For decades, a small program in the Environmental Protection Agency conducted the painstaking scientific work of assessing the toxicity of chemicals.\u00a0<\/p>\n
The calculations done by scientists at IRIS, as it was commonly known, underpin vast numbers of chemical regulations, permits and other environmental rules in the U.S. and abroad.<\/p>\n
Now the Trump administration is suggesting that their library of more than 500 chemical assessments can\u2019t be trusted, opening the door to weakening hundreds of efforts to protect people from harmful chemicals at the state and federal level. The second-guessing could extend even to long-settled standards, environmental scientists said, such as how much arsenic is allowed in drinking water and how much lead is acceptable in paint and soil.<\/p>\n
In an internal memo obtained by ProPublica, David Fotouhi, the deputy administrator of the agency, sharply criticized IRIS this week and directed EPA offices that have used any of the chemical assessments the program has produced to review them. He also advised \u201cexternal entities\u201d that have used the IRIS assessments to consider undertaking similar reviews and cautioned against using them in future regulations.<\/p>\n
The six-page memo said the EPA would be adding \u201cdisclaimer language\u201d to the website of the program \u2014 the Integrated Risk information System<\/a> \u2014 stating that its toxicity findings are not necessarily meant to be used in regulation.<\/p>\n \u201cThis creates the opportunity for companies that pollute to push back on rules and regulations they don\u2019t like,\u201d said Robert Sussman, an attorney who has worked for chemical companies and environmental groups as well as the EPA. \u201cAnybody 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\u2019t valid. It\u2019s a huge setback for the process of protecting people from chemicals.\u201d\u00a0<\/p>\n Fotouhi\u2019s memo echoes industry criticism that the program\u2019s scientists are far too conservative in gauging the toxicity of chemicals. Before President Donald Trump appointed him as the second highest official at the EPA, Fotouhi worked as a lawyer representing companies accused of causing toxic pollution<\/a>.\u00a0<\/p>\n In an emailed statement, the EPA press office wrote that Fotouhi has complied with all applicable government ethics obligations and said his directive would not put people at risk or allow anyone to ignore environmental regulations. Any revisions to permits or regulatory standards must go through a process that includes public participation, the office noted.<\/p>\n \u201cScience is at the heart of the Agency\u2019s work, and this memo reaffirms that point clearly and unequivocally,\u201d the press office wrote.\u00a0<\/p>\n The EPA created IRIS in 1985 as the nation\u2019s clearinghouse for information on the toxicity of chemicals. Its assessments quantify the highest safe level of exposure to a chemical before it triggers health effects, including, in many cases, cancer. The agency previously prided itself on the program\u2019s impartiality and, in an effort to protect its science from the influence of industry, purposefully kept the program separate from the agency offices that craft regulation<\/a>.\u00a0<\/p>\n The memo now tasks those offices with conducting toxicity assessments and brings an end to the program that has powered the EPA\u2019s efforts to protect people from harmful chemicals.\u00a0<\/p>\n IRIS assessments earned a reputation for being extremely detailed and undergoing numerous rounds of review by many scientists. The EPA offices routinely relied on them to set the amount of a particular chemical that industrial facilities are allowed to emit. States use IRIS assessments to decide which chemicals deserve their immediate attention and to calculate limits in rules and regulations. And IRIS reports guide environmental regulation in countries that don\u2019t have the resources to fund their own scientists to review chemicals.<\/p>\n The memo is the latest attack on the program. The Heritage Foundation\u2019s Project 2025 called for the elimination of IRIS on the grounds that it \u201coften sets \u2018safe levels\u2019 based on questionable science\u201d and that its reviews result in \u201cbillions in economic costs.\u201d And last year, congressional Republicans introduced industry-backed legislation<\/a> that would prevent the EPA from using IRIS assessments in environmental rules, regulations, enforcement actions and permits. (The bills were not put to a vote.)\u00a0<\/p>\n IRIS has at times been criticized by independent scientific bodies. More than a decade ago, for example, 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 found that IRIS had made \u201csignificant progress\u201d in addressing the problems.<\/p>\n Still, IRIS\u2019 work stood 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<\/a> in favor of the sponsor\u2019s products.\u00a0<\/p>\n Over the past year, the EPA has essentially shut down IRIS by reassigning most of the dozens of the scientists who worked in the program to other parts of the agency. And the administration has refused to publish a report on a \u201cforever chemical\u201d known as PFNA<\/a>, which was completed by IRIS in April 2025.\u00a0<\/p>\n But, until now, the EPA had not challenged the science in IRIS assessments. The memo changes that. Although the agency will continue to post the documents on its website, it calls their validity into question, arguing that the toxicity levels calculated in IRIS reports are overly cautious and fail to include the perspective of all \u201cstakeholders.\u201d\u00a0<\/p>\n This approach produces values that are more protective than they need to be, according to Fotouhi. \u201cWhen many conservative assumptions are stacked on top of each other, the cumulative effect can produce an estimated \u2018safe\u2019 exposure level that is orders of magnitude below naturally occurring levels in the environment,\u201d he wrote.<\/p>\n Fotouhi pointed specifically to ethylene oxide, a chemical used to sterilize medical equipment \u2014 and one used by Medline, a company he used to represent as an attorney at the firm Gibson, Dunn & Crutcher, according to financial statements he filed and that are contained in ProPublica\u2019s database of Trump administration officials\u2019 disclosures<\/a>. IRIS updated its assessment of ethylene oxide in 2016, after it reviewed the medical literature and found that the chemical was a more potent carcinogen than previously believed.\u00a0<\/p>\n