The detected mean values of Cd, Fe and Mn were compared to the WHO standard as presented in table Table .3: Comparison with WHO maximum standard limit Heavy metal Cd Fe Mn WHO Maximum limit (mg/l) 0.003 2 0.5 Langtang-North Big Dam(mg/l) 0.000111 0.000847 0.000118 Langtang-North Small Dam(mg/l) 0.000104 0.000935 0.000173 Figure .3: Comparison with WHO standard Detected amount of cadmium, iron and manganese are all below the maximum limit of the world health organization (WHO). The average cadmium value (0.101 mg/kg) is less than that of industrial areas, like Warri River (0.229 mg/kg), as shown in table 2. Cadmium is carried by airborne particulate matter from industrialized areas, according to Mathis and Kevern in . This occurs from distant lakes and streams. Given that Jos City is located many kilometers away from Langtang North and that there aren't many other enterprises in the vicinity, it seems unlikely that the sources of cadmium found in the Langtang-North dams come from industrial locations.