Determination of 238U and 232Th in commonly consumed foods in East China

Objective: To determine the activity concentrations of naturally occurring radionuclides 238U and 232Th in commonly consumed foods from East China and to evaluate the associated dietary exposure and potential radiological health risk to the general population. Methods: A total of 61 food items belonging to 10 major dietary categories were collected from local markets in a region of East China, pretreated by drying, homogenization, and acid digestion, and analyzed for 238U and 232Th using inductively coupled plasma mass spectrometry (ICP-MS). Activity concentrations were calculated and used to assess distribution patterns and inter-element correlations across food groups. The annual committed effective dose from dietary intake was estimated based on measured concentrations and regional consumption data. Results: Both 238U and 232Th were widely detected in the analyzed food samples, with activity concentrations ranging from 11 to 4514 and 7 to 1649 mBq/kg (dry weight), respectively. A significant positive correlation between the two radionuclides indicates a common natural origin. Clear food-type dependence was observed, with vegetables and legumes showing relatively higher 238U levels and elevated 238U/232Th ratios, while aquatic products and fruits exhibited lower ratios. The annual committed effective doses from dietary intake were estimated at 0.54 μSv/year for 238U and 1.90 μSv/year for 232Th, which are several orders of magnitude below the recommended public exposure limit of 1 mSv/year. Conclusion: The results provide baseline information on the occurrence of naturally occurring radionuclides in commonly consumed foods and indicate that current dietary intake levels pose negligible radiological risk to the general population. These findings support the continued monitoring of natural radionuclides in food to ensure food safety and public health protection.