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EPA Issues Unreasonable Risk Determination for 1,4-Dioxane

On July 26, 2023,  U.S. Environmental Protection Agency (EPA) released the 2023 Draft Revised Risk Determination for 1,4-Dioxane, which is available for public comment through September 8, 2023, in which the agency proposes to determine that 1,4-dioxane, as a whole chemical substance, presents unreasonable risk to human health. The unreasonable risk determination will drive future EPA regulatory proposals restricting the use of 1,4-dioxane in various applications, including its use in commercial dish soaps, and dishwasher detergents.

As a result of this change in evaluation, EPA now considers certain commercial uses of products containing 1,4-dioxane to present an unreasonable risk to human health due to worker risks of cancer and non-cancer effects from inhalation and dermal exposures during such uses. More specifically, under the 2023 Draft Revised Risk Determination for 1,4-Dioxane, EPA has made an unreasonable risk determination for the following uses of concern to the cleaning industry:

1. Industrial/commercial use: Laundry and dishwashing products: Dish soap
2. Industrial/commercial use: Laundry and dishwashing products: Dishwasher detergent
3. Industrial/commercial use: Paints and coatings: Paint and floor lacquer

In addition, EPA’s proposed changes to the risk determination include two additional conditions of use (COU) in addition to the original 13 COUs from the 2020 risk evaluation that would contribute to the unreasonable risk from 1,4-dioxane. In general, based on the revised risk determination, EPA’s preliminary findings include that worker exposure to 1,4-dioxane from all but four occupational COUs contribute to the unreasonable risk from 1,4-dioxane.

The rationale for EPA now making an unreasonable risk determination for such occupational uses is attributable to the following:

1. The 2023 Draft Revised Risk Determination for 1,4-Dioxanedoes not assume that workers always and appropriately wear personal protective equipment. The 2020 evaluation assumed proper use of personal protective equipment (PPE).
2. The draft supplement treats 1,4 dioxane as a whole chemical substance and considers air and water exposure pathways not evaluated in the December 2020 risk evaluation and exposure to 1,4-dioxane generated as a byproduct.
3. EPA proposes to include the risks to the general population and fenceline communities from drinking water sourced from surface water contaminated with 1,4-dioxane that is discharged from industrial facilities (including where it is produced as a byproduct) as contributing to the unreasonable risk determination.

In the 2023 draft revised unreasonable risk determination, EPA does not propose to identify the consumer use of such products as contributing to the unreasonable risk determination from 1,4-dioxane. However, EPA notes that the manufacture of those consumer products, and the commercial use of those products, generation of 1,4-dioxane as an ethoxylation process byproduct—i.e., the upstream processing of many of these the consumer products—does contribute to the unreasonable risk determination, due to worker risks of cancer and non-cancer effects from inhalation and dermal exposures during those processes and risk to fenceline communities from exposures to drinking water sourced from surface water contaminated with 1,4-dioxane discharged from industrial facilities.

Public Comment. EPA states that it specifically seeks public comment on several aspects of the 2023 draft unreasonable risk determination, including:

1. Its finding that general population exposure to 1,4-dioxane in drinking water contributes to the determination that 1,4-dioxane presents an unreasonable risk
2. Whether the risks to the general population from drinking water exposure can be attributed to specific COUs of 1,4-dioxane
3. EPA is seeking review of the methodologies it used in its most recent risk evaluation of 1,4-dioxane including its use of Monte Carlo Modeling in the Assessment of 1,4-Dioxane Occupational Exposures and Environmental Releases.

Comments on the draft revised risk determination are due September 8, 2023.

Members can also send their comments on the 2023 Draft Revised Risk Determination for 1,4-Dioxane to Bill Balek, ISSA no later than August 15, 2023, for possible inclusion in the association’s comments to EPA.

Next Steps. EPA will review public comments on the 2023 Draft Revised Risk Determination for 1,4-Dioxane and the 2023 Draft Supplement to the Risk Evaluation for 1,4-Dioxane before finalization. Following that, EPA will propose and take public comments on risk management actions in the form of regulations designed to address the unreasonable risk identified in the risk evaluation, as updated by the final revised risk determination.