An analysis of heavy metals contamination and estimating the daily intakes of vegetables from Uganda

Article Authors: Keneth Iceland Kasozi, Eric Oloya Otim, Herbert Izo Ninsiima, Gerald Zirintunda, Andrew Tamale, Justin Ekou, Grace Henry Musoke, Robert Muyinda, Kevin Matama, Regan Mujinya, Henry Matovu, Fred Ssempijja, Ejike Daniel Eze, Mauryn Atino, Bede Udechukwu, Ronald Kayima, Patrick Etiang , Emmanuel Tiyo Ayikobua, Stellamaris Kembabazi, Ibe Michael Usman, Sheu Oluwadare Sulaiman, Phyllis Candy Natabo, Grace Nambatya Kyeyune, Gaber El-Saber Batiha, and Ochan Otim


Environmental contamination with elevated levels of copper (Cu), cobalt (Co), iron (Fe), zinc (Zn), lead (Pb), chromium (Cr6+), cadmium (Cd), and nickel (Ni)—all states of which are found in Uganda—raises health risk to the public. Pb, Cr6+, Cd, and Ni for instance are generally considered nonessential to cellular functions, notwithstanding the importance of the oxidative state of the metals in bioavailability. As such, we aimed in this study (i) to evaluate heavy metal concentrations in four vegetables from a typical open-air market in Uganda, (ii) to assess the safety of consuming these vegetables against the World Health Organization (WHO) recommended limits of heavy metals consumption, and (iii) to formulate a model of estimated daily intake (EDI) among consumers in the country.

This was a cross-sectional study conducted in five georeferenced markets of Bushenyi district in January 2020. Amaranthus, cabbages, scarlet eggplants, and tomatoes were collected from open markets, processed, and analyzed by atomic absorption spectrometry. Modeled EDI, principal component (PCA) and cluster analysis (CA) were conducted to identify relationships in the samples.

The levels of essential elements in the four vegetables were found to fall from Co > Cu > Fe > Zn. Those of non-essential metals were significantly higher and followed the pattern Cd > Cr > Pb > Ni. The highest EDI values were those of Cu in scarlet eggplants, Zn in amaranthus, Fe in amaranthus, Co in amaranthus, Pb in cabbages, total Cr in scarlet eggplant, Cd in cabbages and tomatoes, and Ni in cabbages. In comparison to international limits, EDIs for Zn, Cu, Co and Fe were low while Ni in cabbages were high. PCA showed high variations in scarlet eggplant and amaranthus. The study vegetables were found to be related with each other, not according to the location of the markets from where they were obtained, but according to their species by CA.

The presence of non-essential elements above WHO limits raises policy challenges for the consumption and marketing of vegetables in the study area. Furthermore, low EDIs of essential elements in the vegetables create demand for nutritious foods to promote healthy communities.


University Researchers

  • Affiliation

    Faculty of Agriculture and Animal Sciences, Busitema University Arapai Campus, Soroti, Uganda

    School of Medicine, Kabale University, Kabale, Uganda

    College of Engineering and Sciences, Purdue University Northwest, Hammond, IN, USA

    Department of Wildlife Resources, School of Veterinary Medicine, College of Veterinary Medicine and Biosecurity, Makerere University, Kampala,

    Faculty of Science and Technology, Cavendish University, Kampala, Uganda

    School of Pharmacy, Kampala International University Western Campus, Bushenyi, Uganda

    Faculty of Biomedical Sciences, Kampala International University Western Campus, Bushenyi, Uganda

    School of Health Sciences, Soroti University, Soroti, Uganda

    Instituto de Ciencias Biol ˆ ogicas, Universidade Federal de Minas Gerais, Minas Gerais, Brazil ´

    Directorate of Research, Natural Chemotherapeutics Research Institute, Ministry of Health, Kampala, Uganda

    Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour, AlBeheira, Egypt

    Department of Humanities and Sciences, University of California – Los Angeles, CA, USA

    Department of Chemistry, Faculty of Science, Gulu University, Gulu, Uganda