EPA couldn't use the science behind hundreds of environmental protections if industry-backed law passes

For decades, Republican lawmakers and industry lobbyists have tried to chip away at the small program in the federal Environmental Protection Agency that measures the threat of toxic chemicals.

Most people don’t know what’s known as IRIS — the Integrated Risk Information System. But it is the scientific engine of the agency that protects human health and the environment. Its scientists assess the toxicity of chemicals, estimating the amount of each that triggers cancer and other health effects. These values serve as the independent, nonpartisan basis for the rules, regulations and permits that limit our exposure to toxic chemicals.

Now, IRIS faces the gravest threat to its existence since it was created four decades ago under President Ronald Reagan. Legislation introduced in Congress would prohibit the EPA from using any of IRIS’ hundreds of chemical assessments in environmental rules, regulations, enforcement actions and permits that limit the amount of pollution allowed into air and water.

The EPA also would be forbidden from using them to map the health risks from toxic chemicals. The bills, filed earlier this year in the U.S. Senate and House of Representatives, are championed by companies that make and use chemicals, along with industry groups that have long opposed environmental rules. If it becomes law, the “No IRIS Act” essentially would bar the agency from carrying out its mission, experts told ProPublica.

“They’re trying to undermine the foundations for doing any kind of regulation,” said William Boyd, a UCLA School of Law professor who specializes in environmental law.

Boyd noted that IRIS reports on chemicals’ toxicity are the first step in the long process of creating legal protections from toxic pollutants in air and water.

“If you get rid of step one, you’re totally in the dark,” he said.

If the proposed law is passed, companies could use it to fight the enforcement of long-existing environmental rules or permits that limit their toxic emissions, according to environmental lawyers.

The attack on IRIS has a good chance of succeeding at a time Republicans are eager to support President Donald Trump’s agenda, according to environmental advocates who monitor Congress. The bills dovetail with anti-regulatory efforts that have marked the second Trump administration, which has begun to dismantle climate protections, nominated industry insiders to top positions in the EPA and announced plans for unprecedented cuts that could slash the agency’s budget by 65%.

Project 2025, the ultraconservative playbook that has guided much of Trump’s second presidency, calls for the elimination of IRIS on the grounds that it “often sets ‘safe levels’ based on questionable science” and that its reviews result in “billions in economic costs.”

The policy blueprint echoes industry claims that IRIS does not adequately reflect all of the research on chemicals; there are sometimes significant differences between the program’s conclusions and those of corporate-funded scientists.

IRIS has long been a target of industry and at times has been criticized by independent scientific bodies. More than a decade ago, the National Academies of Sciences, Engineering, and Medicine took issue with the organization, length and clarity of IRIS reviews. A more recent report from the same group said IRIS had made “significant progress” in addressing the problems.

IRIS’ work stands out in a world where much of the science on toxic chemicals is funded by corporations with a vested stake in them. Studies have shown that industry-funded science tends to be biased in favor of the sponsor’s products.

But IRIS’ several dozen scientists do not have a financial interest in their findings. Their work has had a tangible impact on people. The program’s calculations are the hard science that allows the agency to identify heightened disease risk due to chemicals in the air, water and land. These revelations have, in some cases, led to stricter chemical regulations and grassroots efforts to curtail pollution.

A database on toxicity

IRIS was created in 1985. Until then, different parts of the EPA often assessed chemicals in isolation, and their methods and values were not always consistent.

At first, IRIS just collected assessments completed by various divisions of the EPA. Then, in 1996, it began conducting its own, independent reviews of chemicals. Its scientists analyze studies of a chemical and use them to calculate the amount of the substance that people can be exposed to without being harmed. IRIS sends drafts of its reports to multiple reviewers, who critique its methods and findings.

As the tranche of assessments grew, states began relying on IRIS’ numbers to set limits in air and water permits. Some also use them to prioritize their environmental efforts, acting first on the chemicals that IRIS deems most harmful. And countries that don’t have the expertise to assess chemicals themselves often adopt IRIS values to guide their own regulations.

IRIS’ collection of more than 500 assessments of chemicals, groups of related chemicals and mixtures of chemicals is the largest database of authoritative toxicity values in the world, according to Vincent Cogliano, a recently retired scientist who worked on IRIS assessments for more than 25 years.

‘Bitter battles’

From the beginning, industry scientists challenged IRIS with calculations that showed their chemicals to be less dangerous.

“There were a lot of pretty bitter battles,” said Cogliano, who remembers particularly intense opposition to the assessments of diesel engine exhaust and formaldehyde during the 1990s.

Critiques of IRIS assessments intensified over the years and began to slow the program’s work.

“It took so long to get through that there were fewer and fewer assessments,” Cogliano said.

In 2017, opposition to IRIS escalated further. Trump’s budget proposal would have slashed funding for the program. Though Congress funded IRIS and the program survived, some of its work was halted during his first presidency.

Trump appointed David Dunlap, a chemical engineer, to head the division of the EPA that includes IRIS. Dunlap had challenged the EPA’s science on formaldehyde when he was the director of environmental regulatory affairs for Koch Industries. Koch’s subsidiary Georgia-Pacific made formaldehyde and many products that emit it. Georgia-Pacific has since sold its chemicals business to Bakelite Synthetics.

While Dunlap was at the EPA, work on several IRIS assessments was suspended, including the report on formaldehyde. IRIS completed that report last year.

That assessment proved controversial, ProPublica documented in its investigation of the chemical late last year. In calculating the risks that formaldehyde can cause cancer, IRIS decided not to include the chance that the chemical can cause myeloid leukemia, a potentially fatal blood cancer. The EPA said IRIS made this decision because it lacked confidence in its calculation. The agency acknowledged that the omission drastically underestimated formaldehyde’s cancer risk.

‘Depth of the poisoning’

Still, some of IRIS’ assessments have made a huge difference in parts of the country.

In 2016, IRIS updated its assessment of a colorless gas called ethylene oxide. The evaluation changed the chemical’s status from a probable human carcinogen to plainly “carcinogenic to humans.” And IRIS calculated the uppermost amount of the chemical before it starts to cause cancer, finding that it was 30 times lower than previously believed.

The EPA used that information to create a map, which showed that people living near Sterigenics’ sterilizing plant in Willowbrook had an elevated cancer risk because the facility was releasing ethylene oxide into the air. Once people in the DuPage County suburb learned of their risk, they kicked into action.

“That knowledge led us to be able to really activate the groundswell of community members,” said Lauren Kaeseberg, who was part of a group that held protests outside the plant, met with state and local officials and testified at hearings.

Not long after the protests, the state of Illinois passed legislation limiting the release of the pollutant, the local plant shut down and the cancer-causing pollution was gone from the air.

Around the country, the pattern has been repeated. After IRIS issues its estimate of the amount of a chemical that people can safely be exposed to without developing cancer and other diseases, the EPA uses that information to map the threats from chemicals in air. IRIS’ evidence showing that people have an elevated risk of cancer has sparked some hard-hit communities to fight back, suing polluters, shutting down plants and demanding the offending chemical be removed from their environment.

In St. John the Baptist Parish, Louisiana, people had long felt they had more than their share of sickness. The small rectangle of land near the Mississippi River abuts a chemical plant that emits foul-smelling gases. For decades, as they breathed in the fumes, residents suffered from respiratory problems, autoimmune diseases, cancers and other ailments.

In 2016, after IRIS assessed the toxicity of chloroprene, one of the chemicals coming out of the plant’s smokestacks, people in St. John discovered the main source of their problems. The IRIS assessment showed chloroprene was a likely carcinogen and caused damage to the immune system. With this information, the EPA concluded that St. John had the highest cancer risk from air pollution in the country.

“I didn’t realize the depth of the poisoning that was taking place until EPA came to our community in 2016 and brought us that IRIS report,” said Robert Taylor, who has lived his entire life in St. John.

When the agency representatives arrived, Taylor’s wife had cancer, and his daughter was bedridden with a rare autoimmune condition. A lifelong musician who was then 75, Taylor began organizing his neighbors to demand a stop to the deadly pollution. His wife died in December.

The assessments of chloroprene and ethylene oxide — and the activism they sparked around the country — eventually led the EPA to crack down. Last year, the agency announced several rules that aimed to reduce toxic emissions. The rules call for changes in how companies produce and release chemicals — the type of reforms that can be expensive to undertake.

The Biden administration sued Denka, the company that owns the chloroprene-releasing plant in St. John, in an effort to force it to curb the amount of the chemical it released. But the Trump administration intends to drop that suit, according to The New York Times.

Last July, Denka sued the EPA over one of the rules, asking for more time to implement the changes. The company argued that the agency was on a “politically motivated, unscientific crusade” to shut down the plant.

Critics of IRIS have used similarly barbed language in their recent attacks. Announcing the introduction of what he calls the “No Industrial Restrictions in Secret Act” in the House, U.S. Rep. Glenn Grothman, R-Wis., wrote, “Unelected bureaucrats in the Biden Administration have disrupted the work of Wisconsin’s chemical manufacturers and inhibited upon the success of the industry through the abuse of the EPA’s IRIS program.”

The announcement said the bill is supported by Hexion, which has a plant in his district. Hexion makes formaldehyde, a chemical that increases the cancer risk nationwide.

Neither Grothman nor U.S. Sen. John Kennedy, R-La., who introduced the Senate version of the bill, responded to questions from ProPublica, including how they think the EPA could regulate chemicals if the bill passes. The EPA did not answer questions.

The American Chemistry Council, which represents more than 190 companies, sent a letter to Lee Zeldin, the EPA administrator, in late January, calling on him to disband IRIS and prohibit the use of its assessments in rules and regulations. IRIS “has been increasingly used to develop overly burdensome regulations on critical chemistries,” according to the letter, which was first reported by the news site Inside EPA. The letter argued that the program lacks transparency and “has often fallen short of scientific standards.”

The American Petroleum Institute, the Extruded Polystyrene Foam Association, the Independent Lubricant Manufacturers Association, the Fertilizer Institute and the Plastics Industry Association were among dozens of organizations representing industries financially affected by IRIS’ chemical assessments that signed the letter.

‘Off the deep end’

Industry groups have criticized IRIS for being slow and overstepping its authority, noting that outside organizations have found fault with it.

In addition to the National Academies’ criticism in 2011 about the clarity and transparency of its reports, IRIS has responded to recommendations from the Government Accounting Office, according to a report the congressional watchdog recently issued. The GAO, which monitors how taxpayer dollars are spent, placed IRIS on its “high risk list” in 2009. The GAO did so not because it was vulnerable to waste, fraud and abuse — the reasons some programs land on the list — but because the watchdog decided IRIS wasn’t doing enough assessments of dangerous chemicals.

Since 2009, the GAO made 22 recommendations to IRIS, and all have been implemented, according to the agency’s website. The new report acknowledged improvements but noted that the program’s current pace of finalizing assessments “likely cannot increase without more resources.” According to the GAO report, in 2023 and 2024, IRIS had reported needing 26 additional staff members to meet the demand for chemical assessments.

Defenders of the program say the criticisms mask a simple motive: protecting industry profits rather than public health.

“It’s blatant self-interest,” said Robert Sussman, an attorney who was the deputy administrator of the EPA and worked for environmental groups and chemical companies. “What they’re really trying to do here is prevent the EPA from doing assessments of their chemicals.”

Sussman said he has witnessed many attempts to scale back the EPA’s power in his 40-year career and described the current effort to eliminate its use of IRIS’ chemical assessments as “completely off the deep end.”

Weaker bills targeting IRIS were introduced in the House and Senate in February 2024 but did not have the support to advance. Now, after the election, the possibility of success is entirely different, according to Daniel Rosenberg, director of federal toxics policy for the Natural Resources Defense Council, an environmental nonprofit.

“I don’t think there’s any doubt that, if it does pass Congress — and it now could — the president will sign it,” Rosenberg said.

But he also said he thinks that, if the public understood the consequences of doing away with the science at the core of the EPA’s work, people potentially could sway their lawmakers to stand up to the attack on IRIS.

“The current political alignment is clearly very favorable to the chemical lobby, but their actual agenda has never been popular,” Rosenberg said. “There’s never been a case where people are in favor of more carcinogens in their environment.”