Exploring the toxic metal contamination and unveiling the risks in staple grains grown in a CKDu hotspot in Sri Lanka

Abstract

Toxic metals in dietary grains could pose health risks from direct ingestion. This investigation aims to analyze the concentrations of toxic metals in selected dietary grains and conduct a comparative risk assessment in a region endemic to Chronic Kidney Disease of Unknown etiology(CKDu) in a non-endemic region. Six household fields in the CKDu endemic region in Nikawewa Grama Niladhari Division(GND) and three in the reference region; Wewagedara GND were selected for sampling. Inductively Coupled Plasma-Mass Spectrometry(ICP-MS) was used to determine Arsenic (As), Cadmium (Cd), Lead (Pb), Chromium (Cr), Copper (Cu), and Zinc (Zn) in composite samples collected from both GND areas (pulses; [(Vigna radiata; n=20), (Vigna unguiculata; n=20), (Vigna unguiculata subsp.; n=20)] cereal; [(Oryza sativa; n=30)]. Descriptive statistics revealed average As concentrations in samples as follows; Oryza sativa (38.60±13.84 g/kg,) Vigna unguiculata (3.25±1.96 g/kg), As was undetectable in samples of Vigna radiate, and Vigna unguiculata subsp. in CKDu endemic area. The average As concentrations of Oryza sativa in the reference area was 5.56±1.87g/kg and As was not detected in other grain species. All values complied with FAO/WHO & Codex permissible limits (As-100-200 g/kg). The estimated Daily Intake (EDI) value of As (0.257 g/kg/day) in Oryza sativa in the endemic area did not exceed the Tolerable Daily Intake (TDI) (As-0.3 g/kg/day). The average concentrations of Cd and Pb were reported in the CKDu endemic area; Oryza sativa (Cd-1276.92±234.42 g/kg, Pb-419.31±98.78 g/kg), Vigna radiata(Cd-571.31±60.71 g/kg, Pb-344.15±93.75 g/kg), Vigna unguiculata (Cd-1354.33±265.34 g/kg, Pb-408.56±22.20 g/kg), and Vigna unguiculata subsp.(Cd-1546.23±355.23 g/kg, Pb-408.63±115.14 g/kg) and exceeded FAO/WHO permissible limit(Cd-400 g/kg, Pb-300 g/kg). But those values were within the limits in the reference areas. However, Cu, Cr, and Zn remained within FAO/WHO safe limits in both regions. A health risk can be generated owing to long-term consumption of staple grains grown in Nikawewa GND; CKDu endemic area.