The selection of chemical markers in faeces for the identification of geophagia - abstract

Geophagia is the deliberate ingestion of soil and has been associated with geohelminthiasis, lead poisoning and other conditions of public health importance. It seems worthwhile therefore to investigate the extent of geophagia in the general population. One approach to the identification and quantification of geophagia would be to detect in faeces naturally occurring soil-specific chemical markers. These markers should exist in low concentration in food, water and other edibles, be of low bioactivity, and be excreted quantitatively in faeces. This study reports the selection of chemical markers common to Jamaican soils to be used as indicators of geophagia in the general population. Three common Jamaica soils were sterilised and placed in 1g gelatin capsules. Five volunteers were each asked to ingest 10 g of one of the soils with carmine (an inert gastrointestinal dye). A pre-ingestion faecal sample and all post-ingestion faecal samples were collected until no more carmine was seen in the faeces. The procedures was repeated for the other two soils. All faecal and soil samples were examined by Instrumental Neutron Activation Analysis (INAA). A total of 14 elements were found to be common to the three soils used in this study. Of these, dysprosium, europium, cerium, hafnium and thorium wer consistently detected in the post-ingestion faecals but not in the preingestion faecals. These five elements should make excellent markers of geophagia as they are present in insignificant levels in good compared to soil and seem to have low bioactivity. INAA has the highest sensitivity for dysprosium and europium and both have short processing time (30 minutes per sample). INAA and the use of dysprosium and/or europium as chemical markers would appear to be a promising basis for the detection of geophagia in the general population (AU)

The use of eggs in the assessment of selenium status of a community - abstract

Selenium (Se) deficiency appears to play a part in the development of oedematous malnutrition. It occurs in regions where soil Se availability is low. This is likely in wet, tropical limestone-based regions, such as in much of Jamaica. In high Se regions in Venezuela, Se status of the inhabitants and Se concentrations in the locally produced eggs were high. The present study explored the potential use of egg Se concentrations as a monitor for low Se areas in Jamaica. Six areas were selected, three of which were expected to be low Se areas. Homes were visited and free range hens' eggs, soil samples and hair samples were collected. Se concentrations of the sample were measured. For each area, the mean concentrations in ppm dry weight were: Glengoffe, Haynes, E. St. Thomas, Porus, Mavis Bank, Lluidas Vale; YOLK - 1.3, 2.1, 2.2, 1.8, 1.2, 1.6 respectively Total mean is 1.8; WHITE - 1.5, 3.0, 4.4, 2.4, 1.6, 2.1 Total mean is 2.7; SOIL - 0.7, 0.6, 1.1, 1.8, 0.4, 1.9 respectively Total mean is 1.2; HAIR - 0.5, 0.6, 0.6, 0.8, 0.5, 0.5 respectively Total mean is 0.6. In many of the soil samples, the values found were lower than the accepted normal range. However, in egg and hair samples, they were mostly within the normal (literature) range. There were no very low values. There was a linear correlation between egg white and egg yolk concentrations (n=101, r=0.84, p<0.001) and between egg yolk and soil concentration (n=102, r=0.20, p<0.05). Overall, however, egg Se concentration did not reflect closely either soil or hair Se concentration, and therefore is unlikely to be a useful index of Se status of a community (AU)