Medical geochemistry of tropical environments

Geochemically, tropical environments are unique. This uniqueness stems from the fact that these terrains are continuously subjected to extreme rainfal l and drought with resulting strong geochemical fractionation of elements. This characteristic geochemical partitioning results in either severe deple tion of elements or accumulation to toxic levels. In both these situations, the effect on plant, animal and human health is marked. Medical geochemist ry involves the study of the relationships between the geochemistry of the environment in which we live and the health of the population living in thi s particular domain. Interestingly, the relationships between geochemistry and health are most marked in the tropical countries, which coincidentally are among the poorest in the world. The very heavy dependence on the immedi ate environment for sustainable living in these lands enables the medical g eochemist to observe correlations between particular geochemical provinces and the incidence of certain diseases unique to these terrains. The aetiolo gy of diseases such as dental and skeletal fluorosis, iodine deficiency dis orders, diseases of humans and animals caused by mineral imbalances among o thers, lie clearly in the geochemical environment. The study of the chemist ry of the soils, water and stream sediments in relation to the incidence of geographically distributed diseases in the tropics has not only opened up new frontiers in multidisciplinary research, but has offered new challenges to the medical profession to seriously focus attention on the emerging fie ld of medical geochemistry with the collaboration of geochemists and epidem iologists. (C) 1999 Elsevier Science B.V. All rights reserved.