Clays and Clay Minerals, Vol. 56, No. 6, 751–760, 2008.
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Authors
Ferrell Jr., Ray E.
Issue Date
2008
Type
Article
Language
Keywords
Periodicals , Geology , Clay , Geochemistry , Healing Clay , Health , Human Geophagy , Major Elements , Medical Geology , Reference Dose Ratio , Trace Elements
Alternative Title
Medicinal Clay And Spiritual Healing
Abstract
The varied mineralogical composition of earthymate rials and the quantityof elements extracted bysimula ted stomach acid substantiate the diversityof materials consumed by humans practicing geophagy. Direct consumption of ‘edible earths’ for medicinal and spiritual purposes occurs worldwide and is deeplyrooted in ‘folk medicine’ and religion. The legends associated with the healing powers of the clay from Chimayo, New Mexico, provide an excellent example of the roots of geophagy. The clay mineral assemblages revealed byX-ra yd iffraction analysis of 22 samples from New Mexico, North America, and other parts of the world are highlyvariable. One might be monominerallic kaolinite or smectite, and another, a complex mixture of illite, kaolinite, smectite, and chlorite or vermiculite. The quantities of elements (Al, Si, K, Na, Ca, Mg, Fe, Mn, Ti, P, S, Ba, Sr, Pb, Zn, Cd, Co, Cu, Cr, Ni, V, Zr, Se,Mo, Be, Sb, and As) extracted by0.1 2M HCl varied from ~1.0 mg/g to the limit of detectability, 0.0001 mg/g. Potential long-term human health effects were evaluated with the Reference Dose Ratio (RDR). It divides the quantityof the element extracted from 50 g of the total sample by the recommended reference dose (RfD) reported in the Environmental Protection Agency’s (EPA, USA) IRIS (Integrated Risk Information System) database. Median RDR values for Na, Cr, Sb, and As exceeded 1.0 indicating an abnormally high potential intake. Materials consumed byhumans are so varied that caution should be used in comparing the results of one claystudywith those of another without mineralogical and chemical data.
Description
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Citation
Clays and Clay Minerals, Vol. 56, No. 6, 751–760, 2008.
Publisher
The Clay Minerals Society
License
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