Under the Toxic Substances Control Act (TSCA) "new" chemical substances are subject to detailed premanufacturing notice and approval requirements.  This is unique because "traditional" environmental statutes such as the Clean Water Act and the Clean Air Act primarily regulate "end-of-pipe" or "end-of-stack" emissions.  Thus, some environmental lawyers herald TSCA as a proactive tool for EPA to regulate nanoscale materials before they are put in use, rather than simply monitoring and limiting eventual emissions/releases.

A core issue in this discussion has been whether — because of their small size and sometimes unique properties — EPA should treat all nanoscale materials as "new" chemicals under TSCA and subject them to the Act’s premanufacturing notice and approval requirements.  Some argue this is the most conservative, precautionary approach given current EHS uncertainty surrounding some nanoscale materials in certain circumstances.

Earlier today EPA took a large step towards clarifying its approach by publishing a paper explaining its treatment of nanoscale substances under TSCA as "new" versus "existing" chemicals. "TSCA Inventory Status of Nanoscale Substances — General Approach."  EPA’s announced position is consistent with many predictions:  EPA does not intend to consider nanoscale materials "new" substances just because of their diminutive size — they must have a distinct molecular identity that is not shared with any other chemical on TSCA’s existing Chemical Substance Inventory before they are considered "new."

In reaching its position, EPA explains that term "chemical substance" is defined as “any organic or inorganic substance of a particular molecular identity," and that a "molecule" is defined as the smallest amount of matter retaining all of its same chemical properties.  Therefore, EPA reasons if a nanoscale material has the same molecular identity as its bulk counterpart, it is an "existing," not "new," chemical substance. 

However, EPA also indicates it is going to approach these determinations on a case-by-case basis, and “certain nanoscale substances that will be manufactured or imported for commercial purposes are expected to be new chemical substances and therefore subject to TSCA new chemical regulatory requirements. As are any other new chemical substances.”

Apparently realizing this issue may create uncertainty with nano-manufacturers, EPA encourages companies to consult EPA or submit a request for an inventory search to determine whether a particular nanoscale material in question should be treated as a "new" chemical under TSCA. 

However, a sibling issue still remains undecided by EPA  — whether the use of nanoscale materials constitutes a "significant new use" of an existing chemical substance which also triggers TSCA’s  premanufacturing notice and approval requirements.  This is a much tougher issue to resolve.  Under the applicable statute, relevant factors in this consideration are:  (i) the projected volume of manufacturing and processing of a chemical substance, (ii) the extent to which a use changes the type or form of exposure of human beings or the environment to a chemical substance, (iii) the extent to which a use increases the magnitude and duration of exposure of human beings or the environment to a chemical substance, and (iv) the reasonably anticipated manner and methods of manufacturing, processing, distribution in commerce, and disposal of a chemical substance.

How EPA will resolve this issue remains to be seen.  Stay tuned.