An Environmental Protection Agency (EPA) rule putting polluters on the hook to clean up toxic "forever chemicals" was upheld in court on Tuesday despite an industry challenge.

The rule in question formally designates two specific forever chemicals, called PFOA and PFOS, as "hazardous substances." 

That gives the EPA more authority to investigate sites that have been contaminated with these chemicals and hold polluting companies liable for cleanup costs under the nation's Superfund law.

The rule was put forward under the Biden administration and was also backed by the Trump administration. It faced a court challenge from various industries which argued that the EPA did not adequately consider the costs of its action.

The panel of judges, including Obama appointee Patricia Millet and Trump appointees Gregory Katsas and Neomi Rao with the District of Columbia Circuit Court of Appeals, determined that the EPA's action was legal.

"Having adequately considered and reasonably explained its decision to regulate at this initial stage even in the face of acknowledged uncertainties, EPA made a reasoned decision on the record before it in designating the forever chemicals PFOA and PFOS as hazardous substances," said the opinion, which was authored by Millet.  

Forever chemicals are the nickname of a family of chemicals known as PFAS, which have become pervasive and tend to linger in the environment for hundreds or even thousands of years.

Two of the most toxic and well-studied PFAS are PFOA and PFOS, which have been linked to cancer. 

The U.S. Chamber of Commerce, one of the groups that sued over the regulation, said it was weighing next steps. 

"We respectfully disagree with today's decision. EPA's failure to consider costs and consequences, as required by law, produced a deeply flawed rule that is more likely to spawn unnecessary, costly litigation than to drive expeditious, effective cleanup focused on actual risk," Daryl Joseffer, president of the Chamber's litigation center, said in a written statement. 

"We are currently reviewing the decision and considering options," Joseffer added.

Environmental and health advocates, meanwhile, hailed the decision as a win for polluted communities. 

"For too long, industrial polluters have profited from the release of toxic PFAS while sticking taxpayers and communities with the bill when those releases need to be cleaned up. Today's decision affirms EPA's authority to hold those companies responsible for the harms they cause," Jonathan Kalmuss-Katz, senior attorney at Earthjustice, said in a statement.

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