EPA Plans to Improve IRIS Process

Mandated review may determine how best to update chemical health effects database.

By Lynn L. Bergeson, regulatory editor

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The Integrated Risk Information System (IRIS) database of the U.S. Environmental Protection Agency (EPA) has stirred debate for years. EPA has vowed to reform its ways, and soon may be strongly urged to do so, as a result of an underway review mandated by Congress. Specifically, the measure directs the National Research Council (NRC) of the National Academy of Sciences (NAS) to review certain IRIS assessments.  This article describes IRIS and the process underway to restore IRIS dossiers to credible sources of hazard information.

Current database contains information on more than 550 chemical substances.


IRIS Dossiers
EPA's IRIS is a human health assessment program that evaluates information on the possible health effects from exposure to environmental contaminants. EPA provides science-based human health assessments to support its regulatory activities. The IRIS database contains information on more than 550 chemical substances and the potential human health effects from environmental exposure to them. The database is prepared and maintained by EPA's National Center for Environmental Assessment (NCEA) within the Office of Research and Development (ORD).

The heart of the database is its collection of searchable documents that describe the health effects of individual substances and that contain descriptive and quantitative information for noncancer and cancer effects. Noncancer effects include oral reference doses and inhalation reference concentrations (RfDs and RfCs, respectively) for effects known or assumed to be produced through a nonlinear (possibly threshold) mode of action. In most instances, RfDs and RfCs are developed for the noncarcinogenic effects of substances. Cancer effects include descriptors that characterize the weight of evidence for human carcinogenicity, oral slope factors, and oral and inhalation unit risks for carcinogenic effects.

These values are used by federal, state and international regulatory and standard-setting entities for a variety of purposes. For example, EPA relies on IRIS values to calculate risk-based concentrations for chemical-screening purposes. EPA also uses these values to support the health assessment of unregulated contaminants on the Contaminant Candidate List.

NRC Review

EPA has asked NRC to review the IRIS program's process to improve its scientific and technical performance. The NRC committee will focus on the development of IRIS assessments rather than the review process that follows.

In September, Kenneth Olden, director of the NCEA, spoke to the committee and stressed the need for openness and transparency as the new hallmark for NCEA. He suggested EPA meet with stakeholders during the scoping and problem-formulation phase of development to identify relevant health endpoints and reliable studies, and assess whether data gaps exist, and if so, explore options for obtaining data. This would prevent EPA from preparing an IRIS assessment based on incomplete data and being criticized by stakeholders.

According to Olden, EPA will seek public involvement earlier in the process. He also suggested stakeholders could be engaged in preparing the charge for peer reviewers. After the peer-review process is complete, stakeholders could be allowed to review and comment on the resulting peer-reviewed draft — this could eliminate the current practice of using the interagency review process to voice stakeholder concerns.

EPA says it will update the new preamble to the IRIS assessments, and then hold an external peer review. The agency will forward the revised preamble, which is expected to be ready within the next few months, to the NRC committee for its review. The preamble has already been reviewed within EPA and its interagency review process. EPA has tentatively scheduled a weight-of-evidence workshop for March 2013. The next NRC committee meeting will be held in December, at which time EPA intends to have proposals for workshops and how they fit together.


These are welcomed suggestions and their implementation would improve the IRIS process. Stay tuned to this important new review process. IRIS values will continue to be important benchmarks for rulemaking purposes, so understanding these changes will be critical to stakeholders' understanding of the science basis for rules and policies issued by EPA and by state and local governments.



LYNN BERGESON is Chemical Processing's Regulatory Editor. You can e-mail her at lbergeson@putman.net.
Lynn is managing director of Bergeson & Campbell, P.C., a Washington, D.C.-based law firm that concentrates on chemical industry issues. The views expressed herein are solely those of the author.

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