EPA Publishes Final Risk Evaluation For 1,3-Butadiene, Intends To Regulate 11 COUs To Protect Workers

The U.S. Environmental Protection Agency (EPA) announced on January 5, 2026, the availability of the final risk evaluation under the Toxic Substances Control Act (TSCA) for 1,3-butadiene. 91 Fed. Reg. 264. EPA states in its December 31, 2025, press release that it found "potential unreasonable health risks for workers who breathe in this chemical at their jobs in 11 specific industrial settings." As required by TSCA, EPA will now develop a risk management rule to protect workers from the identified risks. According to EPA, "[t]his process will include meticulous consideration of health effects, exposure levels, economic impacts, and benefits of use, with extensive stakeholder engagement to ensure the resulting rules are both protective and practical."

On its web page for the 1,3-butadiene risk evaluation, EPA states that it evaluated 30 conditions of use (COU), adding four COUs to the 28 evaluated in the draft risk evaluation based on the latest Chemical Data Reporting (CDR) and removing two COUs that are no longer active. EPA determined that 11 were significant contributors to unreasonable risk of injury to human health for workers due to inhalation exposure. EPA notes that for these 11 COUs, the determinations "do not reflect the use of personal protective equipment (PPE); however, PPE may reduce exposures and mitigate risk." The COUs significantly contributing to unreasonable risk include:

• Manufacturing — domestic manufacturing;

• Manufacturing — importing;

• Processing as a reactant — intermediate in various industries such as adhesive manufacturing and synthetic rubber manufacturing;

• Processing as a reactant — monomer used in polymerization process in synthetic rubber, plastic material, and resin manufacturing;

• Processing — incorporation into formulation, mixture, or reaction product — monomers in plastic, resin, and synthetic rubber manufacturing;

• Processing — incorporation into formulation, mixture, or reaction product — plasticizer in asphalt paving, roofing, and coating materials manufacturing;

• Processing — incorporation into article — monomer in rubber product manufacturing;

• Processing — use-non-incorporative activities — fuel in petroleum refineries;

• Processing — repackaging in wholesale and retail trade involving synthetic rubber and petrochemical manufacturing;

• Processing — recycling; and

• Disposal.

EPA found no unreasonable risks to:

• Consumers using products with 1,3-butadiene;

• People living near facilities that use 1,3- butadiene; and

• The environment.

EPA's Commitment to Gold Standard Science

EPA states that it "made [the risk] evaluation better" based on:

• Updated data informing actual workplace conditions;

• Public comments that helped EPA understand how 1,3-butadiene is used;

• New reporting from companies about current uses; and

• Expert peer review to make sure its methods were sound.

EPA states that it "removed flawed assumptions from our first draft and used real-world data, including widely accepted approaches used by EPA's Office of Air and Radiation, to strengthen our risk evaluation."

Next Steps

EPA will now develop a risk management rule intended to protect workers from the unreasonable risks identified. According to EPA, this process will include:

• Careful consideration of health effects and exposure levels;

• Analysis of economic impacts;

• Input from workers, companies, and the public; and

• Practical solutions that protect health while allowing important manufacturing to continue.

The final rule will give companies clear direction and ensure workers have the protection they need while these important products continue to be made safely.

Commentary

EPA began the New Year's Eve countdown at "6": the number of TSCA risk evaluations to be completed by the stroke of midnight per the terms of a court-ordered consent decree. Although Bergeson & Campbell, P.C. (B&C^®) believes that language in the consent decree effectively gave EPA some extra time to complete these actions due to the October 2025 lapse in federal appropriations, EPA stayed the course and, even before the close of business on December 31, had announced the release of all six of those final risk evaluations — including 1,3-butadiene. Considering that EPA has only issued final risk evaluations for a little over a dozen or so chemicals since 2016, the publication of six more in a single day was a truly momentous achievement for EPA staff.

These announcements were an exclamation point at the end of a dynamic and challenging year for the TSCA program. The onboarding of new political leadership, the reorganization of the Office of Pollution Prevention and Toxics, the retirement and/or departure of key staff, the deregulatory and cost-cutting priorities, the significant number of active legal challenges, and the concurrent shifts in policies and legal interpretations suggested all the right ingredients for a cocktail of further delay. Instead, EPA persisted and ended the year with a proverbial pop of the champagne. Celebrations are not likely to last long, though, as 2026 will be another impossibly busy year for EPA. Work will continue on additional remaining existing chemical risk evaluations (and reconsideration of others like 1,4-dioxane and formaldehyde), among many other competing priorities.

We also expect to gain some important insight in the new year into the Trump Administration's approach to TSCA risk management. EPA's risk conclusions on 1,3-butadiene, for example, focus heavily on occupational exposures and risks to workers. As noted earlier, however, EPA's materials — the press release, website, and risk evaluation itself — make clear that these conclusions do not reflect the exposure reducing impact of PPE use, and that PPE can mitigate risks. EPA is in the midst of revising its procedural framework rule for TSCA risk evaluations. The current regulation — a 2024 final rule — prohibits EPA from assuming PPE use by workers and reducing exposure estimates accordingly. The 2025 proposed update to this rule suggests that EPA will consider information on the implementation and use of PPE. B&C expects EPA to publish the final updated procedural framework rule in 2026 — very likely before EPA issues a proposed risk management rule for 1,3-butadiene.

How EPA chooses to implement this expected policy change regarding occupational exposures will have enormous implications for the ultimate risk management approach for 1,3-butadiene and many other industrial chemicals. For example, will EPA continue to mandate the use of PPE via regulation under TSCA? Will EPA — during the risk management rule development process — consider the identified risks to workers already fully or partially mitigated when overlaying data on PPE usage, and therefore impose fewer or less stringent regulatory requirements? Will EPA argue that worker protections are already required under the Occupational Safety and Health Act, and therefore further TSCA regulation is unnecessary? Will EPA consider a novel referral of identified risks to the U.S. Occupational Safety and Health Administration pursuant to TSCA Section 9(a)? And for future risk evaluations, will EPA incorporate PPE use and related exposure reductions into its risk determinations in a way that obviates such considerations during the risk management phase? Will the courts finally weigh in on some of these foundational legal and policy issues? For now, EPA has signaled openness to hearing more from the public on ways that EPA can implement practical and health protective approaches. For auld lang syne, B&C again encourages interested stakeholders to stay tuned on these important issues in 2026.

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