Defining SRS Substance Types

A substance in the Substance Registry System is any chemical, biological organism, or physical property that is tracked or regulated by an EPA program or identified in an environmental statute.

Defining SRS Substance Types


A chemical can be defined as an organic or inorganic material that can be categorized as one of the following:

Biological organism

Biological organisms can be categorized as:

Physical properties

Physical properties are measurements in the environment that are important for understanding environmental quality. Examples of physical properties are:

Miscellaneous objects

Miscellaneous objects are substances that have been reported to EPA programs and are not easily categorized as chemicals or biological organisms.

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Multiple Names for a Single Substance

Substances, particularly chemicals, often have multiple valid names. For example, the scientific name for one chemical is Benzene, methyl. Other names for this chemical include Toluene, Toluol, Phenylmethane, and Methyl benzene. Biological organisms likewise can have a variety of names.

EPA programs may have their own names for substances. Prior to implementing SRS, discovering which EPA program tracked or regulated a particular substance was time-consuming and often required a degree of understanding of chemistry.

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Establishing Standard Substance Names

Recognizing this diversity of names for substances, EPA created two data standards: the Chemical Identification Data Standard for chemicals and the Biological Taxonomy Data Standard for biological organisms.

Each of these standards requires EPA to work with its state partners to identify a core set of identifiers. For chemicals, one of those identifiers is the scientific name (SRS Systematic Name), and one is a common name (SRS Registry Name) if it exists. In the example above, the SRS Systematic Name is Benzene, methyl-, and the SRS Registry Name is Toluene. Toluol, Phenylmethane and Methyl benzene are maintained in SRS as synonyms

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Supporting Discovery and Standardization

SRS, therefore, identifies

The core identifiers for each substance are listed at the top of each SRS record.

New EPA programs have begun to adopt the standardized names for their substance lists. Some older EPA programs have replaced their names with the standardized names.

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