Mercury Pollution in the Amazon, Brazil.

Abstract

Mercury pollution due to gold mining activities in Amazonian region has become a matter of worldwide concern in recent years. To assess the extent of mercury pollution and its health effects, the four years'collaborative study between our Institute and Federal University of Rio de Janeiro has been started in 1992 as a part of Global Environmental Research Project in the Environment Agency of Japan. This paper outlines the results of our preliminary study on mercury pollution mainly in Tapajos river basin, where can be considered the oldest and most productive gold mining area in Amazon. Human hair and blood as well as fish samples were collected from gold mining area and five fishing villages and analyzed for total mercury and methylmercury with new methods recently developed in our laboratory. The results to date showed that the inhabitants of fishing villages near gold mining area were more exposed to methylmercury than those far from gold mines. A few hair samples tested had methylmercury levels greater than 50 ppm, the minimum threshold value for methylmercury poisoning. Analysis of hair samples from gold miners and workers in gold shops showed that they were mainly contaminated with inorganic mercury. From these analytical results, together with mercury analysis in fish as well as human blood samples, the mercury pollution mechanisms in the study area are also discussed.