As required by law under the Toxic Substances Control Act (TSCA), EPA will now develop rules to protect workers from the risks that the agency identified. The process will include 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.  

According to EPA, the agency improved its risk evaluation by incorporating real-world data and refining some conservative assumptions from its first draft. 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. The agency claims that this allowed its 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 the agency adds together the risks from bladder cancer and leukemia. This resulted in a higher overall cancer risk estimate used in the risk evaluation.

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.