NORMAN â€” The level of chromium-6 in Norman's drinking water exceeds California's proposed limit for the chemical more than 200 times over, according to a national environmental study released today.
The Washington, D.C.-based Environmental Working Group says hexavalent chromium, or chromium-6, in drinking water has been shown in lab tests to increase the risk of cancer. The Environmental Protection Agency has yet to draw the same conclusion, although its website states that chronic exposure to inhaled chromium-6 can lead to cancer.
Some may recall chromium-6 as the chemical discussed in the biographical movie â€œErin Brockovich.â€
The Environmental Working Group commissioned a study to test water from 35 cities for chromium-6. Norman's result of 12.9 parts per billion far exceeded runner-up Honolulu, which had two parts per billion, and the study's average city of 0.18 parts per billion.
California is proposing a limit of 0.06 for its cities' water supplies.
â€œThey were not surprised that Norman had a high amount, but maybe a little surprised by how high,â€ said Rebecca Sutton, an environmental chemist who worked on the study, citing Norman's high amount of arsenic in some wells a few years ago.
Chromium-6 differs from chromium-3, or trivalent chromium, which the EPA says is an essential nutrient
The EPA mandates a maximum level of total chromium at 100 parts per billion, or 0.1 milligrams per liter, but the federal agency has set no limit specifically for chromium-6. California could become the first state to set an additional standard for chromium-6.
Sutton said Norman's high chromium-6 content most likely occurs naturally from erosion of heavy metals into central Oklahoma's Garber-Wellington aquifer, which serves central Oklahoma.
The report says Norman and the other 34 cities from 23 states were chosen for the study based on reported frequent detections of chromium.
Norman Utilities Director Ken Komiske said chemical levels in Norman's water can apply to any city or town that draws water from the Garber-Wellington aquifer.
According to the U.S. Geological Survey, all major communities within the aquifer's 3,000-square-mile area, except Oklahoma City, get all or part of their groundwater from the Garber-
Sutton said the best defense against consuming chromium-6 or any contaminant is buying a reverse osmosis water filter for the home.
Komiske said Norman complies with EPA and state Department of Environmental Quality standards on total chromium, as its wells typically contain 10 to 80 parts per billion at any given time, depending on the well.
He said Norman does not test specifically for chromium-6 because there is no state or federal requirement to do so. The city could do it on its own, but that would be for the city council and residents to decide.
â€œIt can be treated, but you have to pay for it,â€ Komiske said. â€œIf that's what the customers want to do, and if our council determines that we should look into it further, then we'll look into it. But right now we comply to all