Updated Chronic Copper Bioavailability Models for Invertebrates and Algae.

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Risk Assessment

Background:

• Existing chronic copper (Cu) bioavailability models are nearly two decades old, necessitating an update for current European risk assessment.
• Recent advancements in ecotoxicity data and speciation modeling (WHAM VII) provide opportunities for model refinement.

Purpose of the Study:

• To present updated chronic Cu bioavailability models for invertebrates and algae.
• To incorporate recent ecotoxicity data and utilize the WHAM VII speciation model within an optimized generalized bioavailability model (gBAM) structure.

Main Methods:

• Developed updated chronic Cu bioavailability models for invertebrates and algae using a generalized bioavailability model (gBAM).
• Employed recent ecotoxicity datasets and the Windermere Humic Aqueous Model (WHAM) VII.
• Modeled the effect of pH on Cu2+ toxicity using a log-linear relationship with recalibrated pH slope (SpH) parameters.

Main Results:

• The updated gBAM models predict 80% to 100% of observed effect levels for eight species within a factor of 2.
• Recalibrated SpH parameters were -0.208 for invertebrates and -0.975 for algae.
• Model performance was similar to or better than existing regulatory models, with a noted exception for Hyalella azteca subchronic mortality at high pH.

Conclusions:

• The updated chronic Cu bioavailability model set is robust, accurate, and suitable for regulatory applications.
• These models, alongside a fish bioavailability model, form a complete and consistent set for environmental risk assessment.
• The updated models are currently utilized under the EU Registration, Evaluation, Authorisation, and Restriction of Chemicals (REACH) framework to ensure safe copper usage.