Why was sodium included on the Contaminant Candidate List 1 (CCL)?
The issue of sodium posed a unique challenge for EPA priority setting and contaminant candidate listing process. High levels of salt intake may be associated with hypertension in some individuals, however sodium levels in drinking water are usually low and unlikely to be a significant contribution to adverse health effects. This low level of concern is compounded by the legitimate criticisms of EPA's 20 milligrams per liter (mg/l) Drinking Water Equivalency Level (DWEL or guidance level) for sodium. EPA believes this guidance level for sodium needs updating, and is probably low. If a health benchmark for drinking water were established using current information and current drinking water health assessment procedures, it would likely be higher. This revision could establish a new level at which sodium occurrence would not meet the criteria for inclusion on the CCL as a drinking water contaminant of concern. There was insufficient time to complete a reassessment of the sodium guidance in advance of the CCL issuance. Given the state of the data, EPA faced a dilemma on whether or not to list sodium. A decision not to list would be justified by the fact that much is known about sodium, and it does not appear to be a drinking water risk comparable to other priority contaminants. This was the logic supporting the decision not to include sodium on the previous drinking water priority list in 1991. However, a decision to list sodium would afford EPA the opportunity to address the confusion surrounding the current guidance for sodium in drinking water. Additional information on EPA's final determination on sodium in drinking water is available in the Announcement of Regulatory Determinations for Priority Contaminants on the Drinking Water Contaminant Candidate List (68 FR 42897; July 18, 2003). This document can be obtained at http://water.epa.gov/scitech/drinkingwater/dws/ccl/reg_determine1.cfm.
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