Daily urinary excretion of uranium in members of the public of Southwest Nigeria.

The main aim of this study was to determine and evaluate urinary excretion values of uranium in members of the public of Southwest Nigeria living in areas of low environmental uranium. 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) 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, respectively, were found in young subjects below 15 years. The median of daily excreted uranium was estimated to be 14.2 ng d(-1) for adults and of 45.1 ng d(-1) for children, respectively. The uranium excretion from males and females living in Nigeria in a non-mining area was comparable to reference values reported from other countries with low level of environmental uranium. The data can be considered as baseline values of urinary uranium in unexposed subjects in Nigeria.