The U.S. Environmental Protection Agency (EPA) has released the final report from its Science Advisory Committee on Chemicals (SACC) following a September 2024 review. The report evaluates the human health and environmental risks posed by 1,1-dichloroethane and its analogue, 1,2-dichloroethane.
Key Findings on 1,1-Dichloroethane
The EPA's draft risk evaluation identifies that seven out of eight assessed uses of 1,1-dichloroethane contribute to unreasonable risks. Key areas of concern include manufacturing, processing, and disposal activities. Potential impacts include liver and kidney damage, nasal and immune system effects, and reproductive toxicity. Despite these findings, the EPA concludes that general population exposure via air, water, or soil does not present an unreasonable risk.
1,2-Dichloroethane Insights
While primarily used in vinyl chloride production, 1,2-dichloroethane served as a critical analogue to address data gaps in 1,1-dichloroethane assessments. Structural similarities between the chemicals allowed the EPA to extrapolate toxicity data, despite recognized differences in metabolic reactivity.
Aquatic and Environmental Impacts
Both chemicals were linked to potential chronic risks to aquatic ecosystems. However, the EPA found no evidence of acute risks to aquatic or terrestrial species. Recommendations include further monitoring of unplanned chemical releases and potential storm-induced events, which could disproportionately impact vulnerable populations.
Stakeholder and Peer Review
The SACC peer review emphasized the need for expanded analogues, better accounting for uncertainties in read-across methods, and improvements in assessing storm-related chemical discharges. The committee’s feedback, along with public comments, will shape final risk evaluations.
The EPA's preliminary findings call for stringent controls on 1,1-dichloroethane’s industrial uses to mitigate significant health and environmental risks. A final risk evaluation is expected after reviewing feedback from stakeholders and the public.
