Regulacje i polityka gospodarcza · 14/11/1996

Proposed Selenium Criterion Maximum Concentration for the Water Quality Guidance for the Great Lakes System

EPA is proposing a new acute aquatic life criterion for selenium in the final Water Quality Guidance for the Great Lakes System (the Guidance) that was published on March 23, 1995. The U.S. Court of Appeals for the D.C. Circuit vacated the 1995 acute selenium criterion on September 19, 1996. The proposal takes into account data showing that selenium's two most prevalent oxidation states, selenite and selenate, present differing potentials for aquatic toxicity, as well as new data indicating that all forms of selenium are additive. Additivity increases the toxicity of mixtures of different forms of the pollutant. The new approach produces a different selenium acute criterion (also called the Criterion Maximum Concentration, or CMC) depending upon the relative proportions of selenite, selenate, and other forms of selenium that are present. EPA believes that the proposed revisions more accurately represent the numerical limits for acute criteria for selenium necessary to protect aquatic life in the Great Lakes System. EPA is not proposing to revise any other aspect of the selenium criteria for aquatic life.