On June 15, 2021 (86 FR 31622), the Environmental Protection Agency (EPA or the Agency) responded to a rulemaking petition (“the petition”) requesting revision of the Resource Conservation and Recovery Act (RCRA) corrosivity hazardous waste characteristic regulation. The petition requested that the Agency make two changes to the current corrosivity characteristic regulation: Revise the regulatory threshold for defining waste as corrosive from the current value of pH 12.5, to pH 11.5; and expand the scope of the RCRA corrosivity definition to include non-aqueous wastes in addition to the aqueous wastes currently regulated. The Agency published a tentative denial of the rulemaking petition on April 11, 2016. On June 15, 2021 the Agency published a final denial of the rulemaking petition. This final action wais effective on June 15, 2021.