In the wake of a national survey finding tap water in 31 U.S. cities â€” including Norman â€” 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 â€œErin Brockovich,â€ which involved chromium 6 in tap water.
â€œThere's a long and tortuous saga that led to development of the Public Health Goal,â€ said Sam Delson, spokesman for California's Office of Environmental Health Hazard Assessment. â€œIt'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.â€
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.
â€œIt'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,â€ Delson said.
A 2007 study by the National Toxicology Program, a federal program based at the National
â€œWe considered many, many studies when developing our Public Health Goal, but that's the principle basis for it,â€ 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.
â€œIf 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,â€ Delson said.
â€œIt's not the dividing line between a safe level and an unsafe level,â€ he said. â€œWe're not saying that a higher level would be unsafe.â€
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.
A Public Health Goal is a guideline for the Public Health Department to
Once the department begins the research and evaluation required, it's likely to be four to five years before an enforceable regulation is adopted, California Department of Public Health spokesman Ken August said.
When releasing its survey last week, the Washington, D.C.-based Environmental Working Group recommended a national standard of 0.06 parts per billion.
And in a recent letter to the U.S. Environmental Protection Agency, Sens. Barbara Boxer and Dianne Feinstein, both California Democrats, said they planned to introduce legislation setting a deadline for an enforceable chromium 6 standard.
On Wednesday, the head of the EPA said it would likely tighten drinking water standards to address the potential health risk of chromium 6.
If California is any example, such a standard could spur more than a
Many of the critics argued that the National Toxicology Program's conclusion is at best iffy when applied to humans.
A regulatory advocate for the Association of California Water Agencies, which represents more than 450 public water agencies, wrote that â€œthe NTP study did not find excess cancers at the lowered studied doses in both rats and mice. Equally as important, the stomach composition of humans and rodents is very different, with humans having a much more sophisticated and higher level of gastric juices than rodents.â€
When setting a standard, the California Public Health Department must take into account technical and feasibility issues as well as whether a level is â€œso low that it might be a great hardship on a community to achieve that
Between 1997 and 2008, California tested 7,000 drinking water sources in the state for chromium 6. About 2,200 were found to have the carcinogen present and of those 1,900 were found to have levels between 1 and 10 parts per billion. About 90 had levels above 20 parts per billion. And 231 fell in line with Norman, showing between 11 and 20 parts per billion.
â€œThe cities in California that have been blending in clean water to reduce their levels have basically been getting their level to 5 or below, but not to 1 or below, or 0.06 or below,â€ Delson said. â€œWater can be safe for human consumption at levels higher than the
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
More than 50