Annex I – Sharing Previously Curated Evidence: Polyfluoroalkyl Substances (PFAS) Systematic Evidence Maps Developed by the United States Environmental Protection Agency (US EPA) Office of Research and Development (ORD)
Systematic evidence maps (SEMs) are increasingly used as a problem formulation tool to refine the focus of questions that get addressed in subsequent assessments and expedite assessment development {Thayer, 2022, 10476150}. SEMs can be defined as ¿A comprehensive summary of the characteristics and availability of evidence as it relates to broader themes of policy or decision-making relevance {Wolffe, 2019, 5381339}. Systematic evidence maps do not seek to synthesise evidence but instead to catalogue it, utilising systematic search, selection, and coding strategies to produce searchable databases of studies. These databases are accompanied by descriptive information that helps the reader use and evaluate the evidence map, and interpret its contents.¿ (Environment International Policies and Guidelines, July 20, 2023. https://www.sciencedirect.com/journal/environment-international/about/policies-and-guidelines).
The U.S EPA/ORD Health and Environmental Risk Assessment (HERA) National Research Program has been using SEMs to facilitate developing human health toxicity assessments for environmental chemicals {Thayer, 2022, 10476150}, including for polyfluoroalkyl substances (PFAS) {Carlson, 2022, 9630647; Carlson, 2024, 11320974; Radke, 2022, 8632357; Shirke, 2024, 11143010}. The PFAS SEMs include detailed descriptions of study methods, study results, and study evaluation (potential bias and sensitivity ), but they do not present conclusions on potential human hazard(s) or present toxicity values based on dose-response analysis. SEMs have been used within EPA to understand data gaps, determine the need for updated assessments, inform assessment priorities and refine scope, inform development of analysis plans for mechanistic information, ADME (absorption, distribution, metabolism, elimination), pharmacokinetic/pharmacodynamic and similar evidence, and inform development of study evaluation considerations, among other uses. Increased utilization of SEMs across the environmental health field has the potential to increase transparency and efficiency for data gathering, problem formulation, and evidence surveillance. A SEM template has also been developed for chemical human health assessments to foster consistency within the HERA portfolio of assessment products and expedite development of SEMs {Thayer, 2022, 10476150}. Template availability can also promote harmonization in the environmental health community and create more opportunities for sharing extracted content. Figure 1 shows where the PFAS SEMs integrate into the assessment workflow, the tools (and tool interoperability) used, and a schematic summary of core SEM analyses and outputs.