Measuring extremely low levels of daily urinary Th excretions in adult German population

Abstract

Exposure to thorium can be estimated by measuring its quantity excreted daily in urine. For this purpose, an adequately sensitive analytical method was developed and standardized, employing radiochemical neutron activation analysis (RNAA). The method was applied to measure pg levels of Th in urine samples from which its daily urinary excretion was quantified. It was possible to achieve a limit of detection (LOD) of 10 pg Th (0.04 μBq) in urine samples. The daily urinary excretion of Th was measured in a group of 15 adult German subjects who were not occupationally exposed to Th. The daily urinary excretion ranged between 0.49-3.65 ng. d-1, with the geometric mean of 1.29 ng Th. d-1. This daily urinary excretion of Th provides an important baseline data against which the occupational exposure of workers could be assessed.