Thorium and uranium contents in human urine: influence of age and residential area

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of 232Th and 238U in urine of unexposed Jordanian subjects living in six cities. The range of 232Th excretion in all subjects was found to be 1.4–640 μBq d−1 with an average of 34.8 μBq d−1 (geometric mean 15.8 μBq d−1). Results showed no statistically significant correlation with age and residential area. The average value obtained is in agreement with levels considered normal in some recent publications. The average value of 238U in all samples was found to be 3955 μBq d−1 (geometric mean 1107 μBq d−1), which is higher than reported figures from Germany and India, but in agreement with those figures given in ICRP publication, number 23. The mean values of the different groups were found to be proportional to age up to 60 years. A noticeable drop is observed for subjects greater than 60 years old.