The EPA is initiating the TSCA prioritization process for five chemical substances as candidates for High-Priority Substance designation: 4-tert-octylphenol, benzene, ethylbenzene, naphthalene, and styrene. This procedural notice opens a 90-day public comment period closing March 18, 2025, during which interested persons may submit hazard, exposure, persistence, and use data to inform EPA's screening review. Designation as High-Priority will initiate a three-year risk evaluation for each substance. This notice does not constitute a finding of unreasonable risk; it is the formal start of the prioritization pipeline required under TSCA section 6(b).12