The workshop on risk assessment drew a full house, with standing room only, for a riveting session on how to communicate uncertainty in hazard assessment. As risk assessment becomes increasingly large and complex we need tools to improve its transparency. Overcoming barriers with risk communication is one of the issues faced by risk assessors. So it was both logical and timely that the speakers aimed to provide simple, practical, visual solutions for presenting uncertainty, which is particularly useful for decision makers.
The first speaker, Bette Meek of the University of Ottawa, set the stage by outlining some key elements necessary for addressing uncertainty, variability, and sensitivity. She highlighted the importance of margins of exposure in articulating sources of uncertainty and variability with some interesting case studies. Roberta Grant from the Texas Commission on Environmental Quality provided a summary of the key learnings from The Center for Advancing Risk Assessment Science and Policy (ARASP) workshop. ARASP evaluated the current procedure used by the US EPA Integrated Risk Information System (IRIS) for completeness of the database, study quality, and reference dose calculations. There was a focus on accuracy, precision, and predictability. Adding weight to various components of the risk assessment could add more strength and value to the final report. An audience member asked for recommendations for gap analysis, to which she suggested outlining the steps needed and scoring the various elements to help determine the appropriate data needed to fill the gaps.
The next two speakers, William Farland, Colorado State University, and Christopher Kirman, Summit Toxicology LLP, both suggested visual methods for presenting uncertainty. Concerns by the general public and decision makers prompted improvements in this area as seen by recent communications on climate change and the Risk21 project. It is not unheard of that assessors may struggle with how to present IRIS data, and the solution may be to use more visually stimulating imagery. One idea for an online tool was to use a simple block arrow, which can be used for both cancer and non-cancer assessments, that include nifty features such as a pop up box to display detailed information when the user scrolls their mouse over. It can also be used to display comparisons between risk values obtained from several studies on a single diagram. The user can easily see the strength of the data, uncertainty values, and comparisons between values. Christopher Kirman's summary table format used numerical ratings or weighting for important components of the assessment. Various visual features included highlighting or shading to indicate a data gap, and slider bars that can be used to adjust the values used for calculations and hyperlinks to make the tool dynamic.
The session rounded out with a follow up by Lynn Flowers, US EPA, who provided a US EPA perspective including advancements in the characterization and presentation of uncertainty in human health assessments developed within the IRIS Program.
A thought-provoking panel Q & A session was facilitated by Lynn Pottenger, Dow Chemical Company. The overall message was clear: uncertainty is an issue faced by risk assessors, and finding creative solutions for communicating it is key to improving transparency and increasing its understanding by all stakeholders.
This blog discusses highlights from the SOT Annual Meeting and Workshop “Understanding and Communicating Uncertainty in Hazard Assessment and Dose Response”