GEOCHEMICAL MAPS AS A TOOL FOR THE IDENTIFICATION OF HEALTH RISK AREAS: CASE STUDIES IN THE STATE OF PARANA, BRAZIL

摘要

Geochemical maps show the distribution of elements and chemical compounds in natural materials such as water stream and sediment of hydrographic basins reflecting either the effects of natural or man-made sources. For this reason, they have been considered as basic tools in multipurpose environmental investigations, including geo-medicine and eco-toxicology. Compiling geochemical data produced by mineral exploration projects and drawing integrated geochemical maps could be the first approach to indicate health risk areas. However, the right application of geochemical maps, while investigating the relationship between environmental geochemistry and endemic diseases could only be achieved if the analytical data were produced and interpreted ascording to the (bio-) availability of chemical elements and compounds. Weak extractions in stream sediment samples and chemical analysis of filtered water samples are adequate techniques, since they are able to identify the portion that could be absorbed by the food chain. The association of fluorine and the occurrence of dental fluorosis, as well as chlorine and bromine as geochemical indicators of liver cancer risk areas are relationships between geochemical abundance and geographically well delimited endemic diseases, found in the State of Parana, Brazil. Further investigations are required to establish the real meaning, from the public health point of view, of some risk areas indicated by barium, potassium, calcium, aluminium in stream water and mercury in stream sediments.