contaminant Monitoring Rule (UCMR3) is also expected to play an important role in EPA’s regulatory development process, setting an occurrence baseline against which any new regulatory approach would be measured.
Taken together, the IRIS assessment and UCMR3 data evaluation will determine whether and, if regulated, at what level, any Cr-VI standard is set. However, the current schedule for completing these processes indicate that any final decision on regulating Cr-VI is still several years away, and certainly well behind California’s time frame for regulatory action.