Regional risk assessment Part I: prioritization of potentially contaminated sites

Soil contamination remains a critical barrier to endurable land use and environmental health worldwide. A stepwise and risk-based approach to identify, assess and manage potentially contaminated sites across complex land uses, is presented. Unlike traditional site-specific risk assessments, which are often limited to detailed studies of individual locations, this large-scale approach (known as regional risk assessment - RRA) integrates diverse data sources - historical or current data on anthropogenic activities - with pathways relevance information and receptors vulnerability to support prioritisation when dealing with a very large number of sites. The methodology is implemented within a GIS-based framework, and integrate spatial data on hazards, pathways, and receptors to produce regional-scale risk maps. The output provides a relative ranking of potentially contaminated sites based on estimated risk levels, supporting the prioritisation of sites requiring further site-specific investigation or remediation. Applied to the metropolitan area of Toulouse, the framework demonstrates its applicability across urban and peri-urban landscapes. This methodology responds to emerging regulatory requirements, such as the Soil Monitoring and Resilience Directive, and offers practical support to strategic planning efforts aligned with EU policy initiatives. By enabling more efficient and risk-based site management, the framework contributes to the protection of human health and the land resources.