Scientists are exploring new visual approaches to improve how chemical hazard values (and their inherent uncertainties) are determined and communicated to risk managers and the public so that we can all make more informed decisions about the safety of chemicals.
At the Society of Toxicology (SOT) Annual Meeting in San Diego last month, Drs. Nancy Beck and Lynn H. Pottenger chaired a workshop to help people better understand the confidence associated with hazard values that are derived in a chemical assessment, and to help users understand the limitations for using these values.
The workshop follows a November 2013 ACC Center for Advancing Risk Assessment Science and Policy (ARASP) multi-stakeholder gathering that developed and discussed best practices for presenting hazard characterization summaries and tables. Many of the SOT workshop presentations in San Diego were built on these earlier discussions.
To begin the session, Dr. Bette Meek set the stage by discussing why problem formulation and transparency are critical parts of sound chemicals and risk management. She also introduced attendees to the new WHO/IPCS harmonization project which in resulted in the 2014 Guidance on Evaluating and Expressing Uncertainty in Hazard Characterization. While the document shares the same title as the ARASP workshop, it takes a different and welcomed new, more technical, approach to expressing hazards regarding chemicals.
This approach allows one to understand what percentage of the population might be at risk during a lifetime, and also presents the confidence in the risk value. The approach requires those conducting the risk assessments to draw upon a wider range of existing information to inform this new probabilistic determination. This will allow risk assessors to do a better job communicating the range of possible implications of different risk management options, while making the health protection goals associated with different options more clear.
Improving data presentation
Addressing a different aspect, Dr. Roberta Grant, the second speaker in the workshop, presented methods that don’t necessarily require the risk analyst to change their approach but allows for more complete communication of any approach. The tools Dr. Grant emphasized present existing and available information in a more transparent manner. As shown in her slides, users of the assessment can understand the overarching confidence in the full hazard assessment by clearly expressing the confidence in each key decision made by the risk analyst.
Chris Kirman presented an approach which improves transparency and helps to inform the user on impact of key decisions and the prioritization of research gaps. The graphical tool simulates a sliding scale where one can compare decisions made to what the central estimates would be. As noted in his slides, this useful tool has already been used to help better understand decisions made in at least three recent chemical assessments.
Dr. Bill Farland showed a way of visually expressing hazard characterization information in the context of toxicological, biological monitoring, and exposure information. The graphics he presented allow information to be displayed in different levels of detail, for example offering detail on margins-of-exposure, and provide a general sense of the strength of the available data and confidence in the overall assessment. These graphic tools, like the ones discussed above, provide for useful comparisons with other derived values and exposure levels, both within and across assessments, so that risk assessors and managers can compare risks across substances.
Dr. Lynn Flowers provided a perspective on what EPA’s National Center for Environmental Assessment (NCEA) is doing to help people better understand the characterization of uncertainty in their hazard assessments. Her presentation included how the Agency is addressing comments from the National Academies as well as new approaches EPA is taking to improve tables and figures depicting hazard values they consider when conducting a review.
In the engaging panel discussion, many participants provided comments on the risk managers’ perspective and reminded us all of the necessity of keeping their needs in mind as tools are developed and tested.
ACC and the workshop participants are hopeful that aspects of these tools and approaches will be considered for purpose-specific applications in future assessments. This will help all stakeholders, including the public, better understand the decisions that are made and the uncertainties associated with them.
While ACC looks forward to the workshop EPA will be hosting on Communicating Uncertainty in early 2016, consideration and use of the tools presented at the SOT workshop will help to provide more case studies for robust discussion.