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ACC is encouraged that the U.S. EPA has sought opportunities to get more input to improve the way the Agency conducts chemical risk assessments.
Public workshops are one proven approach to collect input that has been employed by the scientific community for years. And it’s good to see that EPA is making more use of this valuable tool for the Integrated Risk Information System (IRIS) program.
EPA’s most recent workshop focused on methods for applying a “systematic review process” to evaluate potential health hazards of chemical exposures.
A need for clear and consistent data evaluation and integration criteria
In written comments submitted to EPA, ACC and the Center for Advancing Risk Assessment Science and Policy (ARASP) reiterated support for the development of clear and consistent criteria to review studies to determine their relevance, reliability and quality.
Current frameworks for systematic review are numerous and have a variety of scientific focuses. While they do not all review the types of information that are available to IRIS, they do offer some best practices for EPA to consider as it develops a systematic review process for the program.
For example, a systematic review process should adequately consider real-world exposure levels and incorporate mechanistic and mode of action (MOA) information — which describes how a chemical may behave once it is in the body — throughout the review process.
Additionally, systematic review processes should clearly justify the inclusion or exclusion of scientific information to reach conclusions regarding potential health impacts.
Why not benefit from lessons learned by other scientific workshops?
ARASP hosted a workshop focused on Weight-of-Evidence (WoE) and systematic review last year to evaluate some existing data evaluation methods. The workshop produced a set of best practices for conducting WoE analyses and we shared these practices with representatives from EPA and the National Toxicology Program (NTP).
EPA’s August Workshop mainly focused on systematic review methodologies used for human clinical trials and pharmaceutical efficacy studies in animals. Unfortunately, this has less applicability to the types of studies generally relied upon for EPA IRIS assessments
Well-established and better suited criteria do already exist, however, and will be summarized in an upcoming peer reviewed publication developed in coordination with the 2012 ARASP WOE workshop.
Modernizing how EPA addresses risk assessment
To help ensure chemical assessments relate to 21st century understanding of how chemicals interact with the body, EPA must modernize how it formulates the goals, purpose and approaches for an analysis. This should include incorporating current knowledge of toxicology, focusing on the relationship between dose-response with regard to adverse effects, and utilizing mode-of-action information as the central organizing principle to facilitate understanding of cause and effect from chemical exposure.
The WHO/IPCS Key Events Dose Response framework presented by Dr. Bette Meek, as well as the Hypothesis-Based WoE framework developed by Dr. Lorenz Rhomberg and colleagues both offer methods to ensure consistent, transparent study evaluation practices are used to determine the quality and reliability of critical studies.
Systematic review remains a key element for the development of high quality scientific assessments, and it’s clear that there is more work that can be done to improve the credibility and utility of the chemical assessments produced by the IRIS.
ACC will continue to develop tools and best practices to assist the EPA in its mission to enhance this important risk assessment program.
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