PARKERSBURG — In addition to setting maximum contaminant levels for C8, Tuesday’s proposed EPA rules also tighten the focus on its replacement, GenX, and related chemicals.

C8, or PFOA, was phased out of the manufacturing process at the Washington Works plant in Washington, W.Va., and has not been used there and at other sites since before Chemours’ creation in 2015, said Cassie Olszewski, media relations and financial communications manager for Chemours. It was replaced in 2012 by hexafluoropropylene oxide dimer acid, often referred to by the trade name GenX.

But that substance has also been detected in surface water, groundwater, drinking water, rainwater and air emissions.

The EPA proposal includes a “hazard index” to evaluate the risks from mixtures of related chemicals, including GenX. Dave Altman, an attorney who represents the Little Hocking Water Association, said the filtration system there has kept GenX out of treated water but it remains a presence in wells and therefore a concern.

The hazard index “is protective, and it recognizes it’s not just the GenX but the GenX with other compounds,” he said. It converts a previous health advisory about the substance “into something that’s regulatory,” Altman said, adding that he is still evaluating it with experts.

Chemours challenged the non-enforceable, non-binding health advisory that established 10 parts per trillion as the amount not expected to have negative health effects over the course of a lifetime of exposure. Company representatives said the advisory was based on an assessment with “numerous scientific flaws.”

Chemours is reviewing available information about Tuesday’s announcement, Olszewski said.

“Chemours supports government regulation that is grounded in the best available science and follows the law. Agency action regarding HFPO-Dimer Acid that relies on a flawed health advisory or its underlying assessment would call into question if the proposal meets that standard,” she said. “Chemours uses HFPO-DA as a polymerization aid in the production of four fluoropolymers that enable many of today’s essential technologies — from semiconductor manufacturing and 5G to electric vehicles and clean hydrogen. Fluorinated chemistry is critical to modern life.”

Prior sampling showed no GenX in water supplied by the Parkersburg Utility Board, Manager Eric Bennett said. But the most recent level of C8 was 12 parts per trillion, three times the maximum contaminant level recommended by the EPA Tuesday.

But the rule likely won’t change what the utility is already doing to address the presence of C8, Bennett said.

“We’re already in the process of putting in the treatment to essentially eliminate our PFOA, PFAS,” he said.

The utility is set to receive $12.6 million from the West Virginia Infrastructure and Jobs Development Council to install a granular activated carbon filtration system at the water treatment plant. The funds came from last year’s federal infrastructure law and are specifically intended to address contaminants like C8 and other PFAS.

Though not required to, the PUB has long tested for the presence of C8. DuPont and Chemours paid for the installation of carbon filtration systems in a number of local water systems, but Parkersburg’s never reached the levels to make it eligible.

Bennett said the PUB recently received a pilot filtration system that will be installed this week to help determine how often the media in it will need replaced. An engineering proposal for the project is expected to be chosen at the board’s March 28 meeting.

“It would be nice to get to construction early next year,” he said. “That would be ideal.”

Asked what he would tell customers concerned about the level of C8 in the water now, Bennett replied, “I drink the water every day. And I’m not going to stop.”

The filtration systems for several water utilities were installed as a result of a class-action lawsuit over the presence of C8 in water supplies. Attorney Harry Deitzler, of Vienna, was one of the plaintiffs’ lawyers.

“It’s not anything particularly new to us,” Deitzler said of Tuesday’s announcement. “In working on this concern, we have long been aware of the problem, and it is good to know that the EPA is addressing human health and safety in regards to our drinking water.”

U.S. Sen. Shelley Moore Capito, R-W.Va., said in a statement Tuesday she was glad to see a drinking water standard issued for PFOA and PFOS, another related chemical. It’s something she said she’s urged three different administrations to do.

“I’m looking forward to hearing from those who will be impacted by this announcement, including local water systems and ratepayers across the country, on how we can provide assistance for implementation,” Capito said. “No one should have to wonder if their water is safe to drink, and it’s critical that we get this important regulation right.”