On June 20, 2025, the U.S. Environmental Protection Agency (EPA) released the final risk assessment for 1,1-dichloroethane under the Toxic Substances Control Act (TSCA). The assessment concludes that 1,1-dichloroethane poses an unreasonable risk of injury to human health under three conditions of use (COUs), but does not present significant risks to the general public or the environment.
Background
1,1-Dichloroethane is a colorless, oily liquid with a chloroform- or ether-like odor. It is volatile and slightly soluble in water. It is primarily used as an intermediate in the production of other chlorinated solvents and, to a lesser extent, in laboratory research. In December 2019, it was designated as a high-priority substance under TSCA. The scope of the risk evaluation was finalized in August 2020, and a draft assessment was released in 2024 for public comment and scientific peer review.
Key Findings of the Risk Assessment
1. Risks to Human Health
Due to insufficient data, EPA used 1,2-dichloroethane as a surrogate in its risk assessment. The findings include:
- No unreasonable risk was identified for the general population.
- Unreasonable risks were found for workers exposed to 1,1-dichloroethane under the following three conditions of use:
- Processing as an intermediate in the manufacturing of basic organic chemicals.
- Processing as an intermediate in the manufacturing of other chemical products and preparations.
- Recycling.
2. Risks to the Environment
EPA evaluated environmental exposure to 1,1-dichloroethane during its manufacturing, processing, use, or disposal, including exposure to aquatic organisms (via surface water and sediment) and terrestrial organisms (via soil, surface water, and sediment). The assessment found no unreasonable risk to the environment.
Next Steps
EPA will initiate the risk management process under TSCA Section 6 to address the identified unreasonable risks. Under the law, EPA is required to propose a rule within one year. The public will have an opportunity to comment on the proposed rule before it is finalized, ensuring that workers are protected from the identified risks.
Further Information
