Norman Water Quality: Issues of Interest
Below is a link to a report from the Water Research Foundation concerning chromium in drinking water. The title of the report is, ‘State of the Science of Hexavalent Chromium in Drinking Water’, and is dated May 2012. Hexavalent chromium has been demonstrated to be a human carcinogen when inhaled, however, the health effects of hexavalent chromium through ingestion - the primary exposure route for drinking water- are currently under review at the federal level by the U.S. Environmental Protection Agency (USEPA). The Goal of this report is to better inform potential regulatory action on this issue by summarizing what is known about hexavalent chromium, as well as pointing out gaps in current knowledge.
The Environmental Protection Agency has released comments from the peer review of the previous health assessment of hexavalent chromium completed in September 2010. In summary, based on recommendations from the peer review panel in May 2011, EPA will consider the peer review comments and new research regarding the oral assessment of hexavalent chromium and the inhalation assessment. EPA anticipates the new draft assessment will be released for public comment in 2013.
The next step in evaluating the chromium
drinking water standard is to complete the toxicity assessment for oral
ingestion of hexavalent chromium. EPA is developing an updated IRIS assessment of
hexavalent chromium. This assessment will evaluate the potential health effects
of hexavalent chromium from oral and inhalation exposures. An important
component of determining the cancer causing potential of ingested hexavalent
chromium is understanding the rates at which this metal is effectively
detoxified in the gastrointestinal tract. To address this, EPA convened a state
of the science workshop where an expert panel discussed this issue. This
workshop was open to the public, broadcast by webinar/teleconference, and took
place over two non-consecutive days.
The link below will take you to a web site with information about the
two day workshop.
Once the chromium 6 assessment is completed, EPA
will make a determination about revising the total chromium and/or establishing
chromium 6 MCL. If the decision is made to revise the chromium MCL or
establish separate chromium 6 MCL, EPA will undertake the evaluation and
consultation required to propose a new or revised drinking water standard under
the Safe Drinking Water Act.
If revision is determined to be in the public
interest the EPA will publish a proposed standard for comment and consider prior
to promulgating a final regulation. The typical time frame for proposing
a new regulation or revising an existing regulation is 2 years. From that point it is typically between 1 and
1 1/2 years to progress to a final rule. (Please note that these time frames
are typical and that these steps could take place on an expedited
schedule). Also, under the Safe Drinking Water Act, systems have 3
years to come into compliance with a revised standard.
The following is a letter to the editor of the Norman Transcript that was published Tuesday, June 7, 2011 regarding chromium in drinking water. While the following article is somewhat technical, it clearly illustrates the divide between members of the scientific community about the chromium 6 issue and therefore should be of interest to readers.
The Norman Transcript The Norman Transcript Tue Jun 07, 2011, 01:54 AM CDT
NORMAN — Dear Mr. Ken Cook: The Environmental Working Group (EWG) has done very good work in the past and is a valuable public resource. That said, shame on the EWG for starting an unnecessary panic about Hexavalent Chromium (Cr VI) in Hawaii’s drinking water, as well as other municipalities across the country (Chromium-6 in U.S. Tapwater, December 2010). Intentionally or through shear incompetence of the authors, the EWG misleads the public with bad science and inflammatory rhetoric to create a problem where, in all likelihood, there is none. Although I’m a senior scientist for the Hawaii Department of Health, this letter is intended to be more personal — scientist to scientist. Below is a summary of the most flagrant problems with your report. As a fellow professional, I ask that you publish a follow-up report to clarify these issues and restore some degree of credibility to your organization. I have included additional references at the end of this letter that should be helpful. I have also cc’d all of the cities implicated in the EWG report.
The trace levels of Cr VI you reported for tapwater in every city tested, including Honolulu, are within the potential range of normal background across the country (generally <2 to 10 ug/L but up to 20+ ug/L, depending on the geologic and hydrologic setting, Allard 1995, CalEPA 2008, IETEG 2005, Kotas 2000, Raddatz 2011). You intentionally mislead the public into thinking that the Cr VI reported in the water samples is associated with industrial pollution. Chromium VI at the levels you reported is a naturally occurring element in the environment. In contrast, the levels of Cr VI in the PG&E “Erin Brockovich” case in Hinkley, Calif., highlighted in your study are thousands of times higher than what you found in any city and clearly related to industrial pollution (>3,000 ug/L). The natural background level of Cr VI in groundwater being used in the ongoing PG&E investigation, 3.1 ug/L, is in fact higher than the levels you report for all but one city in your study. You had to know this, but presenting your findings in terms of expected, natural background apparently would not have created the media attention that you desired and indeed got. The Cr VI you identified in Honolulu’s water supply, as is probably the case for every other city you tested, is not industrial “pollution” — it’s Mother Nature.
You irresponsibly abuse the public’s trust in your organization and their concern for the health of their loved ones by falsely claiming that USEPA has not set a standard for Cr VI in the drinking water and demanding that it do so. This is a blatant lie. The current USEPA standard for Total Chromium is based on a conservative assumption that 100 percent of the chromium in our drinking water is Cr VI (USEPA 1998, 2010d). This is clearly discussed in their March 2010 review of the drinking water standard for chromium:
“Although the (USEPA) regulates total chromium, the adverse health effects associated with hexavalent chromium (Cr VI) are the basis of the current (drinking water standard) because that is the more toxic species (56 FR 3526, Jan. 31, 1991).”
Any high school student with access to the internet could have determined this. Given that EWG has been working on this issue for years, I can’t believe that your staff is incompetent enough not to know this. You blatantly lied to the public in order to stir their distrust against the USEPA and get the media’s attention. Why should we trust you in the future?
You mislead the public by failing to tell them that the levels of Cr VI you identified in tapwater are within the range of acceptable, highly conservative, cancer-based drinking water goals derived from laboratory toxicological studies and other available guidance (CalEPA 2010, NJDEP 2009, USDHHS 2008, USEPA 1998, 2010a, 2010b, 2010c). The trace level of Cr VI that you reported for the Honolulu sample of 2.0 ug/L is within the very conservative range of 0.43 to 4.3 ug/L for potential cancer risks, based on the tapwater goal presented in USEPA’s Regional Screening Levels guidance (USEPA 2010c) and USEPA’s 10-6 to 10-4 acceptable range for cancer risk (California’s correlative range would be 0.02 to 2.0 ug/L). In your report, you intentionally only present the lower-bound goal, even though USEPA guidance clearly states that the full range of risk-based goals is to be considered when setting standards, along with other important factors such as natural background, dietary exposure (e.g., Roussel 2007, Soares 2010) and the technical and economic feasibility of reducing levels to the lower-bound end of the acceptable range.
The levels of Cr VI in tapwater presented in your report are even further below the more reliable drinking water goal for noncancer health risks. The accuracy of the cancer-based toxicity factor for Cr VI to develop drinking water goals is highly questionable. As you surely know, the toxicity factor simply represents an arbitrary, one million-fold reduction in the concentration (or rather dose) of Cr VI in drinking water that was found to cause cancer in laboratory mice. This is more of a policy decision than actual science. As you presumably determined from the USEPA’s 2010 review of Cr VI toxicity (USEPA 2010a), but failed to mention in your report, a more reliable, health-protective goal of approximately 30 ug/L can be calculated from the updated (but still draft) toxicity factor for noncancer health risks presented in that document. Taking into account other natural, dietary sources of Cr VI, as done to develop the current MCL, would adjust the Total Chromium standard downward to approximately 20 ug/L which, again, conservatively assumes that all of the chromium identified is Cr VI. The levels of Cr VI you identified are well below this goal in every city you tested. Surely your group ran the same calculations.
You continue to mislead the public by failing to tell them that the USEPA’s requirement to only test for Total Chromium in drinking water is, in fact, highly conservative, since 100 percent of the result is assumed to be Cr VI. Surely you know that direct measurement of Cr VI in drinking water is fraught with complications and the potential for error. If proper precautions are not taken, then the Cr VI can easily be converted to non-toxic Cr III during sample collection and analysis. The USEPA standard gets around this problem by requiring that only Total Chromium (i.e., Cr III plus Cr VI) be tested for and, in effect, forcing municipalities to assume that all of the chromium identified is associated with Cr VI. Since most chromium in water is, in fact, usually in the form of Cr VI, this is a more cost effective and more conservative way to address potential health risks. Wouldn’t you agree? The authors of the report knew this common fact about testing for Cr VI, right?
While a closer look at the issue of Cr VI in the nation’s drinking water supplies is useful, your report demonstrates a serious lack of understanding of basic geology, chemistry, toxicology and the nature of USEPA drinking water standards, not to mention economics. Your recommendation that municipalities and, in particular, homeowners consider such things as reverse osmosis to remove trace levels of naturally occurring Cr VI from water is incredibly premature and irresponsible. Have the very real environmental and social issues that we struggle with on a day-to-day basis been solved to the point that we can now afford to go after trace levels of undesirable, but not necessarily toxic, levels of chemicals in Mother Nature? Should Honolulu forgo the billion-dollar upgrade of its wastewater treatment system in order to remove trace levels of naturally occurring Cr VI from the 100 million gallons of water that it supplies daily, even though this has never been proven to pose a health risk?
The PG&E case in California that you misleadingly use to stir panic in your report was indeed a serious problem. Kudos to activists like Erin Brockovich for making sure that these types of very real, environmental problems are brought to public attention and taken care of. But shame on you, EWG, for misusing science and misleading the public to grab headlines. Such irresponsibility puts the public at great risk of unnecessary medical tests and procedures and distracts people who are suffering from an illness from finding the true cause and, hopefully, a cure. Your group has done good work in the past. I hope this case is the rare exception.
Roger Brewer, Ph.D., is an environmental scientist in Honolulu, Hawaii. He can be reached at firstname.lastname@example.org.