EPA ends its 40-year chemical safety science program

EPA Deputy Administrator David Fotouhi issued an internal memo on April 27, 2026, directing the agency to stop using IRIS (the Integrated Risk Information System) to produce independent chemical toxicity assessments. The memo was first reported by ProPublica on May 1, 2026. Fotouhi cited industry complaints that IRIS scientists were "overly conservative" in gauging chemical risks and said the program lacked continuity and failed to consider important scientific issues.

The decision ends a program that has operated since 1985. IRIS was created specifically to separate the science of chemical toxicity from the politics of regulation. Its database contains more than 500 assessments that federal agencies, state governments, and courts have relied on to set safety limits for chemicals in drinking water, air, and soil.

Under Fotouhi's memo, chemical risk assessments will now be written by EPA policy offices: the Office of Air and Radiation, the Office of Water, and the Office of Chemical Safety and Pollution Prevention. These are the same offices that write the regulations themselves. Critics say this eliminates the firewall between science and policy, allowing the offices with the most contact with regulated industries to also determine how dangerous those industries' chemicals are.

Maria Doa, a senior scientist at the Environmental Defense Fund who spent more than 20 years at the EPA, told ProPublica the change means industry can now pressure the science before regulations are written, not just after. Previously, regulated companies could dispute IRIS assessments in court after a rule was finalized, but could not directly shape the underlying toxicity numbers.

The Trump administration's Project 2025 policy blueprint, published by the Heritage Foundation in 2023, explicitly called for eliminating IRIS. The American Chemistry Council, the largest U.S. chemical industry trade group, had lobbied against IRIS for years, arguing its assessments overstated chemical risks and cost the industry billions in compliance costs.

The Council's members include ExxonMobil, Dow, BASF, and more than 180 other chemical manufacturers. According to federal lobbying disclosures, the American Chemistry Council spent $14.8 million on lobbying in 2024, one of its largest annual totals.

David Fotouhi was confirmed as EPA Deputy Administrator on June 10, 2025, after being nominated by President Trump in January 2025. Before his confirmation, Fotouhi was a partner at Gibson Dunn & Crutcher, one of the country's top environmental litigation firms. His clients there included Medline Industries, a company that uses ethylene oxide (a carcinogen) to sterilize medical equipment. Ethylene oxide is one of the chemicals IRIS assessed.

Fotouhi also served as EPA acting general counsel during Trump's first term, from 2017 to 2021. His prior government work and subsequent return to private practice representing polluting industries exemplifies the regulatory revolving door, where officials move between government positions and the industries they regulated.

IRIS assessments have been used to set the legal basis for dozens of major environmental rules. The EPA's 2024 rule tightening limits on ethylene oxide emissions from sterilization facilities relied on an IRIS assessment of the chemical's cancer risks. Several states also use IRIS data independently of federal rules to set their own cleanup standards for contaminated sites.

Environmental lawyer Robert Sussman warned that the memo weaponizes past IRIS assessments against existing regulations. "Anybody who wants to ignore a regulation, permit or enforcement action can now just point to this memo and say the IRIS number it was based on wasn't valid," he told ProPublica. Companies can cite Fotouhi's statement that prior IRIS work was "overly conservative" in litigation to argue that the rules built on those assessments lack a sound scientific foundation.

Fotouhi's memo does not rescind existing IRIS assessments immediately. The more than 500 assessments already in the IRIS database remain on the EPA's website. But the memo stops new assessments from being produced and implies the existing library can't be trusted, which environmental lawyers and public health scientists say will have immediate practical effects.

State environmental agencies in California, New York, Massachusetts, and elsewhere rely on IRIS assessments when federal standards don't cover a specific chemical or when states want stricter limits. Those agencies will now face uncertainty about whether EPA will maintain or disclaim prior assessments, complicating their own rulemaking.

The EPA has faced sustained criticism of IRIS from industry groups and some Republican lawmakers for more than a decade. During Obama's second term, the Government Accountability Office found that IRIS was taking an average of seven years to complete a single chemical assessment, creating a backlog of hundreds of chemicals awaiting review. Industry groups used those delays to argue the program was dysfunctional.

Instead of speeding up the process, Fotouhi's memo shuts the program down entirely. Chris Frey, who led the EPA's Office of Research and Development from 2021 to 2024, told Chemical & Engineering News that industry groups use the scientific process as a proxy to suppress science they don't like. "This is scapegoating," he said, comparing it to tobacco industry tactics in the 1960s and climate denial today. Frey cited the GAO's 2011 reform report, which recommended reforms, not abolition.

The EPA under Lee Zeldin has moved aggressively to roll back environmental rules since January 2025. The agency has proposed eliminating dozens of Clean Air Act standards, reopened Clean Water Act rules, and shed hundreds of staff through the federal workforce reduction program. The IRIS memo fits a pattern of actions that reduce the scientific basis for future environmental regulations while keeping existing industry operations in place.

Public health advocates note that chemical risk assessments don't just affect regulation. They inform what doctors tell patients, what states tell communities near industrial facilities, and what cleanup contractors do at Superfund sites. Removing independent federal science from that chain affects health decisions far beyond formal rulemaking.

The EPA's 2024 ethylene oxide rule tightened emissions limits for sterilization facilities based on an IRIS assessment of the chemical's cancer risks. Robert Sussman told ProPublica the memo weaponizes this past IRIS work against existing regulations: "Anybody who wants to ignore a regulation, permit or enforcement action can now just point to this memo and say the IRIS number it was based on wasn't valid."

The legal mechanism is clear. When EPA issues a rule, regulated companies must comply or sue on grounds the rule lacks a sound scientific foundation. Previously, IRIS assessments were protected by the agency's professional reputation and institutional structure. But when the EPA Deputy Administrator publicly discredits IRIS as "overly conservative," companies can argue in court that the rules built on IRIS science now rest on a discredited foundation. Companies can now argue to a judge that the underlying science EPA relied on has been discredited by the agency itself.