Metals CRADA Phase 1 Report

This report concludes Phase 1 of the Cooperative Research and Development Agreement (CRADA) that the U.S. Environmental Protection Agency entered with eight metals associations to develop a simplified, overarching modeling framework to predict the bioavailability of metals to support the development of updated metals Aquatic Life Ambient Water Quality Criteria (AWQC) under the Clean Water Act. This report provides a review of models that are available to predict the toxicity of metals to aquatic life considering factors that modify toxicity as a function of water chemistry (e.g., pH, hardness, dissolved organic carbon). The document focuses on the performance of Multiple Linear Regression (MLR) and Biotic Ligand Models (BLM) bioavailability modeling approaches for aluminum, copper, lead, and nickel. Given the similarities in performance between the BLM and MLR approaches for several metals, the EPA intends to use MLR models as the metal bioavailability-modeling approach in AWQC development because of the robustness, relative simplicity, transparency, decreased number of input data needed to use the model, and ease of use of the MLR approach compared to the BLM approach. The report underwent independent, external peer review and was revised considering peer review comments.

• Metals CRADA Phase 1 Report: Development of an Overarching Bioavailability Modeling Approach to Support US EPA’s Aquatic Life Water Quality Criteria for Metals (pdf) (1.17 MB, March 2022, EPA 822-R-22-001)
• Metals CRADA Phase 1 Report: Supplemental Materials
• Metals CRADA Phase 1 Report: Final External Peer Review Report (pdf) (1.37 MB, August 2021)
• Metals CRADA Phase 1 Report: EPA’s Response to Comments of External Peer Review (pdf) (1.04 MB, March 2022, EPA 822-R-22-002)

Metals CRADA Phase 1 Report: Supplemental Materials

The report contains six appendices (labeled A-F) and one addendum:

• Appendix A: Publications based on the SETAC Technical Workshop, Bioavailability-Based Aquatic Toxicity Models for Metals, December 2019.
• Appendix B: Explanation of How Toxicity Modifying Factors (TMFs) Affect Individual Metals developed by CRADA Partners. Found in the CRADA Phase 1 Report.
• Appendix C: Table 1: Bioavailability Model Comparisons, Table 2: Supporting Information, and References developed by CRADA Partners (pdf) (511.65 KB)
• Appendix D: Report of aluminum and copper model comparisons. View the published copper portion of the analyses. View the published aluminum MLR portion of the analyses. Any subsequent publications will be listed when available.
• Appendix E: Report of lead model comparisons. The publication for the lead analyses is in preparation and will be listed when available.
• Appendix F: Report of nickel model comparisons. View the published MLR and BLM comparison and refinements to the nickel BLM.
• Addendum: Summary of How Toxicity Modifying Factors (TMFs) Affect Metals Listed in Table 1. Information provided through the peer review by Christopher A. Mebane (USGS). Found in the CRADA Phase 1 Report.