(Reuters) - Public health and environmental groups in a lawsuit in San Francisco federal court say the Environmental Protection Agency should utilize its untapped power under section 4 of the Toxic Substances Control Act (TSCA) to order a chemical company to subsidize health studies on 54 undertested PFAS substances.

The Center for Environmental Health, Cape Fear River Watch and others on Wednesday sued the EPA over its denial of their petition seeking that it order The Chemours Company to fund studies on the effects on animals, humans and the environment of 54 per- and polyfluoroalkyl substances (PFAS) that its North Carolina Fayetteville Works facility manufactures. The plaintiffs say the EPA acted arbitrarily and capriciously when it rejected their petition by concluding that the groups had not proven that data on those versions of the chemical is lacking.

"Because this is pending litigation, EPA has no additional information to share," said EPA spokeswoman Andrea Drinkard. Chemours did not immediately respond to requests for comment.

Ralph DeMeo, a shareholder at Baker Donelson Bearman Caldwell & Berkowitz who is not involved in the lawsuit, said that should the plaintiffs obtain the relief they are seeking, the development "would be unprecedented in PFAS litigation to date, but well within the authority of the EPA."

"The costs to the manufacturers would be massive, and could be a game changer in the 'forever chemical' wars," he added.

PFAS, a family of manmade chemical compounds, have been used for decades to make nonstick coatings such as Teflon and are associated with serious health risks. PFAS, nicknamed 'forever chemicals' because they don't break down easily, have sparked numerous lawsuits against its manufacturers.

The groups say that section 4 of the TSCA authorizes the EPA to require industry to test for the effects on health and the environment of existing chemicals that may present unreasonable risks, and for which information is lacking to evaluate effects.

The EPA on Jan. 7 denied their petition to compel Chemours to fund and carry out this testing pursuant to section 4, the complaint says.

Section 5 of the TSCA has in the past been invoked for companies to fund the testing of new, not yet manufactured PFAS, plaintiffs' attorney Robert Sussman of Sussman & Associates told Reuters. But section 4 has never been used to test PFAS already in existence, either as part of litigation or otherwise. PFAS were first produced in the 1940s.

The plaintiffs say that they are concerned about contamination from 54 types of PFAS that have been detected in the drinking water, blood and produce of residents of the Cape Fear region. Fayetteville Works' 2,150-acre site is located near the region's Cape Fear River and is a "major producer and user of PFAS," the complaint says.

The groups say that the facility discharges into the river, whose watershed provides drinking water for 300,000 people including in downstream Wilmington.

A February 2019 consent order between Chemours, the state of North Carolina and Cape Fear Watch directs Chemours to take several measures to control emissions of PFAS from Fayetteville Works. The deal was filed in Bladen County Superior Court.

The case is Center for Environmental Health et al v. Nishida et al, U.S. District Court for the California Northern District, No. 3:21-cv-01535.

For Center for Environmental Health et al: Robert Sussman of Sussman & Associates and Michael Connett of Waters, Kraus & Paul