NORMAN — Although the amount is slight and measured in parts per billion, an independent lab test on Norman’s tap water places the level of hexavalent chromium, or chromium-6, among the highest of 35 selected U.S. cities tested this year.
The tests measured levels of tap water contaminated by the carcinogenic chemical that came to national attention in the 2000 feature film “Erin Brockovich.”
The tests were done by the Environmental Working Group, a Washington, D.C. based non-profit that specializes in environmental research and advocacy. It is made up of scientists, public policy experts, lawyers and computer researchers. Funding for the report came from the John Merck Fund, the Johnson Family foundation, the Park Foundation and the Turner Foundation.
The Transcript obtained an early copy of the study scheduled for release tonight.
According to EWG, the sample of Norman’s water taken in the Spring of 2010 tested at 12.90 parts per billion of chromium-6. California recently proposed setting a public health goal of 0.06 parts per billion. The town of Hinkley, made famous by the “Erin Brockovich” feature film starring Julia Roberts, tested as high as 550 parts per billion. The U.S. Environmental Protection Agency (EPA) has not set a legal limit for chromium-6 in tap water and does not require water utilities such as Norman to test for it.
City officials on Friday said they had not been notified of the study and were unaware of any concerns with the city’s water supply which is monitored by state and federal agencies as well as the city itself. They confirmed they do not test specificially for chromium-6 which is a subset of the total chromium level.
Norman’s total chromium readings on its wells range from 20 to 80 compared to an EPA maximum limit of 100. Treated water coming directly from the plant would be lower because of the process to remove metals.
“It’s (chromium) a naturally occuring element and it depends on when you test it and where you test it,” said Ken Komiske, Norman’s utilities director. Norman’s tap water is a blend of treated surface water from Lake Thunderbird and raw well water which is pumped directly into the system. Norman also buys some water, as needed, from Oklahoma City on peak demand days.
Hexavalent chromium is commonly discharged from steel and pulp mills as well as metal-plating and leather-tanning facilities. It can also pollute water through erosion of natural deposits and is more common in water drawn from wells rather than surface pools.
Komiske said the EPA is currently evaluating new health effects data on chromium-6.
“We expect that evaluation to be completed in late 2011, and we are prepared to respond in a way that continues to protect public health and meets federal and state standards,” he said.
The sample taken at the tap in Norman contained more than 200 times higher than a safe limit proposed in California. The other two cities with the highest levels were Honolulu and Riverside, Calif., according to the organization. Chromium-6 was found in the drinking water of 31 of 35 cities tested. Only California requires tap water tests for hexavalent chromium and EWG is pushing for a national standard for drinking water.
Dr. Rebecca Sutton, Ph.D., a California environmental scientist, and the principal author of the EWG study, said Norman’s water supply was included in the 35-city sampling because of the total chromium numbers reported. Usually, water systems with high total chromium also have high chromium-6 levels.
Total chromium’s measurement includes “trivalent chromium,” an essential mineral that regulates glucose metabolism, as well as the cancer-causing hexavalent form, also called chromium-6, according to EWG.
“They can both be naturally found,” Sutton said. “I actually was interested in Norman’s numbers and I called the water utility a few months ago.”
“They brought up the fact that the groundwater is coming from the Garber-Welllington aquifer that was known for some heavy metals,” Sutton said. Unrelated to the chromium issue, Norman removed some wells from its water mix when the EPA lowered the level of arsenic allowed in drinking water.
Asked about the risk to Norman water customers, Sutton said, “If I lived in Norman, I would install a reverse osmosis filter on my tap and remove many chemicals.”
Komiske said installing such a device is unrealistic. “We’re talking about 12 parts per billion,” he said. “That’s like something a computer chip manufacturer would use.”
Sutton said she was not aware of any research showing a link between the water and cancer rates in Norman. The only such study done was in China. She hopes the EPA completes its risk assessment that is currently under way.
“We’ve got a process under way. We are pushing them to finalize establishing a safe drinking water standard, working on both ends of this spectrum,” she said. “Industry is doing their best to delay the finalization of the EPA risk assessment.”
The National Toxicology Program (NTP) of the U.S. Department of Health and Human Services has said that chromium-6 in drinking water shows “clear evidence of carcinogenic activity” in laboratory animals, increasing the risk of gastrointestinal tumors. In October, a draft review by the EPA similarly found that ingesting the chemical in tap water is “likely to be carcinogenic to humans.” Other health risks associated with exposure include liver and kidney damage, anemia and ulcers, according to EWG.