Potential of solar treatment to lower the microbial contaminants in geophagic clays
Abstract
Deliberate consumption of earth materials is called geophagia and is practiced worldwide by humans. The various reasons of geophagia practice have been reported in the literature, i.e. why people consume the clays deliberately. Some believe that it reduces morning sickness in pregnant women remedies gastrointestinal distress and supplements minerals and nutrients. Geophagia improves the health of geophagists because the elements in the clays may have nutritional benefits.
Studies were conducted on geophagist individuals to determine the effect of geophagia on pregnant women and children, microbiological infection, anaemia, deficiency of minerals and heavy metal poisoning. Although much has been written internationally about geophagia practice and the materials found on geophagic clay materials, less has been written regarding the health aspects of geophagia, particularly on the microbiological aspects of geophagic clay materials. Furthermore, very little has been investigated about the disinfection of microorganisms in geophagic clay materials to minimize the risk to human health.
This study attempts to find an application, which is available to all, that can be used to disinfect geophagic clay materials which is solar treatment. Samples (marketed and mined) were collected from markets in Pretoria and Potchefstroom (South Africa) and mined from the respective sources. The results of the trace element contents showed low amounts of toxic constituents such as Mn, Cr, Ni, Co, and Pb. At low pH a large amount of metals leached from the clay samples, including Pb, Ni, Co and Fe. The finding of the study indicated that the microbial content of the geophagic clay varied with the origin of the geophagic clay (marketed clays and mined clays, respectively), indicating that marketed clays had the highest microbial content.
Microorganisms in geophagic clays were also inactivated using sunlight. Sunlight has an effect on the microorganisms found in the edible geophagic clays. Escherichia coli, Salmonella enterica and naturally occurring microorganisms were completely inactivated under sunlight. No regrowth and reactivation of bacteria were observed from samples that had reached complete inactivation. Marketed and mined samples achieved a complete inactivation after 2 h of sunlight exposure. Increase in clay temperature was observed in all the geophagic clay samples. During cloudy days, the lower temperature and solar irradiance caused the geophagic clay samples to reach non-complete inactivation.
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To conclude: The study found that geophagic clays are contaminated with microorganisms and are not safe for consumption. However, solar treatment can be applied to disinfect the contaminated geophagic clay.
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