National Primary Drinking Water Regulations; Announcement of the Results of EPA’s Review of Existing Drinking Water Standards and Request for Public Comment and/or Information on Related Issues

Water Docket Environmental Protection Agency (EPA) Mail Code 2822T 1200 Pennsylvania Ave., NW Washington, DC 20460 RE:National Primary Drinking Water Regulations; Announcement of the Results of EPA's Review of Existing Drinking Water Standards and Request for Public Comment and/or Information on Related Issues, 82 Fed. Reg. 3518 (Jan. 11, 2017); Docket ID No. EPA-HQ-OW-2016-0627 To Whom It May Concern The Hexavalent Chromium Panel of American Chemistry Council (ACC) appreciates the opportunity to submit these comments in response to EPA's third six-year review of existing drinking water standards. As detailed below, ACC urges EPA to make the development of a risk assessment for hexavalent chromium (chromium VI) a high priority and set an aggressive completion schedule, including public comment and scientific peer review. Moreover, this assessment should be based on the full scientific database, including the recent mode of action (MOA) research on chromium VI. EPA concludes in the six-year review that the national primary drinking water regulation (NPDWR) for chromium is "not appropriate for revision at this time" because "health effects assessment in process (as of December 2015) or contaminant nominated for health assessment," further noting "Chromium VI is being assessed by the EPA IRIS Program." According to IRIS Program website, Chromium VI is in step 1 of the process, which is draft development. While ACC agrees that the NPDWR should not be revised until the health effects assessment is completed, we urge EPA to accelerate completion of the assessment for the following reasons: The NPDWR for chromium, which includes chromium VI, is 100 parts per billion (ppb). The total chromium standard assumes that 100 percent of the chromium in drinking water is chromium VI. EPA's Office of Drinking Water has completed its occurrence study for chromium VI as part of the third Unregulated Contaminant Monitoring Rule (UCMR-3). The UCMR-3 monitoring data indicate low levels of chromium VI throughout the United States in ground water sources used for drinking water. These levels are below the NPDWR for total chromium. EPA issued a draft IRIS assessment of chromium VI in 2010, which was reviewed by an independent expert peer review panel in May 2011. The peer review panel urged EPA to consider the results of significant new mode of action (MOA) research on chromium VI before finalizing the assessment. The MOA research has been completed. The research investigated the biochemistry, in vivo genotoxicity, histopathology, toxicogenomics, and in vitro genotoxicity of chromium VI. In addition, toxicokinetics data measured the rates and capacity of chromium VI reduction to trivalent chromium in human and rodent stomach contents. The MOA data were used to develop a physiologically based pharmacokinetic (PBPK) model, which allows analysts to extrapolate high dose rodent data to low doses and to translate rodent data to humans, including sensitive individuals (Attachment A). In 2011, the California Office of Environmental Health Hazard Assessment (OEHHA) set a public health goal (PHG) of 0.02 ppb for chromium VI. The PHG was based on data from a 2008 National Toxicology Program (NTP) study that found small intestine tumors in mice, but not rats, exposed to very high levels of chromium VI, and did not consider the MOA research or PBPK model. California finalized a maximum contaminant level for chromium VI of 10 ppb in 2014. Recently, the Texas Commission on Environmental Quality (TCEQ) completed a risk assessment of chromium VI, considering the NTP and MOA data as well as the PBPK model. TCEQ set a reference dose that corresponds to 100 ppb for oral exposure to chromium VI. TCEQ considers this value to protect against potential long-term and short-term adverse health effects (i.e., to be protective of both non-carcinogenic and carcinogenic effects). Recent media reports have implied that the low levels of chromium VI reported in the UCMR-3 dat…

The Chlorine Chemistry Division of the American Chemistry Council is pleased to submit these comments on the Announcement of the Results of EPAs third Six-Year Review of Existing Drinking Water Standards.