Speciation of mercury in head hair of some Brazilian Indian populational groups

In the present paper, biomonitoring of mercury contamination via head hair analysis was made in more than ten Indian tribes living in the Xingu Park, an Indian reservation located in the State of Mate Grosso, Central Brazil. Total mercury was determined by instrumental neutron activation analysis (I NAA), at the Radiochemistry Division of IPEN/CNEN-SP (Sao Paulo, Brazil) an d by cold vapour atomic absorption spectroscopy (CVAAS) at the Jozef Stefan Institute (Ljubljana, Slovenia). Methyl-mercury in the hair samples was determined by CVAAS, by the techniqu e described by May et al, which uses an anion exchange separation of extrac ted inorganic from organic mercury species, followed by destruction of orga nic species by UV irradiation. In all the Indian tribes analysed, the total hair mercury concentration was several orders of magnitude higher than the controls and in many cases hig her than 20 ppm. A part of the hair samples was analyzed for methyl-mercury, which comprised from about 70 to 100% of total mercury found. Hair samples are considered as good indicators of human exposure to methyl-mercury by fish consumption, which is in agreement with the dietary habits of the Indians.