In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high levels of mercury were found in human hair from Jacareacanga and Brasilia Legal located near the main goldmining area as well as from Tres Bocas facing the lake in Amapa state, whereas the levels were much lower in Ponta de Pedras, a long way downstream. The values of male samples were about twice as high as females even in the same family. The predominant form of mercury in hair samples was methylmercury (average 90%), while high hair mercury observed in goldminers and workers in goldshops was mostly in the inorganic form. Longitudinal analyses of long hairs from people in fishing villages showed fairly constant and continuous exposure to methylmercury at least over the last few years with seasonal variations. Fish contained relatively high levels of mercury (up to 3.82 ppm) mostly in the form of methylmercury and most of the fish from upstream and some from downstream exceeded the allowable level of 0.5 ppm in Brazil.
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