METHYLMERCURY IN HAIR SAMPLES FROM DIFFERENT RIVERINE GROUPS, AMAZON,BRAZIL

The present study was aimed to evaluate comparatively the levels of me thylmercury (MeHg) in human hair, collected from different groups of A mazonian populations exposed to contamined fish. The study was underta ken in fishing villages and gold mining areas, mainly in the Tapajos a nd Madeira river basins, two of the main tributaries of Amazon river. The study population included 125 hair samples, chosen from a collecti on of over one thousand samples collected in different periods. Hair a nalyses were conducted with a new efficient extraction technique and m easured with ECD-gas chromatographer. This analytical method presented good accuracy and precision when compared with standard hair samples from IAEA. A highly significant correlation was found at the interlabo ratory exercise between National Institute for Minamata Disease and ou r laboratory at Federal University of Rio de Janeiro. The results of t he present study showed, through hair analysis, a relationship between environmental contamination by mercury and methylmercury and dietary habits of the Amazon population. The highest levels of MeHg in :lair s amples were found in riverine population from upper Tapajos river and in riverine population from some tributaries of Madeira river, followe d by population of fishing villages from Madeira river. Majority of th e women of child-bearing age presented high MeHg concentration in hail samples (10 mg.kg(-1)). On the other hand, Yanomami Indians presented MeHg concentration below the limit tolerable of 6 mg.kg(-1).