Daily urinary excretion of uranium in occupationally unexposed humans from Nigeria

The main aim of this study was to determine and evaluate urinary excretion values of uranium in occupationally unexposed subjects from Nigeria. As several uranium mines are running in Nigeria and the operations could be a risk of contamination for the workers as well as for the members of the public, biomonitoring of urine could provide information about the exposure to uranium for the subjects. Therefore, baseline values of uranium in urine are needed from subjects living in areas without mining activities. Volunteers of both genders (age range 3 to 78 years), living in the south-western region of Nigeria, were asked to collect 24h-urine samples. The concentration measurements of uranium in urine were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In addition, urinary creatinine values were determined for normalization of the renal uranium relative to the creatinine concentrations. The urinary uranium concentrations and their creatinine normalized values ranged from <10.4 to 150 ng L -1 (median 13.8 ng L -1 ) and from 2.52 to 252.7 ng g -1 creatinine (median 33.4 ng g -1 creatinine), respectively, for adult subjects above 15 years of both genders. An increased uranium excretion value of 61.6 ng L -1 (median), and of 76.0 ng g -1 creatinine,