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Environ Geochem Health. 2019 Feb 18. doi: 10.1007/s10653-019-00253-2. [Epub ahead of print]

The geochemistry of geophagic material consumed in Onangama Village, Northern Namibia: a potential health hazard for pregnant women in the area.

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Department of Geology, University of Johannesburg, Johannesburg, South Africa.
GeoBioTec, Geosciences Department, University of Aveiro, Aveiro, Portugal.
EpiUnit, Public Health Institute, University of Porto, Porto, Portugal.
Environmental and Engineering Geology Division, Geological Survey of Namibia, Windhoek, Namibia.
Department of Geology, University of Johannesburg, Johannesburg, South Africa.


Ingestion of geophagic materials might affect human health and induce diseases by different ways. The purpose of this study is to determine the geochemical composition of geophagic material consumed especially by pregnant women in Onangama Village, Northern Namibia and to assess its possible health effects. X-ray fluorescence and inductively coupled plasma mass spectrometry were used in order to determine the major, and trace elements as well as anions concentrations of the consumed material. The geochemical analysis revealed high concentrations of aluminium (Al), calcium (Ca), iron (Fe), magnesium (Mg), manganese (Mn), potassium (K), sodium (Na), and silica (Si); and trace elements including arsenic (As), chromium (Cr), mercury (Hg), nickel (Ni) and vanadium (V) as well as sulphate (SO42-), nitrate (NO3-), and nitrite (NO2-) anions comparing to the recommended daily allowance for pregnant women. The pH for some of the studied samples is alkaline, which might increase the gastrointestinal tract pH (pH < 2) and cause a decrease in the bioavailability of elements. The calculated health risk index (HRI > 1) revealed that Al and Mn might be a potential risk for human consumption. Based on the results obtained from the geochemical analysis, the consumption of the studied material might present a potential health risk to pregnant women including concomitant detrimental maternal and foetal effects.


Geochemistry; Geophagy; Pregnant women; Termite mound soils


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