Clay and Health

Throughout history, clay has had a very close relationship to human health and life in general. When considered in detail, it is fascinating to see how many applications of clay exist. Across the ages, clay has been used in medicine. Animals and humans ingest clay to prevent the absorption of toxic molecules, whilst people bathe in clay to relieve stress. Some theories say that clay is linked to the origin of molecular life. Once fired, clay becomes ceramic and provides humans with many useful objects. Furthermore, clay has been used to build the first shelters and is still widely used to build homes all around the world [1-3]. One conclusion that one can definitely make is that clay seems to be compatible with life in many ways.

In geology, we know that most types of clay form on the upper surface of the earth’s crust, where they form sedimentary deposits at the boundary between the Lithosphere and the Biosphere. Philosophically they can be seen as a boundary between the mineral and the organic world, not only through its localisation on the upper level of the earth’s crust but also by the complexity of clay minerals.

In academia, “clay” refers to a fine-grained soil, which is used as a building material. But “clay mineral” on which most of academic research has been done on refers to a group of minerals. These clay minerals are responsible for the benefits clays provide.

Clay minerals have been studied in academia for a large variety of applications, due to their high surface reactivity: clay minerals are negatively charged on their surface, this charge is compensated by the adsorption of cations or molecules and they have a “high surface area”.  For example, a Montmorillonite (a type of clay mineral) can have a surface area of up to 800m2 per gram of material, which is the equivalent of two tennis courts. They have therefore a strong potential to adsorb many different molecules by considerable amounts. Examples of these clay minerals can be found in “Handbook of Clay Science” by F. Bergaya (France, 2011). One of the applications, receiving more and more interest, is the capacity of clay to regulate indoor humidity.

Fionn McGregor
University of Bath, March 2014

Fionn McGregor holds an MSc in Clay science. He is a PhD Candidate in Earth building materials at the BRE Centre for Innovative Construction Materials, University of Bath, United Kingdom. Contact Fionn at: F.A.P.McGregor@bath.ac.uk

 

1. Rautureau, M., et al., Argiles et santé : Propriétés et thérapies. Editions médicales internationales ed. 2010: Lavoisier. 184 p.
2. Harris, C. Did clay mould life’s origins? 2011; Available from: http://www.ox.ac.uk/media/science_blog/110401.html.
3. Carretero, M.I., C.S.F. Gomes, and F. Tateo, Chapter 5.5 – Clays, Drugs, and Human Health, in Developments in Clay Science, B. Faïza and L. Gerhard, Editors. 2013, Elsevier. p. 711-764.

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