On November 14, 2019, the U.S. Court of Appeals for the Ninth Circuit issued its decision in a case challenging the U.S. Environmental Protection Agency’s (EPA) prioritization and risk evaluation rules. Safer Chemicals, Healthy Families v. EPA, No. 17-72260. Petitioners argued that provisions in the risk evaluation rule relating to EPA’s evaluation of the risks from a substance’s “conditions of use” violate several of the Toxic Substances Control Act’s (TSCA) requirements. Specifically, petitioners claimed that: (1) TSCA requires EPA to evaluate risks associated with a chemical’s uses collectively before determining that the chemical is safe; (2) EPA must consider all of a chemical’s conditions of use in that evaluation; and (3) when considering conditions of use, EPA must evaluate past disposals of all chemicals, as well as the use and subsequent disposal of chemicals not currently or prospectively manufactured or distributed in commerce for that use. Petitioners maintained that various provisions of the risk evaluation rule demonstrate that EPA will not do any of these three things. The court held that it lacks jurisdiction to review petitioners’ first challenge, and that their second challenge fails on the merits. The court granted in part the petition for review with respect to petitioners’ third challenge to EPA’s exclusion of “legacy uses” and “associated disposals” from the definition of “conditions of use,” and those portions of the risk evaluation rule’s preamble are vacated. The court notes that because petitioners’ challenges to EPA’s prioritization rule are “entirely encompassed” within their challenges to the risk evaluation rule, the challenges rise or fall together. The court thus focused only on the risk evaluation rule.