Methods for estimating no‐effect toxicity concentrations in ecotoxicology.

A range of new statistical approaches is being developed and/or adopted in ecotoxicology that, when combined, can greatly improve the estimation of no‐effect toxicity values from concentration–response (CR) experimental data. In particular, we compare the existing no‐effect‐concentration (NEC) threshold‐based toxicity metric with an alternative no‐significant‐effect‐concentration (NSEC) metric suitable for when CR data do not show evidence of a threshold effect. Using a model‐averaging approach, these metrics can be combined to yield estimates of N(S)EC and of their uncertainty within a single analysis framework. The outcome is a framework for CR analysis that is robust to uncertainty in the model formulation, and for which resulting estimates can be confidently integrated into risk assessment frameworks, such as the species sensitivity distribution (SSD). Integr Environ Assess Manag 2024;20:279–293. © 2023 Commonwealth of Australia and The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: Estimating concentrations of "no‐effect" of contaminants is critical to effective environmental risk assessment and management.Concentration–response (CR) data can take many forms and do not always exhibit the clear threshold responses required for no‐effect‐concentration (NEC) threshold‐based toxicity models to be validly applied.We compare the existing NEC threshold‐based toxicity metric with an alternative no‐significant‐effect‐concentration (NSEC) metric suitable for when CR data do not show evidence of a threshold effect.We demonstrate how, embedded in a model‐averaging approach, the NEC and NSEC can be combined in a single analysis to yield estimates of N(S)ECs and of their uncertainty. [ABSTRACT FROM AUTHOR]

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