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New limits proposed for toxin found in state’s drinking water

REGION — In an attempt to become the first state in the country to set a new drinking water standard for the contaminant hexavalent chromium, or chromium-6, the CDPH (California Department of Public Health) proposed an MCL (maximum contaminant level) of 10 parts per billion to the Office of Administrative Law earlier this month. 

Currently, the state’s total chromium standard is set at 50 parts per billion. The total chromium level includes the trivalent form of chromium, or chromium-3, a naturally occurring nutrient that is found in food, and the toxic chromium-6.

The federal standard for total chromium levels is set at 100 parts per billion.

The CDPH proposal was made under a legislative mandate to set the specific MCL for chromium-6, said Dr. Dave Mazzer, acting chief of the CDPH Division of Drinking Water and Environmental Management, during a teleconference call on Aug. 22.

“A law passed in 2001 mandated us to set an MCL for hexavalent chromium, which we have done,” he said.

Chromium-6 is a heavy metal that can occur naturally in groundwater or enter into drinking water sources through industrial plants’ hazardous leaks, according to the state’s OEHHA (Office of Environmental Health Hazard Assessment).

The OEHHA lists chromium-6 as a potent carcinogen when inhaled, and caused cancer in laboratory rats and mice that were exposed to it through drinking water.

If approved, the costs for the total compliance, maintenance and capital improvements would cost a total of $156 million, explained Dr. Mark Starr, deputy director of the CDPH Center for Environmental Health.

The CDPH is estimating that more than 100 systems in the state could potentially be impacted by the proposed MCL.

According to John Carnegie, staff analyst with OMWD (Olivenhain Municipal Water District), they haven’t been contacted by the CDPH about any operational impacts.

“As it stands today, however, we do not anticipate significant costs or operational impacts as hexavalent chromium levels are not anticipated to be anywhere close to the 0.010mg/L Maximum Contaminant Level proposed by CDPH,” Carnegie said in an email.

Mazzera explained that the CDPH arrived at the proposed MCL after evaluating seven other maximum contaminant level ranges for chromium-6, and evaluating occurrences statewide, population and how much it would cost to treat and remove and monitor the contaminant, and whether the contaminant can be measured at those specific levels.

“Taking into consideration the technical and economic feasibility of doing that…complying with the proposed MCL…we came to the conclusion that the MCL of 10 parts per billion that we’re proposing in this draft…is the most feasible MCL for hexivalent chromium at this time,” Mazzera said.

OMWD collects annual samples for chromium-6, and in the most recent sample collected in 2012, there was no indication of the presence of the chromium-6 at or above the state’s detection limit for reporting, explained Carnegie.

In its pursuit of groundwater as a potential source of potable water, OMWD hasn’t testedthe groundwater underneath San Elijo Lagoon for chromium-6 as part of the USGS project.

The chemical has been found in greatest numbers in samples taken between 2000 to Nov. 13, 2012 in counties north of San Diego, including Riverside, Los Angeles, San Bernardino, Santa Cruz and Sacramento.

The CDPH is accepting public comments now through Oct. 11. There are two scheduled public hearings, Oct. 11 one in Sacramento and the other in Los Angeles.

Once final, the department will review the chromium-6 MCL at least every five years after its adoption. As technology improves, the standard may be changed.