Inventory Representation For Chemical Substances

UVCB substances are substances of unknown or variable composition, complex reaction products, and biological materials that cannot be represented by unique structures and molecular formulas. Some UVCB substances are not adequately described by their CA Names and have supplemental definitions that are considered integral parts of the names for TSCA purposes. The guidance, entitled Toxic Substances Control Act Inventory Representation For Chemical Substances Of Unknown Or Variable Composition, Complex Reaction Products And Biological Materials UVCB Substances points out that any substance that matches a CA Name but is not covered by the substance description is not considered to be covered by that Inventory listing. 

Toxic Substances Control Act Inventory Representation For Chemical Substances Of Unknown Or Variable Composition, Complex Reaction Products And Biological Materials UVCB Substances UVCB Substances... 

The Environmental Protection Agency (EPA) explained the conventions applied to listings of polymeric chemical substances for purposes of Premanufacture Notification (PMN) reporting and the TSCA Inventory. The principal guidance document in which the conventions are explained is titled Toxic Substances Control Act Inventory Representation for Polymeric Substances, which was published on 29 March 1995. This discussion of polymer nomenclature conventions under TSCA begins with general guidelines, followed by a discussion of how polymers are identified... 

The EPA explained its preferred methods for representing polymers on the Inventory in its 1995 Toxic Substances Control Act Inventory Representation for Polymeric Substances, and began by defining what substances can be hsted on the Inventory as polymers.For this purpose, EPA defined polymers as sequences of one or more types of monomer units, where a monomer unit is the reacted form of a monomer bonded to two or more other molecules. A polymer must also have a distribution of molecules of different molecular weights attributable primarily to different numbers of monomer units in the molecules. If all the molecules of a specific substance always have the same chain length then that substance is described on the Inventory as a specific substance with a defined structure and molecular weight, and not as a polymer. There are limited exceptions to this rule. Some chemicals that chemists may consider to be polymers do not fall within this definition because they do not have a distribution of molecular weights. 

Toxic Substances Control Act Inventory Representation For Chemical... 

Letter from Mary E. Cushmac, Chief, Policy and Administrative Section, New Chemicals Branch, to Fred H. Parry of Hoechst Celanese Corporation (Aug. 12,1994) in collection of h 7 Letters Toxic Substances Control Act Inventory Representation For Polymeric Substances Polymeric Substances... 

The guidance on how to name complex reaction products is entitled Toxic Substances Control Act Inventory Representation for Combinations of Two or More Substances Complex Reaction Products. It applies only to chemicals made by a chemical reaction, and not to formulated mixtures, which are made simply by mixing with no chemical reaction. Its primary purpose is to explain when complex reaction products should be named as one reaction product, or as a series of individual components. 

Fundamental to the TSCA Inventory is the principle that entries on the Inventory are identified as precisely as possible for the commercial chemical substance, as reported by the submitter. Substances that are chemically indistinguishable, or even identical, may be listed differently on the Inventory, depending on the degree of knowledge that the submitters possess and report about such substances, as well as how submitters intend to represent the chemical identities to the EPA and to customers. Although these chemically indistinguishable substances are named differently on the Inventory, this is not a nomenclature issue, but an issue of substance representation as required by the EPA. Submitters should be aware that their choice for substance representation has an important role in the EPA s determination of how the substance will be listed on the Inventory. 

---