Assessment of heavy metals in onion and potato in imported and local variety of Pakistan and Afghanistan

Abstract

Objectives: Onion and potato (Allium cepa and Solanum tuberosum) are most commonly used vegetables in Pakistan. Different samples of local variety of onion and potato were collected from Khyber Pakhtunkhwa, Pakistan and few samples imported from Afghanistan. Methods: Heavy metal contents of these vegetable were analysed for Cr, Pb, Cu, Co, Zn, Mn, Fe, Ni and Cd using atomic absorption spectroscopy. Results: The order of metal contents was found to be Fe > Zn > Mn > Cu > Cr > Pb > Cd > Ni > Co in onion (local variety), and a similar pattern Zn > Fe > Cu > Mn > Pb > Ni > Cr > Cd was also observed in onion (imported variety). Conclusion: Higher content of Fe Zn were found in onion from Pakistan and Afghanistan respectively. Metal levels observed in vegetables were compared with WHO and established permissible levels reported by different authors. Mean concentration of Fe, Zn, Mn, Cu, Pb, Cr, Ni, Cd and Co are 45.9, 37.63, 6.76, 5.78, 2.26, 1.623, 0.745, 0.636 and 0.0950 respectively. The study concludes that the cultivation, transportation and marketing systems of vegetables may play a significant role in elevating the contaminant levels of heavy metals which may pose a threat to the quality of the vegetables with consequences for the health of the consumers of locally produced foodstuffs. The distribution and characterization of heavy metals in vegetables was studied in detail and discussed in this paper.