North Carolina’s chief administrative law judge and former head of the state’s environmental regulatory agency has eliminated a state cap on the amount of a chemical solvent some municipal wastewater treatment plants discharge. Chief Administrative Law Judge and Director of the Office of Administrative Hearings Dr. Donald van der Vaart revoked permit limits of 1,4-dioxane for wastewater treatment plants that discharge the chemical substance, one the federal Environmental Protection Agency classifies as a likely human carcinogen, into the drinking water sources of tens of thousands of people.

North Carolina Department of Environmental Quality officials did not follow the letter of the law written in state statutes when they calculated discharge limits and established an enforceable water quality standard for 1,4-dioxane, van der Vaart ruled. In his Sept. 12 decision, van der Vaart also said DEQ erred by considering the chemical substance a carcinogen. “The [Environmental Protection Agency] has characterized 1,4-dioxane as ‘likely to be carcinogenic to humans,’” he wrote. “The EPA has not characterized 1,4-dioxane as ‘carcinogenic to humans.’”

DEQ has 30 days to appeal van der Vaart’s decision.