EPA classifies chemical substances as either "existing" chemicals or "new" chemicals. The only way to determine if the substance you are working with is a new chemical is by consulting EPA's Toxic Substances Control Act Chemical Substance Inventory (commonly referred to as the TSCA Inventory or just the Inventory). Any substance that is not on the Inventory is classified as a new chemical. If a substance is "new", it can be manufactured for a commercial purpose only if it is subject to an exemption from PMN reporting or a TSCA reporting exclusion (for example, a Low Volume Exemption, or exclusion as a naturally-occurring material). For substances which are "existing", the Inventory can be used to determine if there are restrictions on manufacture or use under the Toxic Substances Control Act (TSCA).There are approximately 75,000 chemical substances, as defined in Section 3 of the TSCA, on the Inventory at this time.
You can read further at this link for the
TSCA INVENTORY