EPA Releases Draft TSCA Risk Evaluation of 1,1-Dichloroethane and Draft Hazard Assessment of 1,2-Dichloroethane for Public Comment and Peer Review
Released July 1, 2024
Today, the U.S. Environmental Protection Agency (EPA) released its draft risk evaluation for 1,1-dichloroethane and the draft human health hazard assessment supporting the draft risk evaluation for 1,2-dichloroethane (also known as ethylene dichloride) prepared under the Toxic Substances Control Act (TSCA). EPA preliminarily determined 1,1-dichloroethane poses unreasonable risk to human health (of workers) and the environment. The effects to people from exposure to 1,1-dichloroethane and 1,2-dichlorethane are kidney and other cancers, as well as harmful non-cancer renal, nasal, immune system, and reproductive effects.
1,1-Dichloroethane 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. 1,2-Dichloroethane is primarily used to manufacture vinyl chloride.
1,2-Dichloroethane
Although 1,1-dichloroethane and 1,2-dichloroethane have different uses, the two chemicals are very similar in terms of their physical structure. 1,2-Dichloroethane is the better studied of the two chemicals, and therefore there is more data available on the toxicity of 1,2-dichloroethane. As with 1,1-dichloroethane, exposure to 1,2-dichlorethane may increase the risk of kidney and other cancers, as well as harmful non-cancer renal, nasal, immune system, and reproductive effects.
EPA is seeking feedback on the draft human health hazard assessment for 1,2-dichlororethane because data on the toxicity of 1,2-dichloroethane was used to fill gaps in the understanding of the toxicity of 1,1-dichloroethane for the draft risk evaluation. Feedback on the draft hazard assessment for 1,2-dichloroethane will also help inform the full 1,2-dichloroethane draft risk evaluation.
1,1-Dichloroethane
1,1-Dichloroethane is a colorless oily liquid with a chloroform- or ether-like odor and is volatile, meaning it evaporates over hours or days. Environmental releases of 1,1-dichloroethane primarily end up in the air, with lesser amounts in water, sediment, and soil. Given the relatively low quantity directly released to water, surface water will generally not be an important source of exposure other than direct and continuous releases of 1,1-dichloroethane into deep slower moving or stagnant surface waters. Although 1,1-dichloroethane has been detected in the environment and in organisms such as fish exposed to contaminated surface water, it does not appear to bioaccumulate and thus is not measured in people or animals at greater concentrations than exist in the environment.
EPA used hazard data for 1,2-dichloroethane as the best available candidate to provide analogous human health data for the 1,1-dichloroethane risk evaluation because of its structural, physical, chemical, metabolic, cancer and non-cancer toxicological similarities, since there was inadequate human health hazard data available on 1,1-dichloroethane. Using analogues is a well-established risk assessment practice for chemicals that share structural similarities.
EPA’s draft risk evaluation preliminarily shows that exposure to 1,1-dichloroethane may increase the risk of kidney and other cancers, as well as harmful non-cancer renal, nasal, immune system, and reproductive effects to workers. EPA preliminarily found no unreasonable risk to the general population from breathing air where 1,1-dichloroethane was released from facilities or ingesting drinking water or surface water or soil from 1,1-dichloroethane disposed to land (i.e., direct disposal to landfills or land applied biosolids from public wastewater treatment works treating 1,1-dichloroethane-containing wastewater). In its analyses, EPA also accounted for and found no unreasonable risk to potentially exposed and susceptible subpopulations, which included infants exposed to drinking water during formula bottle feeding, subsistence and tribal fishers, pregnant women and people of reproductive age, and individuals with compromised immune systems or neurological disorders. EPA did not assess consumer or bystander exposures because there are no commercial or consumer products or articles that contain 1,1-dichlorethane.
EPA’s draft risk evaluation preliminarily shows that chronic exposure to 1,1-dichloroethane contributes to the unreasonable risk to aquatic species, including invertebrates and algae, from the manufacturing, processing, and disposal of 1,1-dichloroethane. EPA preliminarily determined that there is no unreasonable risk of injury to aquatic and terrestrial species from acute exposures to 1,1-dichloroethane.
Next Steps
Upon publication of the Federal Register notice, EPA will accept public comments on the draft documents for 60 days via docket EPA-HQ-OPPT-2024-0114 at www.regulations.gov. The Agency’s Science Advisory Committee on Chemicals (SACC) will also peer review the draft documents and associated unresolved scientific issues. Following a call for nominations in April 2024, the biographical sketches of the candidates under consideration as prospective peer reviewers were posted for public comment in June 2024.
EPA will hold a virtual public meeting for the SACC to discuss the draft documents from September 17-20, 2024. Registration instructions for the meeting will be announced on the SACC website later this summer, including information about how to register to present oral comments during the meeting. For additional information, please see the Federal Register notice or contact the Designated Federal Official, Alie Muneer at muneer.alie@epa.gov.
In addition, EPA will hold a preparatory virtual public meeting on August 27, 2024, for the SACC and the public to consider and ask questions regarding the scope and clarity of the draft charge questions.
Any feedback received from the public and the SACC will be considered in order to inform the final risk evaluations for 1,1-dichloroethane and 1,2-dichloroethane.