Multi-Matrix Assessment of Potentially Toxic Elements Across Soil and Sambucus nigra Organs: Spatial Patterns, Regulatory Compliance, and Dietary Exposure of Edible Fruits

Urban environments may influence elemental exposure from wild edible fruits. This study evaluated spatial patterns, soil-to-organ concentration ratios, and food-safety implications of potentially toxic elements in soil and four Sambucus nigra organs collected from 94 sites across five ecological sectors in Oradea, Romania (470 samples). Elements were determined by ICP-MS, and the data were evaluated using soil-to-organ concentration ratios, multivariate analyses, regulatory assessment, dietary-exposure assessment, and non-carcinogenic risk analysis. Elemental profiles varied strongly by matrix and sector, with concentrations generally highest in the central urban sector (Z2) and lowest in the woodland-associated sector (Z4). Bark exhibited the highest soil-normalized concentration ratios for potentially toxic elements; however, because bark was analyzed unwashed, these values may include surface deposition and should not be interpreted as evidence of greater internal accumulation relative to the rinsed organs. In fruits, Cr and Ni were detected in 97.9% and 94.7% of samples; Pb, Cd, As, and Sb occurred mainly in Z2, while Hg remained below the detection limit. Z2 fruits contained 5.92 ± 1.10 detected potentially toxic elements per sample, compared with 1.61 ± 0.61 in Z4. No fruit sample exceeded the applicable EU maximum levels for Pb or Cd. For the additional elements evaluated through the screening-level dietary exposure assessment, all calculated THQs and partial HI values were below 1 under the adopted exposure assumptions. The results indicate a pronounced urban multi-element signal but no appreciable non-carcinogenic concern under the adopted assumptions.