EPA confirms health risks of 1,4-dioxane

Tiny amounts of 1,4-dioxane impurities in laundry and dishwasher detergents, dish soap, paints, and other products that get washed down the drain can add up and be enough to contaminate drinking-water sources in populated areas, the US Environmental Protection Agency says in a final supplement to a previous risk evaluation.

The EPA agreed to conduct the supplemental analysis after environmental groups, state attorneys general, and several members of an external advisory panel criticized the agency for ignoring risks to the general population from exposure to 1,4-dioxane in drinking water. The agency finalized that initial risk assessment in late December 2020.

1,4-Dioxane is one of the first 10 chemicals that the EPA is evaluating under the 2016 revisions to the Toxic Substances Control Act (TSCA). The agency completed all 10 assessments under the first administration of Donald J. Trump, but in 2021 it decided to redo them to address exposures to the general population from drinking water and air. It has now revised all 10 evaluations.

For 1,4-dioxane, the EPA is considering regulatory actions under the Safe Drinking Water Act, in addition to risk management options under TSCA. 1,4-Dioxane is a probable carcinogen and can harm nasal tissue and the liver, according to the EPA. The chemical is used as a processing aid, and it is created as a by-product during the ethoxylation of surfactants that are then used in soaps and detergents.