The Nanotechnology Panel comments on EPAs proposed significant new use rules (SNURs) under section 5(a)(2) of the Toic Substances Control Act (TSCA) for the chemical substances rutile, tin zinc, calcium-doped (CAS No. 389623012) and rutile, tin zinc, sodium-doped (CAS No. 389623078) published in the December 28, 2011 edition of the Federal Register, docket EPAHQOPPT20101075.