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GenX chemicals taint sediments

For the first time, researchers find fluoroethers in North Carolina riverbed

by Cheryl Hogue
April 5, 2018 | A version of this story appeared in Volume 96, Issue 15

Drawing shows the chemical structure of hexafluoropropylene oxide dimer acid.

In a finding that has implications for drinking water safety, researchers at the University of North Carolina, Wilmington, have identified fluorochemicals linked to a Chemours plant in river sediment.

Previously, scientists found compounds related to Chemours’s GenX fluorosurfactant in the waters of the Cape Fear River downstream of the company’s plant near Fayetteville, N.C.

New results from state-funded investigations by UNC-Wilmington researchers mark the first time hexafluoropropylene oxide dimer acid (HFPO-DA)—the product of GenX hydrolysis—and related fluoroethers have been found in the river’s sediment.

“An initial conclusion from this study is that sediments are acting as a repository of GenX[-related compounds] that may be released into the overlying water column,” says a report on the studies sent to a state commission earlier this month. This means that sensitive ecosystems as well as drinking water utilities could continue to be affected by the pollution even if Chemours’s plant stops releasing fluoroethers into the environment.

To stem the source of the contamination, Chemours’s Fayetteville plant last year began capturing its fluorocarbon-related wastewater and shipping it to Texas for disposal. In February, state regulators required Chemours to control the facility’s air emissions of poly- and perfluorinated chemicals.

The discovery of fluoroethers in the sediment suggests Chemours could face cleanup liability if regulators decide the contaminated solids need to be removed from the Cape Fear River to protect public health or the environment. The toxicity of these compounds isn’t clear yet.

The UNC-Wilmington investigators used high-resolution mass spectrometry to find several fluoroethers in sediment that researchers previously identified in Cape Fear River water and in treated drinking water in Wilmington: HFPO-DA, five other perfluoroalkyl carboxylic acids, and one sulfonic acid byproduct of Chemours’s Nafion polymers.

The team also discovered two other substances not yet reported in published literature. The researchers are working to elucidate the chemical structures. These compounds appear to be perfluorinated and contain a single atom of chlorine, the report says.


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