Levels of 1,4-Dioxane, a known carcinogen, have again increased in the Cape Fear River, and the precise source of the contamination is still unknown.
Results released by the Cape Fear Public Utility Authority show levels of the compound in untreated water at the Sweeney plant reached 6.3 parts per trillion on Sept. 10; in finished water, the levels dropped to 1.3 ppt.
The EPA’s unenforceable health advisory goal is 0.35 parts per billion — or 350 ppt. The agency does not regulate 1,4-Dioxane in drinking water.
CFPUA’s recent figures are higher than those recorded in August, when the levels were 0.76 ppt in raw water and 0.19 ppt in finished water.
The precise source of the contamination is unknown, a utility spokesman said. Several industrial plants discharge 1,4-Dioxane into the Cape Fear, including DAK Americas in Fayetteville, Invista in Wilmington and other industries farther upstream.
The Cape Fear Public Utility Authority tests for 1,4-Dioxane monthly. The utility has implemented advanced treatment systems to remove as much of the contaminant as possible; however, 1,4-Dioxane is extremely difficult for water treatment plants to remove.
Last month the utility submitted comments to the EPA, which is conducting a draft risk evaluation for 1,4-Dioxane. The EPA decided to exclude exposures to the general population, including children, in assessing 1,4-Dioxane’s risks. The agency reasoned that existing statutes like the Clean Water Act and the Safe Drinking Water Act, address the risks — a justification that the utility disagrees with.
“CFPUA is particularly concerned with EPA’s decision to exclude from its assessment exposures to the general population, including children” wrote the utility’s executive director Jim Flechtner. “… Our experience at CFPU leads us to conclude that, contrary to EPA’s assertion otherwise, these statutes are neither ‘adequate’ nor ‘effective’ in managing risks to the general public from exposure to 1,4-dioxane in drinking water.”
Levels of GenX have also recently increased in finished water, according to weekly sampling data, from 8.6 ppt on July 2 to 18.2 ppt on Aug. 29. Those numbers are still below the peaks of 30 ppt to 40 ppt, recorded in 2018 before Chemours said it stopped accidentally spilling or intentionally discharging the compound into the river.
The NC Department of Health and Human Services has set a health advisory goal of 140 ppt for GenX.
Concentrations of two perfluorinated compounds, PFOA and PFOS, have remained steady, ranging from a combined total of 3 ppt to 5.5 ppt in finished water. The EPA health goal is 70 ppt for both compounds combined, while state regulators have also recommended that people should not drink water containing any individual perfluorinated compound at 10 ppt or greater.
However, 13 other types of perfluorinated compounds have been detected in the utility’s finished water, and six of them exceed the state’s recommended threshold.