Fifth Circuit Vacates EPA Methylene Chloride Rule, Sets Guardrails for TSCA Risk Evaluation and Management

The Fifth Circuit has vacated the US Environmental Protection Agency’s (EPA’s) 2024 methylene chloride risk-management rule and the underlying risk determination. The decision is one of the first appellate rulings to deeply examine the core risk-evaluation and risk-management provisions of the Toxic Substances Control Act (TSCA), as amended in 2016.

On September 15, the court rejected EPA’s “whole chemical” approach and its assumption that workers did not use personal protective equipment (PPE), found insufficient support for the rule’s acute and chronic exposure limits, and concluded that EPA had not adequately justified broad prohibitions or considered economic consequences and feasible alternatives. The holdings also intersect with EPA’s pending reconsideration of its risk-evaluation framework rule and may shape the methodology and administrative record for future TSCA Section 6 actions.

The significance of this decision extends beyond methylene chloride, with the interpretation of foundational statutory terms that recur throughout EPA’s existing chemicals program, including “conditions of use,” “unreasonable risk,” and “to the extent necessary,” and the application of TSCA’s demanding scientific and evidentiary standards.

KEY TAKEAWAYS

• East Fork Enterprises, Inc. v. U.S. Environmental Protection Agency, No. 24-60227, slip op. at __ (5th Cir. Sept. 15, 2026) has implications beyond the specific regulatory action at issue. The decision provides insight into how courts may evaluate challenges to EPA’s scientific and legal reasoning in chemical risk evaluations and the regulatory actions that rely on them.
• The decision may accelerate EPA’s existing chemical programmatic reset but does not settle national TSCA issues. For several of the first 10 risk-assessment and risk-management rules, EPA has substantial records that were previously developed under both the 2017 framework and the Biden administration’s approach. Additionally, related proceedings in the Third, Fifth, Eighth, and Ninth Circuits could produce different interpretations, potentially setting up an interesting circuit split.
• Regulatory planning may need to account for greater uncertainty. Companies should continue preparing for applicable regulatory requirements while preserving flexibility where pending litigation could affect the scope, timing, or ultimate form of those requirements.

THE FIFTH CIRCUIT’S DECISION

EPA’s June 2020 risk evaluation considered 53 conditions of use for methylene chloride and found unreasonable risks for 47 of those conditions. In 2022, without changing the underlying scientific analysis, EPA replaced those use-specific findings with a single whole-chemical determination and no longer assumed that workers used PPE.

EPA relied on that revised determination in its 2024 rule, which prohibited 40 conditions of use and allowed 13 industrial or commercial uses to continue under a workplace chemical protection program. For permitted uses, EPA set a 16 parts-per-million (ppm) short-term limit and a 2 ppm eight-hour limit, compared with the Occupational Safety and Health Administration (OSHA) limits of 125 ppm and 25 ppm, respectively.

The Fifth Circuit first held that TSCA requires EPA to determine unreasonable risk by condition of use. The court reasoned that the statute focuses on the manufacturing, processing, distribution, use, and disposal activities associated with a chemical and repeatedly directs EPA to evaluate risk under the relevant conditions of use. It therefore concluded that EPA lacked authority to replace individual determinations with a single whole-chemical finding.

The court also rejected EPA’s assumption that workers did not use PPE. It concluded that PPE and other controls may be part of the relevant conditions of use where reasonably available evidence shows they are actually used. EPA’s 2020 evaluation had credited information concerning engineering controls, administrative controls, and PPE and had declined to presume widespread noncompliance with OSHA requirements. The court found that EPA did not adequately support or explain its later reversal.

The opinion further treats “unreasonable risk” as a judicially reviewable statutory standard rather than a conclusion that automatically follows from a numerical risk estimate. Emphasizing that TSCA is not a zero-risk statute, the court found that EPA had not adequately supported its acute or chronic exposure limits.

It criticized the agency’s reliance on selected human and animal studies, its treatment of uncertainty, and its failure to engage sufficiently with contrary epidemiological evidence and significant public comments. The court concluded that the analysis did not satisfy TSCA’s best-available-science and substantial-evidence requirements.

Finally, the court held that EPA had not adequately justified the scope of the rule’s prohibitions. Uncertainty about whether facilities could comply with the new exposure limits did not establish that a ban was necessary, and EPA could not shift to regulated parties the burden of proving compliance was possible. While costs are excluded from the initial unreasonable risk determination, the court emphasized that EPA must consider economic consequences and technically and economically feasible alternatives when selecting risk-management measures.

A separate petition was filed by the Sierra Club, contending that EPA had not gone far enough to address risks to fenceline communities, genetically susceptible populations, and potential ozone depletion. The Fifth Circuit denied the Sierra Club’s petition on narrower grounds, granted the industry petition, and vacated the rule and associated risk determination in full.

BROADER IMPLICATIONS FOR TSCA

While East Fork directly concerns methylene chloride, the opinion interprets statutory requirements that apply across EPA’s existing chemicals program, including “conditions of use,” “unreasonable risk,” and “to the extent necessary,” as well as TSCA’s best-available-science and substantial-evidence requirements.

The condition-of-use holding may require more differentiated outcomes, with EPA regulating activities that present unreasonable risk while leaving other uses unregulated or subject to less restrictive measures. It also increases the importance of connecting risk findings to the particular activities, exposure scenarios, and controls reflected in the administrative record.

The timing gives the decision additional programmatic significance. Before oral argument, EPA informed the court that it no longer defended the prior whole-chemical and no-PPE interpretations. EPA’s September 2025 proposal to revise the Risk Evaluation Framework Rule would also restore condition-of-use specific determinations and clarify how the agency considers PPE, engineering controls, and administrative controls.

East Fork therefore reinforces central elements of EPA’s proposed policy shift, although its holdings concerning the meaning of “unreasonable risk,” the adequacy of the scientific record, and the required relationship between an identified risk and the selected remedy go further.

Judicial review has increasingly shaped the boundaries of TSCA Section 6. TSCA’s judicial review structure generally delayed review of policy framework choices until they were incorporated into final risk-management rules. As EPA’s approach shifted across administrations, disputes over conditions of use, exposure pathways, workplace controls, and scientific assumptions accumulated. East Fork is especially significant because it addresses several of those recurring questions in a single merits decision.

Those shifts in approach also mean that EPA may not be starting from a blank slate. For several of the first 10 chemical risk assessments, EPA developed an initial risk evaluation under the 2017 framework during the first Trump administration and later revised or supplemented that analysis under the Biden administration, often using materially different approaches to whole-chemical determinations, exposure pathways, and occupational controls.

Substantial portions of the hazard, exposure, and condition-of-use record therefore already exist under both approaches, although the records are not identical and additional notice-and-comment proceedings may be required.

The opinion also sharpens the line between legal interpretation and scientific judgment following Loper Bright Enterprises v. Raimondo, 603 U.S. 369 (2024). Reviewing courts will interpret TSCA’s statutory terms independently, while EPA retains primary responsibility for technical analysis.

Scientific expertise does not relieve the agency of its obligation to consider the record as a whole, address evidence that detracts from its conclusions, and explain why its methods support a finding of unreasonable risk. The decision does not categorically prohibit conservative assumptions, animal studies, uncertainty factors, or protective exposure limits; it requires a reasoned and transparent record supporting their use.

Similarly, the PPE holding does not establish a universal presumption that workplace controls are fully effective. EPA may consider whether PPE and other controls are actually used and whether available information identifies gaps in coverage or compliance. The agency may not, however, disregard evidence of existing protections or presume noncompliance without adequate support.

Once EPA moves from risk evaluation to risk management, it must demonstrate a closer relationship between the risk identified and the remedy selected, including meaningful consideration of economic consequences and technically and economically feasible alternatives where a use would be substantially prevented.

East Fork does not automatically invalidate other risk-management rules or settle these statutory questions nationwide. The broader appellate landscape includes Fifth Circuit proceedings involving EPA’s 2024 1,4-dioxane determination and its asbestos and perchloroethylene (PCE) rules; a Ninth Circuit challenge to the 2020 1,4-dioxane risk evaluation; an Eighth Circuit challenge involving carbon tetrachloride; and a Third Circuit challenge involving TCE. East Fork is already affecting this related TSCA litigation.

EPA has sought additional time in the pending PCE litigation to evaluate East Fork’s implications, while industry petitioners challenging the TCE rule in the Third Circuit have cited East Fork as a supplemental authority supporting their challenges. These early procedural steps illustrate that the decision’s broader impact may develop through a combination of agency reconsideration and ongoing judicial review.

East Fork’s influence on pending cases will partly depend on the choices made by EPA, regulated parties, and the reviewing courts. EPA could seek remand of actions it is already reconsidering, request that pending cases remain stayed or in abeyance while that reconsideration proceeds, or continue to defend particular rules or determinations on the existing record; petitioners may likewise press for merits decisions notwithstanding ongoing agency reconsideration.

If other courts reach the merits, they may follow, distinguish, or disagree with aspects of East Fork. Divergent interpretations of “conditions of use,” “unreasonable risk,” occupational controls, or TSCA’s substantial-evidence standard could create a circuit split, prolonging national regulatory uncertainty.

CONSIDERATIONS FOR INDUSTRY

For companies who are evaluating chemical-related regulatory risk, East Fork provides a framework for reviewing both pending and final risk-management rules. Companies should identify any chemicals in their portfolios for which EPA relied on approaches implicated by the decision, including a whole-chemical risk determination, an assumption that occupational controls were absent, disputed scientific assumptions or uncertainty factors, or broad restrictions supported by contested alternatives analyses.

The relevance of East Fork will depend on the chemical-specific record and procedural posture, but those issues may warrant closer review of the assumptions underlying existing compliance plans.

For risk evaluations and rulemakings that remain in progress, companies should consider whether the administrative record adequately documents their particular conditions of use, actual workplace exposures and controls, relevant scientific evidence, and the technical and economic feasibility of alternatives.

Where that information is incomplete, companies should consider supplementing the record before it closes, including by updating, resubmitting, or expressly incorporating relevant information developed during earlier iterations of EPA’s risk evaluation.

For final risk determinations and risk-management rules already subject to judicial review, companies should monitor both the litigation and EPA’s response to East Fork. The procedural posture of those matters, including any remand, stay, abeyance, or merits decision, may affect the scope and timing of regulatory obligations.

Those developments have practical consequences for compliance and investment decisions. Companies facing future prohibitions, substitution requirements, workplace-control obligations, or other significant expenditures should identify which requirements remain legally operative and when compliance deadlines apply, while assessing whether pending agency reconsideration or litigation could alter those requirements.

Pending litigation or agency reconsideration alone does not suspend an otherwise effective requirement. Where feasible, companies may want to preserve flexibility, for example, by maintaining exposure-monitoring and control data, sequencing capital expenditures around applicable deadlines, preserving work performed to qualify substitutes, and avoiding unnecessary dismantling of compliance systems that could remain relevant under a revised rule.

The same information can support both regulatory planning and the administrative record. Companies should preserve condition-of-use-specific exposure data, evidence concerning actual PPE and engineering controls, scientific analyses, and information concerning the costs, performance, availability, and feasibility of substitutes for use in reconsideration proceedings, future rulemaking comments, or judicial review.