Determination of some trace metal levels in onion leaves from irrigated farmlands on the bank of River Challawa, Nigeria

The concentration (mg kg-1 dry weight) of Cu, Mn, Ni and Zn were determined in onion leaves samples using atomic absorption spectrometry. A total of 16 samples each of onion leaves freshly harvestedwere collected from the exposed and control sites for analysis. The trace metal (Cu, Mn, Ni and Zn) levels in the onion leaves of the study site were found to be higher than those of the control site. The trend of abundance of the metals are Ni > Cu > Zn > Mn. For the onion leaves samples of the study site and Ni > Cu > Zn > Mn for the onion leaves of the control site. The trace metals levels in either case were found to be above the FAO/WHO and WHO/EU allowed limits, which could put the consumers ofthis valuable vegetable at risk health wise. However, Cu and Zn levels are below the MAFF limits