What is IRIS?
“The IRIS Program was created by EPA in 1985 (during the Reagan admininstration) to provide an internal database of human health assessments for chemicals found in the environment. The goal of the IRIS Program was to foster consistency in the evaluation of chemical toxicity across the Agency. Since then, the IRIS Program has become an important public resource as well. The IRIS Program has evolved with the state of the science to produce high-quality evidence-based assessments and to provide an increasing number of opportunities for public input into the IRIS process.” (Source: EPA).
The IRIS program produces scientific assessments that focus on hazard identification and dose-response assessment. These assessments provide scientific information to inform decisions of partners internal and external to the agency, but they are not themselves policies or decisions.
What IRIS is Not
IRIS assessments are not risk assessments: they do not include exposure assessment or risk characterization. Furthermore, IRIS assessments are not policy documents – they do not set a standard or benchmark for what may constitute acceptable risk. Agency decisions informed by IRIS assessments typically incorporate other scientific input, especially regarding exposure assessment and risk characterization, and undergo public notice, public comment, and interagency processes relevant to the decisions – e.g., under EO 12866. These latter processes are the appropriate opportunity for stakeholders with an interest in policy outcomes to provide input. To summarize, an IRIS assessment is actually NOT a risk assessment – thus, it is not a complete scientific assessment of risk — and it is not a policy document.
What is the Legal Status of An IRIS Assessment?
On March 15, 2024, as reported by InsideEPA and E&ENews, the U.S. District Court for the District of Columbia dismissed a lawsuit by the American Chemistry Council (ACC) v. National Academy of Sciences (NAS), et al.. Judge John D. Bates wrote as part of the Court’s decision that “ACC’s theory of harm depends on EPA‘s adoption of an allegedly too-low IRIS value; the implementation of regulations on the basis of that value; and resulting harm to members’ businesses. Yet, EPA has not finally decided the hazard values it will adopt for formaldehyde. As EPA points out, peer review was only Step 4(b) of a seven-step process.” The judge further wrote: “Even once finalized, the IRIS value itself is unlikely to inflict concrete harm on the companies — as the D.C. Circuit has observed, the IRIS ‘database by itself has no preclusive effect; the data in the database constrain no one until so applied in a particular rule.’ (bold added) Further, it remains uncertain what regulations EPA may premise on that IRIS value.” The judge also noted that “such regulations must themselves go through notice-and-comment, at which time ACC and its members could provide their input on the value (as they have done in the past).” Thus, the Court recognized that an IRIS assessment is not itself a decision and that any decision informed in part by an IRIS assessment is subject to its own notice-and-comment process.
What are the Key Steps In Developing an IRIS Assessment?
IRIS has many steps that provide the public with transparency while also adhering to tenets of information quality, peer review, and scientific integrity:
- Updates to a publicly available IRIS program outlook 3 times a year provide advance awareness of future assessments and when they are likely to start.
- Public release of Assessment Plan for public awareness.
- Public release of Systematic Review Protocols for public awareness.
- Public release of an External Review Draft.
- Interagency science consultation and public comment.
- For scientific integrity and transparency, all comments from the interagency science consultation, as well as from public comment, are made publicly available.
- External peer review, in accordance with the Information Quality Bulletin and peer review handbook. Peer review engages external independent scientific experts covering the range of scientific disciplines pertinent to the assessment. Depending on whether a given assessment is “influential scientific information (ISI)”, or “highly influential scientific information (HISI)” under applicable OMB guidance, the peer review can be a contractor-led letter review, a contractor-led panel review, via the EPA Science Advisory Board, or via the National Academy of Sciences, Engineering, and Medicine (NASEM). External, independent, scientific peer review is essential to the scientific integrity and credibility of the process.
- EPA scientific authors revise the assessment.
- Final EPA agency review.
- Interagency science discussion with other Federal agencies and the Executive Office of the President (EOP).
- EPA scientists make revisions, if needed.
- Post final assessment to the IRIS website.
More detail on the IRIS process, guidelines, tools, https://www.epa.gov/iris/basic-information-about-integrated-risk-information-system
What is the Scientific Credibility of IRIS Assessments?
Many critics of the IRIS program point to a 2011 report by the NASEM that was highly critical of the IRIS program at that time. A major thrust of the 2011 NASEM report was that EPA should adopt systematic review methods, as well as other improvements. What these critics typically fail to acknowledge is that EPA has addressed the NASEM advice from 2011, that NASEM has reviewed these changes, and that NASEM has lauded EPA for improvements to the IRIS program.
Specifically, in December 2022, EPA published the IRIS Handbook, which transparently provides procedures for staff developing IRIS assessments, including how to apply systematic review approaches. Systematic review uses prespecified scientific methods to identify, select, assess, and synthesize the findings of similar, but separate, studies. In IRIS assessments, such studies are used to identify human health hazards associated with exposure to chemicals found in the environment and derive toxicity values for health effects resulting from exposure. The IRIS Handbook went through public comment in 2020, and it received a favorable external peer review from the National Academies of Sciences, Engineering, and Medicine (NASEM) in 2021.
The 2011 report by the NASEM was originally to be a peer review of a draft assessment for formaldehyde. As a result of the extensive feedback from NASEM regarding the need to adopt state-of-the-art systematic review methods, which the Agency has since done, the Agency also revisited the draft formaldehyde assessment. After a pause on the assessment from 2017-2021, EPA completed a revised draft that was favorably reviewed by NASEM in 2023 and the assessment itself was finalized in 2024.
EPA IRIS assessments, in general, are subject to rigorous external independent scientific expert peer review and represent best available science. Thus, the scientific credibility of IRIS assessments is very high.
Is IRIS a GAO “High Risk” Program? – If So, Why, and What Does that Really Mean?
Critics of the IRIS program often mention that the Government Accountability Office (GAO) has included the IRIS program on its list of “high risk” programs since 2009. In its most recent high risk list report, GAO states that the EPA “needs to address capacity issues to more effectively assess and manage chemicals posing risks to human health and the environment.” (bold added)
GAO finds that “the IRIS Program’s approach to meeting user needs for chemical assessments changed considerably as ORD improved its program. For example, ORD is more effectively using its portfolio of toxic chemical assessment products—which include IRIS and other chemical assessments like Provisional Peer-Reviewed Toxicity Values—to provide a range of risk assessments informing EPA’s decision-making on the protection of public health and the environment. Topics such as the assessment of per- and polyfluoroalkyl substances (PFAS) —a group of thousands of chemicals used in a wide range of consumer and other products that can persist in the environment and cause adverse health effects—have been prominent in the program’s recent efforts, as well as across EPA.”
GAO criticisms of the IRIS program are not about its quality. The criticism is that EPA does not have enough resources to produce enough IRIS assessments in response to all of the nominations it receives for chemicals to assess. Nonetheless, GAO recognizes that IRIS has “made progress in carrying out its chemical assessment activities. Since February 2023, the Program has released four final IRIS assessments—including the assessment for formaldehyde—and seven Provisional Peer-Reviewed Toxicity Value assessments. The Program continues to make progress on other assessments in its work plan.” (bold added).
As of February 2025, the IRIS Program has closed all GAO recommendations. However, because of capacity constraints the IRIS Program remains on the high-risk list along with TSCA. GAO has indicated that no further audits will be conducted specifically for IRIS. All of the remaining open recommendations are directed to the Office of Chemical Safety and Pollution Prevention (OCSPP), which implements the Toxic Substances Control Act. The GAO report also included a section on “Benefits” – all of which were anchored to ORD efforts to close out prior recommendations.
Thus, the issues identified by GAO regarding IRIS have nothing to do with fraud, waste, or abuse, but rather with lack of capacity that is a result of the constrained budget available from Congress to support this program. A key implication is that more, not fewer, resources should be made available to the IRIS program to enable it to meet partner needs.
Who is Complaining About IRIS and Why?
The stakeholders who complain about the IRIS program are mainly polluters or those affiliated with polluters. They complain about IRIS as a proxy battle over policy decisions that might come later that would be informed but not dictated by the results of IRIS assessments. Policy decisions typically take into account not only hazard and dose response, which are addressed by IRIS Assessments, but also exposure assessment and risk characterization, which are conducted separately by other EPA program offices or by EPA regional offices, or by states, Tribes, local governments, and others who use IRIS hazard and dose-response to inform their risk assessments. Furthermore, policy decisions bring in policy judgements about acceptable risk and risk management goals that are completely separate from the scientific content of IRIS assessments. Finally, polluters have the opportunity to provide public comment regarding policy outcomes as part of public notice and comment processes with the EPA and via the Office of Management and Budget.
Some members of Congress have introduced draft legislation to either prevent EPA from using IRIS assessments to inform policy decisions, or to eliminate the IRIS program altogether. While in the past there have been numerous “messaging” bills such as this that had no chance of passage, in this Congress this legislation may be able to pass.
What is the Alternative to IRIS?
While there are some other hazard assessment and toxicity assessment products from EPA, such as risk evaluations developed under TSCA, and preliminary peer-reviewed toxicity values used to inform superfund cleanup decisions, and minimum risk levels (MRLs) from the Agency for Toxic Substances and Disease Registry (ATSDR), these assessments are not able to substitute for IRIS. By their design, IRIS assessments are done for chemicals that are of interest to EPA programs other than TSCA. IRIS assessments are done also in response to needs of EPA regions, and in recent years the IRIS nomination opportunity has been enlarged to include state and Tribal partners.
TSCA risk evaluations are done for chemical of interest under the TSCA program but not necessarily for other programs. PPRTVs are a fit-for-purpose assessment for a specific decision context that are generally not suitable for many other EPA programs given their statutory requirements. MRLs are useful to inform site cleanup decisions in emergencies when other toxicity data are not available. However, IRIS assessments are generally considered to be the “gold standard” among assessment products and the preferred choice for hazard identification and dose-response when IRIS assessments are available.
When Polluters Don’t Like a Policy Outcome, Why Do They Attack the Underlying Science?
In 1969, the tobacco industry adopted consultant advice: “Doubt is our product since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public. It is also the means of establishing a controversy.” While it is true that industry employs capable scientists who may be well-qualified to comment on draft Agency scientific assessments, there is an inherent conflict of interest since their salaries are from an employer with vested interests in policy outcomes that may be informed by the science. Industry comments on Agency assessments tend to be one-sided. In some cases, industry-organized and funded comments are convened or delivered by lawyers and lobbyists rather than scientists. Third parties aligned with industry that claim to be interested only in the science may also engage with members of Congress and the judicial branch, thereby revealing a focus on policy and legal outcomes rather than science.
Because science is a search for evidence-based inference and objectivity, science is inherently self-correcting, if and as needed, via the research and peer review process. Thus, the most stable way to develop science to inform policy decisions is to allow scientists to do science.
What we are seeing instead is an evolution of the 1969 industry strategy from fomenting doubt and controversy about science to simply attacking and taking away scientific enterprises themselves. Thus, this is an infringement and attack upon scientific methodology, scientific institutions, scientists, information quality, peer review, and scientific integrity.
The implication for the public, if these attacks are successful, will be to take scientific information away from a science-based Agency whose mission is to protect human health and the environment. Without the science, policy decisions will be ineffective and inefficient in fulfilling this mission, with adverse implications for public health and the environment.