Biomonitoring of metals and trace elements in urine of central Ethiopian populations

Biomonitoring of chemical concentrations in humans is important for detecting, monitoring, and addressing a wide range of health threats. However, it is virtually absent across many African nations, including Ethiopia. This study aims to determine urinary concentrations for metals and trace elements in populations living in the central Ethiopian Rift Valley. The region is unindustralized, rural, and characterized by unique geologic rifting and volcanic activities that have produced vast pyroclastic materials, forming its aquifer and fertile agricultural soils. Millions of people in the region rely on wells for drinking water and are engaged in cereal-based subsistence agriculture. We enrolled a total of 386 residents aged 10-50 years old (201 females and 185 males). The levels of 23 elements except F- were quantified in water and urine samples by ICP-MS. Mean concentrations of B, F-, Ca, and Mg were measured in mg/L levels, while concentrations of Mo, Zn, Sr, Rb, and Li ranged between 100 and 700 mu g/L. Mean concentrations between 5 and 15 mu g/L were found for Ni, Cu, and Mn, while Ag, Be, Cd, Co, Pb, Sb, Th, TI, and U were all below 5 mu g/L. Arsenic and Al had mean concentrations between 30 and 50 mu g/L. Mean urinary concentrations of Ca, Cu, Mg, Pb, Sr, and Zn were significantly higher in males than females, whereas Co and Mn were higher in females. Finally, younger individuals (10-30 years) had significantly higher mean concentrations of B, Cd, Co, Mg, Mo, and Pb than those between 31 and 50 years, whereas only Ca was higher in the older age group. The concentration ranges of B, Mo, Mn, TI, Li, Zn, and in particular F- (0.44-44.6 mg/L) and As (2.2-164 mu g/L) in urine were higher than the reference ranges reported in healthy unexposed North American and European populations, while those for the remaining 16 elements were comparable to published reference ranges from such settings. The established concentration ranges are important to monitor future changes in exposure, and risk factors for disease, that might stem from the economic growth and industrialization that is currently underway in the region.