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SOURCE - Spring 2013

www.ca-nv-awwa.org 25 Inorganic Contaminants, continued from page 19 Cr(VI) A potential revision to the existing total chromium regulation to address hexavalent chromium Cr(VI) would be the most significant regulatory revision from the national perspective. (See Bruce Macler’s article, Cr(VI) Regulatory Update in this issue.) The timing for such a revision is not clear at this time, as EPA first has to finalize its revised risk assessment for Cr(VI). Timing is further complicated by the availability of the monitoring data from the Third Unregulated Contaminant Monitoring Rule (UCMR3). The UCMR3 monitoring will be conducted in 2013- 2015 and includes both total chromium and Cr(VI). So it’s not completely clear how the UCMR3 monitoring might factor into EPA’s decision-making on whether to include revising the total chromium regulation as part of the third six-year review discussed above. Fluoride The current national regulation of fluoride is complicated as EPA has both a primary MCL (4 ppm) for potential adverse health effects and a secondary MCL (2 ppb) for aesthetic effects (tooth discoloration). Since EPA is in the process of revising its risk assessment for fluoride, the timing for any potential change to either standard is not clear at this time. Given the ongoing attention given to fluoride, any potential changes to the fluoride standards are going to generate a fair amount of publicity and scrutiny. Arsenic EPA is in the process of revising its risk assessment for inorganic arsenic (the form of arsenic found in drinking water). It’s not clear when this risk assessment will be finalized, or whether EPA might consider revising its arsenic standard based on the final revised risk assessment. Remember that EPA used its discretionary authority under SDWA to set the arsenic standard at a level higher than was feasible (10 ppb as opposed to the feasible level of 3 ppb that was proposed) based on its cost-benefit analysis. Additionally, ongoing noncompliance with the arsenic standard is still problematic, particularly for small systems. So even with a revised risk assessment, EPA would still likely use the same logic in its cost-benefit analysis to maintain the arsenic standard at its current 10 ppb. S


SOURCE - Spring 2013
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