Data centers, drawing concerns over water and power, may have another surprise impact: Forever chemicals

As AI data centers face intense public pushback over issues including their electricity and water use, another potential environmental impact is percolating: the proliferation of forever chemicals.

Data centers can use these chemicals in at least two ways: in their cooling processes and through their more general use of semiconductors.

Supporters say that their use in cooling can reduce data centers’ significant water use, helping alleviate a major problem associated with the rapid build-out of AI infrastructure.

But critics warn that using even more forever chemicals threatens to exacerbate a massive environmental threat.

Forever chemicals are the nickname of a family of chemicals also known as PFAS that can linger in the environment for hundreds or even thousands of years because of their strong carbon-fluorine bonds, which make them difficult to break down. They have become widespread in both nature and humans because of pollution.

Exposure to certain PFAS has been linked to health issues including cancer, fertility issues, kidney and liver issues and immune system problems.

They are also used in a wide variety of industries because of their nonstick, waterproof, fire-retardant and anticorrosive properties.

Both the chemical industry and outside experts say that these chemicals can be used in data centers’ cooling systems.

“A lot of these cooling systems, though, are what we call ‘closed loop,’ meaning that it’s not like you have fluorinated chemicals flowing in and out of the data center. It means you have a closed system,” said Kyle Doudrick, an environmental engineering professor at the University of Notre Dame.

“Now the worry is that no closed system is perfect and that these chemicals leak out over time, which is probably true. … Nothing is 100 percent sealed,” Doudrick added.

The American Chemistry Council, a trade group representing chemical companies, said in a statement to The Hill that “as AI workloads increase the heat generated by servers and semiconductors, some data centers are exploring liquid-based cooling systems,” including those that use PFAS.

“These technologies can help improve cooling efficiency and, in some cases, significantly reduce water use associated with traditional cooling approaches,” the group’s statement said.

The Hill reached out to Amazon, Oracle, Meta, Google, Microsoft and Apple to ask whether their data centers use PFAS in cooling. Oracle, Meta and Microsoft did not respond to The Hill’s questions.

Amazon said that it doesn’t currently use liquid immersion cooling, adding that this is the main cooling technology driving PFAS concerns. A spokesperson did not respond to a follow-up question about whether the company uses other cooling technologies that contain PFAS.

An Apple spokesperson said that it does not use PFAS-based chemicals in cooling processes at its data centers.

Google also said that it does not use PFAS in its data center cooling systems.

The Data Center Coalition, a trade group representing the data center industry, did not respond to questions from The Hill. However, the group provided a statement from Michele Nellenbach, its vice president of federal affairs, saying, “Virtually every industry contends with PFAS in its supply chain.”

“The data center industry takes compliance and accountability seriously and works closely with the many local, state, regional, and federal bodies responsible for regulation and oversight across environmental, safety, and other key areas,” Nellenbach said.

But the potential for proliferation is sparking concern among environmental activists and scientists.

Lenny Siegel, executive director of the Center for Public Environmental Oversight, told The Hill that even if data center cooling uses PFAS in a closed-loop system, he would still be concerned because “eventually they’ll make it into the environment.”

“What are they going to do when they’re done?” Siegel asked of the data centers. “‘Closed loop’ is a great concept, but it doesn’t deal with leaks or, you know, long-term disposal … of the chemicals.”

Kate Manz, an assistant professor of environmental health science at the University of Michigan, said that if she were living near a data center, she “would feel concerned” about chemicals.

“There’s a lot of concern about what happens to the chemicals that are being used during the cooling process in the data centers, because they can potentially transform into a short-chain chemical called trifluoroacetic acid,” she said.

The European Food Safety Authority has expressed concerns about this chemical’s thyroid impacts.

Trump administration seeks to fast-track data center chemicals

Meanwhile, the Trump administration has been broadly supportive of AI and its associated data centers and has sought to cut red tape to speed their construction.

This has included data center chemicals. The Environmental Protection Agency (EPA) said last year that it would fast-track the approval of chemicals for data center use.

The EPA told The Hill that prioritizing these chemicals simply means they are put at the front of the line so that their review starts quickly, but the actual process for assessing their risks is unchanged. The agency said that so far, fewer than 10 chemicals have been fast-tracked, including one PFAS.

Fast-tracked or not, the EPA is considering the approval of several more PFAS , including some that may be used in data centers or semiconductors.

At least one, a substance known as Opteon 2P50 from chemical company Chemours, is garnering pushback from environmental activists.

A coalition of environmental groups wrote in public comments to the EPA that approving the substance “would expand a class of chemicals that is both highly persistent and hazardous and already contaminates the drinking water supplies for more than 170 million people and the blood of nearly everyone in the country.”

They note that the chemical is “intended to be used as a dielectric fluid to cool electric equipment, a use that will result in environmental releases.”

They also wrote that Opteon 2P50 belongs to a subset of chemicals called hydrofluoroolefins, or HFOs, that “degrade into other toxic shorter-chain PFAS and persist in the environment,” and they added that available data on the substance’s potential health harms is “limited.”

Chemours is defending its product, with spokesperson Jess Loizeaux saying in an email that Opteon 2P50 “is a more efficient and sustainable cooling solution that can help data centers reduce cooling energy use by up to 90% and nearly eliminate water use as they scale to meet the growing demands of AI and high-performance computing.”

Loizeaux said the concerns “fail to account for the intended use” of the chemical, noting that it is designed to be used in a sealed, closed-loop system and that releases would be “tightly controlled” and expected to have an emissions rate of no more than 2 percent per year.

Environmental activists say the agency should be working to rein in, rather than approve, PFAS.

“We aren’t ever going to fix our current PFAS problems and address the rampant contamination that those chemicals have already caused if we are continuously approving more and more new PFAS,” said Jonathan Kalmuss-Katz, a senior attorney with Earthjustice.

PFAS are estimated to be in the bloodstream of virtually every American . Studies have also estimated that they can be found in 83 percent of U.S. waterways.

Meanwhile, the EPA is weighing whether to approve additional ones.

A spokesperson confirmed all six of the substances listed in its April/May docket of chemicals submitted by the industry for review containing “fluoro” in their names are PFAS. It also said that two of the three chemicals that have been submitted in its March docket meet the agency’s definition of PFAS.

“PFAS have been approved under every administration since 2016,” said the EPA spokesperson in an unsigned statement.

Data centers also use semiconductors, which are made using PFAS

The data center boom is also expected to require more semiconductors, a technology that uses PFAS in its production.

A June report from the Semiconductor Industry Association said that leading AI data centers can each contain an estimated 45 million chips.

Christopher Ober, a professor of materials engineering at Cornell University, said he expects that the more chips that are produced, the more PFAS will be needed to produce them.

“If production goes up, need will go up,” he said, though he added that the amount needed per chip can be relatively small.

He said that the strong carbon-fluorine bond found in PFAS makes them particularly important for semiconductor manufacturing.

“Fluorinated materials are kind of magical,” Ober said. “If they were to be banned, I think today we simply couldn’t find an alternative material.”

He said their important properties include their capacity as an “anti-reflective coating.” He added that the chemicals’ “carbon-fluorine bond vacuums up electrons, and so that enables molecules known as photoacid generators to produce very strong acids that trigger a series of chemical reactions used in the patterning process.”

“The fluorinated materials have low surface energy, and so that helps in preventing certain types of wetting that is useful in the lithographic process.”

A 2024 study found that in this lithographic, or printmaking, process for semiconductors, about 47 percent of PFAS are ultimately put into wastewater, while another large subset are ultimately incinerated.

The paper says that incineration “should lead to complete destruction and mineralization of PFAS.”

However, Kalmuss-Katz said in a follow-up email that neither wastewater nor incineration “is a safe method of PFAS disposal.”