Case study: Mixture risk assessment of marine Arctic pollutants: exposure, hazard and risk assessment

The Case Study aims to evaluate the cumulative risk of chemical mixtures in the Arctic marine environment, where pollutants originate from industrial activities, shipping, oil and gas exploration, and long-range atmospheric transport. Arctic ecosystems face unique challenges due to low temperatures, slow degradation rates, and bioaccumulation of persistent pollutants in food webs. This study integrates the Source-To-Outcome Pathway (STOP) framework, which combines Aggregate Exposure Pathways (AEPs) and Adverse Outcome Pathways (AOPs) to systematically assess the impact of chemical mixtures on Arctic species. The study employs environmental monitoring data, ecotoxicological hazard data with the aim to perform risk assessment to evaluate mixture effects. Key findings indicate that Arctic species are exposed to complex mixtures of metals and organics that may potentially result in mixture risk. The work to date has focused on developing data handling workflows for exposure data from national databases and common (eco)toxicological hazard thresholds, linking these together for mixture risk assessment using exampled data sets for Arctic pollutants. The study supports regulatory frameworks by developing improved approaches for mixture risk assessment and predictive toxicology models. Future work will refine STOP applications, strengthen engagement with stakeholders, and expand mixture risk assessment methodologies.