Heavy Metal Accumulation in Vegetables Grown in Rock Soils of Kilembe Copper Mine, Kasese, Western Uganda

Jockus Masereka *

Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, P.O. Box 1410, Mbarara, Uganda.

Denis Byamugisha

Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, P.O. Box 1410, Mbarara, Uganda.

Christopher Adaku

Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, P.O. Box 1410, Mbarara, Uganda.

*Author to whom correspondence should be addressed.


Aim: Active mining in Kilembe copper mine, Kasese district, Uganda ended about four decades ago. However, various health problems are believed to be from the effect of mining activities that took place in the area. In this study therefore, we quantified the concentration of trace metals: chromium (Cr), cadmium (Cd), zinc (Zn), iron (Fe), lead (Pb), arsenic (As) and copper (Cu) in cabbages and tomatoes grown in Kilembe mining area and assessed the health risks from consumption of the vegetables after 40 days and 120 days of growth.

Study Design:  This study employed quantitative research design.

Place and Duration of Study: The experiments were done at Department of Chemistry, Mbarara University of Science and Technology, Uganda from 2018 to 2019.

Methodology: The vegetables were planted, and their roots, leaves, fruits and stems were sampled after 40 days and 120 days. Elemental analysis was performed using atomic absorption spectrophotometry. The estimated daily intake (EDI), target harzard quotient (THQ) and cancer risks were calculated to explore health risks that could arise from consumption of the vegetables.

Results: The levels of Fe, Cu, Zn and Cr did not exceed WHO/FAO permissible limits. The EDI of Fe (294.678 × 10-4 mg/kg/day) was the highest while the lowest was 0.052 × 10-4 mg/kg/day for Cr. The THQ ranged from 0.000004 to 1.3134. Cancer risk values ranged from 0.126 × 10-4 to 28650 × 10-4.

Conclusion: There are discernable non-carcinogenic health risks (THQ >1) and cancer risks associated with consumption of cabbages and tomatoes by the local inhabitants. The risks are escalated in children who consume both vegetables after 40 days of growth. Arsenic and Cd poses the highest carcinogenic health risk while Pb poses the highest non-carcinogenic health risk. Consumption of the vegetables after 120 days of growth poses lower health risks.

Keywords: Trace metals, target hazard quotient, hazard index, estimated daily intake, carcinogenic risk

How to Cite

Masereka, J., Byamugisha, D., & Adaku, C. (2022). Heavy Metal Accumulation in Vegetables Grown in Rock Soils of Kilembe Copper Mine, Kasese, Western Uganda. Asian Journal of Applied Chemistry Research, 12(1), 30–40. https://doi.org/10.9734/ajacr/2022/v12i1213


Download data is not yet available.


Nur-E-Alam M, Salam MA, Dewanjee S, Hasan M F, Rahman H, Rak AE, Islam ARMT, Miah MY. Distribution, concentration, and ecological risk assessment of trace metals in surface sediment of a tropical bangladeshi urban river. Sustainability. 2022;14: 5033.

Hassaan MA, El Nemr A. Pesticides pollution: Classifications, human health impact, extraction and treatment techniques. Egyptian J Aquat Res. 2020;46:207-220.

Wu X, Cobbina SJ, Mao G, Xu H, Zhang Z, Yang L. A review of toxicity and mechanisms of individual and mixtures of heavy metals in the environment. Environ Sci Pollut Res Int. 2016;23:8244-59.

Sall ML, Diaw A, Gningue-Sall D, Efremova Aaron S, Aaron JJ. Toxic heavy metals: Impact on the environment and human health, and treatment with conducting organic polymers, a review. Environ Sci Pollut Res Int. 2020;27:29927–29942.

Edelstein M, Ben-Hur M. Heavy metals and metalloids: Sources, risks and strategies to reduce their accumulation in horticultural crops. Scientia Hort. 2018;234:431-444.

Balali-Mood M, Naseri K, Tahergorabi Z, Khazdair M, Sadeghi M. Toxic Mechanisms of Five Heavy Metals: Mercury, Lead, Chromium, Cadmium, and Arsenic. Front Pharmacol. 2021;12: 643972.

Qu S, Wu W, Nel W, Ji J. The behavior of metals/metalloids during natural weathering: A systematic study of the mono-lithological watersheds in the upper Pearl River Basin, China. Sci Total Environ. 2020;708:134572.

Rehman ZU, Khan S, Qin K, Brusseau ML, Shah MT, Din I. Quantification of inorganic arsenic exposure and cancer risk via consumption of vegetables in southern selected districts of Pakistan. Sci Total Environ. 2016;550:321–329.

Tchounwou PB, Yedjou CG, Patlolla AK, Sutton DJ. Heavy metal toxicity and the environment. Experientia Supplement. 2012;101:133–164.

Kaweesa B. Determination of heavy metal concentration in water and food around river Nyamwamba. BSc Thesis, Makerere University, Kampala, Uganda; 2019.

Mwesigye AR, Tumwebaze SB. Water contamination with heavy metals and trace elements from Kilembe copper mine and tailing sites in Western Uganda; implications for domestic water quality. Chemosphere. 2017;169:281–287.

Hartwig T, Owor M, Muwanga A, Zachmann D, Pohl W. Lake George as a Sink for Contaminants Derived from the Kilembe Copper Mining Area, Western Uganda. Mine Water Environ. 2005;24:114–123.

Mwesigye AR, Young SD, Bailey EH, Tumwebaze SB. Population exposure to trace elements in the Kilembe copper mine area, Western Uganda: A pilot study. Sci Total Environ. 2016;573:366–375.

Owor M, Hartwig T, Muwanga A, Zachmann D, Pohl W. Impact of tailings from the Kilembe copper mining district on Lake George, Uganda. Environ Geol. 2007;51: 1065–1075.

Omara T, Karungi S, Kalukusu R, Nakabuye BV, Kagoya S, Musau B. Mercuric pollution of surface water, superficial sediments, Nile tilapia (Oreochromis nilotica Linnaeus 1758 [Cichlidae]) and yams (Dioscorea alata) in auriferous areas of Namukombe stream, Syanyonja, Busia, Uganda. PeerJ. 2019;7:e7919.

Bamuwamye M, Ogwok P, Tumuhairwe V, Eragu R, Nakisozi H, Ogwang P. Dietary content and potential health risks of metals in commercial black tea in Kampala (Uganda). J Food Res. 2017;6:1-12.

Adedokun A, Njoku K, Akinola M, Adesuyi A, Jolaoso A. Potential human health risk assessment of heavy metals intake via consumption of some leafy vegetables obtained from four market in Lagos Metropolis, Nigeria. J Appl Sci Environ Manage. 2016;20:530-39.

Saha N, Zaman M. Evaluation of possible health risks of heavy metals by consumption of foodstuffs available in the central market of Rajshahi City, Bangladesh. Environ Monit Assess. 2012; 185:3867–78.

Bounar A, Boukaka K, Leghouchi E. Determination of heavy metals in tomatoes cultivated under green houses and human health risk assessment. Qual Assur Safe Crops Foods. 2020;12:76–86.

US EPA. Risk-based concentration table. United States Environmental Protection Agency: Washington, DC; 2009.

Qing X, Yutong Z, Shenggao L. Assessment of heavy metal pollution and human health risk in urban soils of steel industrial city (Anshan), Liaoning, Northeast China. Ecotoxicol Environ Safety. 2015;120:377–385.

Wang X, Sato T, Xing B, Tao S. Health risks of heavy metals to the general public in Tianjin, China via consumption of vegetables and fish. Sci Total Environ. 2005;350:28–37.

Gebeyehu HR, Bayissa LD. Levels of heavy metals in soil and vegetables and associated health risks in Mojo area, Ethiopia. PLoS ONE. 2020;15:e0227883.

FAO/WHO. Joint FAO/WHO Food Standards Programme Codex Committee on Contaminants in Foods, Food CF/5 INF/1. Fifth Session. The Hague, the Netherlands; 2011.


Nhapi I, Wali U, Uwonkunda B, Nsengimana H, Banadda N, Kimwaga R. Assessment of water pollution levels in the Nyabugogo catchment, Rwanda. Open Environ Eng J. 2011;4:40–53.

Islam MS, Ahmed MK, Habibullah-Al-Mamun M. Metal speciation in soil and health risk due to vegetables consumption in Bangladesh. Environ Monit Assess. 2015;187:288.

Liu W, Li X, Li HH, Wang YW. Heavy metal accumulation of edible vegetables cultivated in agricultural soil in the Suburb of Zhengzhou City, People’s Republic of China. Bull Environ Contam Toxicol. 2006; 76:63–170.

Gupta N, Khan DK, Santra SC. An assessment of heavy metal contamination in vegetables grown in wastewater-irrigated areas of Titagarh, West Bengal, India. Bull Environ Contam Toxicol. 2008; 80:115–118.

Romero-Estéveza D, Yánez-Jácome GS, Simbaña-Farinango K, Vélez-Terreros PY, Navarrete H. Determination of cadmium and lead in tomato (Solanum lycopersicum) and lettuce (Lactuca sativa) consumed in Quito, Ecuador. Toxicol Rep. 2020;7:893–899.

Obadahun J, Pascalina PL, Tsaku JE, Jakheng EW, Onweneke OH. Determination of heavy metal in tomatoes ﴾Lycopersium escalentum﴿ and soil grown in Panshekara challawa industrial area of Kano state. Global Sci J. 2021;9:2331-2340.

Nakiguli CK, Ojok W, Omara T, Wasswa J, Ntambi E. Mobility of chromium, copper and arsenic in amended chromated copper arsenate contaminated soils. Asian J Appl Chem Res. 2020;6:33-48.

EPA. Edition of the Drinking Water Standards and Health Advisories. sEPA 822-S-12-001. Washington, DC: Office of Water US Environmental Protection Agency; 2012.