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California chromium 6 regulation a contentious and lengthy process

BY Michael Baker Published: December 26, 2010

In the wake of a national survey finding tap water in 31 U.S. cities — including Norman — contains chromium 6, much attention is being paid to the only state to propose limiting the amount of the carcinogen in drinking water.

The push to regulate the amount of chromium 6 in California's tap water began about a decade ago, coinciding with the release of the 2000 film “Erin Brockovich,” which involved chromium 6 in tap water.

“There's a long and tortuous saga that led to development of the Public Health Goal,” said Sam Delson, spokesman for California's Office of Environmental Health Hazard Assessment. “It's fair to say that a lot of the impetus for that came about 10 years ago around the time that that movie came out.”

California environmental officials have proposed limiting chromium 6 in drinking water to 0.06 parts per billion, a stringent standard that is 215 times less than the 12.9 parts per billion found in Norman's drinking water.

Developing a standard

But developing a feasible limit on the amount of chromium 6 that should be in drinking water has been and continues to be a contentious and lengthy process in California.

“It's been long established that hexavalent chromium, or chromium 6, is carcinogenic when inhaled, but there was some controversy over whether it is carcinogenic when ingested,” Delson said.

A 2007 study by the National Toxicology Program, a federal program based at the National Institute of Environmental Health Sciences, concluded drinking large amounts of chromium 6 could cause cancer. Scientist found a significant number of tumors in rats and mice that drank water laced with chromium 6.

“We considered many, many studies when developing our Public Health Goal, but that's the principle basis for it,” Delson said.

California's Office of Environmental Health Hazard Assessment in August 2009 issued the draft proposal of a stringent 0.06 parts per billion based on what is a negligible risk standard.

“If a million people drank half a gallon a day of water with that level of chromium 6 for 70 years we would expect no more than one additional cancer case to be caused by that,” Delson said.

“It's not the dividing line between a safe level and an unsafe level,” he said. “We're not saying that a higher level would be unsafe.”

Delson said his agency is revising the current draft proposal and should have a new one to present in a couple of months. Even at that, it'll be several more months before it can be approved as an official Public Health Goal, which is not currently an enforceable standard.

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California and chromium 6

Between 1997 and 2008, California health officials tested 7,000 drinking water sources for the presence of chromium 6. Here are the results of those tests.

Peak level in parts

per billion

More than 50








of sources








Total: 2,208

Source: California Department of Public Health


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