Excess lifetime cancer risk and committed effective dose associated with dietary exposure to radioactivity of natural origin from mining areas

Food safety concerns associated with radiotoxicity risks among consumers are widespread in areas with human activities such as mining. Therefore, the study was carried out to determine natural radioactivity levels in total diets in an area with excessive mining activities. Using validated models, the committed effective dose and excess cancer risk were calculated for consumers based on the activity concentration, food intake, exposure frequency, exposure duration, dose, and risk conversion factors. In addition, the percentage contribution of each radionuclide to the committed effective dose was determined. The results showed that the levels of activity concentration of Ra-226 (0.17 Bq/kg), Ra-228 (0.10 Bq/kg), Th-228 (0.08 Bq/kg) and K-40 (33.2 Bq/kg) were below global reference values (0.5-80 Bq/kg). The corresponding order of the total committed effective dose for age groups was: 0.179 mSv/year (adults) < 0.485 mSv/year (children) < 0.571 mSv/y (adolescents) < 0.634 mSv/year (toddlers) and exceeded the typical level (0.3 mSv/year) with the exception of adults. K-40 in diets from this study was the highest contributor (48%) to committed effective dose, followed by Ra-228 (35%), Ra-226 (16%) and Th-228 (1%) respectively. Radionuclide-specific excess cancer risk was found to increase in this order: Th-228 (7 x 10(-8)) < K-40 (3 x 10(-7)) < Ra-226 (2 x 10(-6)) < Ra-228 (3 x 10(-6)). This study showed that both radionuclide-specific and cumulative excess cancer risks (5.5 x 10(-6)) were all within the protective range (1 x 10(-4)-1 x 10(-6)).