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Human geophagia, Calabash chalk and Undongo: Mineral element nutritional implications

By Peter William Abrahams, Theo C. Davies, Abiye O. Solomon, Amanda Jayne Trow and Joanna Wragg

Abstract

The prime aim of our work is to report and comment on the bioaccessible concentrations ? i.e., the soluble content of chemical elements in the gastrointestinal environment that is available for absorption ? of a number of essential mineral nutrients and potentially harmful elements (PHEs) associated with the deliberate ingestion of African geophagical materials, namely Calabash chalk and Undongo. The pseudo-total concentrations of 13 mineral nutrients/PHEs were quantified following a nitric-perchloric acid digestion of nine different Calabash chalk samples, and bioaccessible contents of eight of these chemical elements were determined in simulated saliva/gastric and intestinal solutions obtained via use of the Fed ORganic Estimation human Simulation Test (FOREhST) in vitro procedure. The Calabash chalk pseudo-total content of the chemical elements is often below what may be regarded as average for soils/shales, and no concentration is excessively high. The in vitro leachate solutions had concentrations that were often lower than those of the blanks used in our experimental procedure, indicative of effective adsorption: lead, a PHE about which concern has been previously raised in connection with the consumption of Calabash chalk, was one such chemical element where this was evident. However, some concentrations in the leachate solutions are suggestive that Calabash chalk can be a source of chemical elements to humans in bioaccessible form, although generally the materials appear to be only a modest supplier: this applies even to iron, a mineral nutrient that has often been linked to the benefits of geophagia in previous academic literature. Our investigations indicate that at the reported rates of ingestion, Calabash chalk on the whole is not an important source of mineral nutrients or PHEs to humans. Similarly, although Undongo contains elevated pseudo-total concentrations of chromium and nickel, this soil is not a significant source to humans for any of the bioaccessible elements investigatedpublishersversionPeer reviewe

Year: 2013
DOI identifier: 10.1371/journal.pone.0053304
OAI identifier: oai:cadair.aber.ac.uk:2160/8817
Journal:

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Citations

  1. (2004). 5th Report of the world nutrition situation: nutrition for improved development outcomes.
  2. (1979). A note on geophagy among the Afenmai and adjacent peoples of Bendel State,
  3. (1934). An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. doi
  4. (2011). An interlaboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil. doi
  5. (1982). Atomic absorption methods in applied geochemistry. doi
  6. (1998). Bioavailability of soilborne lead in adults, by stable isotope dilution. doi
  7. Calabash Chalk and Undongo: Mineral Element Nutritional Implications Peter doi
  8. (2007). Calabash chalk may pose health risk for pregnant and breastfeeding women. Available: http://www.hc-sc.gc.ca/ahc-asc/media/ advisories-avis/_2007/2007_136-eng.php Accessed
  9. (2004). Characterisation and analysis of persistent organic pollutants and major, minor and trace elements in Calabash chalk. doi
  10. (1972). Chemistry of the earth.
  11. (2001). Cited in: Njiru H, Elchalal U, Paltiel O
  12. (1938). Cited in: Young SL (2011) Craving earth: Understanding pica: The urge to eat clay, starch, ice, and chalk. doi
  13. (2012). City Department of Health and Mental Hygiene (no date) Calabash chalk containing lead and arsenic. Available: http://www.nyc.gov/html/doh/ downloads/pdf/lead/lead-calabash-chalk-faq.pdf Accessed 22
  14. Clarkson TW (2007) Routes of exposure, dose, and metabolism of metals. doi
  15. (2010). Comparison of batch mode and dynamic physiologically based bioaccessibility tests for PAHs in soil samples. doi
  16. (2002). Comparison of five in vitro digestion models to study the bioaccessibility of soil contaminants. doi
  17. (1991). Dietary reference values for food energy and nutrients for the United Kingdom. doi
  18. (1975). Environmental lead exposure in Christchurch children: soil lead a potential hazard.
  19. (2006). Estimation of relative bioavailability of lead in soil and soil-like materials using young swine. doi
  20. (2011). Evaluation of certain food additives and contaminants. doi
  21. (1984). Fluoride, vanadium, nickel, arsenic and silicon in total parenteral-nutrition.
  22. (2006). Food Standards Agency doi
  23. (2009). Function of geophagy as supplementation of micronutrients in Tanzania. doi
  24. (1978). Geophagic lead nephropathy: case report. doi
  25. (1997). Geophagy (soil consumption) and iron supplementation in Uganda. doi
  26. (1966). Geophagy among the Tiv of Nigeria. doi
  27. (2008). Geophagy and human nutrition: the bioaccessibility of essential and potentially toxic elements in Nigerian and other soils. MSc thesis,
  28. (2010). Geophagy and potential health implications: geohelminths, microbes and heavy metals. doi
  29. (1973). Geophagy in Africa and in the United States. A culturenutrition hypothesis. doi
  30. (1996). Geophagy in the tropics: a literature review. doi
  31. (1998). Geophagy, iron status and anaemia among pregnant women on the coast of Kenya. doi
  32. (1998). Geophagy, iron status and anaemia among primary school children in Western Kenya. doi
  33. (2003). Human bioaccessibility of heavy metals and PAH from soil.
  34. (2005). Human health risks from low-level environmental exposures: no apparent safety thresholds. doi
  35. (2004). In vivo experimental data on the mobility of hazardous chemical elements from clays. doi
  36. (2006). In-vitro testing for assessing oral bioaccessibility of trace metals in soil and food samples. doi
  37. (2012). Involuntary soil ingestion and geophagia: A source and sink of mineral nutrients and potentially harmful elements to consumers of earth materials. doi
  38. (2006). Iron nutrition and possible lead toxicity: an appraisal of geophagy undertaken by pregnant women of UK Asian communities. doi
  39. (1954). Munsell soil color charts. doi
  40. (1990). Nickelsensitive patients with vesicular hand eczema: oral challenge with a diet naturally high in nickel. doi
  41. (1985). Nigerian geophagical clay: A traditional antidiarrheal pharmaceutical. doi
  42. (2001). Oral bioavailability of lead and arsenic from a NIST standard reference soil material.
  43. (2011). Oral bioavailability. In: Swartjes FA, editor. Dealing with contaminated sites (from theory towards practical application). doi
  44. (1974). Physical and chemical analyses of ,2 mm samples.
  45. (2010). Risk of human exposure to arsenic and other toxic elements from geophagy: trace element analysis of baked clay using inductively coupled plasma mass spectrometry. doi
  46. (2003). Safe Upper Levels for vitamins and minerals.
  47. (2010). Scientific opinion on lead in food. doi
  48. (1989). Sikor: an unquantified hazard.
  49. (2000). The bioaccessibility of essential and potentially toxic trace elements in tropical soils from Mukono District, doi
  50. (2004). The potential impact of soil ingestion on human mineral nutrition. doi
  51. (2012). to assess the bioaccessibility of arsenic, antimony, cadmium, and lead in soils. doi
  52. (1980). Trace element levels in soils: effects of sewage sludge. In: Inorganic pollution and agriculture: proceedings of a conference organised by the Agricultural Development and Advisory Service,
  53. (1996). World Health Organisation doi

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