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Chemical Regulation

US EPA disregards risk of 1,4-dioxane in drinking water

Agency’s rush to finalize evaluation of likely carcinogen before 2021 meets widespread criticism

by Britt E. Erickson
January 4, 2021

A person pouring liquid laundry detergent into a clothes washing machine.
Credit: Shutterstock
Small amounts of 1,4-dioxane impurities in laundry detergent do not pose unreasonable health risks to consumers, the US EPA says.

Despite numerous requests to extend the comment period for part of its risk evaluation of the solvent 1,4-dioxane, the US Environmental Protection Agency plowed ahead and finalized the assessment late in the day Dec. 31. The hastily compiled analysis, released as a draft supplement Nov. 19, pleased no one, including environmental groups, state attorneys general, and the chemical industry.

Chemical structure of 1,4-dioxane.

The EPA agreed to do the supplemental analysis to expand the scope of its initial draft evaluation, released in June 2019, to include risks to consumers from small amounts of 1,4-dioxane impurities in laundry and dishwasher detergents, paints, and other products, after numerous stakeholders criticized the agency for omitting such uses.

But in that additional evaluation, the EPA still ignored what environmental groups and state attorneys general say is the biggest source of exposure to 1,4-dioxane to the general population—drinking water. Instead, the agency evaluated the risks from recreational activities, such as swimming in water contaminated with 1,4-dioxane. The EPA acknowledges that people may be exposed to 1,4-dioxane via drinking water, as well as from ambient air and soil, but the agency argues that such exposures fall under the jurisdiction of other environmental statutes, not the Toxic Substances Control Act (TSCA). The 1,4-dioxane assessment is one of the first 10 high-priority chemical assessments the EPA conducted under 2016 revisions to TSCA.

The EPA considers 1,4-dioxane “likely to be carcinogenic to humans.” The solvent is used to manufacture other chemicals, process food, and produce adhesives and sealants. It is also an impurity in household detergents, cleaners, and personal care products.

The American Cleaning Institute (ACI), which represents the cleaning products industry, and the American Chemistry Council (ACC), the US chemical industry’s main lobbying group, agree with the EPA that trace amounts of 1,4-dioxane impurities in household cleaning products do not pose unreasonable health risks to consumers. Nonetheless, neither group is pleased with the EPA’s final assessment.

The ACI is disappointed that the EPA did not evaluate risks to the general population associated with drinking water, as well as risks to workers associated with industrial and commercial cleaning products. The group is concerned that without a federal standard, states will develop a patchwork of different regulations.

The ACC takes issue with changes to the EPA’s evaluation of chronic hazards from dermal exposure to 1,4-dioxane. Those changes reduce the acceptable level of dermal exposure by three orders of magnitude, the group states in comments submitted Dec. 10 to the EPA. “By failing to incorporate the best available science, the final evaluation significantly overstates the risks associated with exposure to 1,4-dioxane,” the ACC says in a statement.

The EPA did identify unreasonable risks to workers exposed to 1,4-dioxane for 13 of the 24 scenarios that it evaluated. The agency plans to propose regulations within one year to address those risks.



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