EPA Publishes TSCA Draft Supplemental Risk Evaluation for 1,4-Dioxane

EPA is requesting public comment on the analysis presented in the new, “Draft Supplement to the Risk Evaluation for 1,4-Dioxane,” under the Toxic Substances Control Act (TSCA). Comments will be due 60 days after the Federal Register notice is published. This draft supplement assesses previously excluded air and water exposure pathways and exposure to 1,4-dioxane generated as a byproduct. It also estimates risks to the general population and people living in fenceline communities, as well as aggregate exposures from multiple facilities located in the same area. Additionally, the draft supplemental analysis provides higher cancer risk estimates for exposures, including those associated with drinking water sourced downstream of release sites. The Scientific Advisory Committee on Chemicals (SACC) provided the impetus for EPA to develop this draft supplement in response to SACC comments on the 2020 risk evaluation.

Other forthcoming actions on this risk evaluation are the Agency’s revised draft unreasonable risk determination for 1,4-dioxane (expected in the next few weeks for public comment), and an external peer review from the 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 also consider and review the draft supplement at a virtual public meeting on September 12–15, 2023, to be announced on the SACC website. For more information about the 1,4-Dioxane risk evaluation, visit EPA’s website.