Dietary exposure to natural and artificial radionuclides through cereal, legume, seed, and nut products: Measurement and uptake assessment

The presence of natural and artificial radionuclides in food products raises concerns about potential health risks associated with long-term ingestion, highlighting the need for systematic assessment of dietary exposure. This study presents a market-basket assessment of natural (²²⁶Ra, ²³²Th, ⁴⁰K) and artificial (¹³⁷Cs) radionuclides in forty cereal, legume, seed, and nut products. Activity concentrations were determined using high-resolution HPGe γ-spectrometry with rigorous quality assurance. Annual committed effective doses were calculated for adults and children using realistic intake scenarios, and lifetime cancer risk (LCR) was estimated following USEPA methodology with Monte Carlo uncertainty analysis (100,000 iterations). Radionuclide levels varied widely across food groups, with ⁴⁰K consistently dominating activity concentrations. Rice, pasta, and legumes were the main contributors to ingestion dose, due to both higher consumption and elevated activities. Total ingestion doses were ≈404 μSv y^-1 for adults and ≈202 μSv y^-1 for children, within the international reference range for mixed diets (300-700 μSv y^-1). Total LCR values (1.41 × 10^-3 for adults; 7.07 × 10^-4 for children) exceeded the USEPA target risk range (10^-6-10^-4), highlighting the importance of rice as the dominant contributor (∼40 %). All radionuclide concentrations were below international safety limits, and ¹³⁷Cs, though detected in some samples, was consistently at levels posing no health concern. Overall, dietary exposure from these foods does not currently present a radiological risk but supports the need for continued monitoring of staple crops.