As required under section 6(b)(4) of the Toxic Substances Control Act (TSCA), EPA is issuing a rule that establishes a process for conducting risk evaluations to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation, under the conditions of use. This process incorporates the science requirements of the amended statute, including best available science and weight of the scientific evidence. Risk evaluation is the second step, after Prioritization, in a new process of existing chemical substance review and management established under recent amendments to TSCA. This rule identifies the steps of a risk evaluation process including: scope, hazard assessment, exposure assessment, risk characterization, and finally a risk determination. This process will be used for the first ten chemical substances undergoing evaluation from the 2014 update of the TSCA Work Plan for Chemical Assessments (to the maximum extent practicable). Chemical substances designated as High-Priority Substances during the prioritization process and those chemical substances for which EPA has initiated a risk evaluation in response to a manufacturer request, will always be subject to this process. The final rule also includes the required "form and criteria" applicable to such manufacturer requests.