Examination of the Mobility Scoring Hierarchy Used to Select Chemicals for the U.S. EPA Contaminant Candidate List Classification Procedure

What role can regulations and policies assume in controlling compounds of emerging concern? In this policy analysis, the manner in which mobility is ranked in an existing regulation, the Contaminant Candidate List (CCL) classification procedure, is considered, with the realization that mobility data comprise but one part of the complex classification process. The premises of this discussion are three-fold: (1) that consideration of the pH-dependence of the physical properties used to determine chemical mobility is not expressly incorporated into the CCL classification process at present; (2) that consideration of the pH of surface water, drinking water, and wastewater undergoing treatment (commonly pH 7-8) is important to determining the potential mobility of a chemical; and (3) that a "very high" category should be added to the mobility scoring hierarchy in addition to the "low," "medium," and "high" categories currently included in the CCL classification procedure.