Geophagic Clays from Cameroon: Provenance, Metal Contamination and Health Risk Assessment

Abstract

This study assessed the mineralogical and geochemical characteristics of geophagic clays sold in some markets in Cameroon to ascertain their provenance, contamination status and human health risk. To achieve this, 40 samples from 13 markets in Cameroon were purchased and analysed using X-ray diffractometry, X-ray fluorescence and laser ablation inductively coupled plasma mass spectrometry for their mineralogy and geochemistry, respectively. The geophagic clays were dominantly made up of kaolinite and quartz. Their chemistry was dominated by SiO2, Al2O3 and LOI with means of 48.76 wt%, 32.12 wt% and 13.93 wt%, respectively. The major, trace and rare earth elements data showed that these geophagic clays were predominantly derived from felsic rocks. The contamination assessment indicated no enrichment of metals from anthropogenic sources, except for Zn in samples from Acacia, Madagascar and Mfoudi markets. The index of geo-accumulation indicated no contamination to moderate contamination of the clays. The non-carcinogenic index values for Fe, Co, Cr, Cu, Ni, Pb and Zn were generally less than 1, suggesting no non-carcinogenic risk exposure to children and adults consuming the geophagic clays from these metals. The carcinogenic risk index (TCR) for Ni and Cr were above 10−6, which implies that children and adults are vulnerable to minimal carcinogenic health risk. The TCR values from Ni posed the highest risk, especially to children consuming clays from some markets.

Deterministic and Probabilistic Health Risk Assessment of Toxic Metals in the Daily Diets of Residents in Industrial Regions of Northern Ningxia, China

“…The HI was calculated using Eq. 4 and used to assess the total noncarcinogenic health risk: an HI value ≤ 1 means that the exposed population is unlikely to experience notable adverse effects, and if the value is > 1, there may be noncarcinogenic effects on human health [ 24 , 25 ]. …”

Optimization of Carboniferous Egyptian Kaolin Treatment for Pharmaceutical Applications

“…Clay-eating, or kaolin-eating (geophagy), remains a global practice that is commonly observed among peoples, as well as numerous animal species, on all the continents, and especially in Africa [7,8,57,58]. These geophagic kaolin are traditionally sold in open markets and herbalists' centers as a vital source of mineral nutrients, without any proper health risk assessment or adequate treatment [58].…”

“…These geophagic kaolin are traditionally sold in open markets and herbalists' centers as a vital source of mineral nutrients, without any proper health risk assessment or adequate treatment [58]. Many researchers have reported elevated concentrations of PTEs, such as As, Cd, Cu, Pb, Ni, and V in the geophagic kaolin samples in numerous countries [7,8,[57][58][59]. The adopted method in this research can be considered a reliable method for the removal of PTEs from geophagic kaolin in order to make such clays safe for human and animal intake and to sustain healthier communities.…”

“…This mineral exhibits many excellent physical, mechanical, and structural properties, which comply with the pharmaceutical technology requirements and which make them very useful for many pharmaceutical applications [1,5]. The chemical compositions of clay minerals include many potentially toxic elements (PTEs) in significantly different concentrations [5][6][7][8]. Some of these elements have harmful effects, such as As, Cd, Co, Cr, Ni, Pb, and V. Excessive exposure to these PTEs could lead to one disease or another [9][10][11][12][13][14].…”

Geophagic Materials Characterization and Potential Impact on Human Health: The Case Study of Maputo City (Mozambique)

“…Geophagists' motivations are diverse, e.g., cultural/social, medicinal, nutritional, spiritual, religious, and physiological [5]. Although associated with pregnant and lactating women, the practice is also reported in children, adolescents, and young people, transversal to religious beliefs, culture, and socioeconomic classes [6,7]. Geophagy can also occur by involuntary ingestion, mostly associated with children and their deliberate hand-to-mouth activities, but can also occur by pica behavior, i.e., voluntary ingestion of soil materials [8,9].…”