Lynn H. Pottenger, PhD, DABT The Dow Chemical Company Communication of Uncertainty in Hazard & Risk Assessment: Panel Discussion Lynn H. Pottenger, PhD, DABT The Dow Chemical Company

Uncertainty Workshop Focus: Focus on identification of sources & communication of uncertainty in a risk assessment Not how to measure Not quantitative analysis methods Uncertainty is inherent—but sources differ: Data-related Derivation of risk estimates How best to communicate this inherent uncertainty? Different types (sources; magnitudes) Different impact on results of assessment Different audiences Different approaches to presenting/communicating uncertainty LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment Key Aspects Transparent Identify & characterize key decisions and their impact Comprehensible Simplify complex concepts Useful Geared towards identified audience LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

This Workshop examined four approaches: Comparing Values to Other Peer Reviewed Numbers Presenting Toxicological Information Visually in the Context of Alternative Values, Exposure Levels, and Biomonitoring Equivalents Unpacking Toxicity Assessments to Understand & Improve Confidence Improving Transparency in Dose-Response Decision Making LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Comparison of Risk Values Provides high level cross-assessment comparison of risk estimates Deeper drill on specifics possible LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Visualization of Tox/Risk/Uncertainty Information The dose-response point that marks the beginning of a low-dose extrapolation. This point can be the lower bound estimate on dose for an estimated incidence or a change in response level from a dose-response model (BMD), or a NOAEL or LOAEL for an observed incidence, or change in level of response. Oral Noncancer Basic Figure Point of Departure (POD) The range for the values are not on scale but are allowing the visualization of the uncertainty between the POD and the risk value. Uncertainty Factors can range from 0 to 3000 (maximum). The possible types of UFs are: interspecies uncertainty (UFA); intraspecies variability (UFH); subchronic to chronic extrapolation (UFS); use of a LOAEL in absence of a NOAEL (UFL); database incomplete (UFD) Uncertainty Factor (UF) Dose (mg/kg/day) An estimate of an exposure for a given duration to the human population (including susceptible subgroups that is likely to be without an appreciable risk of adverse health effects over a lifetime. It is derived from a BMDL, NOAEL, LOAEL or suitable point of departure, with uncertainty/variability factors applied to reflect limitations of the data used. Durations include acute, short-term, subchronic, and chronic and are defined individually in this glossary. Reference Value The shading in the figure represents a decrease in the value and the potential risk of effects; higher value (darker shade) to a lower value (lighter shade). Focus on visualization of range between POD and risk estimate Exposure context possible with inclusion of BE Cross-assessment comparison possible LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Confidence Scoring of 8 Elements Focus on individual assessment Potential to score different elements Includes consideration of confidence LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Improving Transparency: key decisions & impact Detailed focus on individual assessment Analysis of key decisions—data and other; distinguishes science from policy LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Four new approaches and EPA/IRIS current one ACC ARASP workshop approaches: From cross-assessment, more general to more & more detailed, focused on a single assessment From tabular to figures to combined Only one addresses exposure issues Example of EPA/IRIS current practices for description of uncertainty—B[a]P draft ‘Consideration-Decision-Justification’ in tabular form LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

Starting discussion questions… Are these approaches useful and usable? Improvements/Refinements? Additional key aspects to consider? Combined approaches? Intended audiences? Different approaches for different audiences? How can we begin to define a path towards improved integration of uncertainty communication? Either these approaches or others, yet undefined… address a potential path forward re the integration of the approaches (still not addressed) .… entertain discussion on the objectives and intended audience for the various proposals (or perhaps this could be entertained in the presentations).  While I understand that the objective was to inform the risk assessment community, the approaches range from simple (with less transparency) to more complex (with greater transparency).  Tiered structure with different degrees of sophistication, also an option but it would be extremely helpful in my view, to pose questions related to integration and/or refinement of the approaches. LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment

2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment Thank-you! LHP 3/24/2015 2015 SOT: Communication of Uncertainty in Hazard & Risk Assessment