EPA Releases TSCA Draft Revised Risk Determination for 1,4-Dioxane

EPA has released the 2023 Draft Revised Risk Determination for 1,4-Dioxane with a preliminary determination that 1,4-dioxane presents an unreasonable risk of injury to health under the conditions of use. This is one of several recent actions the Agency has taken on 1,4-Dioxane under the Toxic Substances Control Act (TSCA). The unreasonable risk determination is different from the 2020 risk determination in that it “proposes to include risks to fenceline communities and the general population from consuming drinking water sourced from surface water contaminated with 1,4-dioxane from industrial discharges and to identify these risks as contributing to the unreasonable risk from 1,4-dioxane.” The determination is based on the information in the 2020 Risk Evaluation and the recent 2023 Draft Supplement to the Risk Evaluation for 1,4-Dioxane.

EPA will also conduct an external peer review from the Science Advisory Committee on Chemicals (SACC) on multiple issues, including modeling concentrations of 1,4-dioxane in surface water and groundwater and exposure from multiple sources of 1,4-dioxane in air or water. The SACC will consider and review the draft supplement at a virtual public meeting on September 12–15, 2023.

For more information, read the 2023 Draft Revised Risk Determination for 1,4-Dioxane and visit the EPA website. Comments on are due by September 8, 2023 through www.regulations.gov (Docket No. EPA-HQ-OPPT-2016-0723-0095).