Geophagic clay around Uteh-Uzalla near Benin: mineral and trace elements compositions and possible health implications

Mineral composition and heavy metal risk assesment of selected geophagic soils from Tanzania

Geophagy or Pica is the unintentional traditional behavior of eating soil by indigenous people in different countries. practiced in many countries due to nausea among pregnant women and mineral deficiencies without knowing the associated health risks. In this study the mineral composition of geophagic soil and its associated health risk among consumers was determined. Dry soil sticks consumed by women were obtained from open markets in Morogoro, Njombe and Mwanza regions in Tanzania. The elemental concentration of geophagic soil was analyzed using Flame Atomic Absorption spectrophotometer. Health risk assessment methods were used to obtain health information after chronic exposure to geophagic soils. The tests used were Target Hazard Quotients (THQ), Total Target Hazard Quotients (TTHQ) and Cancer Risks (CR). The concentration range of metals in samples obtained from three different regions were 16,335.7-47,773.7 mg/kg for Fe, 46.2-1073.5 mg/kg for Ca, 155.3-514.9 mg/kg for K, 44.5-112.4 mg/kg for Zn, 40.7-95.1 mg/kg for Na, 2.4-66.7 mg/kg for Cu, 109.5-572.6 mg/kg for Mn, 3.8-6.85 mg/kg for Pb, 3.1-93 mg/kg for Ni, 62.7-638.6 mg/kg for Cr and 0.4 mg/kg for Cd. The Provisional Daily Intake (PDI), THQ, TTHQ and CR ranged between 3.0 × 10-3 -34.12 mg/kg/day bw, 0.043-48.75, 34.52-77.36 and 2.55×10-5- 0.23 respectively. The TTHQ>1 was evident for metals in all sampling sites which is indicative of non-carcinogenic health effects. Prolonged exposure to Pb at low concentrations in samples from all the sites can cause pathological effects. The cancer risk values for Pb, Ni, Cr and Cd were <1 in which the consumer is likely not to develop cancer in a life time. Essential minerals - Fe, Ca, Zn, Na, K and toxic metals Pb, Cr, Ni and Cu were detected in all the samples. Cd occurred only in samples from Mwanza region that was below the tolerable daily intake. According to WHO/FAO expert's joint committee any amount of Pb consumption is not permitted. Given the presence of essential minerals in the geophagic soils which are however accompanied by toxic minerals in some cases which might have carcinogenic effects, prolonged consumption should be discouraged to avoid risks of serious adverse effects to the health of the general population.

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

This study aims to characterize and estimate risk assessment associated with geophagic materials consumption in Maputo city (Mozambique). Samples were collected in extraction mines, unprepared and prepared ones, and in Maputo markets. Fractions < 2 mm (total consumed material) and <63 μm were analyzed to determine pH, EC, OM, chemical composition (XRF), and mineral phases present (XRD). The results revealed pH from slightly acidic to slightly alkaline, and electrical conductivity ranging from 13 to 47 μS/cm in mine unprepared and prepared samples, while 264–465 μS/cm in sampled sold in markets. Organic matter content was <2.76%, except in one sample (8.14%), suggesting a potential risk of containing bacteria. Textural analysis revealed that sand-size particles were more representative in all samples (57.2–93.02%). Mineralogical phases identified in the consumed sample were ranked quartz (>60%) > Fe oxides/hidroxides > phyllosilicates (micas and kaolinite) > feldspars, suggesting a risk of dental enamel damage and perforation of the sigmoid colon. The chemical concentration of some elements was higher than recommended daily dose, suggesting a potential risk. However, geophagic materials’ chemical composition does not pose a carcinogenic risk.

Optimization of Carboniferous Egyptian Kaolin Treatment for Pharmaceutical Applications

This paper quantitatively determines the occurrences of potentially toxic elements in Carboniferous kaolin in southwestern Sinai, Egypt. This research describes, in detail, the experimental treatment optimization to be used in pharmaceutical applications. The concentrations of As, Co, Ni, Pb, and V in these kaolin deposits exceed the Permitted Concentrations of Elemental Impurities for oral use in pharmaceutical applications. Herein, six desorbing agents (acetic acid, citric acid, DTPA, EDDS, EDTA, and NTA) were utilized as extracting solutions in batch-wise extractions to select the proper reagents. Parameters such as the pH, the mixing speed and time, and the solid–solution ratio were varied to optimize the extraction conditions. The findings indicate that citric acid and EDTA were effective in the removal of the aforementioned elements. The results reveal that the optimum removal of potentially toxic elements from kaolin can be achieved using citric acid and EDTA concentrations of 0.2 M and 0.1 M, respectively, for the treatment of 5 g of kaolin, under a pH of 4 for citric acid, and a pH of 10 for EDTA. The ideal mixing speed and time are 500 rpm and 6 h, respectively. Using 1:10 S/L of citric acid and EDTA showed removal rates of 100% for all the investigated PTEs. We recommend this treatment for different kinds of kaolin showing various degrees of contamination.