US chemical giant DuPont and its spin-off company Chemours are in the news again in connection with fears of drinking water contamination in the US.

Attention is focused once more on fluoropolymer production, and this time the most severely affected geography is coastal North Carolina, where DuPont and Chemours have production facilities upstream of the city of Wilmington on the Cape Fear River.

DuPont/Chemours have been producing the fluoropolymer processing aid GenX at the site since 2009. The chemical has been touted as a safer replacement for perfluorooctanoic acid, known as PFOA or C8, which DuPont formerly used to fluropolymer coatings such as Teflon.

PFOA was phased out after the chemical group faced heavy fines from the Environmental Protection Agency (EPA) and class-action litigation over the chemical’s alleged ill effects on health and the environment.

Research presented at a recent conference pinpointed the presence of GenX in water supplies also in the state of Ohio, again near plants that were operated by DuPont or, since 2015, Chemours. While the researchers did not test reservoirs of two other drinking water providers one of the study’s authors suggested that the entire watershed downstream of the Chemours plant, a source of drinking water for some 250,000 people, may be contaminated.

Both GenX and PFOA,  belong to the PFAS group of chemicals, are structurally similar and are believed to persist indefinitely in nature, as the researchers explained.

Wilmington residents are now demanding to know if either or both of the chemicals are making their way downriver into the city's drinking water. Following a meeting with Chemours officials, the city’s mayor, Bill Saffo, told television network CBS News he had learned that DuPont had discharged wastewater from fluorochemicals production into the Cape Fear River since 1980.

In response to criticism from area residents, Chemours reportedly has agreed to remove and safely remove contamination, as one media report said DuPont had previously pledged to do in a 2005 agreement with the EPA. At the same time, Chemours said its computer modeling showed the company had reduced the level of GenX flowing into the river from the 631 ppt found earlier to 96 ppt.

Up to now, the EPA has not set legally binding regulations on any member of this class of chemicals, although last year it set a drinking water standard for PFOA and the related chemical PFOS of 70 ppt. Several states have established their own drinking levels for PFOA, with Vermont’s the lowest so far at 20 ppt. Water experts in New Jersey are said to have proposed an even lower level, 14 ppt.

In 2005, to settle the EPA’s allegations it had hid information about the dangers of PFOA, DuPont agreed to pay a fine of $16.5 million. In February of this year, DuPont and Chemours paid $670.7 million to settle out of court around 3,550 personal injury lawsuits involving C8 water contamination in the Ohio River Valley.

All the cases pertained to discharges from DuPont’s former Washington Works at Parkersburg, West Virginia.