1,4-dioxane risk evaluation lands in court, again

The US Environmental Protection Agency is facing another lawsuit over its risk evaluation of the prevalent drinking water contaminant 1,4-dioxane. The EPA released the final assessment on Dec. 31, under the Trump administration. A coalition of 15 attorneys general and New York City is challenging the controversial assessment in a March 22 petition filed with the Ninth US Circuit Court of Appeals.

The petitioners, led by the state of New York, claim the EPA underestimated the risks of 1,4-dioxane to workers and the general public, particularly residents of low-income communities and communities of color. The EPA conducted the assessment under the Toxic Substances Control Act (TSCA). It did not consider the risks of 1,4-dioxane in drinking water, which the state attorneys general and environmental groups say is the biggest source of exposure. The agency claimed that such exposures fall under the jurisdiction of EPA programs that regulate contaminants in water, not under the program that implements TSCA.

Earlier this year, environmental groups also sued the EPA over its 1,4-dioxane risk evaluation, raising similar concerns. The groups are urging the agency to redo the assessment and consider risks from contaminated drinking water.

The EPA classifies 1,4-dioxane as a likely human carcinogen. It has been detected in numerous drinking water sources, including groundwater on Long Island, New York, which supplies drinking water for nearly 3 million residents of the state.

“1,4-dioxane is both poisonous and pervasive—all too often contaminating the water we drink, the places we work, and products we use, and Long Islanders are particularly vulnerable in the state of New York,” New York Attorney General Letitia James says in a statement.

In response to concerns raised about its draft assessment of 1,4-dioxane, the EPA expanded the scope of the evaluation to include risks to consumers from using laundry and dishwasher detergents plus other household products that contain low levels of 1,4-dioxane impurities. The agency concluded that such impurities pose no unreasonable risks to the general population.

The coalition of attorneys general claims that the EPA conducted that supplemental analysis at the request of industry trade groups, which were seeking to stop states such as New York from enacting laws that would limit 1,4-dioxane impurities in cleaning products and require manufacturers to disclose such impurities in household cleaners.