EPA Releases Final Risk Evaluation for 1,4-Dioxane

January 14, 2021

The US Environmental Protection Agency’s controversial final risk evaluation for 1,4-dioxane found unreasonable risks to workers and occupational non-users for 13 out of 24 use conditions, but no unreasonable risks to the environment, the general public, consumers, and bystanders.

On December 31, 2020, the US Environmental Protection Agency (EPA) released the final risk evaluation for 1,4-dioxane under the Toxic Substances Control Act (TSCA). In the original draft risk evaluation for the chemical, released in June 2019, EPA preliminarily found unreasonable risks in certain circumstances for workers, but none to the environment or occupational non-users (defined by EPA as workers nearby but not in direct contact with 1,4-dioxane).

EPA also released a supplemental risk analysis for 1,4-dioxane on November 19, 2020, which expanded the scope of the review to include certain consumer exposures, as well as surface/ ambient water exposures. EPA initiated its supplemental analysis following public comments and peer review feedback to the initial draft risk evaluation. In the supplemental analysis, EPA found that the presence of 1,4-dioxane as a byproduct in certain consumer products did not pose an unreasonable risk subject to TSCA regulations. The supplemental analysis also considered recreational activities in ambient/surface water, for which EPA made a no-risk finding. For more on this supplemental risk analysis, see our December 8, 2020 LawFlash.

Environmentalists and industry groups alike immediately criticized the supplemental analysis for its 20-day comment period, which is unprecedented under the TSCA for its brevity. The various groups also requested that EPA grant a public comment extension, along with additional peer review by the Science Advisory Committee on Chemicals. In its response to comments, EPA defended its comment period, pointing to its first draft evaluation, released in June 2019, which met the minimum 30-day comment period set forth in the statutory and regulatory requirements.[1] In light of the broad range of comments and opposition by environmentalists as well as industry trade associations, the incoming Biden administration may seek to revisit these issues.

The final risk evaluation found unreasonable risks to workers and occupational non-users for 13 out of 24 use conditions. However, the final risk evaluation found no unreasonable risks to the environment, the general public, consumers, and bystanders. EPA is now working to address the unreasonable risks identified in the final risk evaluation (in accordance with the applicable procedures under the TSCA), and may propose steps such as regulating use of 1,4-dioxane, or placing restrictions or prohibitions on manufacture, among others. Under the TSCA, EPA has one year to propose the risk management rules to mitigate those risks, and two years to finalize the proposed actions to address the unreasonable risk. The actions proposed by EPA will be subject to public comment.

The 2016 amendments to the TSCA directed EPA to select the first 10 chemicals for risk evaluation; 1,4-dioxane was among this group. EPA was supposed to finalize all of the risk evaluations for the first 10 chemicals by the end of 2020, but only completed nine; 1,4-dioxane, finalized late on December 31, was the ninth (and last) risk evaluation to be finalized in 2020.

1,4-dioxane is classified by EPA as a likely human carcinogen that is often used as a stabilizer in greases, waxes, paint strippers, antifreeze, and chlorinated solvents. While there are no known direct consumer uses of 1,4-dioxane, the chemical can be found in some consumer products, such as deodorant, cosmetics, and shampoo, where it typically results as a byproduct from ethoxylation, a process used to make the products less harsh to consumers.


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[1] “[T]he draft supplemental analysis was not peer reviewed for the sake of expediency to finalize the first ten risk evaluations. TSCA section 6(b)(4)(H) requires a 30-day notice and comment period on the draft risk evaluation prior to publication of the final risk evaluation. Additionally, 40 CFR 702.49(a) provides for a 60-day public comment period. EPA complied with these statutory and regulatory requirements by providing a 60-day comment period from July 1, 2019 to August 30, 2019 on the draft risk evaluation.” EPA, Summary of External Peer Review and Public Comments and Disposition for 1,4-Dioxane: Response to Support Risk Evaluation of 1,4-Dioxane, pp. 158-59 (Dec. 2020).