The Toxic Substances Control Act (“TSCA”) (15 U.S.C. 2601 et seq.) governs the importation into the customs territory of the United States of a chemical substance in bulk form or as part of a mixture, and articles containing a chemical substance or mixture. Such importations are also governed by these regulations which are issued under the authority of section 13(b) of TSCA (15 U.S.C. 2612(b)).