Methodology for selecting substances for the National Exposure Registry.

The National Exposure Registry was created in response to the pervasiveness of chemical contamination at the nation's waste sites and the relative lack of information on human health outcomes associated with long-term, low-level exposure to most of these substances. A ranking scheme was developed by the Agency for Toxic Substances and Disease Registry (ATSDR) to select the substances for which substance-specific subregistries of the National Exposure Registry would be developed. This scheme uses a general decision analysis approach that incorporates the most relevant and up-to-date data available on the substances found at sites known to ATSDR. There are currently four general subregistries (volatile organic compounds, dioxins, heavy metals, and radioactive substances) made up of persons exposed to specific primary contaminants, as selected by means of this ranking scheme.