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Superfund Chemical Data Matrix (SCDM)

Last Update: January 2021

SCDM is a source for factor values and screening concentration benchmarks that can be applied when evaluating potential National Priorities List (NPL) sites using the Hazard Ranking System (HRS). Factor values are part of the HRS equation for determining the relative threat posed by a hazardous waste site and reflect hazardous substance characteristics, such as toxicity and persistence in the environment, mobility and the potential for bioaccumulation. Screening concentration benchmarks are environment- or health-based concentration limits, including some developed by or used in other EPA regulatory programs. SCDM contains HRS factor values and screening concentration benchmarks for hazardous substances that are frequently found at sites evaluated using the HRS, as well as physical, chemical and radiological data used to calculate those values. The accompanying SCDM Methodology describes how data are selected or calculated for inclusion in SCDM.

On January 30, 2014, EPA released an updated SCDM with many revisions to the HRS factor values and benchmarks. The revisions were based on a comprehensive review and update of all the information contained in SCDM. These revisions were necessary because of updates to some of the toxicity data, as well as updates to several of the equations used to determine screening concentration benchmarks. This update also provided increased consistency across EPA programs. Following the January 2014 publication, revisions were made to SCDM on an as-needed basis to reflect changes within the cited references. A Change Control and Errata Sheet (PDF) (31 pp, 883 K, About PDF) is provided to document and track any changes or corrections that have been made since the January 2014 publication; these changes are reflected in the SCDM Query and reports below.


SCDM should be used for HRS and NPL purposes only.

SCDM contains factor values and benchmarks used for applying the HRS [40 CFR Part 300 Appendix A, 55 FR 51583] to evaluate potential NPL sites. The physical, chemical, toxicological and radiological data used to calculate the factor values and benchmarks are obtained from references listed in the SCDM Methodology. The references and the data extracted from these references were selected to meet specific HRS requirements and conditions which may not be applicable or representative for other uses. SCDM values are updated only on an "as needed" basis. As a screening tool, the HRS and SCDM are used for quickly assessing sites at the screening stage and data used to perform this task may not be applicable for other site specific purposes.

Superfund Chemical Data Matrix Query and Methodology

The SCDM Query allows you to access the SCDM information and generate a list of the corresponding HRS factor values, benchmarks, and data elements.

NOTE: Please do not assume that substances not listed in SCDM cannot be used for HRS scoring. If you have technical questions about SCDM, or if values are needed for a substance that is not listed in SCDM and are thought to be critical to the listing decision, please use the SCDM contact listed below.

For SCDM information, contact:
Linda Gaines, Ph.D., P.E. (
US Environmental Protection Agency
1200 Pennsylvania Avenue, N.W.
Washington, DC 20460
Phone: (703) 603-7189