Heavy Metal and Metalloid Contamination in Agricultural Matrices of Gopalganj, Bangladesh: A Comprehensive Analysis and Health Risk Assessment

Heavy metal contamination in agricultural soils, water, and crops is a critical concern in developing regions due to its implications for food safety and public health. This study assessed the concentrations of six heavy metals – cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) – in soil, irrigation water, and commonly consumed vegetables from three sites in Gopalganj, Bangladesh. The sites represent a gradient of anthropogenic impact: a rural agricultural area (control), a mixed agriculture-urban area, and an industrial-adjacent area. Samples were analyzed using Atomic Absorption Spectroscopy (AAS) with rigorous quality control. Results showed that all metal concentrations in vegetables and soils were below international permissible limits, with mean levels in soils (e.g., Ni ~ 0.4 mg/kg, Cu ~ 0.5 mg/kg, Pb ~ 0.3 mg/kg) and vegetables (Zn ~ 0.4 mg/kg, other metals often not detectable) reflecting background conditions. Irrigation water contained trace metal levels near or below detection limits. Nevertheless, spatial trends were evident: soils at the industrial-influenced site had significantly higher Ni and Cu than the rural site ( p  < 0.05), and slight elevations of Cd, Pb, and Cr were noted in vegetables and water from impacted areas (though still within safe bounds). Pearson correlations suggested common sources for some metals (e.g., Pb–Cu, r  ≈ 0.51; Ni–Pb, r  ≈ 0.36; p  < 0.05). A human health risk assessment indicated that the estimated dietary intakes of these metals through vegetables yield HQ and HI values well below 1, indicating no significant non-carcinogenic risk at present. These findings provide a timely baseline on heavy metal pollution in a fast-developing region of Bangladesh. While current contamination levels appear safe, the detectable influence of industrial activities underscores the need for ongoing monitoring and proactive measures to ensure environmental and food safety in the future. Diagrammatic representation of workflow process