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Chemical Regulation

1,4-dioxane in cleaning products poses risk to workers

Impurity is a bigger health threat than previously thought, US EPA says

by Britt E. Erickson
July 11, 2023 | A version of this story appeared in Volume 101, Issue 23

A person pouring laundry detergent into a cup near a washing machine.
Credit: Shutterstock
Exposure to 1,4-dioxane impurities in cleaning products poses unreasonable risks to workers but not to the general population, the US Environmental Protection Agency finds.

The chemical 1,4-dioxane poses more of a cancer risk to the general population and workers than previously thought, the US Environmental Protection Agency says in a draft analysis released July 7.

The analysis supplements a risk evaluation completed in late 2020 that was widely criticized for not considering risks to the general population from drinking water and air. The EPA’s initial evaluation also did not consider occupational exposures to byproduct 1,4-dioxane generated during the synthesis of surfactants for soaps and detergents. The EPA found no unreasonable risks to the general population and the environment in its 2020 assessment, prompting environmental groups and states to sue the agency.

The draft analysis addresses those concerns. It finds an increased risk of cancer to the general population, including fenceline communities, from exposure to contaminated drinking water and air. It also finds an increased risk to workers from exposure to byproduct 1,4-dioxane.

The EPA considers 1,4-dioxane a probable human carcinogen. The chemical is also associated with “adverse effects to the liver and nasal tissue,” the agency says.

1,4-dioxane is used to make other chemicals, including adhesives and sealants. It is also used as a processing aid and is found as an impurity in soaps and detergents. The chemical, which is a widespread drinking water contaminant, is one of the first 10 high-priority chemicals the EPA is evaluating under the 2016 amendments to the Toxic Substances Control Act.

The agency completed all 10 assessments under the administration of Donald J. Trump, but in 2021 it announced that it would redo them to consider exposures to the general population from drinking water and air.

The EPA is accepting public comments on the draft analysis until Sept. 8. It also plans to have an external advisory committee review the draft analysis at a public meeting in September. The agency says it is particularly interested in current practices for mitigating workplace exposure because the occupational monitoring data for 1,4-dioxane are several decades old.

The EPA plans to consider both the supplemental analysis and the 2020 risk evaluation in a revised risk determination for 1,4-dioxane to be released in the coming weeks.



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