The EPA action came a day after ACC released a study it said shows that the vast majority of fluoropolymers, which are part of the PFAS family, are safe.
The new ACC study says that more than 90 percent of fluoropolymers should be considered safe to use and designated, in regulatory speak, as "polymers of low concern."
The study from ACC's Performance Fluoropolymer Partnership looked at the safety data for 14 fluoropolymers and fluoroelastomers, building on a 2018 review of 4 of the chemicals.
It said the 18 compounds together make up about 96 percent of the global market for commercially available fluoropolymers.
ACC said the study is evidence that PFAS chemicals are different enough from each other that they should not be regulated as a single chemical.
"This paper provides conclusive evidence that an overwhelming percentage of the fluoropolymers in the products we rely on every day are of low concern for human health or the environment according to internationally recognized criteria," said Jay West, PFP executive director. "It also demonstrates even further that regulating the broad family of PFAS as one single category is neither scientifically sound nor appropriate."
ACC said its study indicates the compounds meet the international definition of chemicals of low concern and have "insignificant environmental and human health impacts."
"The result is that the most economically important fluoropolymers [by global market volume] pose minimal threats to humans or the environment," PFP said in a news release.
The definition of polymers of low concern was first developed more than 15 years ago by the Organization for Economic Cooperation and Development and its expert group on polymers, ACC said.
ACC said that the study looks only at the "in-use" phase of the chemicals and does not examine the impacts from manufacturing or end-of-life phases of the polymers.
Those phases, however, also attract attention from regulators and plastics firms have been caught up in expensive cleanup operations for leaks of fluoropolymers into the environment.
The chemicals in the ACC study include polyvinylidene fluoride homopolymer and copolymer; ethylene-chlorotrifluoroethylene copolymer and terpolymer; polychlorotrifluoroethylene and fluoroethylene-vinyl ether copolymer, as well as specialty fluoroplastics, amorphous fluropolymers and fluorinated ionomers.
The study was published in the journal Integrated Environmental Assessment and Management.