Health risk assessment and ionomic profiling under cadmium, lead, zinc, and manganese stress in Amaranthus cruentus

Abstract Background Heavy metals (HMs) in agricultural soils pose a serious risk to crop safety and human health. This study evaluated the accumulation of cadmium (Cd), lead (Pb), zinc (Zn), and manganese (Mn) in Amaranthus cruentus L. cv. Pribina and integrated ionomic profiling with human health risk assessment to identify tissue-specific responses to metal exposure. Results Plants were cultivated in soils supplemented with 15 mg kg −1 Cd, 200 mg kg −1 Pb, 150 mg kg −1 Zn, and 300 mg kg −1 Mn up to full maturity. Cadmium accumulation in seeds up to 0.61 mg kg −1 exceeded established safety limits, indicating potential health risk to consumers. In contrast, Pb remained below detection limits, and Zn and Mn did not accumulate significantly in harvested seeds. Morphometric traits remained largely unaffected, although seed thickness and surface area decreased under Cd, Mn, and Zn exposure. Histochemical staining revealed Zn localization within protein bodies in seed cross sections. Elemental analysis of Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sr, and Zn revealed stable total nutrient concentrations, but significant alterations in inter-element relationships, suggesting tissue-specific maintenance of nutrient homeostasis. Principal component analysis showed that the first two components explained 81.17% of the total variance (PC1 59.15%, PC2 22.02%), clearly separating plant organs based on their elemental composition. Hierarchical cluster analysis further confirmed the strongest response of roots to HM treatments, emphasizing their primary role in metal uptake and redistribution; the unique behavior of Cd relative to other elements; and the distinct separation of roots treated with Pb. Conclusions These findings highlight Cd as the primary risk factor for food safety in contaminated soils and demonstrate that A. cruentus cv. Pribina maintains reproductive capacity under elevated metal concentrations, suggesting a notable degree of tolerance to HM stress. This study offers novel insights into the correlation between ionomic plasticity and potential health risks associated with the consumption of edible pseudocereals under environmental contamination.