Comparative dose assessment of natural radionuclides in food consumed by adults in Germany.

Between 2016 and 2021, Germany conducted its first Total Diet Study to assess dietary exposure to various substances, including natural radionuclides. Activity concentrations of Pb-210, U-234, U-238, Ra-226, and Ra-228 were determined in 163 food samples of the German diet. Po-210 was additionally included using inferred values because of its known high relative contribution to ingestion dose. This study provides the first comprehensive assessment of ingestion doses from natural radionuclides in foods consumed in Germany. Two methodological approaches were applied. A conservative approach assigned 134 activity concentrations per radionuclide to the eight food groups defined in the German Radiation Protection Ordinance, resulting in a mean effective dose of 98 μSv·a-1 (median: 58 μSv·a-1). A refined approach incorporating detailed food consumption data, consistent with current dietary exposure assessment practices, yielded a markedly lower mean annual effective dose of 26 μSv·a-1 (median: 24 μSv·a-1). In both approaches, Po-210 and Ra-228 were the main contributors to the total dose, accounting for 39%/36% and 31%/34%, respectively (conservative/refined). Pb-210 is responsible for 22%/21%, while Ra-226 accounted for 7%/9%. Uranium isotopes contributed only marginally (<1%). The results demonstrate the importance of refined consumption-based assessments for realistic dose estimation and highlight the relevance of Po-210 and Ra-228 in dietary exposure. In addition, the investigation successfully shows, that the conservative approach reliably provides an upper estimate for the ingestion dose as intended. These findings provide a robust basis for radiological risk assessment and support ongoing food safety evaluations.