The U.S. Environmental Protection Agency (EPA) unveiled 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). These documents are part of the ongoing efforts under the Toxic Substances Control Act (TSCA). The EPA's preliminary findings suggest that 1,1-dichloroethane poses an unreasonable risk to human health, particularly to workers, and to the environment. Both chemicals are linked to severe health risks, including cancer and other non-cancer health effects.
1,1-Dichloroethane: Uses and Risks
Industrial Applications
1,1-Dichloroethane is extensively used as an industrial and commercial solvent. It is also a key ingredient in the production of various chlorinated solvents, such as 1,1,1-trichloroethane, which have broad applications in the industry. In addition, 1,1-dichloroethane is utilized in relatively small quantities for laboratory research purposes.
Health and Environmental Impact
Health Risks
- Cancer Risks: The draft risk evaluation indicates that exposure to 1,1-dichloroethane can significantly increase the risk of developing kidney cancer and other types of cancer. This risk is particularly pronounced for workers who are exposed to high levels of the chemical in industrial settings.
- Non-Cancer Health Effects: Beyond cancer, 1,1-dichloroethane poses several non-cancer health risks. These include severe renal (kidney) effects, nasal damage, immune system impairment, and reproductive issues. Workers are primarily at risk due to direct exposure to the chemical in their occupational environment.
Environmental Risks
- Air Contamination: Environmental releases of 1,1-dichloroethane primarily end up in the air, where it can persist and pose inhalation risks to nearby populations.
- Water and Soil Contamination: Although 1,1-dichloroethane is less commonly found in water and soil, direct and continuous releases into slow-moving or stagnant surface waters can lead to contamination. However, it does not bioaccumulate significantly, meaning it is not found in higher concentrations in organisms compared to the environment.
- Aquatic Species Impact: Chronic exposure to 1,1-dichloroethane can severely affect aquatic species, including invertebrates and algae, through contamination from manufacturing, processing, and disposal practices.
1,2-Dichloroethane: Background and Risks
Usage
1,2-Dichloroethane is primarily utilized in the production of vinyl chloride, a key component in making PVC plastics. Despite its different primary use, 1,2-dichloroethane shares many structural and toxicological similarities with 1,1-dichloroethane.
Health Effects
- Cancer Risks: Similar to 1,1-dichloroethane, 1,2-dichloroethane exposure is linked to an increased risk of kidney cancer and other types of cancer.
- Non-Cancer Health Effects: Exposure to 1,2-dichloroethane can also cause non-cancer health issues, such as renal damage, nasal effects, immune system disruption, and reproductive harm.
Data Utilization
Due to the structural similarities and extensive data available for 1,2-dichloroethane, the EPA used this information to fill gaps in the understanding of the toxicity of 1,1-dichloroethane. This approach is a standard practice in risk assessment when dealing with chemicals that share significant structural and toxicological characteristics.
Public and Peer Review Process
Public Comment Period
The EPA is now inviting public comments on the draft documents for a 60-day period following the publication of the Federal Register notice. Interested parties can submit their comments via docket EPA-HQ-OPPT-2024-0114 at www.regulations.gov.
Peer Review
The Science Advisory Committee on Chemicals (SACC) will conduct a peer review of the draft documents and any unresolved scientific issues. In April 2024, the EPA called for nominations for prospective peer reviewers. The biographical sketches of these candidates were posted for public comment in June 2024.
Public Meetings
- Preparatory Meeting: Scheduled for August 27, 2024, this virtual meeting will allow the SACC and the public to discuss the scope and clarity of the draft charge questions.
- SACC Meeting: From September 17-20, 2024, a virtual public meeting will be held for the SACC to review and discuss the draft documents. Registration instructions for the meeting will be announced on the SACC website later this summer, including details on how to register to present oral comments during the meeting.
Next Steps
The EPA will consider all feedback received from the public and the SACC to inform the final risk evaluations for both 1,1-dichloroethane and 1,2-dichloroethane.
