BIOGEOCHEMICAL ANALYSIS AND GEOMEDICAL IMPLICATIONS OF SELENIUM CONCENTRATION IN SOIL AND TEA LEAVES FROM TEA GROWING REGIONS OF KENYA

In this study, tea and soil samples were collected from the tea growing areas of Kenya, namely Western Kenya region, and the Mount Kenya region covering the tea growing sector.

The overall objectives of the research were; first to map the concentration of selenium in soils and in tea leaves from tea growing regions of Kenya. Two, to correlate the selenium concentrations in soil and tea leaf samples, and thirdly, to establish areas with high selenium concentrations in tea leaves.

In order to meet these objectives, the samples collected were prepared and analyzed using ICP, for selenium, zinc, copper, manganese and iron. In total, 256 tea leaf samples were collected from western Kenya region, and a total of 125 samples (including 60 conjugate soil samples) were collected in the Mt. Kenya region for quantitative analyses. Most of the tea plots sampled from the Mt. Kenya region are small scale tea holdings.

The element concentration results obtained from the analyses of the tea leaf samples indicate places where appreciable concentrations of selenium and the associated metallic elements were obtained. It should be emphasized that because there are no prior data on selenium concentration in soil and tea leaf samples undertaken in Kenya, the data presented in this study should be treated as baseline data against which data from future successive studies should be compared.

Clinical management of HIV using selenium supplementation has been undertaken in several studies cited in this study; where it has been reported that selenium deficiency is a significant predictor of HIV related mortality. It is emphasized that this study only set out to establish areas with high selenium concentrations in tea leaves, and not clinical management of HIV patients using tea enriched in selenium as has been construed by some reviewers.