The drumbeat for imposing federal limits on hexavalent chromium in drinking water is reminding many experts of a similar push several years ago for limiting another likely carcinogen, arsenic.
The two contaminants are put in water by both natural and man-made sources and have been the focus of long public health debates. And the technologies for removing both chemicals from water are complicated and very expensive.
"Arsenic is a good parallel for hexavalent chromium," said Alan Roberson, the director of federal relations for the American Water Works Association (AWWA), a trade group for utilities. "You're talking about a lot of the same issues, and it's likely we have a fair amount of it across the country at very low levels."
U.S. EPA worked for years on arsenic before issuing a drinking water rule for it in 2001. And now the agency is finalizing a draft toxicology assessment of hexavalent chromium -- a contaminant made infamous by the hit 2000 movie "Erin Brockovich" -- that says the compound is a likely carcinogen.
How utilities implemented the arsenic rule is instructive of how a limit on hexavalent chromium might play out, observers said.
After elevated arsenic levels were detected in several water supplies across the country, EPA launched an assessment of the health effects of the substance.
It took decades of review before the Clinton administration issued a rule reducing the maximum containment level (MCL) of arsenic in drinking water from 50 parts per billion to 10 ppb in January of 2001, just days before President Clinton left office.
When George W. Bush became president, he put an immediate hold on the arsenic rule and other so-called midnight regulations. Bush's EPA administrator, former New Jersey Gov. Christine Todd Whitman, submitted the proposed rule for three scientific peer reviews, an unusually high number. Whitman eventually signed off on the rule, setting an effective date of January 2006.
The rule forced utilities to install a complicated technology to absorb arsenic and then deal with a large amount of wastewater containing very high levels of arsenic.
The cost of the technology, Roberson said, was backbreaking for many smaller utilities.
It forced many of them to double water prices, and there are still almost 1,000 utilities that still are not yet in compliance with the rule.
Hexavalent chromium-removal technology, Roberson said, would likely cause the same increase in water rates. And that is why utilities need the standard before installing new technologies.
"Utilities have to be able to justify it to their customers," Roberson said. "They have to justify why they are having to raise the rates."
When EPA will issue a drinking water rule for hexavalent chromium remains unclear. The agency is currently working on a toxicology assessment of the chemical and plans to finalize it by September.
A drinking water rule will probably come after that assessment. Administrator Lisa Jackson has made the issue a priority and met with senators about the chemical late last year. Notes from that meeting said it is "likely that EPA will tighten drinking water standards to address risks posed" by the chemical (E&ENews PM, Dec. 22, 2010).
A new standard for hexavalent chromium, however, may still be a long way off. EPA said that once the toxicology assessment is completed, issuing a new drinking water standard typically takes at least two to two-and-a-half years. And in some cases, finalizing drinking water rules has taken significantly longer.
Utilities, enviro groups spar
Water utilities insist they will be ready for a new hexavalent chromium standard.
Robert Renner of the Water Research Foundation, which conducts studies for water utilities, said hexavalent chromium has been on his group's radar for a decade.
"Research on chromium-6 has been conducted and open for years," Renner said, using the alternative name for hexavalent chromium. "Our reports are provided to our subscribers and the results are shared with a lot of audiences."
But how transparent that research has been has become the subject of criticism from environmental groups.
Earlier this month, the nonprofit Environmental Working Group (EWG) released a 2004 report from the research group that suggested hexavalent chromium contamination was widespread and utilities failed to disclose it to consumers(Greenwire, April 4).
Renner criticized that implication and said that the research was publicly available.
"Sensationalizing chromium-6 is a disservice to the public," Renner said. "Detection does not equal risk."
He added that until EPA issues a rule, there is little reason for utilities to alarm their customers about low and likely safe amounts of a contaminant being found in the water supply.
"It's very unusual for a water utility to actively alert consumers to detection of trace amounts," he said. "What would they say? There are no standards. ... The potential health effects of chromium-6 in source water or drinking water are not yet clear."
And that is what irks environmentalists who say it is clear that hexavalent chromium poses a health risk and utilities should alert customers of any contamination.
"We know now how serious this problem is," said Rebecca Sutton of EWG. Sutton went on to highlight another EWG study that found elevated levels of hexavalent chromium in the tap water of 25 or 35 U.S. cities tested (Greenwire, Dec. 20, 2010).
Sutton acknowledged there is little that utilities can do on the chemical until EPA issues its rule. But, added, "I certainly think there are a lot of steps they can take to get on top of the situation, including allowing them to pinpoint if they have a contamination problem and where it is coming from."
While utilities anticipate EPA setting a drinking water standard for hexavalent chromium, the big questions remaining are how low the standard will be, what technologies can be used to achieve that level and how much those technologies cost.
The answers to the technology question may be answered by research by Glendale Water and Power in California.
The Glendale utility was forced to begin dealing with how to remove hexavalent chromium from drinking water about 10 years ago when the City Council set a 5 ppb limit. At that point no treatment options existed, so the utility diluted contaminated water with other water it shipped in to bring the levels of hexavalent chromium down.
Soon after that, said the utility's water quality manager, Dan Askenaizer, the city began researching water treatment options to remove hexavalent chromium. After a few painstaking years of small-scale studies, Askenaizer said two technologies appear to be working.
The first technology uses an ion resin to remove the chromium-6. The resin also appears to change the chemical's molecular makeup from chromium-6 to chromium-3, which actually carries health benefits. Glendale is currently testing that method on 400 gallons per minute.
The second process is reduction coagulation filtration (RCF), which also converts the chemical to chromium-3 then filters out remaining particles. That process is currently being tested on 100 gallons per minute.
Both tests are producing encouraging results, Askenaizer said. The resin is consistently producing water with hexavalent chromium at a level consistently less than 2 ppb. The RCF method is being used on water that starts with more hexavalent chromium in it and is achieving close to 1 ppb.
"We're trying to learn from these tests and how effective they are," Askenaizer said. "And eventually we want to know how much these things cost."
Askenaizer is not done looking for answers. He said the current tests appear to have a limit of 1 ppb -- they do not produce anything lower than that. California has set a draft public health goal of a 0.02 ppb standard for hexavalent chromium (Greenwire, Jan. 3), but Askenaizer said that level is below what can be detected.
"I'm not aware of any technology that could get down to that level," Askenaizer added.
Another problem, he said, is it is unknown how much it would cost for an entire utility to implement either of the technologies.
If his utility can secure more funding -- the studies have received money from the state of California, the city of Los Angeles, EPA and the Water Research Foundation -- Askenaizer wants to try a new membrane technology for straining hexavalent chromium out of the water.
From a research perspective, Askenaizer is actually looking forward to EPA or California setting a new standard. Once that is done, they can begin looking at which technologies are the most effective.
"I'd like to know so we can plan and so we know what we have to meet," he said. "It would be beneficial to have a standard. I think it would answer a lot of questions."