Mercury contamination in farmed fish setup on former garimpo mining areas in the Northern Mato Grosso State, Amazonian region, Brazil.

The garimpo gold mining activity has released about 2.500 tons of mercury in the Brazilian Amazonian environment in the 1980-1995 period. The northern region of Mato Grosso State, an important gold mining and trading area during the Amazonian gold rush is now at a turning point regarding its economic future. Nowadays, the activities related to gold mining have only a low relevance on its economy. Thus, the local communities are looking for economic alternatives for the development of the region. Cooperative fish farming is one of such alternatives. However, some projects are directly implemented on areas degraded by the former garimpo activity and the mercury left behind still poses risks, especially by its potential accumulation in fish. The objective of the present study was to evaluate the levels of mercury contamination in two fish farming areas, Paranaíta and Alta Floresta, with and without records of past gold-washing activity, respectively. Data such as mercury concentration in fish of different trophic level, size, and weight as well as the water physical and chemical parameters were measured and considered. These preliminary data have shown no significant difference between these two fish farming areas, relatively to mercury levels in fish.

Exposure to mercury in pregnant women from Alta Floresta-Amazon basin, Brazil.

The region of Alta Floresta in the South of the Amazon basin, close to the Teles Pires River, was one of the main prospecting gold areas in the Amazon Basin until the beginning of the 1990s. The economic growth was accompanied by a considerable increase in the population, due to a massive influx of migrants from the southern region of the country. Women had an important role during that process. They worked in the "garimpos" in different activities, such as cooking or managing, where they were exposed mainly to indoor elemental mercury during burning of amalgam. They also worked in gold dealers' shops, where a great amount of amalgam was burned daily. Fish consumption was an important dietary protein source and also a possible exposure pathway, due to the high Hg concentrations reported in carnivorous species. The present study evaluates the mercury uptake and consequent risks involved for pregnant women from Alta Floresta at the end of the gold rush period. The survey included women at different pregnancy stages and it was supported by clinical exams, followed by an interview with a specific questionnaire. Mercury hair concentrations ranging from 0.05 to 8.2 microg/g were found among women, with 13% of them showing concentrations above 2 microg/g. According to the results, mean differences in hair mercury concentration were statistically higher for pregnant women if they had worked in gold mining areas, they had consumed alcohol, their husbands had worked as "garimpeiros," they ate fish, and/or they had malaria before and/or during pregnancy