EPA Proposes Major Changes To Chemical Risk Evaluation Process Under TSCA

The US Environmental Protection Agency (EPA) has proposed a new rule to revise how it evaluates the risks of chemicals currently in use under the Toxic Substances Control Act (TSCA). This initiative follows a review prompted by Executive Order 14219 and aims to streamline evaluations while aligning with the current administration's interpretation of TSCA. In response to concerns from the chemical industry and other stakeholders about the burden and complexity of the current risk evaluation process, the proposed modifications aim to streamline evaluations, increase transparency, and ensure a more predictable regulatory process for manufacturers (including importers) of chemical substances.

TSCA requires the EPA to prioritize and evaluate high-priority substances from the TSCA inventory. Risk evaluations under TSCA are primarily initiated by the EPA, either through its prioritization process or in response to manufacturer requests.¹ These evaluations are triggered by statutory requirements, emerging scientific evidence, or industry interest in clearing regulatory uncertainty around specific chemicals.²

The EPA uses risk evaluations to determine whether an existing chemical poses an unreasonable risk of injury to health or the environment—based solely on scientific risk, not costs or other nonrisk factors. These evaluations include unreasonable risks to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation under the specified conditions of use (COUs). COUS are the circumstances under which a chemical is intended, known, or reasonably foreseen to be manufactured, processed, distributed, used, or disposed of.

The EPA initially issued its procedural framework rule in 2017 and then revised it in 2024 under the Biden administration to require a single, comprehensive risk determination for each chemical across all COUs. EPA wants to return to evaluating each COU separately, reversing the 2024 rule and returning to the approach established during the first Trump administration.³ The EPA is seeking public comment on whether the procedural framework rule should include regulatory text specifying that the EPA has discretion to exclude COUs, exposure pathways, and routes and to coordinate actions with other EPA-administered laws to ensure that chemical risks "could be eliminated or reduced to a sufficient extent" by other EPA actions, as permitted under TSCA section 9(b). Notably, if the proposed rule is finalized and subsequently challenged, as anticipated, the courts will not defer to either of the EPA's interpretations. Instead, they will focus on determining the best interpretation of the statute consistent with the Supreme Court's recent decision in Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024).

The proposed rule would allow the EPA to consider occupational exposure controls, such as personal protective equipment (PPE) and industrial engineering controls, in chemical risk evaluations and risk determinations—something previously prohibited under the 2017 rule. This change could reduce findings of unreasonable risk in well-controlled workplace settings. Additionally, the rule would modify the regulatory definitions section in numerous ways, including by eliminating "overburdened communities" from the list of "potentially exposed or susceptible subpopulations" that must be considered in evaluations and by incorporating the definition of "weight of scientific evidence" from Section 2(e) of Executive Order 14303. These changes would influence how the EPA evaluates scientific data in its regulatory decisions.⁴

Finally, as proposed, the rule would require manufacturers (including importers) requesting a risk evaluation to submit less information and only that which is relevant to the COU or COUs identified in the risk evaluation request. These procedural changes would apply to all risk evaluations initiated on or after the date of the final rule and, to the extent practicable, to risk evaluations that are in process as of the date of the final rule but not yet finalized.

The deadline for submitting comments on the proposed rule is 7 November 2025.⁵ Those interested in submitting comments or discussing this proposed rule should contact the authors or another member of our Environment, Land, and Natural Resources practice group.

Footnotes

1. Section 6(b)(2) of TSCA, 15 U.S.C. 2605(b)(2), (4)(C)(ii). The EPA must always have at least 20 high-priority and 20 low-priority chemicals in process.

2. Section §6(b)(4) of TSCA, 15 U.S.C. 2605(b)(4). A manufacturer or consortia of manufacturers can formally request a risk evaluation of a specific chemical substance by submitting a request with supporting information on the chemical's conditions of use and by covering a percentage of the associated costs. The EPA has discretion to grant or deny the request.

3. Section 6(b) of TSCA, 15 U.S.C. 2605(b).

4. "Weight of scientific evidence" means "an approach to scientific evaluation in which each piece of relevant information is considered based on its quality and relevance, and then transparently integrated with other relevant information to inform the scientific evaluation prior to making a judgment about the scientific evaluation. Quality and relevance determinations, at a minimum, should include consideration of study design, fitness for purpose, replicability, peer review, and transparency and reliability of data." The EPA is requesting comment on all aspects of the proposed definition as well as whether the EPA should restore the 2017 definition for "best available science" or promulgate a definition of systematic review.

5. 90 Fed. Reg. 45690. Comments can be submitted via Regulations.gov under Docket ID: EPA-HQ-OPPT-2025-0260.

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