Society For Risk Analysis Annual Meeting 2013

Session Schedule & Abstracts


* Disclaimer: All presentations represent the views of the authors, and not the organizations that support their research. Please apply the standard disclaimer that any opinions, findings, and conclusions or recommendations in abstracts, posters, and presentations at the meeting are those of the authors and do not necessarily reflect the views of any other organization or agency. Meeting attendees and authors should be aware that this disclaimer is intended to apply to all abstracts contained in this document. Authors who wish to emphasize this disclaimer should do so in their presentation or poster. In an effort to make the abstracts as concise as possible and easy for meeting participants to read, the abstracts have been formatted such that they exclude references to papers, affiliations, and/or funding sources. Authors who wish to provide attendees with this information should do so in their presentation or poster.

Common abbreviations

M2-A
Symposium: Cross-Disciplinary Methods for Research Synthesis, Part I

Room: Key Ballroom 1   10:30 AM- 12:00 PM

Chair(s): Lisa Robinson   lisa.a.robinson@comcast.net

Sponsored by EBASG



M2-A.1  10:30  Hypothesis-based weight of evidence: an approach to assessing causation and its application to regulatory toxicology. Rhomberg LR, Bailey EA*; Gradient   lrhomberg@gradientcorp.com

Abstract: Regulators are charged with examining existing scientific information and coming to judgments about the state of knowledge regarding toxicological properties of agents. The process needs to be seen as sound and objective. The challenge is that information is often far from definitive, containing gaps and outright contradictions. The particular results of studies must be generalized and extrapolated to apply to the target populations of the risk assessment. Existing weight-of-evidence approaches have been criticized as either too formulaic, ignoring the complexity and case-specificity of scientific interpretation, or too vague, simply calling for professional judgment that is hard to trace to its scientific basis. To meet these challenges, I discuss an approach – termed Hypothesis-Based Weight of Evidence (HBWoE) – that emphasizes articulation of the hypothesized generalizations, their basis and span of applicability, that make data constitute evidence for a toxicologic concern in the target population. The common processes should be expected to act elsewhere as well – in different species or different tissues – and so outcomes that ought to be affected become part of the basis for evaluating success and defining the limits applicability. A compelling hypothesis is one that not only provides a common unified explanation for various results, but also has its apparent exceptions and failures to account for some data plausibly explained. Ad hoc additions to the explanations introduced to "save" hypotheses from apparent contradictions need to be recognized. In the end we need an "account" of all the results at hand, specifying what is ascribed to hypothesized common causal processes and what to special exceptions, chance, or other factors. Evidence is weighed by considering whether an account including a proposed causal hypothesis is more plausible than an alternative that explains all of the results at hand in different ways.

M2-A.2  10:50  Metals, Mixtures, Pathways: Systematic Review to Support Risk Assessment. von Stackelberg K*, Guzy E, Claus-Henn B; Harvard School of Public Health   kvon@hsph.harvard.edu

Abstract: Synthesizing exposure, toxicological, epidemiologic and biological pathway information to determine the potential for exposure to environmentally-relevant concentrations of mixtures of contaminants in conjunction with genetic influences to lead to specific health outcomes requires a critical evaluation of the intersection of environmental exposures (what are the exposure concentrations in the environment and how do those relate to biologically-effective doses), the evidence for particular effects from toxicological and epidemiological data, and what is known about cellular events at the subclinical scale in terms of disease etiology. This allows an evaluation of biological plausibility with respect to a hypothesized mode-of-action based on the best available understanding of molecular events required for disease progression, evaluated in the context of what is known about how these compounds exert their biological influence, and exposure conditions necessary to achieve absorbed doses relevant to the pathways of interest. We explore these emerging issues in risk assessment in the context of exposures to mixtures of metals, including lead, arsenic, and manganese, and neurodevelopmental health outcomes in children. Included is a discussion of emerging methods for characterizing potential risks from exposure to mixtures together with potential gene-environment interactions (Liu et al. 2012; EC 2011; Sargiannis and Hansen 2012; Backhaus and Faust 2012). We provide a review of the literature on gene-environment and chemical mixture interactions, particularly in the context of neurodevelopmental health outcomes in children. We discuss examples of approaches for synthesizing exposure, effect, and disease etiology with particular emphasis on our own research on exposure to mixtures of metals in sediment and neurodevelopmental effects at the center of the Superfund Research Program at the Harvard School of Public Health (Claus Henn et al. 2011; 2012; Bellinger 2012).

M2-A.3  11:10  Adapting Expert Elicitation Methods for Global Study of Foodborne Disease. Hoffmann SA*, Hald T, Cooke R, Aspinall W, Havelaar A; USDA Economic Research Service, Technical University of Denmark, Resources for the Future, University of Bristol University, Utrecht    shoffmann@ers.usda.gov

Abstract: There is increasing interest in using large expert panels to elicit probability judgments about global health problems. Several such studies are in planning. This paper reports on the methodological advances and results from a global expert elicitation study conducted for the WHO, Global Burden of Foodborne Disease Initiative. The study elicited expert judgment on the relative contributions of different exposure pathways to microbiological, parasitic, and chemical hazards that can be foodborne. Attribution estimates are elicited for each WHO region. This study provides both an important application of expert elicitation and an opportunity to test new methods that will enhance the feasibility of using expert elicitation in large global studies. This expert elicitation provides source attribution estimates for each WHO region for multiple hazards and exposure pathways. This requires assembling multiple panels of experts whose knowledge captures food production, processing, and marketing conditions, water quality, and infectious disease transmission in all parts of the world. The effort pushes on existing methods in multiple ways. First, cost and logistical concerns imposes limitations on conducting elicitations in person, as has been done in the past. Third structuring the elicitation and calibration in ways that capture both global variation and provides meaningful comparisons around the globe. Third, need for transparency and reproducibility creates an opportunity to explore the implications of alternative criteria for selection and recruitment of expert panel members. A major methodological contribution of this study is formal testing for impact of conducting elicitations done by phone with facilitator and computer assistance versus allowing panelists to complete the elicitation on their own after phone orientation.

M2-A.4  11:30  A novel approach to attributing illness to food using consumption data and expert elicitation. Jessup A*, Sertkaya A, Morgan K; Department of Health and Human Services/OASPE   amber.jessup@hhs.gov

Abstract: Policy analysts are often asked to answer questions where there are no published studies or published studies are only peripherally related to the policy question. Often, the policy questions are complex and data needed to provide a useful answer are limited, conflicting, unavailable, or (as is sometimes the case) unobtainable. Further, seldom are analysts given large budgets in time or money to find answers. Meta-analysis and systematic reviews are methods to combine results from a body of established studies. Expert elicitation synthesizes expert opinions when data are lacking, but is typically limited to characterizing uncertainty around generally accepted parameters. Where data and studies are completely lacking, however, innovative methods must be applied. Information linking foodborne illness (FBI) cases to the source of the illness and/or specific food vehicle with sufficient specificity to guide policy is one such area. Previous food attribution research has used microbiological approaches (e.g., microbial sub-typing), epidemiological approaches (e.g., the analysis of outbreak and other surveillance data), and expert elicitation approaches (Pires et al., 2009). None of these studies, however, appear to have produced sufficiently detailed information to produce groupings of foods that are homogenous with respect to risk. We examine the challenges of answering scientific questions needed for policy analysis, moving beyond characterizing uncertainty. First, we discuss the applicability of different research methods (i.e., expert elicitation [EE], meta-analysis, and systematic reviews to the objective of generating FBI attribution rates by highly disaggregated food categories. Next, we develop and apply a hybrid novel method combining EE and food consumption data to estimate FBI cases by highly disaggregated food categories.



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