Browsing by Author "Nkuba, Leonid L."

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    Concentration Levels and the Associated Health Risks of Elements in Food Crops Grown in the Neighbourhood of Minjingu Phosphate Mine, Tanzania
    (SCIENCEDOMAIN international, 2017) Mohammed, Najat K.; Nkuba, Leonid L.
    The concentration levels of heavy metals in food crops (maize and mung beans) grown in the neighbourhood of Minjingu Phosphate mine were analyzed using EDXRF. The metal concentrations in both food crops followed the following pattern Fe > Zn > Cu > Cd > Cr > Pb > As. Maize accumulated higher levels of all analyzed elements than mung beans. The concentration level of metals in maize and mung beans from Minjingu were higher than those from the control site. Except for Cd in both types of samples, the concentration levels of all other metals were below the FAO/WHO recommended limits. The risk assessment showed that consumption of mug beans from Minjingu is without any safety risk while there is a risk in consumption of maize due to the concentration of Cd. However, the number of samples was not sufficient enough to make a definite conclusion; therefore, there is need for further analysis to include more data.
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    DETERMINATION OF RADIOACTIVITY IN MAIZE AND MUNG BEANS GROWN IN THE NEIGHBORHOOD OF MINJINGU PHOSPHATE MINE, TANZANIA
    (College of Natural and Applied Sciences, 2014) Nkuba, Leonid L.; Mohammed, Najat K.
    Two staple foods (maize and mung beans) which were cultivated in Minjingu village, where there is phosphate deposit in Tanzania, were collected directly from the farms. The activity concentrations of 226Ra, 228Th and 40K were determined in the maize and mung beans samples using γ ray spectrometry employing HPGe detector of relative efficiency of 51.0 %. The mean radioactivity level in the food samples were found to be 21.01 ± 0.8 Bq/kg (mung beans), 25.6 ± 0.7 Bq/kg (maize) for 226Ra, 62.6 ± 1.1 Bq/kg (mung beans), 72.9 ± 1.0 Bq/kg (maize) for 228Th and 542.9 ± 8.6 Bq/kg (mung beans), 434.6 ± 18.7 Bq/kg (maize) for 40K. The radioactivity content of the maize and mung beans from Minjingu village were higher than that of similar food samples collected from Bukombe district in Geita Region in Tanzania. The total annual effective dose for consumption of 226Ra and 228Th by adults was calculated to be 2.003 ± 0.044 mSv/year, which is higher than the annual dose limit of 1 mSv/year recommended by the ICRP for the general public. Hence a conclusion could be made that food crops cultivated at Minjingu village might expose the population to high radiation dose which might be detrimental to their health.
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    Heavy Metals and Essential Elements in Selected Medicinal Plants Commonly Used for Medicine in Tanzania
    (SCIENCEDOMAIN international, 2017) Nkuba, Leonid L.; Mohammed, Najat K.
    Several plants in Tanzania are known to be of potential therapeutic value and are used in traditional medicine system of the country. In this paper, two medicinal plants Moringa oleifera (leaves and roots), and Hibiscus sabsdariffa (rosella calyces) were analysed for elemental concentration. Essential and non-essential heavy metals like Mg, K, Mn, Fe, Ni, Cu, Zn, Cd and Pb were quantified in selected medicinal plants by EDXRF technique. The main purpose of this study is to document the presence and the levels of heavy metals in these herbs. High Potassium contents were observed to be 20882.20 ± 253.65 mg/kg in Moringa oleifera roots, in Hibiscus sabsdariffa (rosella calyces) 15732.03 ± 191.27 mg/kg, and 14541.08 ± 206.83 mg/kg in Moringa oleifera leaves. Magnesium was the second abundant element with concentration (5058.13 ± 115.80 mg/kg in Moringa oleifera leaves, 4328.86 ± 132.85 mg/kg Hibiscus sabsdariffa and 1400.59.59 ± 72.09mg/kg in Moringa oleifera roots), followed by Iron (716.57 ± 48.05 mg/kg in Hibiscus sabsdariffa, 556.44 ± 11.77 mg/kg and 309.57 ± 8.96 mg/kg in Moringa oleifera roots and leaves respectively. Except Fe and Ni in all plant samples and Mg in leaves of Moringa oleifera and calyces of Hibiscus sabsdariffa as well as Mn in roots of Moring oleifera, the concentrations of other metals were below the permissible limits in plants set by FAO/WHO. The results presented that there is no risk associated with consumption of analysed medicinal plants. However, since Cd was not detected and it is highly toxic even at very low concentrations. Therefore, further analysis which will employ other analytical techniques and includes more samples is needed to have a definite statistical conclusion on the safety consumption of the analysed medicinal plants. The results also show that the analysed plant species are beneficial sources of appropriate and essential trace elements.