Evaluating potentially toxic element accumulation in crops near abandoned mine tailings in northwestern Mexico: a One Health perspective

This study investigated the accumulation of potentially toxic elements (PTEs) in crops cultivated near abandoned mine tailings (MTs) in San Felipe de Jesús, northwestern Mexico, with the aim of evaluating their compliance with food safety regulations. A total of 26 soil and crop samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). In soils, concentrations of lead (Pb), zinc (Zn), and cadmium (Cd) reached 367 mg kg⁻¹, 781 mg kg⁻¹, and 6.19 mg kg⁻¹, respectively, and declined exponentially with distance from the MTs, consistent with wind-driven dispersion. Soils exhibited moderate to poor resilience, with 34.6% classified as poor based on pH, organic carbon, cation exchange capacity, iron oxides, and calcium oxides. In crops, several forage samples exceeded maximum tolerable levels (MTLs) for livestock: all barley and alfalfa samples surpassed the MTL for potassium (2.5% for cows and horses) and sulfur (0.4% for cows); some also exceeded the MTLs for calcium (1.5% for horses) and iron (500 mg kg⁻¹ for horses). Among food crops, cadmium concentrations exceeded Codex Alimentarius limits in one peanut sample (0.15 mg kg⁻¹; Limit: 0.1 mg kg⁻¹), both pepper samples (0.08-0.09 mg kg⁻¹; Limit: 0.05 mg kg⁻¹), and chiltepin (0.10 mg kg⁻¹; Limit: 0.05 mg kg⁻¹). Lead concentrations in one pepper (0.09 mg kg⁻¹) and chiltepin (0.10 mg kg⁻¹) also surpassed the Codex Limit of 0.05 mg kg⁻¹, whereas all maize samples remained below safety thresholds. These results highlight the health and environmental risks of legacy mining and support the need for phytostabilization and amendment-based remediation to reduce PTE mobility and crop uptake.