Assessment of natural radioactivity and dietary exposure to 238U, 232Th, and 40K in commonly consumed foods from Kirkuk Governorate, Iraq

Abstract

This study provides a radiological assessment of food products commonly consumed in Kirkuk Governorate, Iraq, by measuring the activity concentrations of natural radionuclides (²³⁸U, ²³²Th, and ⁴⁰K) using NaI(Tl) gamma-ray spectroscopy. A total of 55 food samples, including powdered milk, yogurt, tomato paste, flour, juices, vegetables, oils, and meats, were analyzed. The results showed that ⁴⁰K was the most abundant radionuclide (29.8–434.0 Bq kg⁻¹), reflecting its natural presence in biological tissues. Uranium concentrations were generally low, but two food items, an Iraqi powdered milk (48.4 Bq kg⁻¹) and Turkish chickpeas (72.5 Bq kg⁻¹), exceeded the IAEA reference value of 30 Bq kg⁻¹. Thorium levels were consistently low (<16.6 Bq kg⁻¹). Based on estimated consumption rates, the annual effective dose (AED) from all analyzed foods remained below the public dose limit of 1 mSv y⁻¹. To enhance risk prediction, a Random Forest regression model was applied, achieving high accuracy (R² = 0.998), and confirming that ⁴⁰K and ²³⁸U are the main contributors to AED. These findings indicate that while the overall radiological risk from food ingestion in Kirkuk is low, isolated outliers above uranium guidelines warrant follow-up monitoring. The combined use of radiometric analysis and machine learning provides a framework for improving food safety surveillance and supporting public health protection at both national and international levels.