Improving IRIS: Please Join the Conversation

By Kacee Deener

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Over the past few years, EPA has embraced a major new effort to enhance its Integrated Risk Information System (IRIS) Program to improve the scientific foundation of assessments, increase transparency, and improve productivity. IRIS is a human health assessment program that evaluates information on health effects that may result from exposure to environmental contaminants. Information from IRIS is used by EPA and others to support decisions to protect human health.

We think we’ve made terrific progress so far, and we were thrilled that the National Academies’ National Research Council (NRC) agrees. They spent the past two years reviewing IRIS, and in May 2014, they issued a report highlighting our progress and offering recommendations on keeping the progress moving forward (Assistant Administrator Lek Kadeli recently wrote about this on EPA Connect, the Agency’s leadership blog).

In their report, the NRC commended EPA for its substantive new approaches, continuing commitment to improving the process, and successes to date. They noted that the IRIS Program has moved forward steadily in planning for and implementing changes in each element of the assessment process. They also provided several recommendations which they said should be seen as building on the progress we’ve already made.

We are happy to announce that we are taking additional steps to improve the IRIS Program. In October, we will hold a public workshop to discuss specific recommendations from the NRC’s report, which fall under the three broad topics below. We invite you to provide early input by commenting on this blog post, which is the first in a new IRIS blog series geared toward generating online scientific discussion about issues relevant to the IRIS Program. We plan to use blog posts like this more in the future to get your input.

  • Topic 1 – Refining systematic review methodology, including methods to evaluate risk of bias. The NRC stated that EPA should continue to document and standardize its process for evaluating evidence and recommended EPA develop tools for assessing risk of bias in human, animal, and mechanistic studies that are used as primary data sources. The NRC noted the limitations of available approaches for use with observational (nonrandomized) studies, and advocated exploration of differences in applying methods for evaluating epidemiological studies to controlled experimental in vivo and in vitro studies. They noted that these approaches will depend on the complexity and extent of data on a chemical and the resources available to EPA, and that additional methodological work might be needed to develop empirically-supported evaluation criteria for animal or mechanistic studies.
  • Topic 2 – Advancing methodology to systematically evaluate and integrate evidence streams. The NRC stated that EPA should continue to improve its evidence-integration process incrementally, and to enhance its transparency. The committee provided several alternatives for organizing evidence of hazard potential and recommended that the IRIS Program should either continue with the guided-expert-judgment process for evaluating evidence, but make its application more transparent, or adopt a structured approach with rating recommendations. The committee also encouraged the IRIS Program to simultaneously expand its ability to perform quantitative modeling, specifically using Bayesian methods, to inform hazard identification.
  • Topic 3 – Combining quantitative results from multiple studies, presenting appropriate quantitative toxicity information, and advancing analyses and communication of uncertainty. The committee encouraged the IRIS Program to continue its shift towards the use of multiple studies for dose-response assessment, but with increased attention to judging the relative merits of mechanistic, animal and epidemiologic studies, with an ultimate goal of developing formal methods for combining studies and deriving toxicity values in a transparent and replicable manner. The NRC stated that it is critical to consider systematic approaches to synthesizing and integrating the derivation of a range of toxicity values in light of variability and uncertainty. Integral to this latter goal is the NRC recommendation to develop methods to systematically conduct uncertainty analyses and to appropriately communicate uncertainty to the users of IRIS assessments.

We’re interested in hearing your thoughts about the NRC recommendations above. For example, do you have ideas about how we should move forward to address the recommendations in these topic areas? Do you have scientific suggestions for the IRIS Program to consider related to these topics? Do you have suggestions for who we should ask to speak at the workshop? Please add your thoughts, ideas, and suggestions in the comments below and join the conversation!

About the Author: Kacee Deener is the Communications Director in EPA’s National Center for Environmental Assessment.  She joined EPA 13 years ago and has a Masters degree in Public Health.

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