In ecological risk assessments, ecotoxicological models are used to consider higher-level effects in diverse risk-based environmental management decisions. They can provide information for decisions related to environmental quality criteria and standards, assessments of potential impacts associated with past or proposed uses of chemicals, and evaluations of remedial actions or restoration options for cleanup of contaminated sites.
Ecotoxicological models are used for chemical risk assessments in the following ways:
• Deriving environmental quality criteria. For environmental regulatory programs, ecotoxicological models provide a tool to calculate risk-based quality criteria for surface water, sediments, soils, and air, based on protection of population- or ecosystem-level endpoints.
• Assessingpotential impacts associated with past or proposed uses of chemicals. Chemical releases and uses involve risks to individual organisms, populations, and biological communities. Ecotoxicological models provide a method to assess potential risks of chemicals in the environment on endpoints at higher levels of ecological organization.
• Evaluating remedial actions or restoration options for cleanup of contaminated sites. For US EPA Superfund cleanup projects and related efforts, ecotoxicological models can provide information for decisions by answering questions such as which contaminated media or locations pose an unacceptable risk, which cleanup actions will reduce risk the most, what is the ecological risk associated with the cleanup actions themselves, and what is the residual chemical risk after remediation.
• Evaluating ecological significance of estimated risks. As part of the risk characterization phase of an assessment, ecotoxicological modeling can be used in a weight-of-evidence approach to evaluate the ecological significance of effects predicted or observed on organisms.
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