The Environmental Protection Agency has issued an internal directive that could undermine hundreds of federal and state regulations governing toxic chemicals, according to a memo obtained by ProPublica. Deputy Administrator David Fotouhi directed EPA offices this week to review their use of assessments produced by the Integrated Risk Information System, or IRIS, and advised external entities to consider similar reviews.
IRIS is a program created in 1985 that serves as the nation's primary clearinghouse for chemical toxicity information. Its scientists assess safe exposure levels for hundreds of chemicals, including known carcinogens. Those assessments have long underpinned EPA regulations on air emissions, drinking water standards, and hazardous waste disposal. State environmental agencies also rely heavily on IRIS data when drafting their own rules.
What the Right Is Saying
Supporters of the directive say it aims to strengthen, not weaken, the role of science in environmental regulation. The EPA press office stated that "science is at the heart of the agency's work" and that the memo "reaffirms that point clearly and unequivocally." The agency added that any changes to permits or standards must still go through public participation processes.
Conservative policy analysts have long argued that IRIS assessments are overly conservative, inflating toxicity risks in ways that impose unnecessary compliance costs on industry. Project 2025, a policy initiative developed by the Heritage Foundation, specifically called for eliminating IRIS, arguing it "often sets 'safe levels' based on questionable science" and that its reviews result in "billions in economic costs."
Republican congressional staff noted that House members introduced legislation last year that would prevent the EPA from using IRIS assessments in regulations, enforcement actions, and permits. The bills, backed by industry groups, did not receive a floor vote but reflected ongoing GOP concerns about regulatory overreach.
What the Left Is Saying
Environmental advocates and Democratic lawmakers say the directive represents a sweeping rollback of scientific safeguards. Robert Sussman, an attorney who has represented both chemical companies and environmental groups at the EPA, called the move "a huge setback for the process of protecting people from chemicals." He said the memo gives polluters a new avenue to challenge regulations by pointing to disclaimer language on IRIS assessments.
Senator Sheldon Whitehouse of Rhode Island said in a statement that the directive "opens the door to polluting industries cherry-picking which safety standards they want to obey." The Sierra Club issued a warning that long-established limits on arsenic in drinking water and lead in paint could be vulnerable to legal challenge if their underlying IRIS assessments are now deemed unreliable.
Former EPA officials noted that IRIS was deliberately structured to operate independently from the agency's regulatory offices, an arrangement designed to insulate its science from political pressure. They worry that bringing those functions back under one roof could compromise scientific integrity.
What the Numbers Show
The IRIS program has produced more than 500 chemical toxicity assessments since its founding four decades ago. These assessments determine safe exposure levels for substances including arsenic, benzene, formaldehyde, and various heavy metals.
The National Academies of Sciences, Engineering, and Medicine reviewed IRIS operations in 2011 and criticized the organization, length, and clarity of some reviews. However, a more recent assessment by the same body found that IRIS had made "significant progress" in addressing those concerns.
EPA's own regulatory impact analyses have estimated that current chemical standards save between $5 billion and $200 billion annually in health care costs, depending on the methodology used for calculating avoided illnesses and premature deaths.
The Bottom Line
The directive marks a significant shift in how the EPA will handle chemical safety science. While the agency has not announced plans to repeal specific regulations, environmental lawyers say the disclaimer language could give regulated industries new grounds to challenge permits and enforcement actions in court.
EPA officials insist that no existing rules have been invalidated and that any changes must follow formal rulemaking procedures including public comment periods. However, critics note that legal challenges based on the memo's premise—that IRIS assessments may not be suitable for regulatory use—could delay enforcement while cases proceed through the courts.
The directive also affects international environmental standards. At least 17 countries and multiple United Nations agencies have used IRIS data to set their own chemical regulations, according to EPA records. Those nations may now face uncertainty about whether to continue relying on U.S. assessments.