The U.S. Environmental Protection Agency (EPA) has released its draft risk evaluation for 1,3-butadiene under the Toxic Substances Control Act (TSCA). Announced on 3 December 2024, the evaluation preliminarily concludes that 1,3-butadiene poses an unreasonable risk to human health, particularly for workers and surrounding communities exposed through inhalation.
Background on 1,3-Butadiene
1,3-Butadiene is a highly flammable, colourless gas with applications in manufacturing plastics, rubber, adhesives, and fuels. It is predominantly released into the air during production and processing, making airborne exposure the primary risk factor. While minimal amounts enter land or water, general exposure can also stem from vehicle emissions, tobacco smoke, and burning wood.
Health Risks Identified
EPA's draft evaluation highlights multiple health concerns, including:
- Reduced birth weights during pregnancies.
- Increased risks of blood and immune system disorders.
- Associations with leukaemia, particularly among industrial workers exposed to the chemical.
Key Findings
The EPA determined that the general public, especially those in fenceline communities near industrial facilities, face significant inhalation exposure risks. Workplace scenarios, such as maintenance activities by laboratory technicians, were identified as critical contributors to this risk. However, consumer products containing trace amounts of 1,3-butadiene are not considered a significant source of exposure.
Next Steps
The draft evaluation will undergo a 60-day public comment period, concluding on 3 February 2025. The Science Advisory Committee on Chemicals (SACC) will conduct a peer review of the draft at virtual meetings scheduled for February 4 and February 25-28, 2025. Public feedback and SACC recommendations will inform the final risk evaluation.
The EPA’s findings reinforce the need for stricter risk management strategies for 1,3-butadiene, particularly in industrial and occupational settings. Further public and expert input will shape the final evaluation and subsequent regulatory actions.
