Safety questions remain on chromium 6
Lab studies show extreme amounts of the metallic element caused cancer in mice and rats, but how much does it take to be harmful to humans?
NORMAN ├óÔéČÔÇŁ University of Oklahoma associate professor Robert Nairn, an expert on water quality, became popular among friends and colleagues when a report came out Monday that questioned the safety of Norman's water.
├óÔéČ┼ôI got a lot of e-mails from people wondering what's going on,├óÔéČ┬Ł said Nairn, who directs OU's Center for Restoration of Ecosystems and Watersheds.
The concern is about hexavalent chromium, often called chromium 6. Norman had a chromium 6 reading of 12.9 parts per billion, which was highest among one-time samplings from 35 cities tested for a project commissioned by the Environmental Working Group.
Chromium 6 was proved decades ago to cause cancer or respiratory ailments when inhaled, and animal tests conducted in recent years by the National Toxicology Program show evidence that it also can be carcinogenic when ingested orally.
While Norman easily topped the new report's list of cities, the level was thousands times less than that given to lab animals that developed cancer.
It pales when compared to Hinkley, Calif., the city on which the movie ├óÔéČ┼ôErin Brockovich├óÔéČ┬Ł was based, which had up to 580 parts per billion in its drinking water in the 1990s.
In spring 2009, Nairn was involved in the cleaning of shallow groundwater for Tinker Air Force Base, where he said the chemical's content ranged from 5,800 to 7,900 parts per billion.
├óÔéČ┼ôI think (the report) opened some eyes and said we should keep our eyes open for chrome 6,├óÔéČ┬Ł Nairn said. ├óÔéČ┼ôBut I don't have a feel for chrome 6. What I can say is 6,000 (parts per billion) is something to worry about; 500 is something to worry about. But 12.9, I don't know. We don't know.├óÔéČ┬Ł
Below the limit
What is known is that total chromium in Norman's ground wells consistently has tested below the federal and state limit of 100 parts per billion. Total chromium combines chromium 6 and the nutrient chromium 3.
According to a Norman Utilities Department statement, the most recent tests for total chromium had results ranging from 11 to 86 parts per billion in its ground water wells, while samples from the water treatment plant had levels that were not detectable.
Rebecca Sutton, an environmental chemist who worked on the Environmental Working Group study, said chromium 6 often is discharged by steel and pulp mills, and by metal plating and leather tanning facilities.
News Photo Galleriesview all
- 78259Oklahoma tornadoes: 'It took it all'
- 30507Oklahoma Severe Storm Updates
- 26600Oklahoma State football: Limiting Wes Lunt's transfer options makes Mike Gundy look bad
- 26566Oklahoma weather: Crews work to clear storm damage in Oklahoma City as the state braces for severe weather Sunday.
- 7397Bounty hunters look for bail jumpers, fugitives on the streets of Oklahoma City
- 7041Oklahoma City Thunder: What could Serge Ibaka learn from Hakeem Olajuwon?
- 6928Oklahoma tornadoes: Several homes damaged by tornado, but no injuries in Edmond