Natural radionuclide occurrence and ingestion dose in foodstuffs from a Uranium Province, Brazil

Abstract Radiological assessment of dietary intake is a key component of environmental surveillance in areas characterized by enhanced natural radioactivity. In this context, the Lagoa Real Uranium Province, a strategic mineral region in Bahia, Brazil, presents a complex geogenic setting that demands a detailed understanding of radionuclide occurrence in foodstuffs. This study investigates the activity concentrations of naturally occurring radionuclides in agricultural food products from this province and assesses the associated adult committed effective dose due to ingestion. Thirty-seven samples of common beans, cassava, cassava flour, cactus pear, maize, and milk were collected in 2024. Natural uranium ( nat U) was determined by inductively coupled plasma mass spectrometry (ICP-MS), while 226 Ra, 228 Ra, and 210 Pb were measured using liquid scintillation spectrometry (LSS) following radiochemical separation. Despite the uraniferous geology of the region, nat U concentrations in foodstuffs were consistently low (< 0.1 Bq kg −1 in most matrices) with some localized higher values in cassava flour, indicating limited uranium transfer to edible tissues. By contrast, radium isotopes dominated the radiological profile: cassava flour exhibiting 14.2 Bq kg −1 of 226 Ra and 40.5 Bq kg −1 of 228 Ra, whereas milk showed the lowest levels. Elevated activities were particularly noted at the Gameleira farm and, to a lesser extent, at the Tamanduá farm. Ingestion doses fall within the range expected for existing exposure situations and should be interpreted considering natural background variability rather than regulatory dose limits. These findings underscore the importance of food-specific and site-specific monitoring in uranium-bearing environments to ensure radiological safety.