Multivariate and correlation analysis of cadmium contamination in the food chain across spatio-temporal scales

Forage crops that contain elevated levels of metals are a serious hygiene and safety concern because they act as the main route through which these elements enter the food chain. The aim of this study was to evaluate the potential health risks associated with cadmium contamination in the food chain by applying different assessment indices, focusing on commonly consumed forage crops grown at contaminated sites near District Khushab, Pakistan. Across the winter and summer seasons of 2023–24, a total of water (n = 100), forage (n = 240), soil (n = 240), ruminant blood (n = 100), and milk (n = 100) samples were obtained from two separate locations: Jauharabad (S_1) and Noorpur Thal (S_2) and tested to measure cadmium content with an atomic absorption spectrophotometer. Cadmium concentrations averaged 0.09–0.58 mg kg⁻¹ in soil, 0.04–1.02 mg kg⁻¹ in forage, 0.21–1.25 mg L⁻¹ in water, 0.17–2.98 mg L⁻¹ in cow blood, 0.68–4.68 mg L⁻¹ in buffalo blood, 0.24–1.25 mg L⁻¹ in cow milk, and 0.15–0.96 mg L⁻¹ in buffalo milk. A very strong and statistically significant positive correlation was found between water at site S_1 and soil at site S_2 during the winter season. A highly significant strong positive correlation was observed between sites S_1 and S_2 for the crop T. alexandrium during the winter season. In contrast, P. glaucum showed a strong and significant negative correlation in the summer, while no significant effect of cadmium was detected in Z. mays during the same season. In animals, cadmium levels were highest in blood and lowest in milk. All calculated risk indices including BCF, EF, Eri, HRI, and THQ exceeded 1, highlighting potential health hazards for consumers at both sites across both seasons. Regular monitoring of cadmium and other heavy metals in soil, water, and fodder, along with strict enforcement of regulations on industrial waste disposal and wastewater irrigation, is essential to minimize environmental and health risks. Farmers should be guided to use clean water, adopt low metal accumulating forages, and avoid grazing livestock on contaminated pastures. Promoting soil remediation practices and collaboration among agencies, researchers, and farmers will help reduce metal transfer through the food chain and protect both animal and human health.