Non-destructive XRF analysis of Nigerian and Kenyan clays

Ibeanu, I. G. E.; Dim, L. A.; Mallam, Simon; Akpa, T. C.; Munyithya, J.

doi:10.1007/bf02035268

Cited by 16 publications

(9 citation statements)

References 6 publications

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“…In the study of Dean et al (2004), arsenic, mercury and cadmium were not detected. However, Ibeanu et al (1997) found lead, by using EDXRF, in three samples of Nigerian and Kenyan clays at levels that were two to three times higher than the mean level found in the African clay products in the current study. In the UK, the Food Standards Agency (2002) reported for calabash chalk lead levels of 8.2-16.1 mg kg −1 , which were below the range of lead levels of African clay products included in our study (19.2-47.6 mg kg −1 ).…”

Section: Discussioncontrasting

confidence: 72%

Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

Reeuwijk

Klerx

Kooijman

et al. 2013

Food Additives & Contaminants: Part A

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Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contain high levels of metals and metalloids, the aim of this study was to determine lead, arsenic, mercury and cadmium in clay products for oral use available on the Dutch market. Traditional clays originating from Africa (n = 10) and Suriname (n = 26), and health clays (n = 27) were sampled from 2004 up to and including 2012. Total metal and metalloid contents were measured by ICP-MS and showed maximum levels of lead, arsenic, mercury and cadmium of 99.7, 45.1, 2.2 and 0.75 mg kg⁻¹, respectively. In the absence of maximum limits for these type of clays, the potential exposure was estimated from the determined concentration, the estimated daily use level of the clays, and the estimated bioaccessibility of the different metals and arsenic. The intake estimates were compared with existing health-based guidance values. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the toxicological limit by up to 20-fold. Use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the toxicological limit for inorganic arsenic by up to 19-fold. Although limited bioaccessibility from the clay may limit the exposure and exceedance of the health-based guidance values, it was concluded that lead and arsenic intakes from some clay products could be of concern also because of their use by pregnant women and the potential developmental toxicity. As a result the use of these products, especially by pregnant women, should be discouraged.

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Section: Discussioncontrasting

confidence: 72%

Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

Reeuwijk

Klerx

Kooijman

et al. 2013

Food Additives & Contaminants: Part A

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“…There are several classes of clay which include; smectites (montmorillonite, saponite), mica (illite), kaolinite, serpentine, pylophyllite (talc), vermiculite and sepiolite (Nayak and Singh, 2007). The specific elemental composition of each clay material will usually depend on the amount of the element present in the host rock, the chemical association of the elements with stable and/or unstable mineral during weathering and the intensity of drainage and other polygenetic alterations associated with clay materials (Ibeanu et al, 1997). It has a wide range of applications in the building and ceramic industries.…”

Section: Introductionmentioning

confidence: 99%

Determination of radionuclides and elemental composition of clay soils by gamma- and X-ray spectrometry

2013

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Radiochemical and elemental analysis of clay soils collected from different locations within Ekiti State have been performed in this study using gamma and XRF spectrometric measurements. The results of this study show that the mean concentrations of uranium ranged from 2.2 ± 1.0 mg/kg to 3.2 ± 1.1 mg/kg, that of thorium ranged from 4.0 ± 0.5 mg/kg to 5.7 ± 1.7 mg/kg, while potasium presented in % by weight ranged from 0.4 ± 0.2 to 1.3 ± 0.3 in all the locations. The overall mean concentrations of these radionuclides are comparable to values from other locations around the world. The XRF analysis revealed 4 major elements and 11 minor or trace elements present in the clay samples. The distribution of the various major and trace elements in all the sampling sites do not follow any systematic trend but vary from point to point. To assess the level of contamination and the possible anthropogenic impact in the clay soils, the enrichment factor (EF) and the geoaccumulation index (Igeo) were estimated for some potential hazardous elements. The results indicate that Cu, Zn, Ni and Mn have EF < 2 indicating minimal or no enrichment while Pb is moderately enriched in all the locations.

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“…This sour taste is one main reason why people, especially the pregnant women crave for this clay. Consumption of clay is reported to control excessive secretion of saliva and reduce nausea (Ibeanu et al, 1997). The values of the pH (H 2 O) of all the samples were significantly higher than those of pH (KCl) indicating that the samples were all negatively charged.…”

Section: Discussion Ph Of Geophagic Clayey Materialsmentioning

confidence: 95%

Physico-chemical Characterization of Clayey Materials Consumed by Geophagism in Locality of Sabga (North-western Cameroon): Health Implications

Duplex¹,

Ludovic²,

Njopwouo³

et al. 2018

IJAST

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Geophagy is the habitual and intentional consumption of earth and clay deposits by animals and humans. Physicochemical properties of geophagic clayey materials from Sabga were determined in order to appreciate their capability to perform the functions for which they are consumed and possible consequences of the practice in humans. Among the properties investigated are: Tests conducted included colour, particle size distribution (PSD), consistency limits, pH, Electrical Conductivity (EC), Water Retention Capacity (WRC), Organic Matter Content (OMC) and Cation Exchange Capacity (CEC). Results show that the pH values range from 4.1 to 5.6. EC (0.01 to 0.02) and OMC values are low (3.99 to 5.10%). The WRC values are generally very high (above 50%). The samples were observed to have low CEC, ranging from 26.96 to 43.28. Geochemical data indicated that geophagic materials clayey are composed of SiO 2 content ranging from 41.86% to 64.84%, Al 2 O 3 values varies from 12.75% to 23.41%, Fe 2 O 3 values varies from 4.14% to 13.29%, K 2 O content values varies from 0.28 to 2.43%, MgO content varies from 0.00% to 0.36%, CaO ranges between 0.04% and 0.56%, Na 2 O values varies from 0.10 to 1.78%, TiO 2 values varies from 0.22% to 0.95%, P 2 O 3 values varies from 0.02 to 0.05% and MnO content ranges from 0.01% to 0.12%. These values indicate that the geophagic clayey materials are essentially siliceous aluminosilicates. XRD revealed that geophagic clayey materials contain several minerals and the main reflections of the clay minerals identified were smectite and kaolinite. The peaks of other minerals are Kfeldspars, plagioclases, hematite, goethite and quartz. The peaks of traces are ilmenite. The present studies have shown that the high clay content and the high water retention capacity may help to alleviate the symptoms of diarrhea because of its absorption ability. Because of the low CEC of the soils, adsorption of cations H + from the stomach may not be possible for the relief of the gastric acidity. But from results of available elements, there is tendency for some of the cations to be released and absorbed into the gastrointestinal tract. Possible human health short coming in the ingestion of the geophagic clayey materials would include dental enamel damage and perforation of the sigmoid colon. These clayey soils, due to their colour are inferred to contain different forms of iron oxide minerals including hematite and goethite, which may help alleviate symptoms of iron deficiency anaemia.

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Non-destructive XRF analysis of Nigerian and Kenyan clays

Cited by 16 publications

References 6 publications

Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

Determination of radionuclides and elemental composition of clay soils by gamma- and X-ray spectrometry

Physico-chemical Characterization of Clayey Materials Consumed by Geophagism in Locality of Sabga (North-western Cameroon): Health Implications

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