This final rule, issued pursuant to sections 8(a) and 8(d) of the Toxic Substances Control Act (TSCA), withdraws certain chemical substances from the category of voluntary High Production Volume (HPV) Challenge Program orphan (unsponsored) chemical substances that would be subject to reporting requirements under TSCA section 8(a) and 8(d). On August 16, 2006, EPA published two final rules both effective September 15, 2006, with certain exceptions: A Preliminary Assessment Information Reporting (PAIR) rule under TSCA section 8(a) (40 CFR part 712), which requires manufacturers (including importers) of chemical substances in the category of voluntary HPV Challenge Program orphan (unsponsored) chemical substances on the Interagency Testing Committee's (ITC) TSCA section 4(e) Priority Testing List to submit a one-time report on general production/importation volume, end use, and exposure-related information to EPA, and a Health and Safety Data Reporting rule under TSCA section 8(d) (40 CFR part 716), which requires manufacturers (including importers) of chemical substances in this category of HPV Challenge Program orphan (unsponsored) chemical substances to submit certain unpublished health and safety data to EPA. On September 15, 2006, EPA published a final rule that delayed the effective date of the rules published August 16, 2006, until September 29, 2006. The chemical substances listed in this final rule are being withdrawn from 40 CFR parts 712 and 716 for good cause as specified in 40 CFR 712.30(c) and 40 CFR 716.105(c) and, consequently, these listed chemical substances will not be subject to the reporting requirements imposed by the TSCA section 8(a) and 8(d) rules published on August 16, 2006.