This rulemaking would add 20 High-Priority Substances (HPS) and 30 organohalogen flame retardants to the Toxic Substances Control Act (TSCA) section 8(d) model” Health and Safety Data Reporting rule, codified at 40 CFR part 716, to obtain lists and copies of unpublished health and safety studies from manufacturers (including importers) of these chemicals. The Interagency Testing Committee (ITC), established under TSCA section 4(e), discussed and recommended adding these chemicals to the Priority Testing List (PTL) in May 2020 at the request of EPA (for the 20 High-Priority Substances) and the Consumer Product Safety Commission (CSPC) (for the 30 organohalogen flame retardants) to obtain this information to inform risk evaluations each agency is required to conduct pursuant to their respective statutory programs. The amendment process for these additions to 40 CFR part 716 will be pursuant to 40 CFR 716.105(b) and (c), which describes the process for adding chemical substances and mixtures to 40 CFR 716.120 after being added to the PTL. When the ITC adds chemicals to the PTL, those chemicals are added to 716.120 by publication of a rule amendment in the Federal Register. Such amendments are effective 30 days after publication. However, EPA may withdraw the chemical substance or mixture for good cause. Any information showing why a chemical substance or mixture should be withdrawn must be received by EPA within 14 days of publication of the amendment. The types of unpublished health and safety studies EPA and CPSC are seeking include studies on health effects, environmental effects, environmental fate, and occupational, general, and consumer exposure for these chemicals.