An integrated multi-method assessment of toxic element contamination and associated ecological and health risks in heavily contaminated paddy soils of Bangladesh

Paddy soils in rice-producing developing countries are particularly vulnerable to contamination from battery recycling operations and untreated industrial effluents. This study examined toxic element (As, Cr, Cu, Ni, Pb, and Zn) concentrations in paddy soils across three areas of Bangladesh: a battery recycling area (BRA), an industrial area (IA), and a sustainably managed area (SMA). ICP-OES, XRD, and SEM-EDS were used to confirm the TE concentrations, mineral composition, and spatial distribution of TEs on the soil. Pollution indices and health risk assessments were performed to evaluate ecological and human health risks for adults and children. The paddy soils in BRA were heavily contaminated, with a Pb concentration of up to 123,459 mg/kg, exceeding the allowable concentration (100 mg/kg). XRD and SEM-EDS suggested immobilization mechanisms based on mineralogical and speciation evidence in BRA soils. Pollution indices and ecological risk indicated that BRA was the most impacted. Despite average daily soil ingestion, absorption, and inhalation values being below the thresholds, health risk assessment showed notable non-carcinogenic and carcinogenic risks, especially in BRA. This study offers an integrated assessment of the TE status in paddy soil, the associated ecological threats, and the implications for human health, highlighting the pressing need for preventive strategies and public health interventions.