Acute oral toxicity and bioavailability of uranium and thorium in contaminated soil

Abstract

A robust approach was conducted to determining the absolute oral bioavailable (fab) fractions of 238U and 232Th in rats exposed to contaminated soil along with their hematotoxicity and nephrotoxicity. The soil sample is the International Atomic Energy Agency-312 (IAEA-312) certified reference material, whereas blood, bones, and kidneys of in vivo female Sprague-Dawley (SD) rats estimate 238U- and 232Th-fab fractions post-exposure. We predict the bioavailable concentration (Cab) and fab values of 238U and 232Th after acute soil ingestion. The blood 238U (0.750%) and 232Th (0.028%) reach their maximum fab values after 48 h. The 238U (fab: 0.169–0.652%) accumulates mostly in the kidney, whereas the 232Th (fab: 0.004–0.021%) accumulates primarily in the bone. Additionally, 238U is more bioavailable than 232Th. Post 48 h acute ingestion demonstrates noticeable histopathological and hematological alterations, implying that intake of 238U in co-contaminated soil can lead to erythrocytes and proximal tubules damage, whereas, 232Th intake can harm erythrocytes. Our study provides new directions for future research into the health implications of acute oral exposures to 238U and 232Th in co-contaminated soils. The findings offer significant insight into the utilization of in vivo SD rat testing to estimate 238U and 232Th bioavailability and toxicity in exposure assessment.