Participating Databases

United States Environmental Protection Agency Substance Registry Services Go to external website

General information:

The Substance Registry Services (SRS) is the Environmental Protection Agency's (EPA) central system for information about regulated and monitored substances. It is the portal for discovering chemical information at EPA. The system provides a common basis for identification of chemicals, biological organisms, and other substances listed in EPA regulations and data systems, as well as substances of interest from other sources, such as publications.

For each chemical, the SRS provides basic core metadata, including Chemical Abstract Service (CAS) names and CAS numbers. SRS identifies an EPA standardized name for each chemical (e.g., “Toluene” for the chemical with CAS name “Benzene, methyl-”). SRS also includes the molecular weights, molecular formulae, former CAS numbers and descriptions (when available).

A second section of each SRS substance record provides statutory or list information on each chemical. For each US environmental statute, the SRS identifies the list of chemicals named on that statute and the synonym used. For each US EPA data system, the SRS identifies the list of chemicals in that data system and the synonym used. The SRS also has chemical lists for external organizations, such as lists maintained by other US federal agencies or lists maintained by international organizations.

A third section provides links, if available, from the SRS to other sites for additional information. These links might be to other substance registry systems, such as those managed by other federal agencies or international organizations, or to fact sheets about the chemical.

Hazard information:

Hazard information is not available in the SRS. However, the SRS provides links, when known, from each SRS substance record to external sites and fact sheets. These external sites may be for EPA programs, other U.S. agencies, or international organizations.

Search capabilities:

The SRS can be searched by name (Containing, Exact match, or Begins with), CAS number or other identifier, molecular weight, molecular formula, or list (e.g., the HPVIS list). Searches can be tailored, such as a search for chemicals that have a synonym containing the word “cadmium” that is on the HPVIS list. An Advance Search allows users to search using Boolean logic, for example searching for substances that are found on an intersection of two or more lists.


United States Environmental Protection Agency (US EPA).

Peer review:

Core metadata (e.g., CAS name, CAS number, molecular weight) for a majority of the chemicals is made available from a program office at the US EPA that obtains the data from the Chemical Abstract Service. Data quality for core metadata for other chemicals is reviewed on a periodic basis. Programmatic information (e.g., the synonym used by a particular EPA program office) is managed within the SRS by designated stewards from that program office.

Top of Page