Today, the U.S. Environmental Protection Agency (EPA) released its final risk evaluation for 1,1-dichloroethane conducted under the Toxic Substances Control Act (TSCA). EPA determined that 1,1-dichloroethane presents an unreasonable risk of injury to human health driven by three conditions of use (COUs). EPA did not identify exposures to the general population, or to the environment, associated with COUs of 1,1-dichlorethane as significantly contributing to the unreasonable risk. EPA transmitted the notice of availability of this final risk evaluation to the Federal Register on June 17, 2025, pursuant to the terms of the Consent Decree the agency entered into in Community In-Power and Development Association, Inc. et al v. EPA, no. 1:23-cv-02715-DLF, a case in the United States District Court for the District of Columbia.
1,1-Dichlorethane is primarily used as an industrial and commercial solvent and to make many different substances, including other chlorinated solvents (e.g., 1,1,1-trichloroethane) that have broad industrial applications. It is also used in relatively small amounts for laboratory research.
1,1-Dichloroethane Final Risk Evaluation
EPA determined that 1,1-dichloroethane presents an unreasonable risk of injury to human health driven by identified risk to workers from three COUs. The other five COUs that EPA examined do not significantly contribute to the unreasonable risk determination for 1,1-dichloroethane.
EPA received inhalation monitoring data from a TSCA section 4(a)(2) test order submission for the manufacture of 1,1-dichloroethane. The test order submission characterized the facility control operations known and expected to be in place depending on the potential exposure during standard, task-specific, and emergency activities—including engineering controls, administrative controls, personal protective equipment (PPE) (e.g., respirators achieving a level of APF 10–1,000) and chemical safety plans. EPA considered all reasonably available information, including this test order data substantiating the use of PPE, when determining which COUs significantly contribute to the unreasonable risk determination. For COUs that significantly contribute to the unreasonable risk determination based on identified risk to workers, these risk determinations do not reflect the use of PPE; however, as the risk evaluation shows, effective use of PPE in a manner that achieves a minimum APF 10 to 25 will reduce exposures and mitigate risk in the absence of other exposure controls (e.g., engineering controls). Only worker exposure, and not exposure to the general population or the environment, significantly contributes to EPA’s finding of unreasonable risk.
The scope of the risk evaluation for 1,1-dichloroethane included COUs that span the life cycle of the chemical, from manufacture to disposal. For the exposure assessment, EPA used chemical-specific data where available. Surrogate data and modeling were used to characterize scenarios that lacked monitoring data (e.g., laboratory use). For the human health hazard assessment, EPA used 1,2-dichloroethane as an analog. For aquatic environmental hazard, EPA used 1,1,2-trichlorethane and 1,2-dichloropropane as analogs. Using analogues is a well-established risk assessment practice for chemicals that share structural similarities. EPA’s Science Advisory Committee on Chemicals supported this approach.
Next Steps
EPA will now begin the risk management process to address the unreasonable risk presented by 1,1-dichloroethane. The law requires EPA to propose a rule under TSCA Section 6 within one year. The public will have an opportunity to comment on a proposed rule before final requirements are put in place to protect workers from the identified risks.
