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

Symposium: Characterizing Causality for Policy Decisions

Room: Key Ballroom 1   3:30 PM - 5:10 PM

Chair(s): Beth Osterling Owens

Sponsored by DASG

W4-A.1  15:30  Determining Causality in Environmental Assessments. Vandenberg J*, Cogliano V, Owens EO, Cooper G, Ross M; National Center for Environmental Assessment, U.S. Environmental Protection Agency, Research Triangle Park, NC (1, 3, 5) and Washington, DC (2, 4)

Abstract: Within the U.S. EPA, the National Center for Environmental Assessment (NCEA) draws judgments regarding causality for health effects related to environmental pollutant exposure. Formal frameworks and criteria are in place to characterize the strength of the scientific evidence and draw conclusions on causality for exposure-effect relationships. The framework used in the Integrated Science Assessments (ISAs) that support the periodic review of the U.S. National Ambient Air Quality Standards (NAAQS) establishes uniform language concerning causality and brings greater consistency and specificity to the ISAs. The framework relies on the evaluation and integration of multiple lines of evidence to draw conclusions with regard to factors such as consistency, coherence, and biological plausibility of health and ecological effects evidence. To develop this framework, EPA drew on relevant approaches for similar scientific decision-making processes by EPA (e.g., EPA Cancer Guidelines) and other organizations (e.g., Institute of Medicine). This session will present the causal framework in use in the ISAs and discuss how frameworks such as these may be applied to hazard assessments of other chemical exposures that may have different types of evidence bases such as may be encountered in the assessments conducted by the Integrated Risk Information Systems (IRIS). Disclaimer: The views expressed are those of the authors and do not necessarily reflect the views or policies of the US EPA.

W4-A.2  15:50  Evaluation of Causality in the IARC Monographs. Loomis D*, Straif K; International Agency for Research on Cancer

Abstract: The IARC Monographs identify causes of cancer in the human environment. Since 1971 over 900 agents have been evaluated, with more than 100 classified as carcinogenic to humans and over 300 as probably or possibly carcinogenic. Initially the Monographs focused on environmental and occupational exposures to chemicals, but have expanded to other types of agents, such as personal habits, drugs and infections. The process of causal inference used for IARC’s evaluations is laid out in the Preamble to the Monographs. Working groups of invited experts evaluate human, animal and mechanistic evidence and reach a consensus evaluation of carcinogenicity. Human and animal cancer data are first assessed separately according to criteria established in the Preamble. The strength of the evidence for causation is categorised as Sufficient, Limited, Inadequate, or Suggesting lack of carcinogenicity. To arrive at an overall evaluation, the Working Group considers the totality of the evidence and assigns agents to one of 4 causal groups: 1 Carcinogenic to Humans; 2A Probably carcinogenic to humans; 2B Possibly carcinogenic to humans; 3 Not classifiable as to carcinogenicity to humans, or 4 Probably not carcinogenic to humans. The evaluation criteria reflect the Precautionary Principle in that sufficient evidence of carcinogenicity in animals can be used to classify an agent as possibly carcinogenic to humans when human data are inadequate. Mechanistic evidence can be also invoked to upgrade an evaluation in the absence of adequate human cancer data. Alternatively, strong evidence that a relevant mechanism is absent in humans can downgrade an evaluation based on animal cancer data. Comprehensive assessment of the evidence according to established causal criteria has made the Monographs an authoritative source for agencies and researchers worldwide. While the process described here is one of hazard identification, the Preamble also has scope for characterising risk quantitatively.

W4-A.3  16:10  Incorporation of weight-of-evidence best practices in the National Ambient Air Quality Standards review process. Goodman JE*, Prueitt RL, Sax SN, Bailey LA, Rhomberg LR; Gradient

Abstract: The National Academy of Sciences Formaldehyde Review Panel's report called on the United States Environmental Protection Agency (EPA) to undertake a program to develop a transparent and defensible methodology for weight-of-evidence (WoE) assessments. The report contains a proposed "roadmap" for reform and improvement of the risk assessment process. We followed the recommendation of the NAS roadmap and conducted a survey to evaluate best practices for WoE analyses based on almost 50 frameworks, including the National Ambient Air Quality Standards (NAAQS) Causal Framework, to come to insights about their methods, rationales, utility, and limitations. We found that the NAAQS WoE framework has many important features that are necessary for a balanced WoE evaluation. However, the framework needs to be more explicit in some cases, and it is missing some important features. Because of this, it has not been applied consistently in past evaluations of causality, and this has led to biased conclusions regarding causation, as we demonstrate with several ozone examples. We propose specific changes to the EPA NAAQS Causal Framework so that it is consistent with WoE best practices. The full and consistent application of this revised framework will ensure that future assessments of the potential health effects of criteria air pollutants will be thorough, transparent, and scientifically sound.

W4-A.4  16:30  Transparently Implementing the Causal Framework in the EPA NAAQS Review. Patel M*, Owens EO, Kirrane E, Ross M; National Center for Environmental Assessment, U.S. Environmental Protection Agency

Abstract: For Integrated Science Assessments (ISAs), EPA assesses the body of relevant literature to draw conclusions on the causal relationships between relevant air pollutant exposures and health or environmental effects related to the review of the National Ambient Air Quality Standards (NAAQS). Causal determinations are made by applying EPA’s causal framework that describes consideration of the consistency of evidence from various scientific disciplines (e.g., epidemiologic, controlled human exposure, animal toxicological studies), as well as evidence for plausible modes of action for each of five causal determinations. A challenge in the ISAs is communicating the consistent application of the framework across the various evaluated outcomes for which the evidence may vary in quantity, consistency, and the relative contributions from the various scientific disciplines. In order to better communicate how EPA considers the supporting evidence, uncertainties, and coherence across disciplines in drawing causal determinations, EPA developed summary of evidence tables for use in the ISAs. With these tables, EPA concisely summarizes the available evidence across scientific disciplines and demonstrates how this evidence relates to the attributes described in the causal framework. To describe the nature of the available evidence, these tables summarize the types of study designs available, potential biases, the control for potential confounding factors, consistency of evidence, the relative contributions from various scientific disciplines, and the exposure or biomarker levels associated with outcomes. This session will describe how the causal framework used in the NAAQS review is implemented and transparently applied using the ISA for lead as an example. Disclaimer: The views expressed are those of the authors and do not necessarily reflect the views or policies of the US EPA.

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