Potential health risks of contaminated media linked to bioavailability and hematotoxicity of uranium-238 ( 238 U) and

thorium-232 ( 232 Th) remain uncertain. This study investigates the relative bioavailability (RBA), histopathological, and

hematological eff ects of acute oral exposure to 238 U and 232 Th in co-contaminated concrete dust using 174 female Sprague

Dawley (SD) rats. In order to create a range of 238 U and 232 Th concentrations, concrete was spiked with uranyl and thorium

nitrates (~ 50, 100, and 200 mg kg −1 ). Spiked concretes were then crushed, ground, sieved (≤ 75 μm), and blended uniformly

to create co-contaminated concrete dust. SD rats’ diet pellet was amended with co-contaminated concrete dust and orally

ingested over a 48-h exposure period. The RBA values of 238 U and 232 Th in blood samples from rats’ post-exposure

were determined as 22.0% ± 0.86% to 30.8% ± 1.01% and 11.8% ± 0.14% to 13.7% ± 0.29%, respectively. Compared to

232 Th, 238 U blood levels of SD rats fed with co-contaminated concrete dust-amended diets were ~ 100-fold higher due to

solubility diff erences, and 238 U-RBA values were approximately 2-fold greater, revealing that their absorption rates in the

gastrointestinal tract were aff ected by compound solubility. Post-acute 238 U and 232 Th ingestion from co-contaminated

concrete dust demonstrate noticeable histopathological and hematological alterations, implying that intake of 238 U and 232 Th

in co-contaminated concrete dust can lead to erythrocytes damage and elevated hematological attributes. Our study would

be benefi cial for an adequate understanding of the health implications caused by the acute oral exposures of 238 U and 232 Th

in co-contaminated concrete dust, especially in the bioavailability and toxicity assessment.