<i>In Vitro</i> Effect-Based Analysis of Stormwater Pond Sediments: Linkage to the Organic Contaminant Profile

This study investigated the relationship between biological effects and contamination profiles in sediments from 17 stormwater sedimentation facilities across four Swedish municipalities. Sediment extracts were examined using a battery of in vitro bioassays targeting five modes of action: aryl hydrocarbon (AhR), estrogenic (ER), androgenic (AR), antiandrogenic (AntiAR) receptors, and oxidative stress (Nrf2) activities, along with cytotoxicity. Significant differences in biological activities across cities aligned with patterns in previously characterized profiles of 259 urban-sourced organic substances. Concentrations of bioactive substances correlated positively with biological activities; however, they explained only a limited fraction (typically &lt;10%) of the observed effects, suggesting the influence of unmonitored substances. Among the examined substances, polycyclic aromatic hydrocarbons and alkylphenols were the most prominent drivers of chemically explained biological activities across end points. A masking effect between AR and AntiAR was revealed, with negative correlations between AR responses and agonist concentrations indicating dominance of antiandrogenic activity. Cytotoxicity rankings across samples did not align with acute toxicity previously measured on the same sediments using Microtox. However, overall cytotoxicity correlated significantly with chemical contamination indicators. These findings highlight the relevance of effect-based tools in capturing mixture effects in stormwater sediments and support their integration alongside chemical analysis in sediment quality assessments.