Normalisation of spot urine samples to 24-h collection for assessment of exposure to uranium

For dose assessment of workers at Nuclear Research Center Negevexposed to natural uranium, spot urine samples are analysedand the results are normalised to 24-h urine excretion basedon ‘standard’ man urine volume of 1.6 l d^–1.In the present work, the urine volume, uranium level and creatinineconcentration were determined in two or three 24-h urine collectionsfrom 133 male workers (319 samples) and 33 female workers (88samples). Three volunteers provided urine spot samples fromeach voiding during a 24-h period and a good correlation wasfound between the relative level of creatinine and uranium inspot samples collected from the same individual. The resultsshow that normalisation of uranium concentration to creatininein a spot sample represents the 24-h content of uranium betterthan normalisation to the standard volume and may be used toreduce the uncertainty of dose assessment based on spot samples.