Acute oral toxicity and bioavailability of uranium and thorium in contaminated soil (2023)

Nur Shahidah Abdul Rashid, Wooyong Um, Ibrahim Ijang, Kok Siong Khoo, Bhupendra Kumar Singh, Nurul Syiffa Mahzan, Syazwani Mohd Fadzil, Nur Syamimi Diyana Rodzi, Aina Shafinas Mohamad Nasir

Nuclear Engineering and Technology, Volume 55, Issue 4, April 2023, Pages 1460-1467

DOI: https://doi.org/10.1016/j.net.2022.12.011

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.