The U.S. EPA's Framework for Metals Risk Assessment, released March 8, is a guideline document about metals and describes how they should be considered in conducting human health and ecological risk assessment.
EPA states it developed the Framework in consultation with the scientific community, its Science Advisory board, and stakeholders, in an open and transparent process. External scientific experts and the public gave important feedback on the document.
The agency emphasizes that the framework is not a mandate on exactly how a particular program must conduct its assessments, but rather a set of key principles that will be useful in preparing such assessments. It is a reference source from which the different programs within the EPA can evaluate its own methods and practices for assessing metals, and revise or update as appropriate.
The principles pertain to general, fundamental aspects of metals that should be addressed and incorporated into inorganic metals risk assessments. For example:
- Metals are naturally occurring constituents in the environment and vary in concentrations across geographic regions;
- All environmental media have naturally occurring mixtures of metals, and metals are often introduced into the environment as mixtures;
- Some metals are essential for maintaining proper health of humans, animals, plants, and microorganisms;
- Metals, as chemical elements, and unlike organic chemicals, are neither created nor destroyed by biological or chemical processes, although these processes can transform metals from one species to another (valence states) and can convert them between inorganic and organic forms;
- The absorption, distribution, transformation, and excretion of a metal within an organism, depends on the metal, the form of the metal or metal compound, and the organism's ability to regulate and/or store the metal.
The Framework for Metals Risk Assessment is available at www.epa.gov/osa/metalsframework