Risk Evaluation for 1,4-Dioxane
EPA evaluated 1,4-dioxane under the amended Toxic Substances Control Act (TSCA) and completed the final risk evaluation in December 2020. EPA released for public comment and peer review a draft supplement to the risk evaluation in July 2023. The draft supplement considers air and water exposure pathways not evaluated in the December 2020 risk evaluation and exposure to 1,4-dioxane generated as a byproduct. Using the 2020 risk evaluation and 2023 draft supplement, EPA developed and released for public comment a draft revised risk determination in July 2023.
On this page:
- Background on 1,4-dioxane
- 2023 Draft Supplement to the 2020 Risk Evaluation for 1,4-Dioxane (pdf)
- Risk Evaluation of 1,4-dioxane under Amended TSCA
- Review of 1,4-dioxane Prior to Amended TSCA
Uses of 1,4-Dioxane
1,4-dioxane is currently used as a solvent in a variety of commercial and industrial applications such as in the manufacture of other chemicals, a processing aid, functional fluid, a laboratory chemical, in adhesives and sealants, in spray polyurethane foam, in printing inks, and as a dry film lubricant. 1,4-dioxane may be found as a contaminant in consumer products such as soaps and detergents. Information from the 2016 Chemical Data Reporting (CDR) for 1,4-dioxane indicates reported production volume in more than 1.1 million lbs/year (manufacture and import).
Risk Evaluation of 1,4-dioxane under Amended TSCA
In July 2023, EPA released for public comment and peer review the 2023 Draft Supplement to the 2020 Risk Evaluation for 1,4-Dioxane (pdf) to the 2020 1,4-dioxane risk evaluation. The 2023 Draft Supplement to the Risk Evaluation for 1,4-Dioxane evaluated risks from exposure to 1,4-dioxane produced as a byproduct in several manufacturing processes which may remain present as a byproduct in consumer and commercial products, including soaps, detergents, and cleaning products. Additionally, the draft supplement evaluated risks to the general population from 1,4-dioxane present in drinking water or ambient air. EPA used new methods and novel applications of existing methods to evaluate these additional exposure pathways. Written comments on the draft supplement will be accepted until September 8, 2023, through www.regulations.gov (Docket No. EPA-HQ-OPPT-2022-0905).
EPA released the 2023 Draft Revised Risk Determination for 1,4-Dioxane (pdf) using the information in the 2020 risk evaluation and the 2023 draft supplement. Upon publication of the Federal Register notice, written comments on the draft revised risk determination will be accepted until September 8, 2023 through www.regulations.gov (Docket No. EPA-HQ-OPPT-2016-0723).
In December 2020, EPA released the final risk evaluation for 1,4-dioxane. The final risk evaluation shows that there are unreasonable risks to workers and occupational non-users from 13 conditions of use. EPA found no unreasonable risks to the environment, consumers, bystanders, or the general population. As with any chemical product, EPA strongly recommends that users carefully follow all instructions on the product’s label.
In June 2019, EPA released the draft risk evaluation for 1,4-dioxane for public comment and peer review. In November 2020, EPA released a supplemental analysis to the draft risk evaluation which includes eight consumer uses where 1,4-dioxane is present as a byproduct, meaning when 1,4-dioxane is created from the breakdown of other chemicals. The supplemental analysis also assesses exposure to the general population from 1,4-dioxane in surface water.
- Read the draft risk evaluation for 1, 4-dioxane.
- Read the supplemental analysis to the draft risk evaluation.
- Learn more about the peer review for 1,4-dioxane.
In June 2017, EPA released the scope document for 1,4-dioxane which includes the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations EPA expects to consider in its risk evaluation of 1,4-dioxane conducted pursuant to TSCA section 6(b). In June 2018, EPA released the problem formulation for 1,4-dioxane which refined the scope of the 1,4-dioxane risk evaluation by clarifying the chemical uses that EPA expected to evaluate and describing how EPA expected to conduct the evaluation.
- Read the problem formulation for 1,4-dioxane.
- Read the scope document and supplemental files for 1,4-dioxane.
After releasing the scope documents for each of the first 10 chemicals undergoing risk evaluation under TSCA, the dockets for each of these first 10 chemicals were open for public comments. Read EPA’s Responses to Public Comments Received on the Scope Documents for the First Ten Chemicals for Risk Evaluation under TSCA. This document addresses public comments received in response to the scope document.
Review of 1,4-Dioxane Prior to Amended TSCA
Prior to the Frank R. Lautenberg Chemical Safety for the 21st Century Act, EPA began the review of 1,4-dioxane and published the following information.