December 31, 2025
Contact Information
EPA Press Office (press@epa.gov)
WASHINGTON – In compliance with a court ordered deadline, U.S. Environmental Protection Agency (EPA) completed a robust review of 1,3-butadiene using gold standard science. We used the best research, data, and testing available, along with input from the public and independent expert peer reviewers to complete this thorough evaluation. Our comprehensive scientific review found potential unreasonable health risks for workers who breathe in this chemical at their jobs in 11 specific industrial settings. Use of personal protective equipment, which is often used in industrial workplaces will help mitigate these risks. EPA did not find unreasonable risks to the environment, for consumers and to the general population including people living near facilities.
As required by law under the Toxic Substances Control Act (TSCA), EPA will now develop rules to protect workers from the risks we identified. This 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.
EPA is committed to radical transparency throughout the review and risk management process. The review process for butadiene has taken six years, with approximately 20,000 scientific studies considered during the review process for 30 different use cases.
We improved our evaluation by incorporating real-world data and refining some conservative assumptions from our first draft, making our science more accurate and reliable. For example, EPA switched to a more detailed database (NEI) that includes specific details like how tall stacks are, what angle they release emissions at, and emission temperatures, which are not reported in TRI. This allowed our evaluation to move away from defaults to more accurate, facility-specific conditions. The NEI database also provides exact coordinates of where emissions are actually released, rather than just general facility locations. This geographic precision gives a more accurate picture of actual exposure risks.
EPA also took into account additional feedback from peer reviewers recommending that we add together the risks from bladder cancer and leukemia. This resulted in a higher overall cancer risk estimate used in the risk evaluation.
Regarding workplace exposures, which is where the highest risks occur, we followed robust scientific practices during our 1,3-butadiene evaluation to provide clear, reliable results. The final rules will give companies clear regulatory certainty while providing workers with necessary protections. Our safeguards will be tough and practical. We will ensure the protections we put in place are workable, taking additional action if new science emerges or conditions change.
In addition to evaluating workplace exposures, we also thoroughly analyzed risk to the environment, to consumers, and to the general population. We are pleased to report that EPA did not find unreasonable risks to the environment, or for consumers or the general population, including people living near facilities.
Background
1,3-butadiene is a colorless gas essential for manufacturing products Americans use every day, including car tires, adhesives and sealants, paints and coatings, and automotive care products. Consumer products only contain tiny, safe amounts less than 0.001 percent. Unreasonable risks are found in industrial settings where workers could be exposed to much higher levels that could lead to health risks which may include reduced birthweight pregnancies, anemia, leukemia, and bladder cancer.
