EPA’s Science Advisory Board (SAB) Perchlorate Advisory Panel wrapped up discussions on its recommendations for setting a maximum contaminant level goal (MCLG) for perchlorate in drinking water during conference calls held December 5 and 7. The Advisory Panel discussed the latest version of its draft report, focusing largely on ironing out language to be incorporated in a final report that will be sent to the full SAB for review and submittal to the EPA Administrator. The core recommendation of the report, as reflected in a draft letter to the Administrator, was largely unchanged from the previous draft: EPA should “derive a perchlorate MCLG that addresses sensitive life stages through physiologically-based pharmacokinetic/pharmacodynamic modeling based upon its mode of action rather than the default MCLG approach using the RfD and specific chemical exposure parameters,” an approach deemed to be “a more rigorous way to address differences in biology and exposure between adults and sensitive life stages than is possible with the default approach for deriving an MCLG.”
Implementation of SAB recommendations for revised modeling, as well as a pending Small Business Regulatory Enforcement Fairness Act (SBREFA) review, pose significant barriers to a quick completion of any rule-making package. Having the SAB and SBREFA review processes completed and any resulting recommendations considered and, as appropriate, implemented is often critical to avoid lengthy hold-ups during pre-proposal reviews, particularly by the Office of Management and Budget. Current indications are that EPA will not receive a final SAB Advisory Panel report until March, and SBREFA consultations are expected to stretch at least that long. As a result, EPA will be unable to meet the February 2013 statutory deadline for proposing a perchlorate drinking water regulation and the new timeline for rule proposal, as reflected in the recently released 2012 Regulatory Agenda, is December 2013.