EPA 822-R-19-003
Progress Update for the
EPA Cooperative Research and Development Agreement (CRADA)
for Aquatic Life Bioavailability Modeling for Metals
Year 1 - 2018
Summary
In December 2017, the U.S. Environmental Protection Agency (EPA) signed a Cooperative
Research and Development Agreement (CRADA) with eight metals associations (Aluminum
Association, Aluminum REACH Consortium, Cobalt Institute, International Copper Association,
Copper Development Association, International Lead Association, International Zinc
Association, NiPERA Inc.) in order to leverage the knowledge and resources of scientists inside
and outside of the agency to better protect aquatic life. EPA's Office of Science and Technology
within the Office of Water (OW) is the Agency's technical lead on this CRADA. Current science
demonstrates that water chemistry parameters (e.g., pH, dissolved organic carbon, and hardness)
can affect the toxicity of metals by affecting the bioavailability of metals in the water to aquatic
species. EPA is using a two-phased approach to address the CRADA. In the first phase, EPA is
working collaboratively with the metals associations to develop a common modeling approach to
predict the bioavailability and toxicity of metals. In the second phase, EPA will work with the
metals associations to develop models for individual metals. Using the resulting peer-reviewed
models, EPA plans to develop updated Aquatic Life Ambient Water Quality Criteria for metals
to better support states, territories and tribes with criteria that reflect the latest science and are
easier to implement than more complex, previous approaches using metals bioavailability
modeling for criteria development. All approaches and products developed through the CRADA
will be submitted for independent external peer review and made available for public comment.
For more information, visit https://www.epa.gov/wqc/cooperative-research-and-development-
agreement-aquatic-life-bioavailabilitv-modeling-metals.
PHASE I (2018-2019)
Objective: Work together to develop a simplified, overarching modeling approach for
quantifying metal bioavailability and toxicity under the range of water chemistry conditions
found in aquatic environments.
Approach: Develop an overarching modeling approach to predict the bioavailability of metals
(e.g., model parameter set, modeling approach and platform).
Effort and Progress:
1. Review and compare the complexity, accuracy and usability of a variety of existing
models and possible approaches.
a. CRADA partners developed a proposal to begin an analysis in early 2019 and
prepare a report that compares the Biotic Ligand Model (BLM) and Multiple
Linear Regression (MLR) modeling approaches for copper and aluminum as case
studies developed to support planned external peer review of selected approach,

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ii. The CRADA partners are currently conducting the analysis of these two
modeling approaches. Anticipated completion date is April 2019.
b. EPA has drafted an outline for the Phase I report for external peer review. The
final report will include a detailed justification for model selection and key
parameters required (e.g., pH, hardness, DOC, and temperature), model
comparisons/case studies (see above), and recommendations.
2.	Review data quality of ecotoxicity datasets used for model development for individual
metals and datasets potentially used for aquatic life criteria derivation.
a. EPA and CRADA partners have begun comparing data quality evaluation
approaches used in model development with the goal of harmonizing approaches.
3.	Create awareness of the CRADA effort outside of the partnership and engage potential
end-users (e.g., states) to assist with identifying priorities and criteria needs.
a.	December 2017: EPA scientists and a number of the CRADA partners
participated in a Society of Environmental Toxicology and Chemistry (SETAC)
North America sponsored Technical Workshop, "Bioavai lability-Based Aquatic
Toxicity Models for Metals" (December 2017) and are co-authors on five
publications in preparation for submittal to Environmental Toxicology and
Chemistry as a result of the workshop. These five publications taken together
summarize the history of bioavailability modeling, state of the science for both
mechanistic and empirical modeling approaches and provide recommendations
regarding the validation and application of bioavailability-based models to predict
toxicity to aquatic organisms.
b.	January 2018: CRADA Summary/Factsheet posted to EPA's website:
www.epa.gov/sites/production/files/2018-01/documents/metals-crada-summarv-
f.
c.	April 2018: EPA provided an overview of the Metals CRADA to the EPA
Regional Water Quality Standards (WQS) leads and coordinators, and other OW
Offices (Office of Wastewater Management, Office of Wetlands, Oceans and
Watersheds and Office of Ground Water and Drinking Water).
d.	May 2018: EPA provided an overview of the Metals CRADA to participants of
the WQS National Meeting which included EPA Regional WQS leads, several
states, and other OW Offices.
e.	June 2018: EPA presented a poster titled, "EPA - Metals Associations
Collaboration to Develop a Simplified, Overarching Modeling Approach for
Characterizing Metals Bioavailability" at the Aquatic Toxicology Symposium in
Marconi, CA.
f.	August 2018: EPA provided a briefing via webinar hosted by the Association of
Clean Water Administrators (ACWA) Monitoring, Standards and Assessment
Committee to share information regarding the Metals CRADA. The webinar was
attended by 54 people representing 29 states.
g.	October 2018: The CRADA Workplan for the "Development of an overarching
bioavailability modeling approach to support updating US EPA Aquatic Life
Water Quality Criteria for metals" was posted on EPA's website:

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www.epa.gov/sites/production/files/2Q18~10/documents/metals~crada~workplan~
2018.pdf.
h.	November 2018: EPA presented a platform presentation entitled, "Overview of
EPA's Cooperative Research and Development Agreement with metals
associations to develop a simplified metals modeling approach" at the 39th Annual
Meeting of the Society for Environmental Toxicology and Chemistry (SETAC) in
Sacramento, CA. In the same session, "Bioavailability-based aquatic toxicity
models for metals," other CRADA partners were involved in presenting the
following platforms entitled:
i.	State of the science of metals bioavailability in natural waters;
ii.	Metal bioavailability models: Current status, lessons learned,
considerations for regulatory use, and the path forward;
iii.	Guidance on the development of empirical bioavailability models for
metals;
iv.	Validation of bioavailability-based toxicity models for metals; and
v.	Derivation and application of thresholds for metals using bioavailability-
based approaches
i.	December 2018: EPA issued the Final 2018 Aquatic Life Ambient Water Quality
Criteria for Aluminum in Freshwater based on a multiple linear regression model
developed in coordination with CRADA partners (www.epa.gov/wqc/aqiiatic~life~
criteria-aluminum).
PHASE II (2019-2022)
Objective: Develop a framework for EPA to develop specific bioavailability models in support
of updating Aquatic Life Ambient Water Quality Criteria for metals.
Approach: Develop models to predict the bioavailability and toxicity of individual metals.
Effort and Progress: Based upon Phase I outcomes, EPA intends to work with the CRADA
partners for the individual metals to develop and optimize the underlying bioavailability models
applicable to specific metals to support Aquatic Life Ambient Water Quality Criteria
development.
1.	Determine order of metals model/criteria development based on balancing scientific
readiness and priorities depending on environmental protection and states' needs.
a. EPA and CRADA partners have discussed the status of modeling approaches
(e.g., BLM, MLR, other) for the metals represented by the CRADA partners.
2.	Gather/generate and review data on specific metals necessary for bioavailability model
development and criteria derivation, as necessary.
3.	Develop bioavailability models for individual specific metals.
4.	These steps and deliverables will be followed by independent external peer review of the
bioavailability models for individual metals.

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