68 In the ecological context, risk characterization also involves calculation of hazard quotients by comparing contaminant concentrations with toxicity reference values, including effect thresholds and lethal concentrations for sensitive organisms. Interpretation of ecological risk extends beyond numerical comparison and incorporates consideration of effect magnitude, spatial and temporal extent, and ecosystem resilience. This weight-of-evidence approach supports a more robust evaluation of ecological risk significance (U.S. EPA, 1998). 3. SITE-SCALE APPLICATIONS The application of human health and ecological risk assessment as a decision-support tool for mine closure planning is supported by well-documented international experience, as well as by recent applications in the Peruvian context. These cases demonstrate the value of a prospective, staged approach—closure, post-closure, and future use—for guiding closure design and remediation decisions within a risk-based management framework. 3.1 International experiences A representative example is the Ranger Uranium Mine (Australia), where an integrated human health and ecological risk assessment was implemented with a time horizon of up to 10,000 years, although using a methodology different from that described above. The assessment combined long-term environmental monitoring data, ecological response studies, and solute transport modeling, enabling the prioritization of source control measures and water treatment strategies. A distinctive feature of this case was the explicit incorporation of Indigenous cultural use scenarios, including traditional consumption of local resources. This approach allowed closure criteria to be aligned with the social and cultural expectations of the surrounding territory (Iles & Rissik, 2022). Similarly, at the Argyle Diamond Mine (Australia), risk assessment was applied to evaluate the proposed pit lake as a closure component. The assessment indicated low risks to human and ecological receptors, considering site access restrictions, habitat characteristics, and exposure pathways. These results supported the validation of the pit lake as a long-term water management structure and informed the definition of monitoring and adaptive management criteria consistent with closure objectives (McCullough & Sturgess, 2020; Rio Tinto, 2020). In the United States, the Environmental Protection Agency (EPA) has incorporated risk‑based decision‑making as a central element in the cleanup, revitalization, and reuse of abandoned mine lands. The integration of future land‑use considerations into remediation planning is recognized to accelerate environmental risk reduction, ensuring that cleanup actions protect human health and the environment while also supporting viable reuse opportunities (U.S. EPA, 2004).
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