Heavy Metals Content of Common Tubers from Selected Farm Locations in Enugu North District, South East, Nigeria

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Fredrick C. Asogwa
Ebo Paul
Gerald W. Ugodi
Chioma J. Asogwa


The concentration of heavy metals (Cd, Pb, Ni, As, Cr, Mn, Cu, and Zn) in sweet potato (Ipomoea batatas), yam (Dioscorea ssp), and cassava (Manihot esculenta) in four farm locations in some local government areas of Enugu North District was determined. Samples were prepared following standard procedure and digested with a 5:1:1 mixture of trioxonitrate (V) acid, tetraoxosulphate (VI) acid, and perchloric acid as previously reported. Metal concentration was determined using Atomic Absorption Spectrophotometer (Perkin Elmer 1100B model). The range of heavy metals concentration recorded for sweet potato in the four farm locations were 60.26±2.30-312.66±31.24 mg/kg, 20.06±1.27-40.55±4.08 mg/kg, 12.60±2.00-32.06±3.20 mg/kg, 8.20±3.00-15.00±1.07 mg/kg, 0.05±0.07-0.80±1.27 mg/kg, 0.07±0.42-0.18±0.42 mg/kg, 0.01±0.20-0.09±0.03 mg/kg and 0.02±0.07-0.03±0.08 mg/kg respectively for Mn, Ni, Cu, Zn, Cr, Pb, As and Cd while the range in yam was 18.46±2.05-380.20±10.97 mg/kg, 44.20±4.99-66.30±3.87 mg/kg, 17.80±2.18-56.08±6.73 mg/kg, 12.00±2.00-42.30±0.06 mg/kg, 0.01±0.32-0.42±0.27 mg/kg, 0.02±0.07-0.20±0.12 mg/kg, 0.04±2.03-0.10±0.00 mg/kg and 0.01±0.07-0.08±0.47 mg/kg for Mn, Cu, Zn, Ni, Cr, Pb, As and Cd respectively. In cassava, the concentration range was 74.20±10.97-312.20±31.20 mg/kg, 14.20±1.29-38.22±6.07 mg/kg, 10.88±3.03-32.00±0.70 mg/kg, 3.20±0.20-11.20±1.09 mg/kg, 0.01±0.20-0.18±1.27 mg/kg, 0.02±0.03-0.12±0.07 mg/kg, 0.01±0.03-0.10±0.07 mg/kg and 0.03±0.00-0.05±0.42 mg/kg for Mn, Ni, Zn,Cu, Cr, Pb, Cd and As respectively. While Cd was not detected in farm location B and D in all the tuber samples, arsenic was detected in all the samples except in cassava cultivated in farm location B. All the heavy metals analyzed were each below the World Health Organization (WHO) permissible concentration except chromium which was slightly higher than the recommended limit of 0.05 mg/kg. Apart from 0.80±1.27 mg/kg Cr recorded for sweet potato cultivated in location C, the concentration of chromium in all the tubers were below the China’s State Environmental Protection Administration (SEPA) permissible limit of 0.5 mg/kg. Hence, risk assessment of Cr intake was recommended to ascertain the level of human exposure to Cr through the consumption of these tubers in the study area

Heavy metals, food safety, tubers, Enugu north district, permissible limit, risk assessment.

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How to Cite
Asogwa, F. C., Paul, E., Ugodi, G. W., & Asogwa, C. J. (2020). Heavy Metals Content of Common Tubers from Selected Farm Locations in Enugu North District, South East, Nigeria. Asian Journal of Applied Chemistry Research, 7(2), 1-6. https://doi.org/10.9734/ajacr/2020/v7i230176
Original Research Article


Prabhat KR, Sang SL, Ming Z, Yiufai T, Ki Hyun K. Heavy metals in food crops: Health risks, fate, mechanism and management. Environmental International. 2019;125:365−385.

Joan EM Bert EB. Behaviour of metals in soils, U.S EPA office of research and development, EPA/540/S−92/018; 1992.

Alan W. Soils and the environment: An introduction. Cambridge University Press. 1996;1:189−203.

Antonious GF. Enzyme activities and heavy metal concentration in soil amended with sewage sludge. Journal of Environmental Sciences and Health Part A. 2009;44:1019−1024.

Commission regulation no. 22/2002 of setting maximum levels for certain contaminants in food stuff. Commission of the European Community: Brussels. Official Journal of the European Communities; 2002.

Toxicological profile information sheet. Agency for toxic substances and disease registry; 2004.

Sanoussi AF, Adjatin A, Dansi A, Adebowale A, Sani LO, Sani A. Mineral composition of ten edible sweet potato (Impomea batatas L) landraces of Benin. International Journal of Current Microbiology and Applied Sciences. 2016l;5(1):103−115.

Naskar SK., Mukherjee A, Nedunche−zhiyan M, Rao KR. Evaluation of sweet potato cultivars for quality traits. In: New R and D initiatives in horticulture for accelerated growth and prosperity, 3rd Indian Horticultural Congress, held at Bhubaneswar, Orissa, India. Abstracts P. 6−8 November, 2008;340.

Yoshimoto M, RC Ray, KI Tomlins. Physiological functions and utilization of sweet potato. In: Sweet Potato, Post Harvest Aspects in Food. 2010;978−1−60876−344−6.

Teow CC, Truong VD, Mcfeeters RF, Thompson RL, Pecota KV, Yencho GC. Antioxidant activities, phenolics and β−carotene contents of sweet potato genotypes with varying flesh colors. Food Chemistry. 2007;103:829−838.

Chibowski S. Studies of radioactive contaminants and heavy metals in vegetables and fruits from lubin, Poland, Polish Journal of Environmental Studies. 2000;9:249.

Tomlins K, Rees D, Coote C, Bechoff A, Okwadi J, Massingue J et al. Sweet potato utilization, storage, small scale processing and marketing in Africa In: Sweet potato, post harvest aspects in food. R C. Ray and K. I. Tomlins. 2010;978−1−60876−343−6.

Osu RS, Solomon MM, Abai EJ, Etim IG. Health risk assessment of heavy metal intake via cassava consumption from crude oil impacted soils with and without palm bunch as additive. International Journal of Technical Research and Application. 2015;3(4):140-148.

Oti Wilberforce JO. Heavy metal accumulation in tubers grown in lead-zinc derelict mine and there significance to health and phytoremediation. Americal Chemical Science Journal. 2015;8(3):1-9.

George FA, Sam OD, Jason MU, John CS. Heavy metals uptake in plant parts of sweet potato grown in soil fertilized with municipal sewage sludge. International Journal of Geology. 2011;5(1):14-20.

Langard S, Nordberg GF, Friberg L, Nordberg GF, Kessler E, Vonk VB. Chromium in: Hand book on the toxicology of metals. Amsterdam: Elsevier/North Holland Biomedical Press. 1986;2:185-210.

Kaufaman DB, Dinichola W, Mcintosh R. Acute potassium dichromate poisoning treated by peritoneal dialysis. American medical association. American Journal of Disease. 1970;119:374-376.

Haladu KA, Chindo IY, Shibdawa MS, Rilwan MZ, Buteh DS. Heavy metal content of some tubers. Chemistry Research Journal. 2018;3(4):110-115.

Divya L, Jessen G, Midhum G. Heavy metal contamination of some common tubers sold in local markets of Ernakulam District, Kerala, India. Research Journal of Biological Sciences. 2015;4(3):49-52.