3.2 Geophagical Clays-Extraction, Preparation, and Distribution: Dr. Don Vermeer
Dr. Vermeer addressed deliberate consumption of clays or earths, called geophagy (as defined in Section 2.0). He explained that geophagy has been observed on all continents, but that it is particularly prevalent among certain cultural groups. He noted that geophagy involves much higher ingestion rates than the incidental ingestion data presented by Dr. Freeman, but he stressed that the clays consumed are typically from known, and usually uncontaminated sources, as described below.
Noting that the geophagical practices in Africa are an antecedent to those practices in African-Americans, Dr. Vermeer first described the African tradition of consuming processed clays. He showed photographs of a typical source of geophagical clays, which were located about 2-3 feet below the surface. Dr. Vermeer stressed that surface soils are rarely consumed, and thus contamination confined to surface soils is likely not an issue for culturally-associated geophagical consumption of clays. He then explained how the extracted clays are stored and processed into their final shapes, and he noted how the processing practices can vary from village to village. Dr. Vermeer said that some clays were prepared with various herbs and leaves for medical purposes.
Production of the geophagical clays, according to Dr. Vermeer, is estimated to be as high as 500 tons per year in African villages he visited. Consumption of these clays appears to be greatest among women, particularly pregnant ones, but was also prevalent among children. Dr. Vermeer noted that typical consumption of these clays among women ranges from 30 to 50 grams per day, but much higher levels of consumption have been observed.
Dr. Vermeer then characterized geophagical practices in the United States, which he said were transferred to the New World largely via the slave trade, though he acknowledged that indigenous Indian groups throughout the New World and European immigrants in the southern Appalachian region consumed geophagical clays. To illustrate the current practice of geophagy in the United States, Dr. Vermeer presented research he conducted on this activity in Holmes County, Mississippi, where clays are primarily extracted from the B horizon, 18 to more than 36 inches below the surface, and rarely from surface deposits. An extraction site typically is associated with one extended family. He added that geophagy has been documented to occur in recent years in various southern communities, including Atlanta, as well as in Hispanic cultures. In conclusion, Dr. Vermeer stressed that the geophagical clays consumed in the United States are primarily from known, and usually uncontaminated sources.