The Effect of Natural Geochemical Background on Neurological and Mental Health

Abstract

The natural geochemical (geogenic) background is exerted through the local drinking water, food grown on the local soils and the atmospheric aerosols inhaled. The misbalance of certain elements, in the most acute case, may lead to the development of so-called ‘endemic’ symptoms and diseases. Compared to anthropogenic contamination, the effect of the geogenic background may have an implicit character due to its not extreme, chronic and pervading action. Moreover, the brain must be viewed somewhat separately to the other body organs from the toxicological point of view because of the specific protective blood–brain (hematoencephalic) barrier. Nowhere is homeostasis and the control of the constant of internal milieu more pronounced than in the brain. However, certain metal compounds, presumably of lipophilic character, can overcome the natural defence and are especially dangerous to the nervous system. The neurologically detrimental geogenic excess was determined and assumed for Al, As, Ba, Cd, Fe, Hg, Mn, Pb, Se, Tl and Zn. Moreover, deficiency of certain elements can cause disturbances to the brain functioning. These elements are Cu, Fe, I, Li and Se. There are also elements for which small-dose neurological effects were described and the natural geochemical anomalies have been reported. These are B, Br, Rb, Sn and, possibly, others. Nevertheless, the information on their chronic environmental neurological activity is still a matter of future studies. In this review, we focus on the geogenic background as a cause of neurological and mental effects on human health.