Risk Assessment of Toxicologically Relevant Metals (TRMs) in Urban Surface Soils and Columba livia Feathers

Abstract : Metals of toxicological interest (MTI: cadmium [Cd], chromium [Cr], mercury [Hg], and lead [Pb]) are priority contaminants in urban environments due to their persistence, bioavailability, and potential toxicity to ecosystems and human health. In this study, their presence in urban surface soils was determined using quantitative analytical chemistry techniques, and ecological risk (Er), non-carcinogenic risk (HQ), and carcinogenic risk (CRi) were assessed. Additionally, ecotoxicological risk (RQ) was estimated using Columba livia feathers as a biomonitor. The results confirmed the presence of all four MTI in the analyzed soils, with low ecological and non-carcinogenic risk values. However, a relevant individual carcinogenic risk associated with Cd was identified, particularly in the child population. In Columba livia feathers, Cd and Hg showed high bioaccumulation, with very high RQ values (>400), indicating cumulative exposure in urban biota. Overall, these findings suggest that, although soil concentrations do not exceed regulatory thresholds, bioaccumulation processes may increase the risk in living organisms, highlighting the importance of incorporating biomonitors into environmental assessments of urban systems.