CASRN and the TSCA Inventory

One of the most widely held misconceptions associated with the CAS Registry is that all substances with a CASRN are on the TSCA Inventory. The numbers show otherwise 40 million CASRN have been assigned for chemical substances, but only about 84,000 substances are presently listed on the TSCA Inventory. 

Under TSCA Section 8(b), the EPA is required to develop and maintain a list of all chemical substances that are manufactured, processed, or used in the U.S. for commercial purposes (note that the term manufacture includes importation under the TSCA). The initial Inventory was developed from 1978 to 1980 using input from the chemical industry that allowed existing chemical 

New substances may be added to the TSCA Inventory through the Premanufacture Notification (PMN) process, which typically adds 

The TSCA Inventory is divided into two parts (1) the publicly accessible non-confidential Inventory that is readily accessed using the CASRN for chemical substances and (2) a confidential Inventory accessible only by the EPA through their TSCA Inventory Master File. For substances listed on the confidential portion of the Inventory, a generic name that masks the specific chemical identity of the substance and an accession number are placed on the non-confidential portion of the Inventory, and the specific chemical name is placed only on the confidential portion of the Inventory. 

The confidential portion of the Inventory can be accessed only in two ways. First, one could submit a PMN for the substance because upon 

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