Exposure of aboriginal people to methylmercury due to gold mining in the Amazon, Brazil

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅｔｈｅｅａｒｌｙ 1980’ｓ,ｒａｐｉｄｉｎｃｒｅａｓｅｓｉｎｇｏｌｄｍｉｎｉｎｇａｃｔｉｖｉｔｉｅｓｕｓｉｎｇｍｅｒｃｕｒｙａｍａｌｇａｍａｔｉｏｎｔｅｃｈｎｉｑｕｅｉｎｍａｎｙｄｅｖｅｌｏｐｉｎｇｃｏｕｎｔｒｉｅｓｈａｓｂｅｅｎｏｎｅｏｆｔｈｅｍａｉｎｓｏｕｒｃｅｓｏｆｍｅｒｃｕｒｙｐｏｌｌｕｔｉｏｎ ,ｐａｒｔｉｃｕｌａｒｌｙｉｎｔｈｅＡｍａｚｏｎａｎｄｏｔｈｅｒｔｒｏｐｉｃａｌｒｅｇｉｏｎｓ(Ｍａｌｍ ,1990 ;Ｒａｍｅｌ,1996;Ｉｋｉｎｇｕｒａ,1996;Ｌａｃｅｒｄａ,…

Exposure of aboriginal people to methylmercury due to gold mining in the Amazon, Brazil

This paper outlines the results of our study aiming at evaluating the actual extent of human exposure to Hg mainly in Tapajos River Basin in central Amazonia, which is considered to be the oldest and most productive gold mining area in the Amazon. Human hair and blood as well as fish samples were collected from gold mining areas and various fishing villages located at different distances from main gold mining areas, and analyzed for total mercury(T Hg) and methylmercury (MeHg) with new methods recently being developed in our laboratory. The results to date showed the inhabitants of fishing villages particularly in the upstream Tapajos areas were constantly exposed to MeHg at abnormally high levels, with little confounding exposure to inorganic Hg. A highly significant correlation between Hg in hair and blood was observed in fishing villages, and the ratios of hair Hg to blood Hg were very close to 250g, generally established for MeHg. While, the levels of MeHg in hair and blood of gold miners and goldshop workers were low, indicating that they were mainly exposed to Hg in inorganic form. From these data, together with the levels of MeHg in fish, Hg contamination mechanisms are discussed.