Implementation of Health Assessment Workspace Collaborative (HAWC) in Toxicity Evaluations of Data-Poor Chemicals for Transparency and Consistency in Assessment Products for the Superfund Program

Background and Purpose:  Human health risk assessments increasingly use systematic review methodology to promote transparency and consistency. U.S. EPA version of Health Assessment Workspace Collaborative (HAWC) is an interactive content management system routinely used for data rich human health assessments. Other assessments of data-poor chemicals typically found in Superfund sites have always considered and documented study quality and reliability criteria in the selection of key studies and endpoints for toxicity value derivation..  For the first time, U.S. EPA ORD has initiated the use of HAWC that include two important steps of the systematic review workflow (study quality evaluation and data extraction) to support toxicity assessments of data-poor chemicals. Methods:  Literature searches and screening were conducted to identify PECO-relevant studies to inform the derivation of provisional toxicity values for six data-poor chemicals. Subchronic and chronic oral and inhalation studies for each chemical were identified and summarized, and studies with the lowest LOAEL for each exposure route and duration were identified.  Each study was evaluated for quality across 9 metrics: reporting quality; allocation; observational bias/blinding; confounding/variable control; selective reporting/attrition; chemical administration and characterization; exposure timing, frequency, and duration; outcome assessment; and results presentation.  Evaluations were performed by two independent screeners using standardized core and prompting questions in HAWC and culminated in an overall study quality rating of good, adequate, deficient, or critically deficient.  A third reviewer resolved conflicts between screeners and finalized the overall rating.  Finally, health endpoints observed at the LOAEL were extracted into HAWC.  Results: Use of HAWC enabled the application of a consistent set of metrics for evaluation of the quality of studies used for the assessment of data-poor chemicals.  In addition, the study evaluation and extracted data will be made publicly available in HAWC, along with interactive visualizations that document the basis for each metric rating and the endpoint data supporting the toxicity value.  Studies evaluated in HAWC for the Superfund program were limited to those considered suitable for toxicity value derivation and received an overall rating of “adequate” based on the individual domain rating. Most studies lacked reporting information in the allocation and observational bias/blinding metrics. Conclusions:  Use of HAWC for data-poor chemicals has several important benefits.  First, standardized evaluation metrics increase the consistency of study quality assessments as well as the transparency of judgements. Second, evaluation of each study by two independent reviewers increases the rigor of evaluation and reduces the role of individual bias.  Third, the online and interactive study evaluation and data visualizations in HAWC increase accessibility to important study information compared with static study summaries and tabular data reported in written summaries in older assessments.  Finally, using a single evaluation and data extraction tool increases consistency across U.S. EPA health assessment products and should enable efficient migration of data between assessments.

Impact/Purpose

Human health risk assessments increasingly use systematic review methodology to promote transparency and consistency. U.S. EPA version of Health Assessment Workspace Collaborative (HAWC) is an interactive content management system routinely used for data rich human health assessments. Other assessments of data-poor chemicals typically found in Superfund sites have always considered and documented study quality and reliability criteria in the selection of key studies and endpoints for toxicity value derivation.  For the first time, U.S. EPA ORD has initiated the use of HAWC that include two important steps of the systematic review workflow (study quality evaluation and data extraction) to support toxicity assessments of data-poor chemicals.

Citation

Taylor, M., Alli Flynn, C. Heit, K. Salinas, M. Riccardi, E. Golden, K. DeShong, AND S. Stevens. Implementation of Health Assessment Workspace Collaborative (HAWC) in Toxicity Evaluations of Data-Poor Chemicals for Transparency and Consistency in Assessment Products for the Superfund Program. Society of Toxicology 2025, Orlando, FL, March 15 - 20, 2025.

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