ENVIRONMENTAL OCCURRENCE AND HUMAN HEALTH RELEVANCE OF ANTIMONY (Sb) IN URBAN SOILS OF ALCALÁ DE HENARES

Antimony (Sb) is a semi-metallic element increasingly used in vehicle brake pads, flame-retardant plastics, batteries, and polyethylene terephthalate (PET) bottles. Despite its recognised toxicity and classification as a priority pollutant in Europe, Sb remains insufficiently monitored in urban environments. This study assessed total Sb concentrations in 137 surface soil samples from Alcalá de Henares (Spain), collected from urban parks (n=97), industrial zones (n=22), and gardens (n=18). Sb was detected in 91.8% of the samples, with significantly higher concentrations in urban soils (median: 0.352 mg/kg) than in industrial and garden areas (0.292 and 0.124 mg/kg respectively; p-value<0.05). Although values remained below regional generic reference levels, pollution indices indicated localised anthropogenic inputs. Multivariate analysis grouped Sb with Rh and Mo, suggesting common emission sources—most likely traffic and industrial activities. Spatial analysis revealed elevated Sb concentrations in urban hotspots with dense road infrastructure. Inhalation risk was characterised using the US EPA methodology and was found to be below regulatory thresholds. Nevertheless, the high coefficient of variation and significant enrichment factors in some areas highlight the heterogeneity of Sb distribution and underscore its relevance as an urban soil contaminant. Given its bioaccumulative properties, persistence, and known toxicological effects—including developmental and respiratory toxicity—this study reinforces the need for Sb to be systematically included in soil monitoring and regulatory frameworks. Particular attention should be given to urban recreational spaces and garden soils, where incidental exposure through soil ingestion or dust inhalation may affect vulnerable populations such as children.