Sunnyvale’s groundwater is polluted with chromium 6, a carcinogenic heavy metal, according to a 2007 Water Quality Report released by the city in 2008.
The average concentration in the city’s seven wells — 1.4 parts per billion — is considered to be a very low dose and poses little danger, experts said. Chromium 6, also known as hexavalent chromium, was made infamous by the movie Erin Brockovich and a series of articles in 2000 about findings of chromium 6 in San Fernando Valley groundwater at levels as high as 30 ppb.
Sunnyvale residents receive 7 percent of their water from the wells, two of which in the southwest part of the city had concentrations between 2.2 and 3.1 ppb in 2002, in the most recent testing available. The tests were conducted in 2002, and the levels are considered to be below state and federal regulations.
However, the state has no specific standard for chromium 6.
The California Department of Public Health, which is responsible for regulating water quality, allows 50 ppb of total chromium, which includes chromium 6 and trivalent chromium, a harmless and somewhat beneficial nutrient. The U.S. Environmental Protection Agency allows 100 ppb of total chromium.
The CDPH was required according to a section of the state Health and Safety Code to establish a primary drinking water standard — a maximum contaminant level — for hexavalent chromium on or before January 2004, , but the CDPH points the finger at the state Office of Environmental Health and Hazard Assessment for the delay in scientific research. Sam Delson, and OEHHA spokesman, called the history of efforts to create standards “long and complicated.”
Sometime this year, OEHHA expects to release a report that would set a draft public health goal, which is the concentration at which adverse health effects are not expected to occur from a lifetime of exposure.
George Alexeeff, OEHHA deputy director of scientific affairs, said that the state would base its standard on a two-year study that was completed by the National Toxicology Program, a division of the U.S. Department of Health and Human Services, in July 2008.
“They concluded that there was a positive association between exposure of hexavalent chromium in the drinking water and tumors in…rats and mice,” said Alexeeff. Chromium 6 was placed on the state’s list of toxics that cause developmental and reproductive hazards in December 2008. Previous scientific evidence was considered spotty and inconclusive.
Alexeeff declined to say what the public health guideline (PHG) would be. A draft PHG that the office proposed in 2005 was 0.2 ppb, according to an April 2008 state information sheet, but the final PHG is expected to be somewhat higher.
“No amount is really completely safe, but in the world we’ve got to live in we can’t get rid of it all…so you remediate it to as low as possible,” said Joseph Landolph, Ph.D., a researcher and OEHHA adviser on carcinogens at the Norris Comprehensive Cancer Center at the University of California’s Keck School of Medicine.
He added that he thought the health goal should be lower than 10 ppb, based on scientific evidence, and said of Sunnyvale’s 1.4 ppb, “I wouldn’t lose sleep about that.”
It could take at least year after the release of the PHG for the state to develop a maximum concentration level that takes technical feasibility and cost into account, Alexeeff added.
“We’ve got a lot of chromium in the earth already, so it’s fine when it stays there,” said Landolph, referring to naturally occurring chrome iron ore. It is rarely found in water except when deposited through industrial discharge or from the burning of fossil fuels.
Once processed into chromium 6, it’s been used in stainless steel, for chrome parts on cars and airplanes, for tanning, in pigments and as an anti-corrosive in industrial water storage tanks.
It is unclear where the chromium 6 in Sunnyvale’s groundwater could have come from.
The San Francisco Bay Regional Water Quality Control Board has been overseeing the cleanup of a plume of toxins in the shallow groundwater beneath a 660-acre Lockheed Martin campus, at 1111 Lockheed Martin Way in northern Sunnyvale, since 1987. Chromium 6, from metal processing wastewater, was among numerous toxins that were found.
Since 1993, Lockheed has pumped up, treated and discharged groundwater into the city’s sewer system under a permit.
“It was confined to the shallow zone…which is not the drinking water supply. The plume was contained and is decreasing,” said Alec Naugle, an engineering geologist with the water quality board.
He added that a geological layer with low permeability, combined with the fact that Lockheed is downhill from the city’s residents and wells, makes it highly unlikely that chromium 6 could penetrate into the deeper aquifers from which drinking water is pumped.
According to an April 2007 report, Naugle said, Lockheed’s pumping and treatment had reduced the chromium 6 from a maximum concentration of 1100 ppb at a level of 30 to 55 feet in 1987 down to a maximum concentration of 59 ppb. Only three of the 18 wells on the site had between 5 and 20 ppb.
Nationally, there were nearly 2.9 million pounds of chromium releases to water and nearly 197 million pounds to land from 1987 to 1993, according to the EPA.
The NTP study found that 30 percent of the drinking water sources monitored in California had chromium 6 levels above 1 ppb. Of those, 87 percent had concentrations less than 10 ppb.
While the state has required monitoring since 2001, Sunnyvale is the only one of several neighboring cities that clearly reported the presence of chromium 6.
Santa Clara did not mention chromium at all in its most recent report. Mountain View found up to 2 ppb of total chromium, which it said was naturally occurring, but did not test specifically for chromium 6.
The California Water Service Company, which provides water to parts of Cupertino and Sunnyvale, tested for total chromium, reporting a maximum of 15 ppb and an average of 4 ppb in local groundwater in its 2007 Water Quality Report. However, it did not test for chromium 6 separately.
The San Francisco Public Utilities Commission and Santa Clara Valley Water District, which supply the rest of Sunnyvale’s water, did not report any detectable concentration of chromium 6.